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  Subjects -> CHEMISTRY (Total: 845 journals)
    - ANALYTICAL CHEMISTRY (51 journals)
    - CHEMISTRY (595 journals)
    - CRYSTALLOGRAPHY (21 journals)
    - ELECTROCHEMISTRY (25 journals)
    - INORGANIC CHEMISTRY (41 journals)
    - ORGANIC CHEMISTRY (45 journals)
    - PHYSICAL CHEMISTRY (67 journals)

CHEMISTRY (595 journals)                  1 2 3 | Last

Showing 1 - 200 of 735 Journals sorted alphabetically
2D Materials     Hybrid Journal   (Followers: 8)
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 26)
ACS Catalysis     Full-text available via subscription   (Followers: 34)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 18)
ACS Combinatorial Science     Full-text available via subscription   (Followers: 23)
ACS Macro Letters     Full-text available via subscription   (Followers: 24)
ACS Medicinal Chemistry Letters     Full-text available via subscription   (Followers: 39)
ACS Nano     Full-text available via subscription   (Followers: 244)
ACS Photonics     Full-text available via subscription   (Followers: 11)
ACS Synthetic Biology     Full-text available via subscription   (Followers: 21)
Acta Chemica Iasi     Open Access   (Followers: 2)
Acta Chimica Sinica     Full-text available via subscription   (Followers: 1)
Acta Chimica Slovaca     Open Access   (Followers: 1)
Acta Chromatographica     Full-text available via subscription   (Followers: 9)
Acta Facultatis Medicae Naissensis     Open Access  
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 5)
Acta Scientifica Naturalis     Open Access   (Followers: 2)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 5)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 8)
Adsorption Science & Technology     Full-text available via subscription   (Followers: 5)
Advanced Functional Materials     Hybrid Journal   (Followers: 51)
Advanced Science Focus     Free   (Followers: 3)
Advances in Chemical Engineering and Science     Open Access   (Followers: 56)
Advances in Chemical Science     Open Access   (Followers: 13)
Advances in Chemistry     Open Access   (Followers: 15)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 18)
Advances in Drug Research     Full-text available via subscription   (Followers: 22)
Advances in Enzyme Research     Open Access   (Followers: 9)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 8)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 16)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 9)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 21)
Advances in Nanoparticles     Open Access   (Followers: 15)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 15)
Advances in Polymer Science     Hybrid Journal   (Followers: 41)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 17)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 20)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 5)
Advances in Science and Technology     Full-text available via subscription   (Followers: 12)
African Journal of Bacteriology Research     Open Access  
African Journal of Chemical Education     Open Access   (Followers: 2)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 7)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 2)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 3)
AMB Express     Open Access   (Followers: 1)
Ambix     Hybrid Journal   (Followers: 3)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 67)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 14)
American Journal of Chemistry     Open Access   (Followers: 27)
American Journal of Plant Physiology     Open Access   (Followers: 14)
American Mineralogist     Hybrid Journal   (Followers: 14)
Analyst     Full-text available via subscription   (Followers: 40)
Angewandte Chemie     Hybrid Journal   (Followers: 203)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 219)
Annales UMCS, Chemia     Open Access   (Followers: 1)
Annals of Clinical Chemistry and Laboratory Medicine     Open Access   (Followers: 4)
Annual Reports in Computational Chemistry     Full-text available via subscription   (Followers: 3)
Annual Reports Section A (Inorganic Chemistry)     Full-text available via subscription   (Followers: 4)
Annual Reports Section B (Organic Chemistry)     Full-text available via subscription   (Followers: 8)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 12)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 15)
Anti-Infective Agents     Hybrid Journal   (Followers: 3)
Antiviral Chemistry and Chemotherapy     Hybrid Journal  
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 7)
Applied Spectroscopy     Full-text available via subscription   (Followers: 23)
Applied Surface Science     Hybrid Journal   (Followers: 28)
Arabian Journal of Chemistry     Open Access   (Followers: 6)
ARKIVOC     Open Access   (Followers: 2)
Asian Journal of Biochemistry     Open Access   (Followers: 1)
Atomization and Sprays     Full-text available via subscription   (Followers: 4)
Australian Journal of Chemistry     Hybrid Journal   (Followers: 7)
Autophagy     Hybrid Journal   (Followers: 2)
Avances en Quimica     Open Access   (Followers: 1)
Biochemical Pharmacology     Hybrid Journal   (Followers: 10)
Biochemistry     Full-text available via subscription   (Followers: 310)
Biochemistry Insights     Open Access   (Followers: 6)
Biochemistry Research International     Open Access   (Followers: 6)
BioChip Journal     Hybrid Journal  
Bioinorganic Chemistry and Applications     Open Access   (Followers: 9)
Bioinspired Materials     Open Access   (Followers: 5)
Biointerface Research in Applied Chemistry     Open Access   (Followers: 2)
Biointerphases     Open Access   (Followers: 1)
Biology, Medicine, & Natural Product Chemistry     Open Access   (Followers: 1)
Biomacromolecules     Full-text available via subscription   (Followers: 19)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 10)
Biomedical Chromatography     Hybrid Journal   (Followers: 6)
Biomolecular NMR Assignments     Hybrid Journal   (Followers: 3)
BioNanoScience     Partially Free   (Followers: 5)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 118)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 91)
Bioorganic Chemistry     Hybrid Journal   (Followers: 10)
Biopolymers     Hybrid Journal   (Followers: 18)
Biosensors     Open Access   (Followers: 2)
Biotechnic and Histochemistry     Hybrid Journal   (Followers: 1)
Bitácora Digital     Open Access  
Boletin de la Sociedad Chilena de Quimica     Open Access  
Bulletin of the Chemical Society of Ethiopia     Open Access   (Followers: 2)
Bulletin of the Chemical Society of Japan     Full-text available via subscription   (Followers: 24)
Bulletin of the Korean Chemical Society     Hybrid Journal   (Followers: 1)
C - Journal of Carbon Research     Open Access   (Followers: 3)
Cakra Kimia (Indonesian E-Journal of Applied Chemistry)     Open Access  
Canadian Association of Radiologists Journal     Full-text available via subscription   (Followers: 3)
Canadian Journal of Chemistry     Hybrid Journal   (Followers: 10)
Canadian Mineralogist     Full-text available via subscription   (Followers: 4)
Carbohydrate Research     Hybrid Journal   (Followers: 26)
Carbon     Hybrid Journal   (Followers: 66)
Catalysis for Sustainable Energy     Open Access   (Followers: 7)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 8)
Catalysis Science and Technology     Free   (Followers: 7)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysts     Open Access   (Followers: 8)
Cellulose     Hybrid Journal   (Followers: 7)
Cereal Chemistry     Full-text available via subscription   (Followers: 4)
ChemBioEng Reviews     Full-text available via subscription   (Followers: 1)
ChemCatChem     Hybrid Journal   (Followers: 8)
Chemical and Engineering News     Free   (Followers: 14)
Chemical Bulletin of Kazakh National University     Open Access  
Chemical Communications     Full-text available via subscription   (Followers: 72)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 24)
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 3)
Chemical Research in Toxicology     Full-text available via subscription   (Followers: 20)
Chemical Reviews     Full-text available via subscription   (Followers: 182)
Chemical Science     Open Access   (Followers: 22)
Chemical Technology     Open Access   (Followers: 16)
Chemical Vapor Deposition     Hybrid Journal   (Followers: 5)
Chemical Week     Full-text available via subscription   (Followers: 8)
Chemie in Unserer Zeit     Hybrid Journal   (Followers: 58)
Chemie-Ingenieur-Technik (Cit)     Hybrid Journal   (Followers: 26)
ChemInform     Hybrid Journal   (Followers: 8)
Chemistry & Biodiversity     Hybrid Journal   (Followers: 6)
Chemistry & Biology     Full-text available via subscription   (Followers: 30)
Chemistry & Industry     Hybrid Journal   (Followers: 5)
Chemistry - A European Journal     Hybrid Journal   (Followers: 146)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 15)
Chemistry and Materials Research     Open Access   (Followers: 20)
Chemistry Central Journal     Open Access   (Followers: 4)
Chemistry Education Research and Practice     Free   (Followers: 5)
Chemistry in Education     Open Access   (Followers: 9)
Chemistry International     Hybrid Journal   (Followers: 2)
Chemistry Letters     Full-text available via subscription   (Followers: 44)
Chemistry of Materials     Full-text available via subscription   (Followers: 258)
Chemistry of Natural Compounds     Hybrid Journal   (Followers: 9)
Chemistry World     Full-text available via subscription   (Followers: 22)
Chemistry-Didactics-Ecology-Metrology     Open Access   (Followers: 1)
ChemistryOpen     Open Access   (Followers: 2)
Chemkon - Chemie Konkret, Forum Fuer Unterricht Und Didaktik     Hybrid Journal  
Chemoecology     Hybrid Journal   (Followers: 4)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 15)
Chemosensors     Open Access  
ChemPhysChem     Hybrid Journal   (Followers: 9)
ChemPlusChem     Hybrid Journal   (Followers: 2)
ChemTexts     Hybrid Journal  
CHIMIA International Journal for Chemistry     Full-text available via subscription   (Followers: 2)
Chinese Journal of Chemistry     Hybrid Journal   (Followers: 6)
Chinese Journal of Polymer Science     Hybrid Journal   (Followers: 10)
Chromatographia     Hybrid Journal   (Followers: 24)
Clay Minerals     Full-text available via subscription   (Followers: 10)
Cogent Chemistry     Open Access  
Colloid and Interface Science Communications     Open Access  
Colloid and Polymer Science     Hybrid Journal   (Followers: 10)
Colloids and Surfaces B: Biointerfaces     Hybrid Journal   (Followers: 7)
Combinatorial Chemistry & High Throughput Screening     Hybrid Journal   (Followers: 4)
Combustion Science and Technology     Hybrid Journal   (Followers: 18)
Comments on Inorganic Chemistry: A Journal of Critical Discussion of the Current Literature     Hybrid Journal   (Followers: 2)
Composite Interfaces     Hybrid Journal   (Followers: 6)
Comprehensive Chemical Kinetics     Full-text available via subscription   (Followers: 2)
Comptes Rendus Chimie     Full-text available via subscription  
Comptes Rendus Physique     Full-text available via subscription   (Followers: 1)
Computational and Theoretical Chemistry     Hybrid Journal   (Followers: 9)
Computational Biology and Chemistry     Hybrid Journal   (Followers: 12)
Computational Chemistry     Open Access   (Followers: 2)
Computers & Chemical Engineering     Hybrid Journal   (Followers: 9)
Coordination Chemistry Reviews     Full-text available via subscription   (Followers: 3)
Copernican Letters     Open Access   (Followers: 1)
Critical Reviews in Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 5)
Crystal Structure Theory and Applications     Open Access   (Followers: 4)
CrystEngComm     Full-text available via subscription   (Followers: 13)
Current Catalysis     Hybrid Journal   (Followers: 2)
Current Metabolomics     Hybrid Journal   (Followers: 5)
Current Opinion in Colloid & Interface Science     Hybrid Journal   (Followers: 9)
Current Opinion in Molecular Therapeutics     Full-text available via subscription   (Followers: 17)
Current Research in Chemistry     Open Access   (Followers: 8)
Current Science     Open Access   (Followers: 61)
Dalton Transactions     Full-text available via subscription   (Followers: 23)
Detection     Open Access   (Followers: 2)
Developments in Geochemistry     Full-text available via subscription   (Followers: 2)
Diamond and Related Materials     Hybrid Journal   (Followers: 12)
Dislocations in Solids     Full-text available via subscription  
Doklady Chemistry     Hybrid Journal  
Drying Technology: An International Journal     Hybrid Journal   (Followers: 4)
Eclética Química     Open Access   (Followers: 1)
Ecological Chemistry and Engineering S     Open Access   (Followers: 3)
Ecotoxicology and Environmental Contamination     Open Access  
Educación Química     Open Access   (Followers: 1)
Education for Chemical Engineers     Hybrid Journal   (Followers: 5)
EJNMMI Radiopharmacy and Chemistry     Open Access  
Elements     Full-text available via subscription   (Followers: 3)
Environmental Chemistry     Hybrid Journal   (Followers: 7)
Environmental Chemistry Letters     Hybrid Journal   (Followers: 4)
Environmental Science & Technology Letters     Full-text available via subscription   (Followers: 5)

        1 2 3 | Last

Journal Cover Angewandte Chemie International Edition
  [SJR: 6.229]   [H-I: 397]   [219 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1433-7851 - ISSN (Online) 1521-3773
   Published by John Wiley and Sons Homepage  [1579 journals]
  • Localized Supramolecular Peptide Self-Assembly Directed by Enzyme-Induced
           Proton Gradients
    • Authors: Jennifer Rodon Fores; Miguel Leonardo Martinez Mendez, Xiyu Mao, Déborah Wagner, Marc Schmutz, Morgane Rabineau, Philippe Lavalle, Pierre Schaaf, Fouzia Boulmedais, Loïc Jierry
      Abstract: Electrodes are ideal substrates for surface localized self-assembly processes. Spatiotemporal control over such processes is generally directed through the release of ions generated by redox reactions occurring specifically at the electrode. The so-used gradients of ions proved their effectiveness over the last decade but are in essence limited to material-based electrodes, considerably reducing the scope of applications. Herein is described a strategy to enzymatically generate proton gradients from non-conductive surfaces. In the presence of oxygen, immobilization of glucose oxidase (GOx) on a multilayer film provides a flow of protons through enzymatic oxidation of glucose by GOx. The confined acidic environment located at the solid–liquid interface allows the self-assembly of Fmoc-AA-OH (Fmoc=fluorenylmethyloxycarbonyl and A=alanine) dipeptides into β-sheet nanofibers exclusively from and near the surface. In the absence of oxygen, a multilayer nanoreactor containing GOx and horseradish peroxidase (HRP) similarly induces Fmoc-AA-OH self-assembly.The power of enzymes: A multilayer film including a bi-enzyme reaction system establishes a proton gradient going from the bottom to the top of the film, leading to the localized self-assembly of peptides that underpin a supramolecular hydrogel. This approach constitutes an alternative to an electrode surface to induce pH-sensitive self-assembly processes.
      PubDate: 2017-11-16T04:52:48.986701-05:
      DOI: 10.1002/anie.201709029
       
  • Atropoenantioselective Redox-Neutral Amination of Biaryls Via Borrowing
           Hydrogen and Dynamic Kinetic Resolution
    • Authors: Jian Wang; Jianwei Zhang
      Abstract: We report here a novel atropoenantioselective redox-neutral amination of biaryls triggered by a cascade of borrowing hydrogen and DKR strategy under the co-catalysis of chiral Ir-complex and achiral Brønsted acid. This protocol features broad substrate scope and good functional group tolerance, and allows the rapid assembly of axially chiral biaryls in good to high yields and with high to excellent enantioselectivities.
      PubDate: 2017-11-16T04:26:22.603193-05:
      DOI: 10.1002/anie.201711126
       
  • Reaction of thiocarbonyl fluoride formed from difluorocarbene with amines
    • Authors: Ji-Chang Xiao; Jiao Yu, Jinhong Lin
      Abstract: The reaction of thiocarbonyl fluoride generated from difluorocarbene with various amines under mild conditions is described. Secondary amines, primary amines, and o-phenylenediamines are converted to thiocarbamoyl fluorides, isothiocyanates, and difluoromethylthiolated heterocycles, respectively. Thiocarbamoyl fluorides were further transformed into trifluoromethylated amines using a one-pot process. As thiocarbonyl fluoride is generated in situ and is rapidly fully converted in one pot under mild conditions, no special safety precautions are needed.
      PubDate: 2017-11-16T03:55:53.78185-05:0
      DOI: 10.1002/anie.201710186
       
  • Restoration of ribozyme tertiary contact and function using a molecular
           glue for RNA
    • Authors: Chikara Dohno; Maki Kimura, Kazuhiko Nakatani
      Abstract: Some RNA classes require folding into the proper higher-order structures to exert their functions. Hammerhead ribozyme (HHR) requires a folding conformation stabilized by tertiary interaction for full activity. Here, we developed a rationally engineered HHR that was inactive, but could be activated by a synthetic RNA-binding ligand, naphthyridine carbamate tetramer with Z-stilbene linker (Z-NCTS). Binding of Z-NCTS could induce the formation of an active folding structure and thereby restore ribozyme activity, where Z-NCTS acts as a molecular glue to bring two isolated RNA loops into contact with each other. Next, we designed a Z-NCTS-responsive genetic switch using the HHR sequence inserted into the 3 untranslated region as a cis-acting element. We demonstrated that the rationally designed ribozyme switch enabled regulation of gene expression by Z-NCTS and was functional in mammalian cells.
      PubDate: 2017-11-16T00:26:31.537635-05:
      DOI: 10.1002/anie.201709041
       
  • Bioinspired Chemical Communication between Synthetic Nanomotors
    • Authors: Chuanrui Chen; Xiaocong Chang, Hazhir Teymourian, Doris E Ramírez Herrera, Berta Esteban Fernández de Ávila, Xiaolong Lu, Jinxing Li, Sha He, Chengcheng Fang, Yuyan Liang, Fangzhi Mou, Jianguo Guan, Joseph Wang
      Abstract: While chemical communication plays a key role in diverse natural processes, the intelligent chemical communication between synthetic nanomotors remains unexplored. Here we demonstrate the design and operation of bio-inspired synthetic nanomotors capable of chemical communication among themselves that influences their propulsion behavior. The chemical message is sent from a moving 'activator' motor to a nearby 'activated' (receiver) one, and involves release of silver ions from a Janus PS/Ni/Au/Ag 'activator' motor to the 'activated' Janus SiO2/Pt nanomotor. The transmitted silver signal is translated rapidly into a dramatic speed change associated with the enhanced catalytic activity of 'activated' motors. The concept of establishing chemical communication between different synthetic nanomotors paves the way to intelligent nanoscale robotic systems that are capable of cooperating with each other.
      PubDate: 2017-11-15T21:55:57.787346-05:
      DOI: 10.1002/anie.201710376
       
  • Distal Weak Coordination of Acetamides in Ruthenium(II)-Catalyzed C-H
           Activation Processes
    • Authors: Qingqing Bu; Torben Rogge, Vladislav Kotek, Lutz Ackermann
      Abstract: C-H activations with challenging arylacetamides were accomplished by versatile ruthenium(II) biscarboxylate catalysis. The distal C-H functionalization was characterized by ample scope, including twofold oxidative C-H functionalizations and alkyne hydroarylations, through facile base-assisted internal electrophilic-type substitution (BIES) C-H ruthenation by weak O coordination.
      PubDate: 2017-11-15T15:25:41.142387-05:
      DOI: 10.1002/anie.201711108
       
  • Fluorine in a C-F Bond as the Key to Cage Formation
    • Authors: Maxwell Gargiulo Holl; Cody Ross Pitts, Thomas Lectka
      Abstract: Cage molecules have long been employed to trap reactive or fleeting species, as their rigid nature allows them to enforce situations that otherwise would not persist. In this minireview, we discuss our use of rigid cage structures to investigate the close noncovalent interactions of fluorine with other functional groups and determine how mutual proximity affects both physical properties and reactivity. Unusual covalent interactions of fluorine are also explored: the cage can close to form the first solution-phase C-F-C fluoronium ion.
      PubDate: 2017-11-15T15:25:31.345344-05:
      DOI: 10.1002/anie.201710423
       
  • Highly Selective Manganese(I)/Lewis Acid Cocatalyzed Direct C−H
           Propargylation using Bromoallenes
    • Authors: Can Zhu; Luca Jonas Schwarz, Sara Cembellin, Steffen Greßies, Frank Glorius
      Abstract: A manganese(I)/Lewis acid cocatalyzed direct C−H propargylation with high selectivity has been developed. BPh3 was discovered to not only promote the reactivity, but also enhance the selectivity to afford the propargylation products rather than allene derivatives. Secondary, tertiary or even quaternary carbon centers at the propargylic position could be directly constructed. Both internal and terminal alkynes are easily accessible. The chirality was successfully transferred from an axially chiral allene to the central chirality. The reactivity of the manganese catalyst in this chemistry was found to be unique comparing other transition metal catalysts.
      PubDate: 2017-11-15T15:25:27.043793-05:
      DOI: 10.1002/anie.201710835
       
  • PbS/CdS core/shell QDs suppress charge transfer and enhance triplet
           transfer
    • Authors: Zhiyuan Huang; Zihao Xu, Melika Mahboub, Xin Li, Jordan Taylor, Hill Harman, Tianquan Lian, MingLee Tang
      Abstract: Here, we observe that a sub-monolayer CdS shell on PbS quantum dots (QDs) enhances triplet energy transfer (TET) by suppressing competitive charge transfer from QDs to molecules. The CdS shell increases the linear photon upconversion quantum yield (QY) from 3.5% for PbS QDs to 5.0% for PbS/CdS QDs when functionalized with a tetracene acceptor, 5-CT. While transient absorption spectroscopy reveals that both PbS and PbS/CdS QDs show the formation of the 5-CT triplet (with rate constants of 5.91 ±0.60 ns-1 and 1.03 ±0.09 ns-1 respectively), ultrafast hole transfer occurs only from PbS QDs to 5-CT. Although the CdS shell decreases the TET rate, it enhances TET efficiency from 60.3± 6.1% to 71.8 ±6.2% by suppressing the hole transfer process. In addition, the CdS shell prolongs the lifetime of the 5-CT triplet and thus enhances TET from 5-CT to the rubrene emitter, further bolstering the upconverison QY.
      PubDate: 2017-11-15T12:56:16.110287-05:
      DOI: 10.1002/anie.201710224
       
  • Atomically Dispersed Copper–Platinum Dual Sites Alloyed with Palladium
           Nanorings Catalyze the Hydrogen Evolution Reaction
    • Authors: Tingting Chao; Xuan Luo, Wenxing Chen, Bin Jiang, Jingjie Ge, Yue Lin, Geng Wu, Xiaoqian Wang, Yanmin Hu, Zhongbin Zhuang, Yuen Wu, Xun Hong, Yadong Li
      Abstract: Designing highly active catalysts at an atomic scale is required to drive the hydrogen evolution reaction (HER). Copper–platinum (Cu-Pt) dual sites were alloyed with palladium nanorings (Pd NRs) containing 1.5 atom % Pt, using atomically dispersed Cu on ultrathin Pd NRs as seeds. The ultrafine structure of atomically dispersed Cu-Pt dual sites was confirmed with X-ray absorption fine structure (XAFS) measurements. The Pd/Cu-Pt NRs exhibit excellent HER properties in acidic solution with an overpotential of only 22.8 mV at a current density of 10 mA cm−2 and a high mass current density of 3002 A g−1(Pd+Pt) at a −0.05 V potential.Ring in the new year: Atomically dispersed copper–platinum (Cu-Pt) dual sites alloyed with palladium (Pd) nanorings exhibit excellent performance in the hydrogen evolution reaction. Electrocatalytic activity surpasses that of commercial platinum/carbon (Pt/C) catalysts.
      PubDate: 2017-11-15T12:31:44.406343-05:
      DOI: 10.1002/anie.201709803
       
  • Activation and Deactivation of Gold/Ceria–Zirconia in the
           Low-Temperature Water–Gas Shift Reaction
    • Authors: James H. Carter; Xi Liu, Qian He, Sultan Althahban, Ewa Nowicka, Simon J. Freakley, Liwei Niu, David J. Morgan, Yongwang Li, J. W. (Hans) Niemantsverdriet, Stanislaw Golunski, Christopher J. Kiely, Graham J. Hutchings
      Abstract: Gold (Au) on ceria–zirconia is one of the most active catalysts for the low-temperature water–gas shift reaction (LTS), a key stage of upgrading H2 reformate streams for fuel cells. However, this catalyst rapidly deactivates on-stream and the deactivation mechanism remains unclear. Using stop–start scanning transmission electron microscopy to follow the exact same area of the sample at different stages of the LTS reaction, as well as complementary X-ray photoelectron spectroscopy, we observed the activation and deactivation of the catalyst at various stages. During the heating of the catalyst to reaction temperature, we observed the formation of small Au nanoparticles (NPs; 1–2 nm) from subnanometer Au species. These NPs were then seen to agglomerate further over 48 h on-stream, and most rapidly in the first 5 h when the highest rate of deactivation was observed. These findings suggest that the primary deactivation process consists of the loss of active sites through the agglomeration and possible dewetting of Au NPs.After the Gold Rush: Stop–start scanning transmission electron microscopy was used to track gold (Au) species formed during the low-temperature water–gas shift reaction over Au/CeZrO4. Au nanoparticles formed during the heating of the catalyst to reaction temperature agglomerate under reaction conditions. X-ray photoelectron spectroscopy reveals that catalyst deactivation is an outcome of particle agglomeration.
      PubDate: 2017-11-15T12:31:36.172704-05:
      DOI: 10.1002/anie.201709708
       
  • Access to Chiral Hydropyrimidines through Palladium-Catalyzed Asymmetric
           Allylic C−H Amination
    • Authors: Pu-Sheng Wang; Meng-Lan Shen, Tian-Ci Wang, Hua-Chen Lin, Liu-Zhu Gong
      Abstract: A palladium-catalyzed asymmetric intramolecular allylic C−H amination controlled by a chiral phosphoramidite ligand was established for the preparation of various substituted chiral hydropyrimidinones, the precursors of hydropyrimidines, in high yields with high enantioselectivities. In particular, dienyl sodium N-sulfonyl amides bearing an arylethene-1-sulfonyl group underwent a sequential allylic C−H amination and intramolecular Diels–Alder (IMDA) reaction to produce chiral fused tricyclic tetrahydropyrimidinone frameworks in high yields and with high levels of stereoselectivity. Significantly, this method was used as the key step in an asymmetric synthesis of letermovir.Getting to the core of it: An asymmetric palladium-catalyzed intramolecular allylic C−H amination controlled by a chiral phosphoramidite ligand was used to provide efficient access various substituted chiral hydropyrimidines. This methodology was successfully applied to the asymmetric synthesis of letermovir (see scheme; IMDA=intramolecular Diels–Alder reaction).
      PubDate: 2017-11-15T12:31:26.820412-05:
      DOI: 10.1002/anie.201709681
       
  • Creation of “Rose Petal” and “Lotus Leaf” Effects on Alumina by
           Surface Functionalization and Metal-Ion Coordination
    • Authors: Rahul Dev Mukhopadhyay; Balaraman Vedhanarayanan, Ayyappanpillai Ajayaghosh
      Abstract: Functional differences between superhydrophobic surfaces, such as lotus leaf and rose petals, are due to the subtle architectural features created by nature. Mimicry of these surfaces with synthetic molecules continues to be fascinating as well as challenging. Herein, we demonstrate how inherently hydrophilic alumina surface can be modified to give two distinct superhydrophobic behaviors. Functionalization of alumina with an organic ligand resulted in a rose-petal-like surface (water pinning) with a contact angle of 145° and a high contact angle hysteresis (±69°). Subsequent interaction of the ligand with Zn2+ resulted in a lotus-leaf-like surface with water rolling behavior owing to high contact angle (165°) and low-contact-angle-hysteresis (±2°). In both cases, coating of an aromatic bis-aldehyde with alkoxy chain substituents was necessary to emulate the nanowaxy cuticular feature of natural superhydrophobic materials.A new leaf: Surface-functionalization and coordination-polymer chemistry are utilized to create metal–organic framework (MOF)-based nanoarchitectures on an alumina surface, which modify the surface′s inherent superhydrophilicity to the distinctive superhydrophobic behaviors of rose petals and lotus leaves.
      PubDate: 2017-11-15T12:30:55.4635-05:00
      DOI: 10.1002/anie.201709463
       
  • Living Supramolecular Polymerization of a Perylene Bisimide Dye into
           Fluorescent J-Aggregates
    • Authors: Wolfgang Wagner; Marius Wehner, Vladimir Stepanenko, Soichiro Ogi, Frank Würthner
      Abstract: The self-assembly of a new perylene bisimide (PBI) organogelator with 1,7-dimethoxy substituents in the bay position affords non-fluorescent H-aggregates at high cooling rates and fluorescent J-aggregates at low cooling rates. Under properly adjusted conditions, the kinetically trapped “off-pathway” H-aggregates are transformed into the thermodynamically favored J-aggregates, a process that can be accelerated by the addition of J-aggregate seeds. Spectroscopic studies revealed a subtle interplay of π–π interactions and intra- and intermolecular hydrogen bonding for monomeric, H-, and J-aggregated PBIs. Multiple polymerization cycles initiated from the seed termini demonstrate the living character of this chain-growth supramolecular polymerization process.Living supramolecular polymerization: The first perylene bisimide (PBI) based multicycle living polymerization system is reported. The bay-substituted PBI organogelator forms off-pathway H-aggregates that are transformed into thermodynamically favored fluorescent J-aggregates by a living seeded polymerization.
      PubDate: 2017-11-15T12:01:43.962032-05:
      DOI: 10.1002/anie.201709307
       
  • Lead- and Iodide-Deficient (CH3NH3)PbI3 (d-MAPI): The Bridge between 2D
           and 3D Hybrid Perovskites
    • Authors: Antonin Leblanc; Nicolas Mercier, Magali Allain, Jens Dittmer, Vincent Fernandez, Thierry Pauporté
      Abstract: 3D and 2D hybrid perovskites, which have been known for more than 20 years, have emerged recently as promising materials for optoelectronic applications, particularly the 3D compound (CH3NH3)PbI3 (MAPI). The discovery of a new family of hybrid perovskites called d-MAPI is reported: the association of PbI2 with both methyl ammonium (MA+) and hydroxyethyl ammonium (HEA+) cations leads to a series of five compounds with general formulation (MA)1−2.48x(HEA)3.48x[Pb1−xI3−x]. These materials, which are lead- and iodide-deficient compared to MAPI while retaining 3D architecture, can be considered as a bridge between the 2D and 3D materials. Moreover, they can be prepared as crystallized thin films by spin-coating. These new 3D materials appear very promising for optoelectronic applications, not only because of their reduced lead content, but also in account of the large flexibility of their chemical composition through potential substitutions of MA+, HEA+, Pb2+ and I− ions.Back on the MAPI: A family of hybrid perovskites (d-MAPI) is presented. Association of PbI2 with methylammonium (MA+) and hydroxyethylammonium (HEA+) cations leads to five compounds with the general formula (MA)1−2.48x(HEA)3.48x[Pb1−xI3−x]. These materials, which can be prepared as thin films, are lead- and iodide-deficient compared to (CH3NH3)PbI3 (MAPI). Keeping a 3D architecture, they are a bridge between 2D hybrid perovskites and MAPI.
      PubDate: 2017-11-15T12:01:37.051225-05:
      DOI: 10.1002/anie.201710021
       
  • Multi-Step Crystallization of Barium Carbonate: Rapid Interconversion of
           Amorphous and Crystalline Precursors
    • Authors: Michael L. Whittaker; Paul J. M. Smeets, Hasti Asayesh-Ardakani, Reza Shahbazian-Yassar, Derk Joester
      Abstract: The direct observation of amorphous barium carbonate (ABC), which transforms into a previously unknown barium carbonate hydrate (herewith named gortatowskite) within a few hundred milliseconds of formation, is described. In situ X-ray scattering, cryo-, and low-dose electron microscopy were used to capture the transformation of nanoparticulate ABC into gortatowskite crystals, highly anisotropic sheets that are up to 1 μm in width, yet only about 10 nm in thickness. Recrystallization of gortatowskite to witherite starts within 30 seconds. We describe a bulk synthesis and report a first assessment of the composition, vibrational spectra, and structure of gortatowskite. Our findings indicate that transient amorphous and crystalline precursors can play a role in aqueous precipitation pathways that may often be overlooked owing to their extremely short lifetimes and small dimensions. However, such transient precursors may be integral to the formation of more stable phases.The precipitation of witherite (BaCO3) from aqueous solution involves not one, but two precursors: amorphous barium carbonate (ABC) and a crystalline barium carbonate monohydrate (gortatowskite) that crystallizes in a quasi-2D habit. Both intermediates are very short-lived and their characterization requires rapid, cryogenic, and/or low-dose in situ techniques.
      PubDate: 2017-11-15T12:01:29.01018-05:0
      DOI: 10.1002/anie.201709526
       
  • Intermolecular Pummerer Coupling with Carbon Nucleophiles in
           Non-Electrophilic Media
    • Authors: Kilian Colas; Raúl Martín-Montero, Abraham Mendoza
      Abstract: A new Pummerer-type C−C coupling protocol is introduced based on turbo-organomagnesium amides, which unlike traditional Pummerer reactions, does not require strong electrophilic activators, engages a broad range of C(sp3)-, C(sp2)-, and C(sp)-nucleophiles, and seamlessly integrates with C−H and C−X magnesiation. Given the central character of sulfur compounds in organic chemistry, this protocol allows access to unrelated carbonyls, olefins, organometallics, halides, and boronic esters through a single strategy.The Pummerer coupling allows C−C bond formation to be performed in a single operation but it is limited by the need of electrophilic activators. Reported herein is an efficient and orthogonal protocol for electrophile-free Pummerer C−C coupling, which addresses the scope and limitations of traditional approaches, by using DIPAMgCl⋅LiCl.
      PubDate: 2017-11-15T12:01:22.993115-05:
      DOI: 10.1002/anie.201709715
       
  • Double Catalytic Kinetic Resolution (DoCKR) of Acyclic anti-1,3-Diols: The
           Additive Horeau Amplification
    • Authors: Jérémy Merad; Prashant Borkar, Frédéric Caijo, Jean-Marc Pons, Jean-Luc Parrain, Olivier Chuzel, Cyril Bressy
      Abstract: The concept of a synergistic double catalytic kinetic resolution (DoCKR) as described in this article was successfully applied to racemic acyclic anti-1,3-diols, a common motif in natural products. This process takes advantage of an additive Horeau amplification involving two successive enantioselective organocatalytic acylation reactions, and leads to diesters and recovered diols with high enantiopurities. It was first developed with C2-symmetrical diols and then further extended to non-C2-symmetrical anti diols to prepare useful chiral building blocks. The protocol is highly practical as it only requires 1 mol % of a commercially available organocatalyst and leads to easily separable products. This procedure was applied to the shortest reported total synthesis of (+)-cryptocaryalactone, a natural product with anti-germinative activity.Give a second chance to your catalyst! The concept of a synergistic double catalytic kinetic resolution (DoCKR) was successfully applied to racemic acyclic anti-1,3-diols, a common motif in natural products. The organocatalyzed double acylation led to diesters and recovered diols having high enantiopurities. It was first developed with C2-symmetrical diols and then further extended to non-C2-symmetrical anti diols to prepare useful chiral building blocks.
      PubDate: 2017-11-15T12:01:08.382675-05:
      DOI: 10.1002/anie.201709844
       
  • Formation of Olefins by Eliminative Dimerization and Eliminative
           Cross-Coupling of Carbenoids: A Stereochemical Exercise
    • Authors: Paul R. Blakemore; Reinhard W. Hoffmann
      Abstract: Two carbenoids combine to generate an olefin by a mechanism involving formation of an ate complex, 1,2-metalate rearrangement, and β-elimination. As each stage of this eliminative coupling is stereospecific, the overall stereochemical outcome can be understood and, in principle fully controlled, providing that the absolute stereochemical configurations of the reacting carbenoid species are defined. In contrast to traditional alkene syntheses, the eliminative cross-coupling of carbenoids offers a connective approach to olefins capable of precisely targeting a given isomer regardless of the nature of the features distinguishing the isomers. The formation of olefins by the eliminative dimerization and eliminative cross-coupling of carbenoids is reviewed with a range of illustrative examples, including the reactions of α-lithiated haloalkanes, epoxides, and carbamates. An emphasis is placed on stereochemical analysis and methods to generate sp3-hybridized carbenoids in stereodefined form are surveyed.Mutual elimination of electrofugal (M) and nucleofugal (X) leaving groups from pairs of reacting carbenoids results in the generation of a C−C double bond. This eliminative coupling process is inherently regio- and stereospecific and offers a programmable synthesis of olefins. Homo- and cross-coupling variants are reviewed and prospects for further development are highlighted.
      PubDate: 2017-11-15T12:00:49.995407-05:
      DOI: 10.1002/anie.201707026
       
  • Atom-Specific Mutagenesis Reveals Structural and Catalytic Roles for an
           Active-Site Adenosine and Hydrated Mg2+ in Pistol Ribozymes
    • Authors: Sandro Neuner; Christoph Falschlunger, Elisabeth Fuchs, Maximilian Himmelstoss, Aiming Ren, Dinshaw J. Patel, Ronald Micura
      Abstract: The pistol RNA motif represents a new class of self-cleaving ribozymes of yet unknown biological function. Our recent crystal structure of a pre-catalytic state of this RNA shows guanosine G40 and adenosine A32 close to the G53–U54 cleavage site. While the N1 of G40 is within 3.4 Å of the modeled G53 2′-OH group that attacks the scissile phosphate, thus suggesting a direct role in general acid–base catalysis, the function of A32 is less clear. We present evidence from atom-specific mutagenesis that neither the N1 nor N3 base positions of A32 are involved in catalysis. By contrast, the ribose 2′-OH of A32 seems crucial for the proper positioning of G40 through a H-bond network that involves G42 as a bridging unit between A32 and G40. We also found that disruption of the inner-sphere coordination of the active-site Mg2+ cation to N7 of G33 makes the ribozyme drastically slower. A mechanistic proposal is suggested, with A32 playing a structural role and hydrated Mg2+ playing a catalytic role in cleavage.Smoking gun: Atom-specific mutagenesis revealed that the ribose moiety of a conserved adenosine (A32) and a hydrated Mg2+ ion in the active site of the pistol ribozyme contribute to the cleavage activity. A mechanistic proposal is suggested in which A32 plays a structural role and the hydrated Mg2+ plays a catalytic role in cleavage.
      PubDate: 2017-11-15T12:00:41.68711-05:0
      DOI: 10.1002/anie.201708679
       
  • The Metal–Support Interaction Concerning the Particle Size Effect of
           Pd/Al2O3 on Methane Combustion
    • Authors: Kazumasa Murata; Yuji Mahara, Junya Ohyama, Yuta Yamamoto, Shigeo Arai, Atsushi Satsuma
      Abstract: The particle size effect of Pd nanoparticles supported on alumina with various crystalline phases on methane combustion was investigated. Pd/θ, α-Al2O3 with weak metal-support interaction showed a volcano-shaped dependence of the catalytic activity on the size of Pd particles, and the catalytic activity of the strongly interacted Pd/γ-Al2O3 increased with the particle size. Based on a structural analysis of Pd nanoparticles using CO adsorption IR spectroscopy and spherical aberration-corrected scanning/transmission electron microscopy, the dependence of catalytic activity on Pd particle size and the alumina crystalline phase was due to the fraction of step sites on Pd particle surface. The difference in fraction of the step site is derived from the particle shape, which varies not only with Pd particle size but also with the strength of metal–support interaction. Therefore, this interaction perturbs the particle size effect of Pd/Al2O3 for methane combustion.Size and phase matters: Pd/θ-Al2O3 and Pd/α-Al2O3 exhibit a different size effect from Pd/γ-Al2O3. Based on a structural analysis using spectroscopy and microscopy, the dependence of catalytic activity on size and the alumina crystalline phase was due to the fraction of step sites on the Pd particle. This difference in fraction is derived from the particle shape, which varies with Pd particle size and strength of metal–support interaction.
      PubDate: 2017-11-15T12:00:32.115649-05:
      DOI: 10.1002/anie.201709124
       
  • Modulation of Quorum Sensing in a Gram Positive Pathogen by Linear
           Imprinted Copolymers with anti-Infective Properties
    • Authors: Anfal Motib; Antonio Guerreiro, Firas Al-Bayati, Elena Piletska, Irfan Manzoor, Sulman Shafeeq, Anagha Kadam, Oscar Kuipers, Luisa Hiller, Todd Cowen, Sergey Piletsky, Peter Andrew, Hasan Yesilkaya
      Abstract: Here we describe the development, characterization and biological testing of a new type of linear molecularly imprinted polymer (LMIP) designed to act as anti-infective by blocking the quorum sensing (QS) mechanism and so preventing virulence of the pathogen Streptococcus pneumoniae. The LMIP is prepared (polymerized) in presence of a template molecule, but unlike in traditional molecular imprinting approaches no cross-linker is used. This results in soluble low molecular weight polymer that can act as drug agent in vitro and in vivo. The LMIP was characterized by mass spectrometry to determine its monomer composition. Fragments identified were then aligned along the peptide template by computer modeling, predicting the possible monomer sequence of the LMIP. These findings provide proof of principle that LMIP can be used to block QS, setting the stage for studies on a novel drug-discovery platform and class of materials to target Gram positive pathogens.
      PubDate: 2017-11-15T10:39:17.465365-05:
      DOI: 10.1002/anie.201709313
       
  • Simple Access to the Heaviest Alkaline-Earth Metal Hydride: A Strongly
           Reducing Hydrocarbon-Soluble Barium Hydride Cluster
    • Authors: Sjoerd Harder; Brant Maitland, Michael Wiesinger, Christian Färber, Gerd Ballmann, Holger Elsen, Christian Fischer
      Abstract: Reaction of Ba[N(SiMe3)2]2 with PhSiH3 in toluene gave simple access to the unique Ba hydride cluster Ba7H7[N(SiMe3)2]7 that can be described as a square pyramide spanned by five Ba2+ ions with two flanking BaH[N(SiMe3)2] units. This heptanuclear cluster is well soluble in aromatic solvents and the hydride 1H NMR signals and coupling pattern suggests that the structure is stable in solution. At 95 °C, no coalescence of hydride signals is observed but the cluster slowly decomposes to undefined Ba hydride species. Complex Ba7H7[N(SiMe3)2]7 is a very strong reducing agent that already at room temperature reacts with Me3SiCH=CH2, norbornadiene and ethylene. The highly reactive alkylbarium intermediates cannot be observed and deprotonate the (Me3Si)2Nˉ ion, as confirmed by the crystal structure of Ba14H12[N(SiMe3)2]12[(Me3Si)(Me2SiCH2)N]4.
      PubDate: 2017-11-15T09:26:29.221764-05:
      DOI: 10.1002/anie.201709771
       
  • Frontispiece: Mechanism-Based Inhibitors of the Human Sirtuin 5 Deacylase:
           Structure–Activity Relationship, Biostructural, and Kinetic Insight
    • Authors: Nima Rajabi; Marina Auth, Kathrin R. Troelsen, Martin Pannek, Dhaval P. Bhatt, Martin Fontenas, Matthew D. Hirschey, Clemens Steegborn, Andreas S. Madsen, Christian A. Olsen
      Abstract: Medicinal Chemistry C. A. Olsen and co-workers describe the identification of inhibitors of sirtuin 5 hydrolase with high potencies through an extensive structure–activity relationship study in their Communication on page 14836 ff.
      PubDate: 2017-11-15T06:53:57.778097-05:
      DOI: 10.1002/anie.201784761
       
  • A Manganese Pre-Catalyst: Mild Reduction of Amides, Ketones, Aldehydes,
           and Esters
    • Authors: Colin M. Kelly; Robert McDonald, Orson L. Sydora, Mark Stradiotto, Laura Turculet
      Abstract: A new (N-phosphinoamidinate)manganese complex is shown to be a useful pre-catalyst for the hydrosilative reduction of carbonyl compounds, and in most cases at room temperature. The Mn-catalyzed reduction of tertiary amides to tertiary amines, with a useful scope, is demonstrated for the first time by use of this catalyst, and is competitive with the most effective transition-metal catalysts known for such transformations. Ketones, aldehydes, and esters were also successfully reduced under mild conditions by using this new Mn catalyst.Hey Man(ganese): A newly prepared (N-phosphinoamidinate)manganese pre-catalyst (see Scheme) has been shown to be effective for the hydrosilative reduction of a diverse scope of carbonyl compounds, and in most cases can be used at room temperature. The reaction proceeds under reaction conditions which are competitive with the most effective transition-metal catalysts known for such transformations, and thereby establishes a new class of synthetically useful Mn-catalyzed transformations.
      PubDate: 2017-11-15T05:41:21.074537-05:
      DOI: 10.1002/anie.201709441
       
  • Enantioselective Copper-Catalyzed Alkylation of Quinoline N-Oxides with
           Vinylarenes
    • Authors: Songjie Yu; Hui Leng Sang, Shaozhong Ge
      Abstract: An asymmetric copper-catalyzed alkylation of quinoline N-oxides with chiral Cu–alkyl species, generated by migratory insertion of a vinylarene into a chiral Cu−H complex, is reported. A variety of quinoline N-oxides and vinylarenes underwent this Cu-catalyzed enantioselective alkylation reaction, affording the corresponding chiral alkylated N-heteroarenes in high yield with high-to-excellent enantioselectivity. This enantioselective protocol represents the first general and practical approach to access a wide range of chiral alkylated quinolines.A highly enantioselective copper-catalyzed alkylation of quinoline N-oxides with vinylarenes was developed. A wide range of quinoline N-oxides and vinylarenes reacted to afford the corresponding chiral alkylated quinolines in high yield with excellent enantioselectivity.
      PubDate: 2017-11-15T05:41:16.980625-05:
      DOI: 10.1002/anie.201709411
       
  • Quantitative Prediction of Rate Constants for Aqueous Racemization To
           Avoid Pointless Stereoselective Syntheses
    • Authors: Andrew Ballard; Hiwa O. Ahmad, Stefania Narduolo, Lucy Rosa, Nikki Chand, David A. Cosgrove, Peter Varkonyi, Nabil Asaad, Simone Tomasi, Niklaas J. Buurma, Andrew G. Leach
      Abstract: Racemization has a large impact upon the biological properties of molecules but the chemical scope of compounds with known rate constants for racemization in aqueous conditions was hitherto limited. To address this remarkable blind spot, we have measured the kinetics for racemization of 28 compounds using circular dichroism and 1H NMR spectroscopy. We show that rate constants for racemization (measured by ourselves and others) correlate well with deprotonation energies from quantum mechanical (QM) and group contribution calculations. Such calculations thus provide predictions of the second-order rate constants for general-base-catalyzed racemization that are usefully accurate. When applied to recent publications describing the stereoselective synthesis of compounds of purported biological value, the calculations reveal that racemization would be sufficiently fast to render these expensive syntheses pointless.The racemization potential of complex organic molecules has been predicted using simple quantum mechanical calculations and a group additivity scheme. Organic chemists can first check whether a given synthetic targets will be configurationally stable before embarking on a potentially lengthy and expensive chiral synthesis.
      PubDate: 2017-11-15T05:41:02.351555-05:
      DOI: 10.1002/anie.201709163
       
  • Oxidative P−P Bond Addition to Cobalt(−I): Formation of a Low-Spin
           Cobalt(III) Phosphanido Complex
    • Authors: Peter Coburger; Serhiy Demeshko, Christian Rödl, Evamarie Hey-Hawkins, Robert Wolf
      Abstract: The first homoleptic cobalt phosphanido complex [K(thf)4][Co{1,2-(PtBu2)2C2B10H12}2] (1) was prepared by an unprecedented oxidative P−P bond addition of an ortho-carborane-substituted 1,2-diphosphetane to cobalt(−I) in [K(thf)0.2][Co(η4-cod)2)] (cod=1,5-cycloctadiene). Compound 1 is a rare distorted tetrahedral 3d6 complex with a low-spin ground state configuration. Magnetic measurements revealed that the complex is diamagnetic between 2 to 270 K in the solid state and at 298 K in [D8]THF solution. Based on DFT calculations, the unusual singlet ground state is caused by the strong σ-donor and moderate π-donor properties of the bis(phosphanido) ligand.Cobalt in a P pod: The first homoleptic cobalt phosphanido complex is formed via consecutive oxidative additions of P−P bonds to cobalt(−I). X-ray crystallography and magnetic measurements show that this new cobalt(III) compound is a rare example of a tetrahedral complex with a low-spin ground state.
      PubDate: 2017-11-15T05:40:47.410606-05:
      DOI: 10.1002/anie.201709140
       
  • High-Pressure Band-Gap Engineering in Lead-Free Cs2AgBiBr6 Double
           Perovskite
    • Authors: Qian Li; Yonggang Wang, Weicheng Pan, Wenge Yang, Bo Zou, Jiang Tang, Zewei Quan
      Abstract: Novel inorganic lead-free double perovskites with improved stability are regarded as alternatives to state-of-art hybrid lead halide perovskites in photovoltaic devices. The recently discovered Cs2AgBiBr6 double perovskite exhibits attractive optical and electronic features, making it promising for various optoelectronic applications. However, its practical performance is hampered by the large band gap. In this work, remarkable band gap narrowing of Cs2AgBiBr6 is, for the first time, achieved on inorganic photovoltaic double perovskites through high pressure treatments. Moreover, the narrowed band gap is partially retainable after releasing pressure, promoting its optoelectronic applications. This work not only provides novel insights into the structure–property relationship in lead-free double perovskites, but also offers new strategies for further development of advanced perovskite devices.High pressure is adopted to modulate the crystal structure and engineer the band gap of the Cs2AgBiBr6 double perovskite. A 22.3 % band gap narrowing is achieved for the inorganic photovoltaic double perovskite. The narrowed band gap is partially retainable after releasing the pressure, promoting its optoelectronic applications.
      PubDate: 2017-11-15T05:40:39.597746-05:
      DOI: 10.1002/anie.201708684
       
  • Scandium-Catalyzed Self-Assisted Polar Co-monomer Enchainment in Ethylene
           Polymerization
    • Authors: Jiazhen Chen; Yanshan Gao, Binghao Wang, Tracy L. Lohr, Tobin J. Marks
      Abstract: Direct coordinative copolymerization of ethylene with functionalized co-monomers is a long-sought-after approach to introducing polyolefin functionality. However, functional-group Lewis basicity typically depresses catalytic activity and co-monomer incorporation. Finding alternatives to intensively studied group 4 d0 and late-transition-metal catalysts is crucial to addressing this long-standing challenge. Shown herein is that mono- and binuclear organoscandium complexes with a borate cocatalyst are active for ethylene + amino olefin [AO; H2C=CH(CH2)nNR2] copolymerizations in the absence of a Lewis-acidic masking reagent. Both activity (up to 4.2×102 kg mol−1⋅h−1> atm−1>) and AO incorporation (up to 12 % at 0.2 m [AO]) are appreciable. Linker-length-dependent (n) AO incorporation and mechanistic probes support an unusual functional-group-assisted enchainment mechanism. Furthermore, the binuclear catalysts exhibit enhanced AO tolerance and enhanced long chain AO incorporation.Self-assisted: Sc-catalyzed ethylene + amino olefin (AO) copolymerizations proceed with appreciable activity and AO incorporation in the absence of Lewis acid masking agents. Linker-length-dependent AO enchainment patterns and mechanistic probes support an unusual amino-group-assisted enchainment pathway. Binuclear-catalyst-mediated copolymerization rates are less sensitive to AO concentration, and incorporation patterns at large linker lengths implicate bimetallic cooperative enchainment.
      PubDate: 2017-11-15T05:40:27.299449-05:
      DOI: 10.1002/anie.201708797
       
  • Enantioselective Total Synthesis of 3β-Hydroxy-7β-kemp-8(9)-en-6-one, a
           Diterpene Isolated from Higher Termites
    • Authors: Yuzhou Wang; Anne Jäger, Margit Gruner, Tilo Lübken, Peter Metz
      Abstract: The first total synthesis of the title diterpene was accomplished starting from the Wieland–Miescher ketone. A diastereoselective sulfa-Michael addition enabled the generation of the delicate β,γ-unsaturated ketone moiety, while the tetracyclic kempane skeleton was readily constructed through domino metathesis.Sulfur helps! The first total synthesis of the title diterpene was accomplished starting from the Wieland–Miescher ketone. A diastereoselective sulfa-Michael addition enabled the generation of the delicate β,γ-unsaturated ketone moiety, while the tetracyclic kempane skeleton was readily constructed through domino metathesis.
      PubDate: 2017-11-15T05:37:04.033313-05:
      DOI: 10.1002/anie.201708561
       
  • Crossover between Tilt Families and Zero Area Thermal Expansion in Hybrid
           Prussian Blue Analogues
    • Authors: Anthony E. Phillips; A. Dominic Fortes
      Abstract: Materials in the family of Prussian blue analogues (C3H5N2)2K[M(CN)6], where C3H5N2 is the imidazolium ion and M=Fe, Co, undergo two phase transitions with temperature; at low temperatures the imidazolium cations have an ordered configuration (C2/c), while in the intermediate- and high-temperature phases (both previously reported as R3‾m) they are dynamically disordered. We show from high-resolution powder neutron diffraction data that the high-temperature phase has zero area thermal expansion in the ab-plane. Supported by Landau theory and single-crystal X-ray diffraction data, we re-evaluate the space group symmetry of the intermediate-temperature phase to R3‾. This reveals that the low-to-intermediate temperature transition is due to competition between two different tilt patterns of the [M(CN)6]3− ions. Controlling the relative stabilities of these tilt patterns offers a potential means to tune the exploitable electric behaviour that arises from motion of the imidazolium guest.A different tilt: A reassessment of the symmetry of two cyanide-bridged perovskite analogues reveals that phase transitions in these materials arise from competition between two different tilt patterns. Tilt engineering of the hybrid materials provides a way to access combinations of distortions that are rare or impossible among the inorganic perovskites.
      PubDate: 2017-11-15T05:36:58.602923-05:
      DOI: 10.1002/anie.201708514
       
  • Metallo-Supramolecular Gels that are Photocleavable with Visible and
           Near-Infrared Irradiation
    • Authors: Sabrina Theis; Aitziber Iturmendi, Christian Gorsche, Marco Orthofer, Markus Lunzer, Stefan Baudis, Aleksandr Ovsianikov, Robert Liska, Uwe Monkowius, Ian Teasdale
      Abstract: A photolabile ruthenium-based complex, [Ru(bpy)2(4AMP)2](PF6)2, (4AMP=4-(aminomethyl)pyridine) is incorporated into polyurea organo- and hydrogels via the reactive amine moieties on the photocleavable 4AMP ligands. While showing long-term stability in the dark, cleavage of the pyridine–ruthenium bond upon irradiation with visible or near-infrared irradiation (in a two-photon process) leads to rapid de-gelation of the supramolecular gels, thus enabling spatiotemporal micropatterning by photomasking or pulsed NIR-laser irradiationLight as a liquidizer: Supramolecular ruthenium-based metallopolymer hydrogels undergo photocleavage and rapid de-gelation upon irradiation with visible and NIR light. They are stabile in the dark or in the absence of solvents.
      PubDate: 2017-11-15T05:34:27.940022-05:
      DOI: 10.1002/anie.201707321
       
  • Cationic Nitrogen-Doped Helical Nanographenes
    • Authors: Kun Xu; Yubin Fu, Youjia Zhou, Felix Hennersdorf, Peter Machata, Ilka Vincon, Jan J. Weigand, Alexey A. Popov, Reinhard Berger, Xinliang Feng
      Abstract: Herein, we report the design and synthesis of a series of novel cationic nitrogen-doped nanographenes (CNDNs) with nonplanar geometry and axial chirality. Single-crystal X-ray analysis reveals helical and cove-edged structures. Compared to their all-carbon analogues, the frontier orbitals of the CNDNs are energetically lower lying, with a reduced optical energy gap and greater electron-accepting behavior. Cyclic voltammetry shows all the derivatives to undergo quasireversible reductions. In situ spectroelectrochemical studies prove that, depending on the number of nitrogen dopants, either neutral radicals (one nitrogen dopant) or radical cations (two nitrogen dopants) are formed upon reduction. The concept of cationic nitrogen doping and introducing helicity into nanographenes paves the way for the design and synthesis of expanded nanographenes or even graphene nanoribbons with cationic nitrogen dopants.Nitrogen plus: A new bottom-up synthetic method allows the generation of cationic nitrogen-doped nanographenes with nonplanar helical structures. The new nanographenes have interesting properties and have potential use as optical and electronic materials.
      PubDate: 2017-11-15T05:33:40.075188-05:
      DOI: 10.1002/anie.201707714
       
  • 3D Laser Micro- and Nanoprinting: Challenges for Chemistry
    • Authors: Christopher Barner-Kowollik; Martin Bastmeyer, Eva Blasco, Guillaume Delaittre, Patrick Müller, Benjamin Richter, Martin Wegener
      Abstract: 3D printing is a powerful emerging technology for the tailored fabrication of advanced functional materials. This Review summarizes the state-of-the art with regard to 3D laser micro- and nanoprinting and explores the chemical challenges limiting its full exploitation: from the development of advanced functional materials for applications in cell biology and electronics to the chemical barriers that need to be overcome to enable fast writing velocities with resolution below the diffraction limit. We further explore chemical means to enable direct laser writing of multiple materials in one resist by highly wavelength selective (λ-orthogonal) photochemical processes. Finally, chemical processes to construct adaptive 3D written structures that are able to respond to external stimuli, such as light, heat, pH value, or specific molecules, are highlighted, and advanced concepts for degradable scaffolds are explored.It's all in print: Recent progress in micro- and nanoprinting by 3D laser lithography is highlighted and the critical chemical challenges identified. These include the design of functional photoresists for the generation of multifunctional nanostructures as well as the ability to write disparate material properties from one resist with different colors of light and the ability to conduct subdiffraction 3D lithography.
      PubDate: 2017-11-15T05:33:30.781435-05:
      DOI: 10.1002/anie.201704695
       
  • Selected Copper-Based Reactions for C−N, C−O, C−S, and
           C−C Bond Formation
    • Authors: Subhajit Bhunia; Govind Goroba Pawar, S. Vijay Kumar, Yongwen Jiang, Dawei Ma
      Abstract: Metal-catalyzed cross-coupling reactions belong to the most important transformations in organic synthesis. Copper catalysis has received great attention owing to the low toxicity and low cost of copper. However, traditional Ullmann-type couplings suffer from limited substrate scopes and harsh reaction conditions. The introduction of several bidentate ligands, such as amino acids, diamines, 1,3-diketones, and oxalic diamides, over the past two decades has totally changed this situation as these ligands enable the copper-catalyzed coupling of aryl halides and nucleophiles at both low reaction temperatures and catalyst loadings. The reaction scope has also been greatly expanded, rendering this copper-based cross-coupling attractive for both academia and industry. In this Review, we have summarized the latest progress in the development of useful reaction conditions for the coupling of (hetero)aryl halides with different nucleophiles. Additionally, recent advances in copper-catalyzed coupling reactions with aryl boronates and the copper-based trifluoromethylation of aromatic electrophiles will be discussed.Recent advances in copper/ligand-catalyzed cross-couplings of (hetero)aryl halides and nucleophiles, copper-catalyzed coupling reactions with aryl boronates, and copper-enabled trifluoromethylations of aromatic electrophiles are discussed in this Review.
      PubDate: 2017-11-15T05:33:20.034978-05:
      DOI: 10.1002/anie.201701690
       
  • Time-Resolved Interception of Multiple-Charge Accumulation in a
           Sensitizer–Acceptor Dyad
    • Authors: Stéphanie Mendes Marinho; Minh-Huong Ha-Thi, Van-Thai Pham, Annamaria Quaranta, Thomas Pino, Christophe Lefumeux, Thierry Chamaillé, Winfried Leibl, Ally Aukauloo
      Abstract: Biomimetic models that contain elements of photosynthesis are fundamental in the development of synthetic systems that can use sunlight to produce fuel. The critical task consists of running several rounds of light-induced charge separation, which is required to accumulate enough redox equivalents at the catalytic sites for the target chemistry to occur. Long-lived first charge-separated state and distinct electronic signatures for the sequential charge accumulated species are essential features to be able to track these events on a spectroscopic ground. Herein, we use a double-excitation nanosecond pump–pump–probe experiment to interrogate two successive rounds of photo-induced electron transfer on a molecular dyad containing a naphthalene diimide (NDI) linked to a [Ru(bpy)3]2+ (bpy=bipyridine) chromophore by using a reversible electron donor. We report an unprecedented long-lived two-electron charge accumulation (t=200 μs).A molecular dyad containing a naphthalene diimide (NDI) linked to a [Ru(bpy)3]2+ (bpy=bipyridine) chromophore by a reversible electron donor is used in a double-excitation nanosecond pump–pump–probe experiment to investigate two successive rounds of photoinduced electron transfer. An unprecedented long-lived two-electron charge accumulation occurs. css=charge-separated state.
      PubDate: 2017-11-15T05:33:02.7788-05:00
      DOI: 10.1002/anie.201706564
       
  • Real Sociedad Española de Química Prizes 2017
    • PubDate: 2017-11-15T05:26:14.331919-05:
      DOI: 10.1002/anie.201710990
       
  • Systemic Delivery of Bc12-Targeting siRNA by DNA Nanoparticles Suppresses
           Cancer Cell Growth
    • Authors: Mohammad Aminur Rahman; Pengfei Wang, Zhixiang Zhao, Dongsheng Wang, Sreenivas Nannapaneni, Chao Zhang, Zhengjia Chen, Christopher C. Griffith, Selwyn J. Hurwitz, Zhuo G. Chen, Yonggang Ke, Dong M. Shin
      Abstract: Short interfering RNA (siRNA) is a promising molecular tool for cancer therapy, but its clinical success is limited by the lack of robust in vivo delivery systems. Rationally designed DNA nanoparticles (DNPs) have emerged as facile delivery vehicles because their physicochemical properties can be precisely controlled. Nonetheless, few studies have used DNPs to deliver siRNAs in vivo, and none has demonstrated therapeutic efficacy. Herein, we constructed a number of DNPs of rectangular and tubular shapes with varied dimensions using the modular DNA brick method for the systemic delivery of siRNA that targets anti-apoptotic protein Bcl2. The siRNA delivered by the DNPs inhibited cell growth both in vitro and in vivo, which suppressed tumor growth in a xenograft model that specifically correlated with Bcl2 depletion. This study suggests that DNPs are effective tools for the systemic delivery of therapeutic siRNA and have great potential for further clinical translation.DNPs can deliver: DNA nanoparticles (DNPs) were utilized as vehicles for the systemic delivery of siRNA to suppress tumor growth by specifically knocking down an anti-apoptotic protein Bcl2.
      PubDate: 2017-11-15T05:26:05.789856-05:
      DOI: 10.1002/anie.201709485
       
  • Rational Design of Single Molybdenum Atoms Anchored on N-Doped Carbon for
           Effective Hydrogen Evolution Reaction
    • Authors: Wenxing Chen; Jiajing Pei, Chun-Ting He, Jiawei Wan, Hanlin Ren, Youqi Zhu, Yu Wang, Juncai Dong, Shubo Tian, Weng-Chon Cheong, Siqi Lu, Lirong Zheng, Xusheng Zheng, Wensheng Yan, Zhongbin Zhuang, Chen Chen, Qing Peng, Dingsheng Wang, Yadong Li
      Abstract: The highly efficient electrochemical hydrogen evolution reaction (HER) provides a promising pathway to resolve energy and environment problems. An electrocatalyst was designed with single Mo atoms (Mo-SAs) supported on N-doped carbon having outstanding HER performance. The structure of the catalyst was probed by aberration-corrected scanning transmission electron microscopy (AC-STEM) and X-ray absorption fine structure (XAFS) spectroscopy, indicating the formation of Mo-SAs anchored with one nitrogen atom and two carbon atoms (Mo1N1C2). Importantly, the Mo1N1C2 catalyst displayed much more excellent activity compared with Mo2C and MoN, and better stability than commercial Pt/C. Density functional theory (DFT) calculation revealed that the unique structure of Mo1N1C2 moiety played a crucial effect to improve the HER performance. This work opens up new opportunities for the preparation and application of highly active and stable Mo-based HER catalysts.Single Mo atoms dispersed on N-doped carbon was prepared as a catalyst. It showed high catalytic activity and stability for the hydrogen evolution reaction (HER), and its structure was characterized by electronic microscopy and XAFS measurements. The unique catalytic properties for HER were investigated by DFT calculations.
      PubDate: 2017-11-15T05:25:52.824997-05:
      DOI: 10.1002/anie.201710599
       
  • Layer-by-Layer Assembled Conductive Metal–Organic Framework Nanofilms
           for Room-Temperature Chemiresistive Sensing
    • Authors: Ming-Shui Yao; Xiao-Jing Lv, Zhi-Hua Fu, Wen-Hua Li, Wei-Hua Deng, Guo-Dong Wu, Gang Xu
      Abstract: The utility of electronically conductive metal–organic frameworks (EC-MOFs) in high-performance devices has been limited to date by a lack of high-quality thin film. The controllable thin-film fabrication of an EC-MOF, Cu3(HHTP)2, (HHTP=2,3,6,7,10,11-hexahydroxytriphenylene), by a spray layer-by-layer liquid-phase epitaxial method is reported. The Cu3(HHTP)2 thin film can not only be precisely prepared with thickness increment of about 2 nm per growing cycle, but also shows a smooth surface, good crystallinity, and high orientation. The chemiresistor gas sensor based on this high-quality thin film is one of the best room-temperature sensors for NH3 among all reported sensors based on various materials.A wafer-thin sensor: The preparation of a crystalline, highly-oriented, and thickness-controlled thin film with an electronically conductive MOF is reported. Chemiresistive sensors based on these thin films show a high response, excellent selectivity, fast response speed, and good long-term stability towards NH3 gas at room temperature.
      PubDate: 2017-11-15T05:25:42.833649-05:
      DOI: 10.1002/anie.201709558
       
  • Antibacterial Narrow-Band-Gap Conjugated Oligoelectrolytes with High
           Photothermal Conversion Efficiency
    • Authors: Bing Wang; Guangxue Feng, Martin Seifrid, Ming Wang, Bin Liu, Guillermo C. Bazan
      Abstract: Two conjugated oligoelectrolytes (COEs), WMG1 and WMG2, were designed with the goal of achieving near infrared absorption and high photothermal conversion efficiency. Specifically, electron-rich thiophene and electron-poor benzo[1,2-c:4,5-c′]bis[1,2,5]thiadiazole subunits were introduced into the conjugated core to modulate the optical gap and to reduce the fluorescence emission efficiency. WMG1 and WMG2 show absorption maxima at around 800 nm, which favors tissue penetration. Although relatively small in size, WMG1 and WMG2 exhibit photothermal conversion efficiencies of circa 60 % and 54 %, respectively. WMG1 shows dark toxicity to the Gram positive bacterium B. subtilis and good photothermal killing efficiency toward both B. subtilis and Gram negative E. coli, features that demonstrate the promising potential of the COE molecular design for photothermal applications.Two conjugated oligoelectrolytes (COEs), WMG1 and MWG2, that exhibit NIR absorption and high photothermal conversion efficiencies were prepared. WMG1 shows good photothermal killing efficiency toward pathogens and traditional dark toxicity to Gram positive bacteria, demonstrating the potential of COEs for photothermal applications.
      PubDate: 2017-11-15T05:25:30.6654-05:00
      DOI: 10.1002/anie.201709887
       
  • Biomimic Peptide-Gated Nanoporous Membrane for On-Demand Molecule
           Transport
    • Authors: Kai Xiao; Kai Wu, Lu Chen, Xiang-Yu Kong, Yuqi Zhang, Liping Wen, Lei Jiang
      Abstract: The controllable molecule transport is crucial to realize many highly valuable applications both in vivo and in vitro. Nanoporous membrane, with nanoscopic pores, high porosity, uniform pore dimension, and controllable surface chemical properties, hold tremendous potential to achieve this function. Here, we report a nano-gating system for on-demand molecule transport based on peptide-gated nanoporous membrane. Acting as gatekeeper, the peptides introduced to the nanoporous membrane provide an opportunity to realize on-demand on-off-states transport profiles via reversible conformational switch of peptides. This nano-gating system with sustained release performance provides a more sophisticated molecule transport platform, which anticipates applications in localized drug delivery with feedback function.
      PubDate: 2017-11-15T04:59:34.554379-05:
      DOI: 10.1002/anie.201708695
       
  • Photo-induced Pedalo-type Motion in an Azodicarboxamide-based Molecular
           Switch
    • Authors: Saeed Amirjalayer; Alberto Martinez-Cuezva, Jose Berná, Sander Woutersen, Wybren Jan Buma
      Abstract: Well-defined structural changes of molecular units that can be triggered by light are crucial for the development of photoactive functional materials. Here we report on a novel switch that has azodicarboxamide as its photo triggerable element. Time-resolved UV-pump/IR probe spectroscopy in combination with quantum chemical calculations shows that the azodicarboxamide functionality -in contrast to other azo-based chromophores- does not undergo trans-cis photoisomerization. Instead, a photo-induced pedalo-type motion occurs, which due to its volume-conserving properties enables to design functional molecular systems with controllable motion in a confined space.
      PubDate: 2017-11-15T04:59:31.670382-05:
      DOI: 10.1002/anie.201709666
       
  • Deep Level Defect-Enhanced Photothermal Performance of Bismuth
           Sulfide-Gold Heterojunction Nanorods for CT Imaging-Guided Photothermal
           Therapy of Cancer
    • Authors: Yan Cheng; Yun Chang, Yanlin Feng, Hui Jian, Zhaohui Tang, Haiyuan Zhang
      Abstract: Bismuth sulfide (Bi2S3) nanomaterials are emerging as a promising theranostic platform for CT imaging and photothermal therapy of cancer. Herein, the photothermal property of Bi2S3 nanorods (NRs) was unveiled to intensely correlate to their intrinsic deep level defects (DLDs) that potentially could work as electron-hole nonradiative recombination centers to promote phonon production, ultimately leading to photothermal performance. Bi2S3-Au heterojunction NRs were designed to hold more significant DLD property, exhibiting more potent photothermal performance than Bi2S3 NRs. Under 808 nm laser irradiation, Bi2S3-Au NRs could trigger higher cellular heat shock protein 70 expression and more apoptotic cells than Bi2S3 NRs, and caused severe cell death and tumor growth inhibition, showing great potential for CT imaging-guided photothermal therapy of cancer.
      PubDate: 2017-11-15T02:50:24.934908-05:
      DOI: 10.1002/anie.201710399
       
  • Subporpholactone, Subporpholactam, Imidazolosubporphyrin, and Iridium
           Complexes of Imidazolosubporphyrin: Formation of Iridium Carbene Complexes
           
    • Authors: Atsuhiro Osuka; Kota Yoshida
      Abstract: Pyrrole-modified subporphyrins bearing a non-pyrrolic cyclic unit, subporpholactone, subporpholactam, and imidazolosubporphyrin were newly synthesized. They show subporphyrin-like absorption and fluorescence spectra that are red-shifted in the order of subporpholactam < subporpholactone < imidazolosubporphyrin. Metalation of the imidazolosubporphyrin with (pentamethylcyclopentadienyl)iridium(III) dichloride dimer gave a complex, in which the Ir(III) atom was attached at the peripheral nitrogen atom of the imidazole moiety and the ortho-position of the meso-phenyl group. Reaction of this complex with diphenylacetylene gave different products depending on an additive; a phenyl-rearranged product in the presence of NaBArF4 (ArF = 3,5-bis(trifluoromethyl)phenyl) and two isomeric carbene complexes in the presence of KPF6.
      PubDate: 2017-11-15T00:50:55.703344-05:
      DOI: 10.1002/anie.201711166
       
  • Achieving Strong Positive Cooperativity through Activating Weak
           Non-Covalent Interactions
    • Authors: Yan-Long Ma; Hua Ke, Arto Valkonen, Kari Rissanen, Wei Jiang
      Abstract: Positive cooperativity achieved through activating weak non-covalent interactions is common in biological assemblies but is rarely observed in synthetic complexes. Two new naphthotubes have been synthesized and the syn isomer binds DABCO-based organic cations with high orientational selectivity. Surprisingly, the ternary complex with two hosts and one guest shows a high cooperativity factor (α=580), which is the highest reported for synthetic systems without involving ion-pairing interactions. The X-ray single-crystal structure revealed that the strong positive cooperativity likely originates from eight C-H⋅⋅⋅O hydrogen bonds between the two head-to-head-arranged syn tube molecules. These relatively weak hydrogen bonds were not observed in the free hosts and only emerged in the complex. Furthermore, this complex was used as a basic motif to construct a robust [2+2] cyclic assembly, thus demonstrating its potential in molecular self-assembly.
      PubDate: 2017-11-14T21:56:11.80446-05:0
      DOI: 10.1002/anie.201711077
       
  • In Situ Scatheless Cell Detachment Reveals Connections Between Adhesion
           Strength and Viability at Single-Cell Resolution
    • Authors: Sifeng Mao; Wanling Zhang, Qiushi Huang, Masqooh Khan, Haifang Li, Katsumi Uchiyama, Jin-Ming Lin
      Abstract: Single-cell biology provides insights to some of the most fundamental processes in biology and promotes the understanding of life's mysteries. And as the technologies to study single-cells expand, they will require sophisticated analytical tools to make sense of various behaviors and components of single-cells as well as their relations in adherent tissue culture. In this paper, we revealed cell heterogeneity and uncovered the connections between cell adhesion strength and cell viability at single-cell resolution by extracting single adherent cells of interest from standard tissue culture via a microfluidic chip based Live Single-Cell Extractor (LSCE). We not only uncovered cell heterogeneity and the connections between cell adhesion strength and cell viability, but also provided a new methodology for single-cell biology.
      PubDate: 2017-11-14T10:20:26.224809-05:
      DOI: 10.1002/anie.201710273
       
  • Oxime Ether Radical Cations Stabilized by N-Heterocyclic Carbene
    • Authors: Youngsuk Kim; Kimoon Kim, Eunsung Lee
      Abstract: N-heterocyclic carbene nitric oxide (NHCNO) radicals, which can be regarded as iminoxyl radicals stabilized by NHCs, were found to react with a series of silyl and alkyl triflates to generate the corresponding oxime ether radical cations. The structures of the resulting oxime ether radical cations were determined by X-ray crystallography, along with EPR and computational analysis. In contrast, lutidinium triflate produced a 1:1 mixture of [NHCNO+][OTf-] and [NHCNHOH+][OTf-] upon the reaction with NHCNO. This study adds an important example of stable singlet carbenes stabilizing main group radicals due to their π-conjugating effect, the synthesis and structures of which have never been elucidated previously.
      PubDate: 2017-11-14T08:27:31.675903-05:
      DOI: 10.1002/anie.201710530
       
  • A Simple Pre-lithiation Strategy to Build High-Rate and Long-life
           Lithium-ion Battery with Improved Low-temperature Performance
    • Authors: Yonggang Wang; Yao Liu, Bingchang Yang, Xiaoli Dong, Yongyao Xia
      Abstract: Lithium-ion batteries (LIBs) are being used to power the commercial electric vehicles (EVs). However, the charge/discharge rate and life of current LIBs still cannot satisfy the further development of EVs. Furthermore, the poor low temperature performance of LIBs limits their application in cold climates and high altitude areas. Herein, a simple pre-lithiation method is developed to fabricate a new LIB. In this strategy, a Li3V2(PO4)3 cathode and a pristine hard carbon anode are used to form a primary cell, and the initial Li+ extraction from Li3V2(PO4)3 is used to pre-lithiate the hard carbon. Then, the self-formed Li2V2(PO4)3 cathode and pre-lithiated hard carbon anode are used to form a 4 V LIB. It is demonstrated that the LIB exhibits a maximum energy density of 208.3 Wh kg-1, a maximum power density of 8291 W kg-1 and a long-life of 2000 cycles. When operated at -40 oC, the LIB can keep 67 % capacity of room temperature, which is much better than conventional LIBs.
      PubDate: 2017-11-14T08:27:14.633853-05:
      DOI: 10.1002/anie.201710555
       
  • Internal Peptide Late-Stage Diversification: Peptide Isosteric Triazoles
           for Primary and Secondary C(sp3)‒H Activation
    • Authors: Michaela Bauer; Wei Wang, Mélanie L. Lorion, Chuan Dong, Lutz Ackermann
      Abstract: Secondary C(sp3)-H arylations were accomplished by peptide bond isosteric triazoles in palladium catalysis. The unique power of this approach was reflected by enabling secondary C(sp3)-H functionalizations on terminal peptides as well as the unprecedented positional-selective C(sp3)-H functionalization of internal peptides, setting the stage for modular peptide late-stage diversification.
      PubDate: 2017-11-14T08:27:02.805478-05:
      DOI: 10.1002/anie.201710136
       
  • Organocatalyzed photo-controlled radical polymerization of
           semi-fluorinated (meth)acrylates driven by visible light
    • Authors: Mao Chen; Honghong Gong, Yucheng Zhao, Xianwang Shen, Jun Lin
      Abstract: Fluorinated polymers are important materials that are widely used in many areas. Herein, we report the development of a metal-free photo-controlled radical polymerization of semi-fluorinated (meth)acrylates with a new visible light absorbing organocatalyst. This method allows the production of a variety of semi-fluorinated polymers with narrow molar weight distributions from semi-fluorinated trithiocarbonates or perfluoroalkyl iodide. The high performance of "ON/OFF" control and chain extension experiments further demonstrate the utility and reliability of this method. Furthermore, to streamline the preparation of semi-fluorinated polymers, a scalable continuous-flow approach has been developed. Given the broad interest in fluorinated materials and photopolymerization, we expect this method will facilitate the development of advanced materials with unique property.
      PubDate: 2017-11-14T07:50:34.584287-05:
      DOI: 10.1002/anie.201711053
       
  • Conductive Microporous Covalent Triazine-Based Framework for
           High-Performance Electrochemical Capacitive Energy Storage
    • Authors: Weiqiao Deng; Yajuan Li, Shuanghao Zheng, Xue Liu, Pan Li, Lei Sun, Ruixia Yang, Sen Wang, Zhongshuai Wu, Xinhe Bao
      Abstract: Nitrogen enriched porous nanocarbon, graphene and conductive polymers attracted increasing attention in the application of supercapacitors. However, the electrode material possessing large specific surface area (SSA) and high nitrogen doping concentration simultaneously, which is needed for excellent supercapacitors, has not been achieved thus far. Herein, we developed a class of tetracyanoquinodimethane-derived conductive microporous covalent triazine-based frameworks (marked as TCNQ-CTFs) with high nitrogen content (> 8%) and large SSA (> 3600 m²/g) at the same time. These CTFs exhibited excellent specific capacitances with the highest value exceeding 380 F/g, considerable energy density of 42.8 Wh/kg and remarkable cycling stability without any capacitance degradation after 10000 cycles. This class of CTFs should hold a great potential as high-performance electrode material for electrochemical energy storage system.
      PubDate: 2017-11-14T07:20:58.267971-05:
      DOI: 10.1002/anie.201711169
       
  • Cobalt-catalyzed Suzuki biaryl coupling of aryl halides
    • Authors: Robin Bedford; Soneela Asghar, Sanita Tailor, Elorriaga David
      Abstract: Readily accessed cobalt pre-catalysts with N-heterocyclic carbene ligands catalyze the Suzuki cross-coupling of aryl chlorides and bromides with alkyllithium-activated arylboronic pinacolate esters. Preliminary mechanistic studies indicate that the cobalt is reduced to Co(0) during catalysis.
      PubDate: 2017-11-14T05:51:16.799501-05:
      DOI: 10.1002/anie.201710053
       
  • Transition Metal pi-Ligation of a Tetrahalodiborane
    • Authors: Holger Braunschweig; Rian D. Dewhurst, J. Oscar C. Jimenez-Halla, Eduard Matito, Jonas Muessig
      Abstract: The reaction of tetraiododiborane (B2I4) with trans- [Pt(BI2)I(PCy3)2] led to isolation of the diplatinum(II) complex [{(Cy3P)(I2B)Pt}2(μ2:h3:h3-B2I4)], supported by the bridging diboranyl dianion ligand [B2I4]2-. The complex is the first transition metal complex of a diboranyl dianion, as well as the first example of intact coordination of a B2X4 (X = halide) unit of any type to a metal center.
      PubDate: 2017-11-14T03:50:45.56548-05:0
      DOI: 10.1002/anie.201709515
       
  • Crochelins, siderophores with a novel iron-chelating moiety from the
           nitrogen-fixing bacterium Azotobacter chroococcum
    • Authors: Oliver Baars; Xinning Zhang, Marcus I. Gibson, Alan T. Stone, Francois M. M. Morel, Mohammad R. Seyedsayamdost
      Abstract: Microbes utilize siderophores to access essential iron resources. Over 500 siderophores are known, but they utilize a small set of common moieties to bind iron. Azotobacter chroococcum expresses iron-rich nitrogenases with which it reduces N2. Though an important agricultural inoculant, the structures of its iron-binding molecules remain unknown. Herein, we examine the 'chelome' of A. chroococcum using a small molecule discovery and bioinformatics approach. We find that it produces vibrioferrin and amphibactins as well as a novel family of siderophores, the crochelins. Detailed characterization shows that the most abundant member, crochelin A, binds iron in a hexadentate fashion using a new iron-chelating γ-amino acid. Insights into the biosynthesis of crochelins and the mechanism by which iron may be removed upon import of the holo-siderophore are presented. Our work expands the repertoire of iron-chelating moieties in microbial siderophores.
      PubDate: 2017-11-14T03:20:33.194916-05:
      DOI: 10.1002/anie.201709720
       
  • Metal-Free Boron-Containing Heterogeneous Catalysts
    • Authors: Yuanxing Fang; Xinchen Wang
      Abstract: Metal-free catalysts have distinct advantages over metal and metal oxide catalysts, such as lower cost as well as higher reliability and sustainability. Among the nonmetal compounds used in catalysis, boron-containing compounds with a few unique properties have been developed. In this Minireview, the recent advances in the field of boron-containing metal-free catalysts are presented, including binary and ternary boron-containing catalytic materials. Additionally, the three main applications in catalysis are considered, namely, electrocatalysis, thermal catalysis, and photocatalysis, with the role of boron discussed in depth for each specific catalytic application. Boron-containing compounds could have a substantial impact on the field of metal-free catalysts in the future.B the cat's whiskers: Metal-free catalysts have distinct advantages over metal and metal oxide catalysts, such as lower cost as well as higher reliability and sustainability. Among the nonmetal compounds used in catalysis, boron-containing compounds have a few unique properties. This Minireview presents advances in the field of metal-free boron-containing catalysts and considers the three main applications: electro-, thermal, and photocatalysis.
      PubDate: 2017-11-14T02:47:21.627816-05:
      DOI: 10.1002/anie.201707824
       
  • A De Novo Heterodimeric Due Ferri Protein Minimizes the Release of
           Reactive Intermediates in Dioxygen-Dependent Oxidation
    • Authors: Marco Chino; Linda Leone, Ornella Maglio, Daniele D'Alonzo, Fabio Pirro, Vincenzo Pavone, Flavia Nastri, Angela Lombardi
      Abstract: Metalloproteins utilize O2 as an oxidant, and they often achieve a 4-electron reduction without H2O2 or oxygen radical release. Several proteins have been designed to catalyze one or two-electron oxidative chemistry, but the de novo design of a protein that catalyzes the net 4-electron reduction of O2 has not been reported yet. We report the construction of a diiron-binding four-helix bundle, made up of two different covalently linked α2 monomers, through click chemistry. Surprisingly, the prototype protein, DF-C1, showed a large divergence in its reactivity from earlier DFs (DF: due ferri, two iron). DFs release the quinone imine and free H2O2 in the oxidation of 4-aminophenol in the presence of O2, whereas FeIII-DF-C1 sequesters the quinone imine into the active site, and catalyzes inside the scaffold an oxidative coupling between oxidized and reduced 4-aminophenol. The asymmetry of the scaffold allowed a fine-engineering of the substrate binding pocket, that ensures selectivity.Not just a four-helix bundle: The use of a diiron-binding four-helix bundle scaffold with an asymmetric active site leads to an enhancement in selectivity of the iron-catalyzed oxidative coupling of phenols. The stabilization of the oxidized intermediate in the binding pocket enables the net four-electron O2 reduction, without release of any detectable H2O2.
      PubDate: 2017-11-14T02:46:57.796618-05:
      DOI: 10.1002/anie.201707637
       
  • A pH-Dependent, Mechanically Interlocked Switch: Organometallic
           [2]Rotaxane vs. Organic [3]Rotaxane
    • Authors: Philipp J. Altmann; Alexander Pöthig
      Abstract: We present the first [2]rotaxane featuring a functional organometallic host. In contrast to the known organic scaffolds, this assembly shows a high post-synthetic modifiability. The reactivity of the Ag8 pillarplex host is fully retained, as is exemplified by the first transmetalation in a rotaxane framework to provide the respective Au8 analogue. Additionally, a transformation under acidic conditions to give a purely organic [3]rotaxane is demonstrated which is reversible upon addition of a suitable base, rendering the assembly a pH-dependent switch. Hereby, it is shown that the mechanically interlocked nature of the system enhances the kinetic stability of the NHC host complex by a factor of>1000 and corresponds to the first observation of a stabilizing “rotaxand effect”.A [2]rotaxane featuring a functional organometallic Ag8 host, its transmetalation to the respective Au8 analogue, and reversible switching to an organic [3]rotaxane under acidic conditions are demonstrated. The interlocked assembly enhances the kinetic stability of the NHC host complex by a factor of>1000, which corresponds to the first observation of a stabilizing “rotaxand effect”.
      PubDate: 2017-11-14T02:40:59.44196-05:0
      DOI: 10.1002/anie.201709921
       
  • Unprecedented Sensitivity in a Probe for Monitoring Cathepsin B:
           Chemiluminescence Microscopy Cell-Imaging of a Natively Expressed Enzyme
    • Authors: Michal E. Roth-Konforti; Christoph R. Bauer, Doron Shabat
      Abstract: Until recently, chemiluminescence cell images could only be obtained using luciferase-activated probes. Moreover, chemiluminescence microscopy cell-imaging has not been demonstrated for natively expressed enzymes like cathepsin B. Herein, we describe the design, synthesis, and evaluation of the first chemiluminescence probe for the detection and imaging of cathepsin B. The probe activation mechanism relies on the release of a dioxetane intermediate, which undergoes chemiexcitation to emit green light with high efficiency under physiological conditions. Using the probe, we obtained clear images of cancerous leukemia and colon cells. This is the first demonstration of chemiluminescence cell images obtained by a probe for a natively expressed endogenous enzyme. We anticipate that the concept presented in this study will be broadly used to develop analogous probes for other important proteases relevant to biomolecular processes.Chemiluminescence cell-imaging: The first chemiluminescence probe for the detection of cathepsin B is described. The probe showed unprecedented sensitivity compared to that of a classic fluorescent probe for cathepsin B and provided the first chemiluminescence microscopy cell images of a natively expressed enzyme, enabling the differentiation between cancerous cells and normal tissue.
      PubDate: 2017-11-14T02:40:53.363248-05:
      DOI: 10.1002/anie.201709347
       
  • Unraveling the Mechanism for the Sharp-Tip Enhanced Electrocatalytic
           Carbon Dioxide Reduction: The Kinetics Decide
    • Authors: Huijun Jiang; Zhonghuai Hou, Yi Luo
      Abstract: The electrocatalytic reduction reaction of carbon dioxide can be significantly enhanced by the use of a sharp-tip electrode. However, the experimentally observed rate enhancement is many orders of magnitudes smaller than what would be expected from an energetic point of view. The kinetics of this tip-enhanced reaction are shown to play a decisive role, and a novel reaction-diffusion kinetic model is proposed. The experimentally observed sharp-tip enhanced reaction and the maximal producing rate of carbon monoxide under different electrode potentials are well-reproduced. Moreover, the optimal performance shows a strong dependence on the interaction between CO2 and the local electric field, on the adsorption rate of CO2, but not on the reaction barrier. Two new strategies to further enhance the reaction rate have also been proposed. The findings highlight the importance of kinetics in modeling electrocatalytic reactions.Getting to the point: The mechanism for the sharp-tip enhanced electrocatalytic carbon dioxide reduction is revealed by a model taking both the thermodynamics and kinetics into account. Further ways to improve the reaction are predicted.
      PubDate: 2017-11-14T02:40:45.73222-05:0
      DOI: 10.1002/anie.201708825
       
  • Revealing Conformational Variants of Solution-Phase Intrinsically
           Disordered Tau Protein at the Single-Molecule Level
    • Authors: Lydia H. Manger; Alexander K. Foote, Sharla L. Wood, Michael R. Holden, Kevin D. Heylman, Martin Margittai, Randall H. Goldsmith
      Abstract: Intrinsically disordered proteins, such as tau protein, adopt a variety of conformations in solution, complicating solution-phase structural studies. We employed an anti-Brownian electrokinetic (ABEL) trap to prolong measurements of single tau proteins in solution. Once trapped, we recorded the fluorescence anisotropy to investigate the diversity of conformations sampled by the single molecules. A distribution of anisotropy values obtained from trapped tau protein is conspicuously bimodal while those obtained by trapping a globular protein or individual fluorophores are not. Time-resolved fluorescence anisotropy measurements were used to provide an explanation of the bimodal distribution as originating from a shift in the compaction of the two different families of conformations.An anti-Brownian electrokinetic trap was employed to prolong measurements of single tau proteins in solution. Once trapped, the fluorescence anisotropy was recorded to investigate the diversity of conformations sampled by the single molecules. The distribution of anisotropy values obtained from trapped tau protein is conspicuously bimodal while those obtained by trapping a globular protein or individual fluorophores are not.
      PubDate: 2017-11-14T02:40:41.116996-05:
      DOI: 10.1002/anie.201708242
       
  • One-pot synthesis of contracted and expanded porphyrins with meso-CF3
           groups, from affordable precursors
    • Authors: Zeev Gross; Qiu-cheng Chen, Matan Soll, Amir Mizrahi, Irena Saltsman, Natalia Fridman, magal Saphier
      Abstract: Corrole and sapphyrin with the smallest meso-substituents reported so far were prepared in a one-pot synthesis that relies on a non-aldehydic precursor for introducing CF3 groups. The substantial amounts of products obtained by this facile pathway allowed for the full characterization of 5,10-15-tris(trifluoromethyl)corrole, the access to a variety of stable chelates thereof and investigations that disclose the unique structural and chemical properties induced by the CF3 substituents. The novel 5,10,15,20-tetra(trifluoromethyl)sapphyrin does undergo only single protonation, which according to its crystal structure is stabilized by favorable non-bonding F/H interaction between the meso-CF3 and the inverted pyrrolic NH.
      PubDate: 2017-11-13T23:51:03.808439-05:
      DOI: 10.1002/anie.201710106
       
  • A General Strategy for Development of Near-Infrared Fluorescent Probes for
           Bioimaging
    • Authors: Ming Xian; Wei Chen, Shi Xu, Jacob J Day, Difei Wang
      Abstract: Near-infrared (NIR) fluorescent dyes with favorable photophysical properties are highly useful for bioimaging, but such dyes are still rare. Here, we describe the development of a unique class of NIR dyes via modifying the rhodol-scaffold with fused tetrahydroquinoxaline rings. These new dyes showed large Stokes shifts (>110 nm). Among them, WR3, WR4, WR5 and WR6 displayed high fluorescence quantum yields and excellent photostability in aqueous solutions. Moreover, their fluorescence properties were tunable by easy modifications on the phenolic hydroxyl group. Based on WR6, two NIR fluorescent turn-on probes, WSP-NIR and SeSP-NIR, were devised for the detection of H2S. The probe SeSP-NIR was applied in visualizing intracellular H2S. The dyes presented herein are expected to be useful fluorophore scaffolds in the development of new NIR probes for bioimaging.
      PubDate: 2017-11-13T21:56:21.515051-05:
      DOI: 10.1002/anie.201710688
       
  • Total Syntheses of the Monoterpenoid Indole Alkaloids
           (±)-Alstoscholarisine B and C
    • Authors: Steven M. Weinreb; Jeremy D Mason
      Abstract: Total syntheses of the monoterpenoid indole alkaloids (±)-alstoscholarisine B (2) and C (3) have been accomplished starting from readily available indole-2-acetic ester 6 and unsaturated N-sulfonyllactam 7.
      PubDate: 2017-11-13T08:15:23.962915-05:
      DOI: 10.1002/anie.201710943
       
  • Synthesis of Pyrrole-Fused Corannulenes: 1,3-Dipolar Cycloaddition of
           Azomethine Ylides to Corannulene
    • Authors: Yuki Tokimaru; Shingo Ito, Kyoko Nozaki
      Abstract: In the long history of corannulene chemistry, the 1,3-dipolar cycloaddition to corannulene is unprecedented. Reported herein is the 1,3-dipolar cycloaddition of a polycyclic aromatic azomethine ylide to corannulene, a reaction which occurs exclusively at the rim bond of corannulene, from the convex side in an exo fashion. The cycloadducts were successfully converted, by successive oxidative dehydrogenation, into pyrrole-fused corannulenes, which exhibited pronounced solvatofluorochromism.Along the rim: Reported is the 1,3-dipolar cycloaddition of a polycyclic aromatic azomethine ylide to corannulene, a reaction which occurs exclusively at the rim bond of corannulene, from the convex side in an exo fashion. The cycloadducts were converted, by oxidative dehydrogenation, into pyrrole-fused corannulenes, which exhibited pronounced solvatofluorochromism.
      PubDate: 2017-11-13T06:30:29.215607-05:
      DOI: 10.1002/anie.201707087
       
  • Singlet Oxygen during Cycling of the Aprotic Sodium–O2 Battery
    • Authors: Lukas Schafzahl; Nika Mahne, Bettina Schafzahl, Martin Wilkening, Christian Slugovc, Sergey M. Borisov, Stefan A. Freunberger
      Abstract: The biggest hurdle facing the development of Na–O2 batteries is parasitic chemistry. In their Communication (
      DOI : 10.1002/anie.201709351) S. A. Freunberger et al. show evidence that the highly reactive singlet oxygen forms at all stages of cycling, especially at high charging voltages, and that it is the main driver for parasitic reactions. However, trace water, which is needed for high capacities also drives the parasitic chemistry. Ways to prevent or eliminate singlet oxygen are therefore needed to improve cyclability.
      PubDate: 2017-11-13T06:18:12.491277-05:
       
  • EU-40 Materials Prize for Bettina V. Lotsch / Honorary Membership of the
           Polish Chemical Society for Hans-Ulrich Reissig / Welch Award for
           John B. Goodenough
    • PubDate: 2017-11-13T06:18:10.546681-05:
      DOI: 10.1002/anie.201710408
       
  • Direct Aryl C−H Amination with Primary Amines using Organic
           Photoredox Catalysis
    • Authors: Kaila A. Margrey; Alison Levens, David A. Nicewicz
      Abstract: The direct catalytic C−H amination of arenes is a powerful synthetic strategy with useful applications in pharmaceuticals, agrochemicals, and materials chemistry. Despite the advances in catalytic C−H functionalization, the use of aliphatic amine coupling partners is limited. Described herein is the construction of C−N bonds, using primary amines, by direct C−H functionalization with an acridinium photoredox catalyst under an aerobic atmosphere. A wide variety of primary amines, including amino acids and more complex amines are competent coupling partners. Various electron-rich aromatics and heteroaromatics are useful scaffolds in this reaction, as are complex, biologically active arenes. We also describe the ability to functionalize arenes that are not oxidized by an acridinium catalyst, such as benzene and toluene, thus supporting a reactive amine cation radical intermediate.To be direct: Described herein is the construction of C−N bonds, using primary amines, by direct C−H functionalization with an acridinium photoredox catalyst under an aerobic conditions. The method tolerates a wide variety of primary amines, including amino acids, and the regiochemistry is influenced by the arene substitution pattern. Also notable is that it can be used in a flow chemistry setup.
      PubDate: 2017-11-13T06:18:08.393631-05:
      DOI: 10.1002/anie.201709523
       
  • Orientation-Induced Adsorption of Hydrated Protons at the Air–Water
           Interface
    • Authors: Shavkat I. Mamatkulov; Christoph Allolio, Roland R. Netz, Douwe Jan Bonthuis
      Abstract: The surface tension of the air—water interface increases upon addition of inorganic salts, implying a negative surface excess of ionic species. Most acids, however, induce a decrease in surface tension, indicating a positive surface excess of hydrated protons. In combination with the apparent negative charge at pure air–water interfaces derived from electrokinetic experiments, this experimental observation has been a source of intense debate since the mid-19th century. Herein, we calculate surface tensions and ionic surface propensities at air–water interfaces from classical, thermodynamically consistent molecular dynamics simulations. The surface tensions of NaOH, HCl, and NaCl solutions show outstanding quantitative agreement with experiment. Of the studied ions, only H3O+ adsorbs to the air–water interface. The adsorption is explained by the deep potential well caused by the orientation of the H3O+ dipole in the interfacial electric field, which is confirmed by ab initio simulations.Surface tensions and ionic surface propensities at air–water interfaces were calculated by molecular dynamics simulations. The surface tensions of NaOH, HCl, and NaCl solutions agree remarkably well with experiment, and of the studied ions, only H3O+ adsorbs to the air–water interface. The adsorption is explained by the deep potential well caused by the orientation of the H3O+ dipole in the interfacial electric field.
      PubDate: 2017-11-13T06:17:57.233164-05:
      DOI: 10.1002/anie.201707391
       
  • Catalytic Hydroalkylation of Allenes
    • Authors: Mitchell Lee; Mary Nguyen, Chance Brandt, Werner Kaminsky, Gojko Lalic
      Abstract: We have developed a catalytic method for the hydroalkylation of allenes using alkyl triflates as electrophiles and silane as a hydride source. The reaction has an excellent substrate scope and is compatible with a wide range of functional groups, including esters, aryl halides, aryl boronic esters, sulfonamides, alkyl tosylates, and alkyl bromides. We found evidence for a reaction mechanism that involves unusual dinuclear copper ally complexes as catalytic intermediates. The unusual structure of these complexes provides a rationale for their unexpected reactivity.A catalytic method was developed for the hydroalkylation of allenes using alkyl triflates as electrophiles and silane as a hydride source. The reaction has an excellent substrate scope and is compatible with a wide range of functional groups, including esters, aryl halides, aryl boronic esters, sulfonamides, alkyl tosylates, and alkyl bromides. The reaction mechanism appears to involve unusual dinuclear copper ally complexes as catalytic intermediates.
      PubDate: 2017-11-13T06:17:44.587838-05:
      DOI: 10.1002/anie.201709144
       
  • Oxidative Dissolution of Resoles: A Versatile Approach to Intricate
           Nanostructures
    • Authors: Min Zhang; Hao Song, Yannan Yang, Xiaodan Huang, Yang Liu, Chao Liu, Chengzhong Yu
      Abstract: Resoles are base-catalyzed phenol-formaldehyde resins with a 3-dimensional cross-linked framework. The chemistry of resoles is generally considered as highly chemical resistant, thus calcination is always used in the treatment of resole-type resin, which significantly limit the diversity of nanostructured materials derived from resole-type resins. Here we report that selected metal nitrate solutions can be applied to dissolve various types of nanostructured resoles through an oxidative dissolution mechanism. This strategy not only allows for controlled dissolution of resoles, but more importantly provides a new approach to selectively etch resole based nanocomposites, giving rise to a variety of nanostructured materials with unprecedented architectures and great potential in bio-applications.
      PubDate: 2017-11-13T05:51:43.171497-05:
      DOI: 10.1002/anie.201709591
       
  • Valence-Engineering of Quantum Dots Using Programmable DNA Scaffolds
    • Authors: Jianlei Shen; Qian Tang, Li Li, Jiang Li, Xiaolei Zuo, Xiangmeng Qu, Hao Pei, Lihua Wang, Chunhai Fan
      Abstract: Precise control over the valency of quantum dots (QDs) is critical and fundamental for quantitative imaging in living cells. However, prior approaches on valence control of QDs remain restricted to single types of valences. A DNA-programmed general strategy is presented for valence engineering of QDs with high modularity and high yield. By employing a series of programmable DNA scaffolds, QDs were generated with tunable valences in a single step with near-quantitative yield (>95 %). The use of these valence-engineered QDs was further demonstrated to develop 12 types of topologically organized QDs-QDs and QDs-AuNPs and 4 types of fluorescent resonance energy transfer (FRET) nanostructures. Quantitative analysis of the FRET nanostructures and live-cell imaging reveal the high potential of these nanoprobes in bioimaging and nanophotonic applications.A DNA-programmed general strategy is presented for valence engineering of quantum dots (QDs) with high modularity and high yield. By employing a series of programmable DNA scaffolds, we generated QDs with tunable valences in a single step with near-quantitative yield (>95 %). We demonstrated the use of these valence-engineered QDs to develop 12 types of topologically organized QDs-QDs and QDs-AuNPs and 4 types of FRET) nanostructures.
      PubDate: 2017-11-13T04:47:14.983168-05:
      DOI: 10.1002/anie.201710309
       
  • Mesoporous Carbon@Titanium Nitride Hollow Spheres as an Efficient SeS2
           Host for Advanced Li–SeS2 Batteries
    • Authors: Zhen Li; Jintao Zhang, Bu Yuan Guan, Xiong Wen (David) Lou
      Abstract: The introduction of a certain proportion of selenium into sulfur-based cathodes is an effective strategy for enhancing the integrated battery performance. However, similar to sulfur, selenium sulfide cathodes suffer from poor cycling stability owing to the dissolution of reaction intermediate products. In this study, to exploit the advantages of SeS2 to the full and avoid its shortcomings, we designed and synthesized a hollow mesoporous carbon@titanium nitride (HMC@TiN) host for loading 70 wt % of SeS2 as a cathode material for Li–SeS2 batteries. Benefiting from both physical and chemical entrapment by hollow mesoporous carbon and TiN, the HMC@TiN/SeS2 cathode manifests high utilization of the active material and excellent cycling stability. Moreover, it exhibits promising areal capacity (up to 4 mAh cm−2) with stable cell performance in the high-mass-loading electrode.A double trap: A hollow mesoporous carbon@titanium nitride (HMC@TiN) host has been designed and synthesized for loading 70 wt % of SeS2 as a cathode material for Li–SeS2 batteries (see picture). As a result of both physical and chemical entrapment by the hollow mesoporous carbon and TiN, the HMC@TiN/SeS2 cathode showed high utilization of the active material and excellent cycling stability.
      PubDate: 2017-11-13T04:46:51.896525-05:
      DOI: 10.1002/anie.201709176
       
  • A Multivalent Structure-Specific RNA Binder with Extremely Stable Target
           Binding but Reduced Interaction to Nonspecific RNAs
    • Authors: Jeong Min Lee; Ahreum Hwang, Hyeongjoo Choi, Yongsang Jo, Bongsoo Kim, Taejoon Kang, Yongwon Jung
      Abstract: By greatly enhancing binding affinities against target biomolecules, multivalent interactions provide an attractive strategy for biosensing. However, there is also a major concern for increased binding to nonspecific targets by multivalent binding. A range of charge-engineered probes of a structure-specific RNA binding protein PAZ as well as multivalent forms of these PAZ probes were constructed by using diverse multivalent avidin proteins (2-mer, 4-mer, and 24-mer). Increased valency vastly enhanced the binding stability of PAZ to structured target RNA. Surprisingly, nonspecific RNA binding of multivalent PAZ can be reduced even below that of the PAZ monomer by controlling negative charges on both PAZ and multivalent avidin scaffolds. The optimized 24-meric PAZ showed nearly irreversible binding to target RNA with negligible binding to nonspecific RNA, and this ultra-specific 24-meric PAZ probe allowed SERS detection of intact microRNAs at an attomolar level.Multivalent probe for a biosensor: An RNA binding monomer and multivalent scaffold proteins were optimized to develop a multivalent probe with near irreversible binding to target RNA and negligible binding to nonspecific RNA. The resulting ultra-specific 24-meric RNA binder allowed SERS detection of intact miRNAs at an attomolar level.
      PubDate: 2017-11-13T04:46:34.906879-05:
      DOI: 10.1002/anie.201709153
       
  • A Magneto-optical Molecular Device: Interplay of Spin Crossover,
           Luminescence, Photomagnetism, and Photochromism
    • Authors: Marta Estrader; Jorge Salinas Uber, Leoní A. Barrios, Jordi Garcia, Paul Lloyd-Williams, Olivier Roubeau, Simon J. Teat, Guillem Aromí
      Abstract: A bis(pyrazolylpyridyl) ligand, L, containing a central photochromic dithienylethene spacer predictably forms a ferrous [Fe2L3]4+ helicate exhibiting spin crossover (SCO). In solution, the compound [Fe2L3](ClO4)4 (1) preserves the magnetic properties and is fluorescent. The structure of 1 is photo-switchable following the reversible ring closure/opening of the central dithienylethene via irradiation with UV/visible light. This photoisomerization switches on and off some emission bands of 1 and provides a means of externally manipulating the magnetic properties of the assembly.Fluoro-photo-magnificence: An iron-containing spin-crossover molecule has been synthesized that contains a photoswitchable unit. This unit allows its magnetic properties and its fluorescent response using light to be reversibly tuned.
      PubDate: 2017-11-13T04:46:26.937338-05:
      DOI: 10.1002/anie.201709136
       
  • Fluorinated Vinylsilanes from the Copper-Catalyzed Defluorosilylation of
           Fluoroalkene Feedstocks
    • Authors: Hironobu Sakaguchi; Masato Ohashi, Sensuke Ogoshi
      Abstract: Herein, a copper-catalyzed C-F bond defluorosilylation reaction of tetrafluoroethylene and other polyfluoroalkenes is described. Mechanistic studies, based on a series of stoichiometric reactions with copper complexes, revealed that the key steps of this defluorosilylation reaction are: i) the 1,2-addition of a silylcopper intermediate to the polyfluoroalkene, and ii) a subsequent selective β-fluorine elimination, which generates a Cu-F species. The β-fluorine elimination is facilitated by the Lewis acidic F-Bpin, which is generated in situ during the defluorosilylation.
      PubDate: 2017-11-12T21:55:55.299306-05:
      DOI: 10.1002/anie.201710866
       
  • Columnar Liquid-Crystal from a Giant Macrocycle Mesogen
    • Authors: Shin-ichiro Kawano; Masahiro Kato, Shinya Soumiya, Masato Nakaya, Jun Onoe, Kentaro Tanaka
      Abstract: Columnar liquid crystals composed of a giant macrocyclic mesogen were prepared. The giant macrocyclic mesogen has a square hollow with a 2.5 nm diagonal, which was bounded by diindolo[3,2-b:2',3'-h]carbazole (diindolocarbazole) moieties as the edges and bis(salicylidene)-o-phenylenediamine (salphen) moieties as the corners. The shape and size of the macrocycle were directly observed by scanning tunneling microscopy (STM). Each side of the bright square in the STM image corresponds to a diindolocarbazole moiety, and the length of the sides was consistent with the result of the single crystal analysis of diindolocarbazole. Finally, we successfully obtained a giant macrocycle with long and branched side chains, which exhibited a rectangular columnar LC phase over a wide temperature range. To the best of our knowledge, it contained the largest discrete inner space of any thermotropic columnar liquid crystal composed of macrocyclic mesogens.
      PubDate: 2017-11-12T21:55:50.891517-05:
      DOI: 10.1002/anie.201709542
       
  • Magnetic actuation of discrete liquid entities with a deformable
           paramagnetic liquid substrate
    • Authors: Damien Baigl; Jacopo Vialetto, Masayuki Hayakawa, Nikita Kavokine, Masahiro Takinoue, Subramanyan Namboodiri Varanakkottu, Sergii Rudiuk, Manos Anyfantakis, Mathieu Morel
      Abstract: Magnetic actuation of drops has mainly relied on volume forces exerted on the liquid to be transported, which is poorly efficient with conventional diamagnetic liquids such as water or oil, unless magnetosensitive particles are added. Here, we describe a new way to magnetically control the motion of discrete liquid entities, in an additive-free and surface tension-independent manner. Our strategy consists of using a paramagnetic liquid as a deformable substrate to direct, using a magnet, the motion of various floating liquid entities, ranging from naked drops to liquid marbles. We show that a broad variety of liquids, including diamagnetic (water, oil) and nonmagnetic ones can be efficiently transported using the moderate magnetic field (≈ 50 mT) produced by a cost-effective, cm-sized permanent magnet. Complex trajectories can be achieved in a reliable manner and multiplexing potential is demonstrated through on-demand drop fusion.
      PubDate: 2017-11-12T21:55:35.938217-05:
      DOI: 10.1002/anie.201710668
       
  • Supramolecular Radical Anions Triggered by Bacteria in situ for Selective
           Photothermal Therapy
    • Authors: Yuchong Yang; Ping He, Yunxia Wang, Haotian Bai, Shu Wang, Jiang-Fei Xu, Xi Zhang
      Abstract: In this work, we explored a supramolecular complex that can be selectively reduced to radical anions in situ by facultative anaerobic bacteria. To this end, a water-soluble bifunctional monomer bearing perylene diimide was synthesized, and its supramolecular complex with cucurbit[7]uril was fabricated on the basis of host-guest complexation, which could be reduced to forming radical anions in the presence of E. coli. It was interestingly found that this supramolecular complex could display different ability of generating radical anions by facultative anaerobic and aerobic bacteria in terms of their various reductive abilities. The selective antibacterial activity of the supramolecular complex could be realized by photothermal performance of radical anions under near-infrared irradiation. It is anticipated that this method may lead to a novel bacteria-responsive photothermal therapy to regulate balance of bacterial flora.
      PubDate: 2017-11-11T07:35:49.424-05:00
      DOI: 10.1002/anie.201708971
       
  • Molecular Magnesium Hydrides
    • Authors: Jun Okuda; Debabrata Mukherjee
      Abstract: Solid magnesium hydride [MgH2]∞ has been continuously pursued as a potential hydrogen storage material. Organic chemists were rather interested in soluble magnesium hydride reagents from mid-20th century. But it was only in the last two decades that molecular magnesium hydride chemistry received a major boost from organometallic chemists with a series of structurally well-characterized examples that continues to build a whole new class of compounds. Nearly 40 such species have been isolated, ranging from mononuclear terminal hydrides to large hydride clusters with more than 10 magnesium atoms. They provide not only insights into the structure and bonding of MgH motifs, but also serve as models for hydrogen storage materials. Some of them are also recognized to participate in useful catalytic transformations. An overview of these molecular magnesium hydrides is given here, focusing on their synthesis and structural characterization.
      PubDate: 2017-11-11T07:21:16.105058-05:
      DOI: 10.1002/anie.201708592
       
  • Three-Dimensional Graphene Networks with Abundant Sharp Edge Sites for
           Efficient Electrocatalytic Hydrogen Evolution
    • Authors: Gui Yu; Huping Wang, Xu-Bing Li, Lei Gao, Hao-Lin Wu, Jie Yang, Le Cai, Tian-Bao Ma, Chen-Ho Tung, Li-Zhu Wu
      Abstract: To achieve sustainable production of hydrogen (H2) through water splitting, establishing efficient and earth-abundant electrocatalysts is of great necessity. Here, we firstly reveal that morphology engineering of graphene can modulate the electronic structure of carbon skeleton and in turn endow it with excellent ability of proton reduction. Three-dimensional (3D) graphene networks with the high density of sharp edge sites are synthesized. Electrocatalytic measurements indicate that the obtained 3D graphene networks can electrocatalyze H2 evolution with an extremely low onset potential of ~18 mV in 0.5 M H2SO4 solution, together with good stability. A combination of control experiments and density functional theory (DFT) investigations indicates that the exceptional H2 evolution performance is attributed to the abundant sharp-edge sites of the advanced frameworks, which are responsible for promoting the adsorption and reduction of protons.
      PubDate: 2017-11-11T07:20:58.248438-05:
      DOI: 10.1002/anie.201709901
       
  • An in-situ Dynamic Continuum of Supramolecular Phosphoglycopeptides
           Enables Formation of 3D Cell Spheroids
    • Authors: Huaimin Wang; Junfeng Shi, Zhaoqianqi Feng, Rong Zhou, Shiyu Wang, Avital A. Rodal, Bing Xu
      Abstract: Higher-order assemblies of proteins, with a structural and dynamic continuum, is a new paradigm in biology, but these insights have yet to be applied in designing biomaterials. Dynamic assemblies of supramolecular phosphoglycopeptides (sPGPs) transform a 2D cell sheet to 3D cell spheroids. A ligand-receptor interaction between a glycopeptide and a phosphopeptide produces sPGPs that form nanoparticles, which transform to nanofibrils upon partially enzymatic dephosphorylation. The assemblies form dynamically and hierarchically in situ on the cell surface, and interact with extracellular matrix molecules and effectively abolish contact inhibition of locomotion (CIL) of the cells. Integrating molecular recognition, catalysis, and assembly, these active assemblies act as a dynamic continuum to disrupt CIL, thus illustrating a new kind of biomaterials for regulating cell behavior.
      PubDate: 2017-11-10T15:10:02.76281-05:0
      DOI: 10.1002/anie.201710269
       
  • Direct Dehydroxytrifluoromethoxylation of Alcohols
    • Authors: Xiaohuan Jiang; Zhijie Deng, pingping tang
      Abstract: The first example of a direct dehydroxytrifluoromethoxylation of alcohols has been developed. This method generated an alkyl fluoroformate in situ from alcohols and followed nucleophilic trifluoromethoxylation with trifluoromethyl arylsulfonate (TFMS) as the trifluoromethoxylation reagent. This reaction is operationally simple, scalable and proceeds under mild reaction conditions, and provides access to a wide range of trifluoromethyl ethers from alcohols. In addition, this method is suitable for the late-stage trifluoromethoxylation of complex small molecules
      PubDate: 2017-11-10T10:55:32.77827-05:0
      DOI: 10.1002/anie.201711050
       
  • Simultaneous application of photothermal therapy and anti-inflammatory
           prodrug using pyrene-aspirin loaded gold nanorod-graphitic-nanocapsules
    • Authors: Qian Dong; Xuewei Wang, Xiaoxiao Hu, Langqiu Xiao, Liang Zhang, Lijuan Song, Minglu Xu, Yuxiu Zou, Long Chen, Zhuo Chen, Weihong Tan
      Abstract: Photothermal therapy (PTT) has been extensively developed as an effective approach against cancer. In some cases, however, PTT can trigger inflammatory responses, in turn simulating tumor regeneration and hindering subsequent therapy. We herein developed a therapeutic strategy able to deliver enhanced PTT and simultaneously inhibite PTT-induced inflammatory response. 1-Pyrene methanol was utilize to synthesize anti-inflammatory prodrug pyrene-aspirin (P-aspirin) with cleavable ester bond, and also facilitate loading the prodrug on gold nanorod (AuNR)-encapsulated graphitic nanocapsule (AuNR@G), a photothermal agent, through π-π interaction. Such AuNR@G-P-aspirin complexes were used for near-infrared laser-triggered photothermal ablation of solid tumor and simultaneous inhibition of PTT-induced inflammation through the release of aspirin in tumor milieu. This strategy showed excellent effects in vitro and in vivo, thus having profound significance for the extended development of PTT.
      PubDate: 2017-11-10T10:05:28.746181-05:
      DOI: 10.1002/anie.201709648
       
  • Biocatalytic Oxidative Cascade for the Conversion of Fatty Acids to
           alpha-Ketoacids via Internal H2O2 Recycling
    • Authors: Somayyeh Gandomkar; Alexander Dennig, Andela Dordic, Lucas Hammerer, Mathias Pickl, Thomas Haas, Mélanie Hall, Kurt Faber
      Abstract: The functionalization of bio-based chemicals is essential to allow valorization of natural carbon sources. An atom-efficient biocatalytic oxidative cascade was developed for the conversion of saturated fatty acids to alpha-ketoacids. Employment of P450 monooxygenase in the peroxygenase mode for regioselective alpha-hydroxylation of fatty acids combined with enantioselective oxidation by alpha-hydroxyacid oxidase(s) resulted in internal recycling of the oxidant H2O2, thus minimizing degradation of ketoacid product and maximizing biocatalyst lifetime. The O2-dependent cascade relies on catalytic amounts of H2O2 and releases water as sole by-product. Octanoic acid was converted under mild conditions in aqueous buffer to 2-oxooctanoic acid in a simultaneous one-pot two-step cascade in up to>99% without accumulation of hydroxyacid intermediate. Scale-up allowed isolation of final product in 91% isolated yield and the cascade was applied to fatty acids of various chain lengths (C6:0-C10:0).
      PubDate: 2017-11-10T10:02:56.442776-05:
      DOI: 10.1002/anie.201710227
       
  • Diversity of Dimerization Behaviors of N-Substituted Dicyanomethyl
           Radicals: Boundary between Dynamically Stabilized Radicals and a Stable
           Radical
    • Authors: Kohei Okino; Daisuke Sakamaki, Shota Hira, Yuki Inoue, Shu Seki
      Abstract: Herein we demonstrate the characteristic switching of the dimerization behaviors of amine-substituted dicyanomethyl radicals, from - to -dimerization, simply by varying the electron-donating substituents. Dicyanomethyl radicals with 4,4'-ditolylamine (DT·) and with phenothiazine (PT·) are in equilibrium between the monomeric radical form and the corresponding dimer connected by a reversible C-C bond (-dimer) in solutions. On the other hand, a radical with julolidine skeleton (JD·) do not undergo -dimerization and is isolated as stable radical in spite of the absence of bulky protecting groups. X-ray single crystal analysis reveals that JD· forms the -dimer in the crystalline state, and the variable temperature spectroscopic measurements reveals that JD· is in equilibrium with the -dimer in toluene solution. DFT calculations suggests the importance of the electrostatic interaction in the driving force of the -dimerization of JD· due to its polarized structure.
      PubDate: 2017-11-10T10:02:29.383711-05:
      DOI: 10.1002/anie.201710354
       
  • Spata-13,17-diene Synthase, an Enzyme with Sesqui-, Di- and Sesterterpene
           Synthase Activity from Streptomyces xinghaiensis
    • Authors: Jan Rinkel; Lukas Lauterbach, Jeroen Sidney Dickschat
      Abstract: A terpene synthase from the marine bacterium Streptomyces xinghaiensis was characterised, including a full structure elucidation of its products from various substrates and an in-depth investigation of the enzyme mechanism by isotopic labelling experiments, substrate and metal cofactor variations, and mutation experiments. The results revealed an interesting dependency of Mn2+ catalysis on the presence of Asp-217, a residue that is occupied by a highly conserved Glu in most other bacterial terpene synthases.
      PubDate: 2017-11-10T10:02:24.492833-05:
      DOI: 10.1002/anie.201711142
       
  • Site-Selective O-Arylation of Glycosides
    • Authors: Dawen Niu; Weidong Shang, Ze-Dong Mou, Hua Tang, Xia Zhang, Jie Liu, Zhengyan Fu
      Abstract: Direct and site-selective O-arylation of carbohydrates has been a challenge in synthesis. Here we report a method that is based on the copper-catalyzed O-arylation reaction to address this challenge. Proper choice of the ancillary ligand to copper is critical for the efficiency and site-selectivity of this transformation. This method features mild conditions, tolerates various functional groups, and demonstrates broad substrate scope.
      PubDate: 2017-11-10T08:25:43.313768-05:
      DOI: 10.1002/anie.201710310
       
  • Molecular Barium Hydrido Complex Stabilized by a Super Bulky
           Hydrotris(pyrazolyl)borate Ligand
    • Authors: Xianghui Shi; Cuiping Hou, Chulu Zhou, Yanyao Song, Jianhua Cheng
      Abstract: Hydrogenolysis of the scorpionate-supported barium alkyl complex (Tp^Ad,iPr)Ba[CH(SiMe3)2](THF) (Tp^Ad,iPr = hydrotris(3-adamantyl-5-isopropyl-pyrazolyl)borate) afforded the dinuclear barium hydrido complex [(Tp^Ad,iPr)Ba(µ-H)]2 (2), which was characterized by NMR spectroscopy and single crystal X-ray analysis. Exposure of 2 with 1 atm of CO resulted in a reductive coupling process to form the cis-ethendiolate dianion (3). Reaction of 2 with one equivalent of PhCC-CCPh gave barium 1,4-diphenyl-2-butyne-1,4-diyl complex {[(Tp^Ad,iPr)Ba]2(PhCH-CC-CHPh) (4).
      PubDate: 2017-11-10T05:55:45.723332-05:
      DOI: 10.1002/anie.201709344
       
  • How Large Can We Build a Cyclic Assembly' Impact of Ring Size on
           Chelate Cooperativity in Noncovalent Macrocyclizations
    • Authors: Carlos Montoro-García; María J. Mayoral, Raquel Chamorro, David González-Rodríguez
      Abstract: Self-assembled systems rely on intramolecular cooperative effects to control their growth and regulate their shape, thus yielding discrete, well-defined structures. However, as the size of the system increases, cooperative effects tend to dissipate. We analyze here this situation by studying a set of oligomers of different lengths capped with guanosine and cytidine nucleosides, which associate in cyclic tetramers by complementary Watson–Crick H-bonding interactions. As the monomer length increases, and thus the number of C(sp)–C(sp2) σ-bonds in the π-conjugated skeleton, the macrocycle stability decreases due to a notable reduction in effective molarity (EM), which has a clear entropic origin. We determined the relationship between EM or ΔS and the number of σ-bonds, which allowed us to predict the maximum monomer lengths at which cyclic species would still assemble quantitatively, or whether the cyclic species would not able to compete at all with linear oligomers over the whole concentration range.After decoding the relationship between monomer length and chelate cooperativity it was possible to predict at which monomer length cyclic species still compete with linear oligomers in ring–chain self-assembly processes.
      PubDate: 2017-11-10T04:35:44.618185-05:
      DOI: 10.1002/anie.201709563
       
  • Low-Density Open Cellular Sponges as Functional Materials
    • Authors: Shaohua Jiang; Seema Agarwal, Andreas Greiner
      Abstract: Low-density macroporous sponges with densities less than 100 mg cm−3 are both a challenge and an opportunity for advanced chemistry and material science. The challenge lies in the precise preparation of the sponges with property combinations that lead to novel applications. Bottom-up and top-down chemical and engineering methods for the preparation of sponges are a major focus of this Review, with an emphasis on carbon and polymer materials. The light weight, sustainability, breathability, special wetting characteristics, large mass transfer, mechanical stability, and large pore volume are typical characteristics of sponges made of advanced materials and could lead to novel applications. Some selected sponge properties and potential applications are discussed.Less is more: Low-density macroporous sponges made of carbon or polymer materials offer an opportunity for advanced chemistry and materials science. The light weight, sustainability, breathability, special wetting characteristics, high mass transfer, mechanical stability, and large pore volumes of these materials suggest they may be “perfect” sponges. This Review critically addresses the status of the field along with opportunities and future directions.
      PubDate: 2017-11-10T04:30:58.383782-05:
      DOI: 10.1002/anie.201700684
       
  • Ynamide Preactivation Allows a Regio- and Stereoselective Synthesis of
           α,β-Disubstituted Enamides
    • Authors: Lucas L. Baldassari; Aurélien de la Torre, Jing Li, Diogo S. Lüdtke, Nuno Maulide
      Abstract: A novel ynamide preactivation strategy enables the use of otherwise incompatible reagents and allows preparation of α,β-disubstituted enamides with high regio- and stereoselectivity. Mechanistic analysis reveals the intermediacy of a triflate-bound intermediate as a solution-stable, effective keteniminium reservoir, whilst still allowing subsequent addition of organometallic reagents.Activate first, attack later: Thanks to an ynamide preactivation strategy, otherwise incompatible reagents can be used to prepare α,β-disubstituted enamides with high regio- and stereoselectivity. Mechanistic analysis reveals the intermediacy of a triflate-bound species as a solution-stable, effective keteniminium reservoir, which is amenable to the subsequent addition of organometallic reagents.
      PubDate: 2017-11-10T04:30:25.979013-05:
      DOI: 10.1002/anie.201709128
       
  • Bioorthogonal Click and Release Reaction of Iminosydnones with
           Cycloalkynes
    • Authors: Sabrina Bernard; Davide Audisio, Margaux Riomet, Sarah Bregant, Antoine Sallustrau, Lucie Plougastel, Elodie Decuypere, Sandra Gabillet, Ramar Arun Kumar, Jijy Elyian, Minh Nguyet Trinh, Oleksandr Koniev, Alain Wagner, Sergii Kolodych, Frédéric Taran
      Abstract: We report the discovery of a new bioorthogonal click-and-release reaction involving iminosydnones and strained alkynes. This transformation leads to two products resulting from the ligation and fragmentation of iminosydnones under physiological conditions. Optimized iminosydnones were successfully used to design innovative cleavable linkers for protein modification, thus opening up new areas in the fields of drug release and target-fishing applications. This click-and-release technology offers the possibility of exchanging tags on proteins for functionalized cyclooctynes under mild and bioorthogonal conditions.Click and cleave: Iminosydnones reacted smoothly with cycloalkynes under physiological, copper-free conditions to form a click pyrazole product and release a urea product. Possible applications of this new reaction for drug release and protein trans-tagging have been explored in proof-of-principle experiments.
      PubDate: 2017-11-10T04:12:44.198972-05:
      DOI: 10.1002/anie.201708790
       
  • Living ab initio Emulsion Polymerization of Methyl Methacrylate in Water
           Using a Water-Soluble Organotellurium Chain Transfer Agent under Thermal
           and Photochemical Conditions
    • Authors: Weijia Fan; Masatoshi Tosaka, Shigeru Yamago, Michael F. Cunningham
      Abstract: Ab initio emulsion polymerization of methyl methacrylate (MMA) using a water-soluble organotellurium chain transfer agent in the presence of the surfactant Brij 98 in water is reported. Polymerization proceeded under both thermal and visible light-irradiation conditions giving poly(methyl methacrylate) (PMMA) with controlled molecular weight and low dispersity (Đ
      PubDate: 2017-11-10T02:25:24.39975-05:0
      DOI: 10.1002/anie.201710754
       
  • Porous polyelectrolytes: charge pores for more functionalities
    • Authors: Weiyi Zhang; Qiang Zhao, Jiayin Yuan
      Abstract: The past decade has witnessed rapid advances in porous polyelectrolytes and there is tremendous ongoing interest in their synthesis and applications in environment, energy, biomedicine and catalysis. The porous polyelectrolytes research is motivated by the synergy of, apart from the flexible choice of functional organic groups and processing technologies, the charge and pores spanning length scales from individual polyelectrolyte backbones to their nano/micro superstructures. This review surveys recent progresses on porous polyelectrolytes including membranes, particles, scaffolds, high surface area powders/resins, and their derivatives. Our focus is the interplay between surface chemistry, Columbic interaction and poreconfinement that defines new chemistry and physics in such materials for implications including energy conversion, molecular separation, water purification, sensing/actuation, catalysis, tissue engineering, and nanomedicine.
      PubDate: 2017-11-09T21:55:42.425679-05:
      DOI: 10.1002/anie.201710272
       
  • Lysosome-Targeting Amplifiers of Reactive Oxygen Species as Anticancer
           Prodrugs
    • Authors: Steffen Daum; M. S. Viktor Reshetnikov, Miroslav Sisa, Tetyana Dumych, Maxim D. Lootsik, Rostyslav Bilyy, Evgenia Bila, Christina Janko, Christoph Alexiou, Martin Herrmann, Leopold Sellner, Andriy Mokhir
      Abstract: Cancer cells produce elevated levels of reactive oxygen species, which has been used to design cancer specific prodrugs. Their activation relies on at least a bimolecular process, in which a prodrug reacts with ROS. However, at low micromolar concentrations of the prodrugs and ROS, the activation is usually inefficient. Herein, we propose and validate a potentially general approach for solving this intrinsic problem of ROS-dependent prodrugs. In particular, known prodrug 4-(N-ferrocenyl-N-benzylaminocarbonyloxymethyl)phenylboronic acid pinacol ester was converted into its lysosome-specific analogue. Since lysosomes contain a higher concentration of active ROS than the cytoplasm, activation of the prodrug was facilitated with respect to the parent compound. Moreover, it was found to exhibit high anticancer activity in a variety of cancer cell lines (IC50=3.5–7.2 μm) and in vivo (40 mg kg−1, NK/Ly murine model) but remained weakly toxic towards non-malignant cells (IC50=15–30 μm).Targeting cancer: A potentially general approach for improving the anti-cancer activity of ROS-dependent prodrugs is presented and validated. In particular, a known prodrug was converted into its lysosome-specific analogue. Because lysosomes contain a higher concentration of active ROS than the cytoplasm, activation of the prodrug was facilitated with respect to the parent compound.
      PubDate: 2017-11-09T12:21:09.271013-05:
      DOI: 10.1002/anie.201706585
       
  • C3-Symmetric Tricyclo[2.2.1.02,6]heptane-3,5,7-triol
    • Authors: Volodymyr Kozel; Constantin-Gabriel Daniliuc, Peer Kirsch, Günter Haufe
      Abstract: The smallest tricyclic C3-symmetric triol was obtained as a racemate using a simple one-pot synthesis from readily available commercial starting materials and reagents. Classical resolution provided the “propeller-like” enantiopure triols, which have a high potential for application in asymmetric synthesis, molecular recognition, and material sciences. In their Communication (
      DOI : 10.1002/anie.201709279), G. Haufe et al. provide more details, including the synthesis of a chiral dopand for liquid crystals.
      PubDate: 2017-11-09T12:20:53.980869-05:
       
  • meso-Aryl [20]π Homoporphyrin: The Simplest Expanded Porphyrin with the
           Smallest Möbius Topology
    • Authors: K. S. Anju; Mainak Das, B. Adinarayana, Cherumuttathu H. Suresh, A. Srinivasan
      Abstract: An unstable conjugated homoporphyrin was successfully stabilized by introducing meso-aryl substitutents. It was evident from the moderate diatropic ring current found by NMR analysis that the newly formed 20π conjugated free base and its protonated form exhibited Möbius aromatic character. Furthermore, complexation as a ligand with an RhI ion afforded a unique binding mode and retained the Möbius aromaticity. Overall, these compounds are the smallest Möbius aromatic molecules, as confirmed by spectral and crystal-structure analysis and supported by theoretical studies.Assessing the limits: The simplest expanded porphyrin with the smallest Möbius topology—[20]π homoporphyrin—was successfully stabilized by meso-aryl substituents. The resulting ligands coordinated a RhI ion through an unexpected binding mode. Spectral and structural analysis confirmed the Möbius aromatic character of the free base (top right in the picture) as well as the protonated (bottom left) and metal-coordinated states (bottom right).
      PubDate: 2017-11-09T12:20:51.347664-05:
      DOI: 10.1002/anie.201709859
       
  • Proximity-Triggered Covalent Stabilization of Low-Affinity Protein
           Complexes in vitro and in vivo
    • Authors: Marko Cigler; Thorsten G. Müller, Daniel Horn-Ghetko, Marie-Kristin von Wrisberg, Maximilian Fottner, Roger S. Goody, Aymelt Itzen, Matthias P. Müller, Kathrin Lang
      Abstract: The characterization of low-affinity protein complexes is challenging due to their dynamic nature. Here, we present a method to stabilize transient protein complexes in vivo by generating a covalent and conformationally flexible bridge between the interaction partners. A highly active pyrrolysyl tRNA synthetase mutant directs the incorporation of unnatural amino acids bearing bromoalkyl moieties (BrCnK) into proteins. We demonstrate for the first time that low-affinity protein complexes between BrCnK-containing proteins and their binding partners can be stabilized in vivo in bacterial and mammalian cells. Using this approach, we determined the crystal structure of a transient GDP-bound complex between a small G-protein and its nucleotide exchange factor. We envision that this approach will prove valuable as a general tool for validating and characterizing protein–protein interactions in vitro and in vivo.Triggered by proximity: Site-specific incorporation of structurally flexible unnatural amino acids allows the covalent trapping of low-affinity and transient protein–protein interactions under native conditions. This crosslinking approach can be used to aid the co-crystallization and structure elucidation of low-affinity protein complexes.
      PubDate: 2017-11-09T12:20:41.967915-05:
      DOI: 10.1002/anie.201706927
       
  • Facile Supramolecular Processing of Carbon Nanotubes and Polymers for
           Electromechanical Sensors
    • Authors: Chae Bin Kim; Ki Beom Jeong, Beom Joo Yang, Jong-Won Song, Bon-Cheol Ku, Seunghyun Lee, Seoung-Ki Lee, Chiyoung Park
      Abstract: We herein report a facile, cost-competitive, and scalable method for producing viscoelastic conductors via one-pot melt-blending using polymers and supramolecular gels composed of carbon nanotubes (CNTs), diphenylamine (DP), and benzophenone (BP). When mixed, a non-volatile eutectic liquid (EL) produced by simply blending DP with BP (1:1 molar ratio) enabled not only the gelation of CNTs (EL-CNTs) but also the dissolution of a number of commodity polymers. To make use of these advantages, viscoelastic conductors were produced via one-pot melt-blending the EL and CNTs with a model thermoplastic elastomer, poly(styrene-b-butadiene-b-styrene) (SBS, styrene 30 wt %). The resulting composites displayed an excellent electromechanical sensory along with re-mendable properties. This simple method using cost-competitive EL components is expected to provide an alternative to the use of expensive ionic liquids as well as to facilitate the fabrication of novel composites for various purposes.Sense of gel: A supramolecular, non-volatile eutectic liquid (EL), consisting of diphenylamine and benzophenone, can not only dissolve many commodity polymers but also form bucky gels with CNTs upon grinding. A viscoelastic conductor composed of the EL, CNTs, and polymers was prepared by one-pot melt-blending. The resulting viscoelastic conductor behaves as a highly sensitive, self-healing electromechanical sensor.
      PubDate: 2017-11-09T12:20:31.408802-05:
      DOI: 10.1002/anie.201708111
       
  • New Three-Component Enantioselective Cyclization Reaction Catalyzed by an
           Unnatural Amino Acid Derivative
    • Authors: Fernando P. Cossío; Andrea Ruiz-Olalla, Maria de Gracia Retamosa, Abel de Cózar, Tamara Bello
      Abstract: A new three-component diastereo- and enantioselective cyclization reaction is described. The reaction takes place between a ketone, a carboxylic acid and a nitroalkene to yield a bicyclic octahydro-2H-indol-2-one scaffold possessing three chiral centers. This reaction involves a rearrangement of the nitro group under simple thermal conditions. A plausible mechanism is proposed for this new reaction based on DFT calculations and isotope labeling experiments. A new concise enantioselective synthesis of alkaloid (+)-pancracine is presented as an example of the potential of this novel organocatalytic cyclization reaction in the synthesis of natural products.
      PubDate: 2017-11-09T08:55:57.992159-05:
      DOI: 10.1002/anie.201708952
       
  • Electrochemiluminescence Bioassays can outperform Fluorescence Assays
           using a New Water-soluble Luminol Derivative
    • Authors: Michael Mayer; Shigehiko Takegami, Michael Neumeier, Simone Rink, Axel Jacobi von Wangelin, Silja Schulte, Moritz Vollmer, Axel Georg Griesbeck, Axel Duerkop, Antje Jutta Baeumner
      Abstract: The most efficient and commonly used electrochemilumi-nescence (ECL) emitters are luminol, [Ru(bpy)3]2+ and derivatives thereof. Luminol stands out due to its low excitation potential, yet applications are limited by the insolubility under physiological conditions. The water-soluble m-carboxy luminol was synthesized in 15% yield and exhibited high solubility under physiological conditions and afforded a four-fold ECL signal increase (vs. luminol). Entrapment in DNA-tagged liposomes enabled a DNA assay with a detection limit of 3.2 pmol L-1 which is 150 times lower than the corresponding fluorescence approach. This remarkable sensitivity gain and the low excitation potential establish m-carboxy luminol as a superior ECL probe with direct relevance to chemiluminescence and enzymatic bioanalytical approaches.
      PubDate: 2017-11-09T04:56:29.283494-05:
      DOI: 10.1002/anie.201708630
       
  • Supramolecular Polymerization Controlled through Kinetical Trapping
    • Authors: Hao Chen; Zehuan Huang, Han Wu, Jiang-Fei Xu, Xi Zhang
      Abstract: This communication is aimed to introduce a new method of controllable supramolecular polymerization through kinetic trapping. To this end, two bifunctional monomers with cucurbit[7]uril (CB[7]) and adamantane end groups were synthesized. The CB[7]-containing monomer was pre-saturated with a pH-responsive competitive guest for kinetic control. Then, the kinetics of supramolecular polymerization of the two monomers was easily controlled through the modulation of pH. As a result, supramolecular polymerization was kinetically trapped at certain stages and supramolecular polymers with different molecular weights were obtained. Considering that competitive binding is widely available in many supramolecular systems, this strategy is of general applicability. It is anticipated this research will enrich the methodology of controllable supramolecular polymerization.
      PubDate: 2017-11-09T04:26:09.250169-05:
      DOI: 10.1002/anie.201709797
       
  • Integrated Transmission Electron and Single Molecule Fluorescence
           Microscopy Correlates Reactivity with Ultrastructure in a Single Catalyst
           Particle
    • Authors: Bert Marc Weckhuysen; Hans Gerritsen, Sajjad Mohammadian, Sam Kalirai, Pieter Bruijnincx, Florian Meirer, Eelco Vogt, Zoran Ristanovic, Frank Hendriks
      Abstract: Establishing structure-activity relationships in complex, hierarchically structured nanomaterials, such as fluid catalytic cracking (FCC) catalysts, requires characterization with complementary, correlated analysis techniques. An integrated setup has been developed to perform transmission electron microscopy (TEM) and single molecule fluorescence (SMF) microscopy on such nanostructured samples. Correlated structure-reactivity information was obtained for 100 nm thin, microtomed sections of a single FCC catalyst particle using this novel SMF-TEM high-resolution combination. High reactivity in a thiophene oligomerization probe reaction correlated well with TEM-derived zeolite locations, while matrix components, such as clay and amorphous binder material, were found not to display activity. Differences in fluorescence intensity were also observed within and between distinct zeolite aggregate domains, indicating that not all zeolite domains are equally active.
      PubDate: 2017-11-09T04:26:03.235487-05:
      DOI: 10.1002/anie.201709723
       
  • GOx@ZIF-8(NiPd) nanoflower: an artificial enzyme system for tandem
           catalysis
    • Authors: Qingqing Wang; Xueping Zhang, Liang Huang, Zhiquan Zhang, Shaojun Dong
      Abstract: This work reports a facile approach to fabricate an artificial enzyme system for tandem catalysis. NiPd hollow nanoparticles and glucose oxidase (GOx) were simultaneously immobilized on ZIF-8 via a co-precipitation method. The as-prepared GOx@ZIF-8(NiPd) nanoflower not only exhibited the peroxidase-like activity of NiPd hollow nanoparticles but also maintained the enzymatic activity of GOx. A colorimetric sensor for rapid detection of glucose was fabricated through the GOx@ZIF-8(NiPd) based multi-enzyme system and the cascade reaction for the visual detection of glucose was successfully combined into one step. Moreover, the GOx@ZIF-8(NiPd) modified electrode showed good bioactivity of GOx and high electrocatalytic activity for the oxygen reduction reaction (ORR), which could also be used for electrochemical detection of glucose. The proposed strategy for the fabrication of artificial multi-enzyme system builds a potential bridge of cooperation between nanozyme and natural enzyme.
      PubDate: 2017-11-09T03:55:57.977899-05:
      DOI: 10.1002/anie.201710418
       
  • Thermally-activated delayed fluorescence in Y3N@C80 endohedral fullerene:
           time resolved luminescence and electron paramagnetic resonance studies
    • Authors: Michal Zalibera; Denis S Krylov, Dimitrios Karagiannis, Paul-Anton Will, Frank Ziegs, Sandra Schiemenz, Wolfgang Lubitz, Sebastian Reineke, Anton Savitsky, Alexey Alexandrovich Popov
      Abstract: Endohedral fullerene Y3N@C80 exhibits luminescence with reasonable quantum yield and extraordinary long lifetime. By variable-temperature steady-state and time-resolved luminescence spectroscopy, we demonstrate that above 60 K the Y3N@C80 exhibits thermally-activated delayed fluorescence with maximum emission at 120 K and a negligible prompt fluorescence. Below 60 K, a phosphorescence with a lifetime of 192 ms is observed. Spin distribution and dynamics in the triplet excited state is investigated with X- and W-band EPR and ENDOR spectroscopies and DFT computations. Finally, electroluminescence of the Y3N@C80/PFO film is demonstrated opening the possibility for red-emitting fullerene-based organic light-emitting diodes (OLEDs).
      PubDate: 2017-11-09T03:55:35.398246-05:
      DOI: 10.1002/anie.201710637
       
  • Schottky Catalysts Boost Hydrogen Evolution: the Case of MoB/g-C3N4
           Interface Materials
    • Authors: Zechao Zhuang; Yong Li, Zilan Li, Fan Lv, Zhiquan Lang, Kangning Zhao, Liang Zhou, Lyudmila Moskaleva, Shaojun Guo, Liqiang Mai
      Abstract: Moderate proton adsorption on metallic catalysts is a prerequisite for efficient hydrogen evolution reaction (HER). However, precisely tuning the proton adsorption without perturbing metallicity still remains a formidable challenge. Herein, we fabricate an ingenious Schottky catalyst based on metal-semiconductor junction principles. When selecting metallic MoB as a paradigm, the introduction of n-type semiconductive g-C3N4 induces a vigorous charge transfer across the MoB/g-C3N4 Schottky junction, and increases the local electron density in MoB surface, proved by multiple spectroscopic techniques. This Schottky catalyst exhibits a superior HER activity with a low Tafel slope of 46 mV dec-1 and a high exchange current density of 17 μA cm-2, far better than that of pristine MoB. First-principle calculations reveal that Schottky contact dramatically lowers the kinetic barriers of both proton adsorption and reduction coordinates, therefore benefiting the surface hydrogen generation.
      PubDate: 2017-11-08T21:56:09.393972-05:
      DOI: 10.1002/anie.201708748
       
  • Fast Heavy-Atom Tunneling in Trifluoroacetyl Nitrene
    • Authors: Zhuang Wu; Ruijuan Feng, Hongmin Li, Jian Xu, Guohai Deng, Manabu Abe, Didier Bégué, Kun Liu, Xiaoqing Zeng
      Abstract: Chemical reactions involving quantum mechanical tunneling (QMT) increasingly attract the attention of scientists. In contrast to the hydrogen-tunneling as frequently observed in chemistry and biology, tunneling solely by heavy atoms is rare. Herein, we report heavy-atom tunneling in trifluoroacetyl nitrene, CF3C(O)N. The carbonyl nitrene CF3C(O)N in the triplet ground state was generated in cryogenic matrices by laser (193 or 266 nm) photolysis of CF3C(O)N3 and characterized by IR and EPR spectroscopy. In contrast to the theoretically predicted activation barriers (>10 kcal mol−1), CF3C(O)N undergoes rapid rearrangement into CF3NCO with half-life times of less than 10 min and unprecedentedly large 14N/15N kinetic isotope effects (1.18–1.33) in solid Ar, Ne, and N2 matrices even at 2.8 K. The tunneling disappearance of CF3C(O)N becomes much slower in the chemically active toluene and in 2-methyltetrahydrofuran at 5 K.Tunnel vision: Trifluoroacetyl nitrene (CF3C(O)N) in the triplet ground state was generated and characterized. In contrast to the theoretically predicted activation barrier of more than 10 kcal mol−1, the nitrene undergoes a fast [1,2]-CF3-shift into singlet trifluoromethyl isocyanate (CF3NCO) via heavy-atom tunneling in cryogenic matrices (2.8–23.0 K).
      PubDate: 2017-11-08T10:27:19.432751-05:
      DOI: 10.1002/anie.201710307
       
  • Chemoselective and Bioorthogonal Ligation Reactions. Concepts and
           Applications. 2 Volumes Edited by W. Russ Algar, Philip Dawson, and
           Igor L. Medintz.
    • Authors: Jörg Rademann
      Abstract: Wiley-VCH, Weinheim 2017. 724 pp., hardcover, € 249.00.—ISBN 978-3527334360
      PubDate: 2017-11-08T10:27:12.736108-05:
      DOI: 10.1002/anie.201710401
       
  • Recognizing Through-Bond and Through-Space Self-Exchange Charge/Spin
           Transfer Pathways in Bis(triarylamine) Radical Cations with Similar
           Geometrical Arrangements
    • Authors: Masashi Uebe; Tatsuya Kazama, Ryohei Kurata, Daisuke Sakamaki, Akihiro Ito
      Abstract: Radical cations of bis(triarylamine)s, 3 and 4, in which the triarylamine redox centers are bridged by an ortho-phenylene and ortho-carborane cluster, respectively, have been prepared to elucidate the difference in intramolecular charge/spin-transfer (ICT/IST) pathway owing to the two different bridging units affording similar geometrical arrangements between the redox centers. Electrochemistry, absorption spectroscopy, VT-ESR spectroscopy, and DFT calculations reveal that 3.+ and 4.+ are classified into class II and class I mixed-valence systems, respectively, and therefore, through-bond and through-space mechanisms are dominant for the ICT/IST phenomena in 3.+ and 4.+, respectively. Moreover, SQUID measurements for dicationic species provide the fact that virtually no spin-exchange interaction is observed for spins in 42+, while the antiferromagnetic interaction for spins in 32+, in accordance with the existence of a conjugation pathway for the ortho-phenylene bridge.On-road or off-road: Ortho-phenylene- and ortho-carborane-bridged bis(triarylamine) radical cations (see picture: left and right, respectively) exhibited different aspects of their intramolecular charge/spin-transfer pathways: through-bond and through-space, respectively.
      PubDate: 2017-11-08T10:27:11.075161-05:
      DOI: 10.1002/anie.201709874
       
  • Reduction of a Cerium(III) Siloxide Complex to Afford a Quadruple-Decker
           Arene-Bridged Cerium(II) Sandwich
    • Authors: Rory P. Kelly; Laurent Maron, Rosario Scopelliti, Marinella Mazzanti
      Abstract: Organometallic multi-decker sandwich complexes containing f-elements remain rare, despite their attractive magnetic and electronic properties. The reduction of the CeIII siloxide complex, [KCeL4] (1; L=OSi(OtBu)3), with excess potassium in a THF/toluene mixture afforded a quadruple-decker arene-bridged complex, [K(2.2.2-crypt)]2[{(KL3Ce)(μ-η6:η6-C7H8)}2Ce] (3). The structure of 3 features a [Ce(C7H8)2] sandwich capped by [KL3Ce] moieties with a linear arrangement of the Ce ions. Structural parameters, UV/Vis/NIR data, and DFT studies indicate the presence of CeII ions involved in δ bonding between the Ce cations and toluene dianions. Complex 3 is a rare lanthanide multi-decker complex and the first containing non-classical divalent lanthanide ions. Moreover, oxidation of 1 by AgOTf (OTf=O3SCF3) yielded the CeIV complex, [CeL4] (2), showing that siloxide ligands can stabilize Ce in three oxidation states.CeII in the sandwich: A quadruple-decker sandwich of divalent cerium was assembled from siloxide-supported CeIII and toluene under strongly reducing conditions. The siloxide ligands and the δ-bonds between the Ce centers and the toluene dianion are key in the assembly.
      PubDate: 2017-11-08T10:26:55.7662-05:00
      DOI: 10.1002/anie.201709769
       
  • A Simply Synthesized, Tough Polyarylene with Transient Mechanochromic
           Response
    • Authors: Fabian Kempe; Oliver Brügner, Hannah Buchheit, Sarah Noemi Momm, Felix Riehle, Sophie Hameury, Michael Walter, Michael Sommer
      Abstract: A simple, straightforward and high-yielding route to tough polyarylenes of type poly(meta,meta,para-phenylene) (PmmpP) is developed. PmmpP is already tough in its as-synthesized state at intermediate molar mass of Mw ~60 kg/mol and exhibits outstanding mechanical properties for further optimized molecular weight (Mw = 96 kg/mol, E = 0.9 GPa, ε = 300 %). Statistical copolymers with para,para spiropyran (SP) are mechanochromic, whereby the tough behavior allows to investigate mechanochromism. Strained samples instantaneously lose color upon force release. DFT calculations show this phenomenon to be caused by i) the tough PmmpP matrix that allows build-up of sufficiently large forces to be transduced to SP, and ii) the relatively unstable corresponding merocyanine (MC) form arising from the aromatic comonomer. MC units covalently incorporated into PmmpP show a drastically reduced half life time of 3.1 s compared to 4.5 h obtained for SP derivatives with common 6 nitro substitution.
      PubDate: 2017-11-08T07:25:45.473438-05:
      DOI: 10.1002/anie.201709142
       
  • Magnesium Boryl Reactivity with 9-BBN and Ph3B: Rational B-B' Bond
           Formation and Diborane Isomerization
    • Authors: Michael Stephen Hill; Anne-Frederique Pecharman, Claire McMullin, Mary Mahon
      Abstract: Reactions of a magnesium-based pinacolatoboryl nucleophile with the electrophilic dialkylboranes, 9-BBN and Ph3B, provide facile B-B' single bond formation. Although the Ph3B derivative is thermally stable, when heated, the unsymmetrical diborane(5) anion derived from 9-BBN is found to isomerize to two regioisomeric species via a proposed mechanism involving dehydroboration of the borabicyclo[3.3.1]nonane and syn-diboration of the resultant alkenyl carboccycle.
      PubDate: 2017-11-08T06:56:23.444515-05:
      DOI: 10.1002/anie.201709902
       
  • Hydrogen Atom Transfer-Initiated Radical Cyclization of Alkene-Tethered
           Ketones
    • Authors: Josep Bonjoch; BEN BRADSHAW, MAR SALADRIGAS, Caroline Bosch, Gisela V. Saborit
      Abstract: An unprecedented hydrogen atom transfer-based C-C coupling reaction between alkenes and ketones using Fe(acac)3 and PhSiH3 in EtOH is described. This mild protocol features high site-selectivity and allows for the construction of sterically congested structures containing tertiary alcohols and quaternary centers. The overall process introduces a novel strategic bond disconnection for ring-closing reactions.
      PubDate: 2017-11-08T06:56:17.099947-05:
      DOI: 10.1002/anie.201709659
       
  • Asymmetric Imine Hydroboration Catalyzed by Chiral Diazaphospholenes
    • Authors: Matt Rhodes Adams; Chieh-Hung Tien, Robert McDonald, Alexander William Harrison Speed
      Abstract: The first use of diazaphospholenes as chiral catalysts has been demonstrated with enantioselective imine hydroboration. A chiral diazaphospholene prepared in a simple three-step synthesis from commercial materials has been shown to achieve the highest enantioselectivity for hydroboration of alkyl imines with pinacolborane reported to date. Enantiomer ratios of up to 88:12 were obtained with low (2 mol %) catalyst loadings. Shown are 20 examples of asymmetric reduction employing this main-group catalysis protocol, including the synthesis of the pharmaceuticals ent-rasagiline and fendiline.
      PubDate: 2017-11-08T06:25:55.498785-05:
      DOI: 10.1002/anie.201709926
       
  • Engineering of a DNA polymerase for direct m6A sequencing
    • Authors: Andreas Marx; Joos Aschenbrenner, Stephan Werner, Virginie Marchand, Martina Adam, Yuri Motorin, Mark Helm
      Abstract: Methodologies for the detection of RNA modifications are of fundamental importance for advancing epitranscriptomics. N6-methyladenosine (m6A) is the most abundant RNA modification in mammalian mRNA and involved in regulation of gene expression. Current detection techniques are laborious and rely on antibody based enrichment of m6A containing RNA prior to sequencing, as m6A modifications are generally "erased" during reverse transcription (RT). To overcome the drawbacks associated with indirect detection, we aimed to generate novel DNA polymerase variants for direct m6A sequencing. Therefore, we developed a screen to evolve an RT-active KlenTaq DNA polymerase variant that sets a mark for N6-methylation. We identified a mutant that exhibits increased misincorporation opposite m6A as compared to unmodified A. Application of the generated DNA polymerase in Next-Generation Sequencing allowed the identification of m6A sites directly from the sequencing data of untreated RNA samples.
      PubDate: 2017-11-08T05:55:47.807739-05:
      DOI: 10.1002/anie.201710209
       
  • A Stable Nano-Cobalt Catalyst for Selective Dehydrogenation of Formic Acid
           with Highly Dispersed CoNx Active Sites
    • Authors: Conghui Tang; Annette-Enrica Surkus, Feng Chen, Marga-Martina Pohl, Giovanni Agostini, Matthias Schneider, Henrik Junge, Matthias Beller
      Abstract: Novel nano-structured catalysts with highly dispersed cobalt have been synthesized using pyrolysis of metal phenanthroline complexes. Materials with significantly different properties are obtained by simply tuning the metal/ligand ratio. As an example for the catalytic potential of this class of compounds, the first atomically dispersed cobalt-catalyzed dehydrogenation of formic acid is described. From TEM, XPS, XRD characterizations, KSCN poisoning and acid leaching, the formation of CoNx species as the active site seems key to success for this reaction. Excellent stability and recyclability makes this new catalyst also attractive for other applications.
      PubDate: 2017-11-08T04:56:53.429561-05:
      DOI: 10.1002/anie.201710766
       
  • Photoinduced Remote Functionalizations via Iminyl Radical-Promoted C-C and
           C-H Bond Cleavage Cascades.
    • Authors: Elizabeth M. Dauncey; Sara P. Marcillo, James J. Douglas, Nadeem S. Sheikh, Daniele Leonori
      Abstract: A photoinduced cascade strategy leading to a variety of differentially functionalized nitriles and ketones has been developed. These protocols rely on the oxidative generation of iminyl radicals from simple oximes. Radical transposition by sp3-sp3 C-C and sp3 C-H bond cleavages gives access to distal carbon-radicals that undergo SH2-functionalizations. These mild, visible-light-mediated protocols allow remote fluorinations, chlorinations and azidations and have been applied to the modification of bioactive and structurally complex molecules.
      PubDate: 2017-11-08T03:56:48.35164-05:0
      DOI: 10.1002/anie.201710790
       
  • Highly Crystalline Mesoporous C60 with Ordered Pores: A New Class of
           Nanomaterials for Energy Applications
    • Authors: Mercy Benzigar; Stalin Joseph, Hamid Ilbeygi, Dae-Hwan Park, Sujoy Sarkar, Goutam Chandra, Siva Umapathy, Sampath Srinivasan, Siddulu Talapaneni, Ajayan Vinu
      Abstract: Highly ordered mesoporous C60 with well-ordered porous structure and a high crystallinity is prepared through the nanohard templating method using saturated solution of C60 in 1-chloronaphthalene (51 mg mL-1) as a C60 precursor and SBA-15 as a hard template. The high solubility of C60 in 1-chloronaphthalene helps not only to encapsulate a huge amount of the C60 into the mesopores of the template but also supports the oligomerization of C60 and the formation of crystalline walls made of C60. The obtained mesoporous C60 exhibits a rod shaped morphology, a high specific surface area (680 m2 g-1), tuneable pores, and a highly crystalline wall structure. This exciting ordered mesoporous C60 offers high supercapacitive performance and a high selectivity to H2O2 production and methanol tolerance for ORR. We expect that this simple strategy could be adopted to make a series of mesoporous fullerenes with different structures and carbon atoms as a new class of energy materials.
      PubDate: 2017-11-08T03:25:53.911643-05:
      DOI: 10.1002/anie.201710888
       
  • Cover Picture: Selective Utilization of the Methoxy Group in Lignin to
           Produce Acetic Acid (Angew. Chem. Int. Ed. 47/2017)
    • Authors: Qingqing Mei; Huizhen Liu, Xiaojun Shen, Qinglei Meng, Hangyu Liu, Junfeng Xiang, Buxing Han
      Pages: 14773 - 14773
      Abstract: Selective transformation of lignin into a valuable chemical, acetic acid, is possible. In their Communication on page 14868 ff. B. Han, H. Liu et al. propose a strategy for selective transformation of methoxy groups, which are abundant in lignin, into pure acetic acid. The conversions of methoxy groups in kraft lignin and organosolv lignin reached 87.3% and 80.4%, respectively, and no by-product was generated. This work opens the way to the production of pure chemicals by using lignin as the feedstock.
      PubDate: 2017-10-27T05:01:40.017929-05:
      DOI: 10.1002/anie.201710736
       
  • Inside Cover: Organoiridium Photosensitizers Induce Specific Oxidative
           Attack on Proteins within Cancer Cells (Angew. Chem. Int. Ed. 47/2017)
    • Authors: Pingyu Zhang; Cookson K. C. Chiu, Huaiyi Huang, Yuko P. Y. Lam, Abraha Habtemariam, Thomas Malcomson, Martin J. Paterson, Guy J. Clarkson, Peter B. O'Connor, Hui Chao, Peter J. Sadler
      Pages: 14774 - 14774
      Abstract: Photodynamic therapy can be used to introduce novel mechanisms of killing cancer cells that overcome resistance. In their Communication on page 14898 ff., P. B. O'Connor, H. Chao, P. J. Sadler et al. describe luminescent organoiridium complexes, with long-lived excited states, which selectively damage cancer cells upon activation by two-photon red light, thus producing oxygen which attacks key cellular proteins (cover art by Juanjuan Huang).
      PubDate: 2017-11-06T08:11:01.488039-05:
      DOI: 10.1002/anie.201710973
       
  • Graphical Abstract: Angew. Chem. Int. Ed. 47/2017
    • Pages: 14777 - 14795
      PubDate: 2017-11-15T06:53:50.499915-05:
      DOI: 10.1002/anie.201784711
       
  • Spotlights on our sister journals: Angew. Chem. Int. Ed. 47/2017
    • Pages: 14796 - 14799
      PubDate: 2017-11-15T06:54:01.382711-05:
      DOI: 10.1002/anie.201784713
       
  • Tomoya Miura
    • Pages: 14800 - 14800
      Abstract: “My favorite molecules are terminal alkynes. If I could be a piece of lab equipment, I would be a pair of tweezers ...” This and more about Tomoya Miura can be found on page 14800.
      PubDate: 2017-08-17T08:12:06.190078-05:
      DOI: 10.1002/anie.201707581
       
  • Schlenk Lectureship: S. Harder / Kabiller Prize: R. S. Langer / Kabiller
           Young Investigator Award: L. Zhang / Wilhelm Manchot Research
           Professorship: P. S. Baran
    • Pages: 14801 - 14801
      PubDate: 2017-10-25T10:01:37.11452-05:0
      DOI: 10.1002/anie.201710438
       
  • Gérard Férey (1941–2017)
    • Authors: Christian Serre
      Pages: 14802 - 14802
      Abstract: Gérard Férey, a leader in the field of solid-state chemistry and a pioneer of metal–organic frameworks (MOFs), passed away on August 19, 2017 in Paris. Férey developed both open-framework templated metal fluorophosphates (the ULM-n series) and a series of topical porous MOFs (the MIL-n series). He also created the automated assembly of secondary building units methodology to predict the structure of new porous solids.
      PubDate: 2017-10-19T02:08:01.149221-05:
      DOI: 10.1002/anie.201709508
       
  • Active Cocatalysts for Photocatalytic Hydrogen Evolution Derived from
           Nickel or Cobalt Amine Complexes
    • Authors: Yi Huang; Bin Zhang
      Pages: 14804 - 14806
      Abstract: A cost-effective and robust strategy for the anchoring of molecular hydrogen evolution cocatalysts onto semiconductors has recently been reported. The composite materials were highly efficient and stable towards photocatalytic H2 evolution. This study provides guidance for the design and construction of highly active heterogeneous photocatalysts.
      PubDate: 2017-10-11T07:25:21.688528-05:
      DOI: 10.1002/anie.201708844
       
  • Flash Vacuum Pyrolysis: Techniques and Reactions
    • Authors: Curt Wentrup
      Pages: 14808 - 14835
      Abstract: Flash vacuum pyrolysis (FVP) had its beginnings in the 1940s and 1950s, mainly through mass spectrometric detection of pyrolytically formed free radicals. In the 1960s many organic chemists started performing FVP experiments with the purpose of isolating new and interesting compounds and understanding pyrolysis processes. Meanwhile, many different types of apparatus and techniques have been developed, and it is the purpose of this review to present the most important methods as well as a survey of typical reactions and observations that can be achieved with the various techniques. This includes preparative FVP, chemical trapping reactions, matrix isolation, and low temperature spectroscopy of reactive intermediates and unstable molecules, the use of online mass, photoelectron, microwave, and millimeterwave spectroscopies, gas-phase laser pyrolysis, pulsed pyrolysis with supersonic jet expansion, very low pressure pyrolysis for kinetic investigations, solution-spray and falling-solid FVP for involatile compounds, and pyrolysis over solid supports and reagents. Moreover, the combination of FVP with matrix isolation and photochemistry is a powerful tool for investigations of reaction mechanism.Quick as a flash: This review describes flash pyrolysis methods for the synthesis of unusual molecules and for the characterization of reactive intermediates. The most important methods are presented, and an overview of typical reactions and observations that are possible with the various techniques are presented.
      PubDate: 2017-10-25T10:02:34.016056-05:
      DOI: 10.1002/anie.201705118
       
  • Mechanism-Based Inhibitors of the Human Sirtuin 5 Deacylase:
           Structure–Activity Relationship, Biostructural, and Kinetic Insight
    • Authors: Nima Rajabi; Marina Auth, Kathrin R. Troelsen, Martin Pannek, Dhaval P. Bhatt, Martin Fontenas, Matthew D. Hirschey, Clemens Steegborn, Andreas S. Madsen, Christian A. Olsen
      Pages: 14836 - 14841
      Abstract: The sirtuin enzymes are important regulatory deacylases in a variety of biochemical contexts and may therefore be potential therapeutic targets through either activation or inhibition by small molecules. Here, we describe the discovery of the most potent inhibitor of sirtuin 5 (SIRT5) reported to date. We provide rationalization of the mode of binding by solving co-crystal structures of selected inhibitors in complex with both human and zebrafish SIRT5, which provide insight for future optimization of inhibitors with more “drug-like” properties. Importantly, enzyme kinetic evaluation revealed a slow, tight-binding mechanism of inhibition, which is unprecedented for SIRT5. This is important information when applying inhibitors to probe mechanisms in biology.SAR studies of mechanism-based inhibitors, combined with structural insight from X-ray co-crystal structures, provide potent inhibitors of the sirtuin 5 hydrolase. Kinetic investigations furthermore reveal unprecedented slow, tight-binding behavior of several compounds.
      PubDate: 2017-11-02T04:53:18.966003-05:
      DOI: 10.1002/anie.201709050
       
  • Analysis of Molecular Orientation in Organic Semiconducting Thin Films
           Using Static Dynamic Nuclear Polarization Enhanced Solid-State NMR
           Spectroscopy
    • Authors: Katsuaki Suzuki; Shosei Kubo, Fabien Aussenac, Frank Engelke, Tatsuya Fukushima, Hironori Kaji
      Pages: 14842 - 14846
      Abstract: Molecular orientation in amorphous organic semiconducting thin-film devices is an important issue affecting device performance. However, to date it has not been possible to analyze the “distribution” of the orientations. Although solid-state NMR (ssNMR) spectroscopy can provide information on the “distribution” of molecular orientations, the technique is limited because of the small amount of sample in the device and the low sensitivity of ssNMR. Here, we report the first application of dynamic nuclear polarization enhanced ssNMR (DNP-ssNMR) spectroscopy for the orientational analysis of amorphous phenyldi(pyren-1-yl)phosphine oxide (POPy2). The 31P DNP-ssNMR spectra exhibited a sufficient signal-to-noise ratio to quantify the distribution of molecular orientations in amorphous films: the P=O axis of the vacuum-deposited and drop-cast POPy2 shows anisotropic and isotropic distribution, respectively. The different molecular orientations reflect the molecular origin of the different charge transport behaviors.The orientation of organic semiconducting molecules in an amorphous thin film was studied by static dynamic nuclear polarization enhanced solid-state NMR spectroscopy. In a vacuum-deposited film of the electron transport material POPy2, the P=O axis tends to orient perpendicular to the substrate. There is a close relationship between the orientational distribution and charge transport behavior.
      PubDate: 2017-10-25T02:40:37.056891-05:
      DOI: 10.1002/anie.201707208
       
  • Reducing the Charge Carrier Transport Barrier in Functionally Layer-Graded
           Electrodes
    • Authors: Yanyan Zhang; Oleksandr I. Malyi, Yuxin Tang, Jiaqi Wei, Zhiqiang Zhu, Huarong Xia, Wenlong Li, Jia Guo, Xinran Zhou, Zhong Chen, Clas Persson, Xiaodong Chen
      Pages: 14847 - 14852
      Abstract: Lithium-ion batteries (LIBs) are primary energy storage devices to power consumer electronics and electric vehicles, but their capacity is dramatically decreased at ultrahigh charging/discharging rates. This mainly originates from a high Li-ion/electron transport barrier within a traditional electrode, resulting in reaction polarization issues. To address this limitation, a functionally layer-graded electrode was designed and fabricated to decrease the charge carrier transport barrier within the electrode. As a proof-of-concept, functionally layer-graded electrodes composing of TiO2(B) and reduced graphene oxide (RGO) exhibit a remarkable capacity of 128 mAh g−1 at a high charging/discharging rate of 20 C (6.7 A g−1), which is much higher than that of a traditionally homogeneous electrode (74 mAh g−1) with the same composition. This is evidenced by the improvement of effective Li ion diffusivity as well as electronic conductivity in the functionally layer-graded electrodes.A functionally graded electrode was developed to address reaction polarization issue in lithium-ion batteries by increasing effective Li ion diffusivity as well as electronic conductivity. As evidence, a layer-graded electrode composed of TiO2(B) and reduced graphene oxide exhibits much higher capacity (128 mAh g−1) than that of traditional homogeneous electrode (74 mAh g−1) at a high charging current density of 6.7 A g−1.
      PubDate: 2017-10-20T04:40:43.775772-05:
      DOI: 10.1002/anie.201707883
       
  • Structural Snapshots of α-1,3-Galactosyltransferase with Native
           Substrates: Insight into the Catalytic Mechanism of Retaining
           Glycosyltransferases
    • Authors: David Albesa-Jové; M. Ángela Sainz-Polo, Alberto Marina, Marcelo E. Guerin
      Pages: 14853 - 14857
      Abstract: Glycosyltransferases (GTs) are a key family of enzymes that catalyze the synthesis of glycosidic bonds in all living organisms. The reaction involves the transfer of a glycosyl moiety and can proceed with retention or inversion of the anomeric configuration. To date, the catalytic mechanism of retaining GTs is a topic of great controversy, particularly for those enzymes containing a putative nucleophilic residue in the active site, for which the occurrence of a double-displacement mechanism has been suggested. We report native ternary complexes of the retaining glycosyltransferase α-1,3-galactosyltransferase (α3GalT) from Bos taurus, which contains such a nucleophile in the active site, in a productive mode for catalysis in the presence of its sugar donor UDP-Gal, the acceptor substrate lactose, and the divalent cation cofactor. This new experimental evidence supports the occurrence of a front-side substrate-assisted SNi-type reaction for α3GalT, and suggests a conserved common catalytic mechanism among retaining GTs.Crystal clear: A crystal structure was obtained for a native ternary complex of the GT6 family glycosyltransferase α-1,3-galactosyltransferase (α3GalT), which contains a putative nucleophile in the active site, in a productive mode for catalysis. The configuration of the active center supports the occurrence of a front-side substrate-assisted SNi-type reaction, and suggests a conserved common catalytic mechanism among retaining glycosyltransferases.
      PubDate: 2017-10-20T02:02:44.428829-05:
      DOI: 10.1002/anie.201707922
       
  • Induction of Single-Handed Helicity of Polyacetylenes Using Mechanically
           Chiral Rotaxanes as Chiral Sources
    • Authors: Fumitaka Ishiwari; Kazuko Nakazono, Yasuhito Koyama, Toshikazu Takata
      Pages: 14858 - 14862
      Abstract: Effective induction of preferred-handed helicity of polyacetylenes by pendant mechanically chiral rotaxanes is discussed. Polyacetylenes possessing optically active mechanically chiral rotaxanes in the side chains were synthesized by the polymerization of the corresponding enantiopure [2]rotaxane-type ethynyl monomers prepared by the chiral-phase HPLC separations. The CD Cotton effects revealed that the polyacetylenes took preferred-handed helical conformations depending on the rotaxane chirality. The preferred-handed helix was not disturbed by an additional chiral substituent on the rotaxane side chain. These results demonstrate the significance and utility of mechanically chiral rotaxanes for the effective construction of asymmetric fields.Mechanically chiral compounds are utilized as a chiral source. Polyacetylenes with optically active mechanically chiral rotaxanes in the side chains show strong circular dichroism on the main-chain absorption regions, indicating that the rotaxanes efficiently induce helicity with preferred handedness. These results demonstrate the significance and utility of mechanically chiral rotaxanes for the construction of asymmetric fields.
      PubDate: 2017-10-18T03:20:32.616941-05:
      DOI: 10.1002/anie.201707926
       
  • Experimental and Computational Study of an Unexpected Iron-Catalyzed
           Carboetherification by Cooperative Metal and Ligand Substrate Interaction
           and Proton Shuttling
    • Authors: Osama El-Sepelgy; Aleksandra Brzozowska, Luis Miguel Azofra, Yoon Kyung Jang, Luigi Cavallo, Magnus Rueping
      Pages: 14863 - 14867
      Abstract: An iron-catalyzed cycloisomerization of allenols to deoxygenated pyranose glycals has been developed. Combined experimental and computational studies show that the iron complex exhibits a dual catalytic role in that the non-innocent cyclopentadienone ligand acts as proton shuttle by initial hydrogen abstraction from the alcohol and by facilitating protonation and deprotonation events in the isomerization and demetalation steps. Molecular orbital analysis provides insight into the unexpected and selective formation of the 3,4-dihydro-2H-pyran.Not as innocent as it looks: Allenols underwent cycloisomerization to deoxygenated pyranose glycals in the presence of an iron complex, the cyclopentadienone ligand of which acted as proton shuttle to facilitate protonation and deprotonation events in the isomerization and demetalation steps. Molecular orbital analysis provided insight into the unexpected and selective formation of the 3,4-dihydro-2H-pyran products.
      PubDate: 2017-10-24T06:13:18.681513-05:
      DOI: 10.1002/anie.201708240
       
  • Selective Utilization of the Methoxy Group in Lignin to Produce Acetic
           Acid
    • Authors: Qingqing Mei; Huizhen Liu, Xiaojun Shen, Qinglei Meng, Hangyu Liu, Junfeng Xiang, Buxing Han
      Pages: 14868 - 14872
      Abstract: Selective transformation of lignin into a valuable chemical is of great importance and challenge owing to its complex structure. Herein, we propose a strategy for the transformation of methoxy group (-OCH3) which is abundant in lignin into pure highly valuable chemicals. As an example to apply this strategy, a route to produce acetic acid with high selectivity by conversion of methoxy group of lignin was developed. It was demonstrated that the methoxy group in lignin could react with CO and water to generate acetic acid over RhCl3 in the presence of a promoter. The conversions of methoxy group in the kraft lignin and organosolv lignin reached 87.5 % and 80.4 %, respectively, and no by-product was generated. This work opens the way to produce pure chemicals using lignin as the feedstock.Made from biomass: The transformation of methoxy groups in lignin into acetic acid is possible by selective reaction of the methoxy groups with CO and water over RhCl3. The conversion of the methoxy groups in lignin can reach 87.5 % with 100 % selectivity to acetic acid.
      PubDate: 2017-09-22T06:06:22.007315-05:
      DOI: 10.1002/anie.201706846
       
  • Carbene Footprinting Reveals Binding Interfaces of a Multimeric
           Membrane-Spanning Protein
    • Authors: Lucio Manzi; Andrew S. Barrow, Jonathan T. S. Hopper, Renata Kaminska, Colin Kleanthous, Carol V. Robinson, John E. Moses, Neil J. Oldham
      Pages: 14873 - 14877
      Abstract: Mapping the interaction sites between membrane-spanning proteins is a key challenge in structural biology. In this study a carbene-footprinting approach was developed and applied to identify the interfacial sites of a trimeric, integral membrane protein, OmpF, solubilised in micelles. The diazirine-based footprinting probe is effectively sequestered by, and incorporated into, the micelles, thus leading to efficient labelling of the membrane-spanning regions of the protein upon irradiation at 349 nm. Areas associated with protein–protein interactions between the trimer subunits remained unlabelled, thus revealing their location.A distinctive footprint: A carbene-footprinting approach was used to identify the interfacial sites of a trimeric integral membrane protein solubilised in micelles. The diazirine probe was incorporated into the micelles and labelled the membrane-spanning regions of the protein upon irradiation at 349 nm (see picture). Areas associated with protein–protein interactions between the trimer subunits remained unlabelled, thus revealing their location.
      PubDate: 2017-10-20T01:30:55.718353-05:
      DOI: 10.1002/anie.201708254
       
  • A Radiolabeling-Free, qPCR-Based Method for Locus-Specific Pseudouridine
           Detection
    • Authors: Zhixin Lei; Chengqi Yi
      Pages: 14878 - 14882
      Abstract: Pseudouridine (Ψ) is the most abundant post-transcriptional RNA modification. Methods have been developed for locus-specific Ψ detection; however, they often involve radiolabeling of RNA, require advanced experimental skills, and can be time-consuming. Herein we report a radiolabeling-free, qPCR-based method to rapidly detect locus-specific Ψ. Pseudouridine residues were labeled chemically, and the resulting adducts induced mutation/deletion during reverse transcription (RT) to generate qPCR products with different melting temperatures and hence altered melting curves. We validated our method on known Ψ sites in rRNA and then used it to sensitively detect Ψ residues in lncRNA and mRNA of low abundance. Finally, we applied our method to pseudouridine synthase identification and showed that Ψ616 in PSME2 mRNA is dependent on PUS7. Our facile and cost-effective method takes only 1.5 days to complete, and with slight adjustment it can be applied to the detection of other epitranscriptomic marks.A day and a half to complete the hunt: A rapid and cost-effective method has been developed to detect pseudouridine, a prevalent post-transcriptional RNA modification, in the human transcriptome. Pseudouridine was labeled chemically, and the resulting adducts induced mutation/deletion during reverse transcription (RT) to generate qPCR products with different melting temperatures and hence altered melting curves (see picture).
      PubDate: 2017-10-19T07:40:41.469186-05:
      DOI: 10.1002/anie.201708276
       
  • Cobalt versus Osmium: Control of Both trans and cis Selectivity in
           Construction of the EFG Rings of Pectenotoxin 4
    • Authors: Ahria Roushanbakhti; Yifan Liu, Paul C. M. Winship, Michael J. Tucker, Wasim M. Akhtar, Daryl S. Walter, Gail Wrigley, Timothy J. Donohoe
      Pages: 14883 - 14887
      Abstract: Catalytic oxidative cyclisation reactions have been employed for the synthesis of the E and F rings of the complex natural product target pectenotoxin 4. The choice of metal catalyst (cobalt- or osmium-based) allowed for the formation of THF rings with either trans or cis stereoselectivity. Fragment union using a modified Julia reaction then enabled the synthesis of an advanced synthetic intermediate containing the EF and G rings of the target.Two types of oxidative cyclisation reaction, utilising either osmium or cobalt catalysis, provide complete control of the relative stereochemistry of THF rings embedded in the complex pectenotoxin-4 ring system. In this manner, rapid access to either trans (Co) or cis (Os) 2,5-disubstituted THF rings of the natural product molecule was facilitated.
      PubDate: 2017-10-19T06:41:35.519226-05:
      DOI: 10.1002/anie.201708278
       
  • Peptide Logic Circuits Based on Chemoenzymatic Ligation for Programmable
           Cell Apoptosis
    • Authors: Yong Li; Sujuan Sun, Lin Fan, Shanfang Hu, Yan Huang, Ke Zhang, Zhou Nie, Shouzhou Yao
      Pages: 14888 - 14892
      Abstract: A novel and versatile peptide-based bio-logic system capable of regulating cell function is developed using sortase A (SrtA), a peptide ligation enzyme, as a generic processor. By modular peptide design, we demonstrate that mammalian cells apoptosis can be programmed by peptide-based logic operations, including binary and combination gates (AND, INHIBIT, OR, and AND-INHIBIT), and a complex sequential logic circuit (multi-input keypad lock). Moreover, a proof-of-concept peptide regulatory circuit was developed to analyze the expression profile of cell-secreted protein biomarkers and trigger cancer-cell-specific apoptosis.It's only bio-logical: A versatile peptide-based bio-logic system has been developed by using sortase A (SrtA), an emerging peptide ligation enzyme, as a generic processor. By modular design of peptide inputs, cancer cells apoptosis can be programmed by peptide logic circuits.
      PubDate: 2017-10-24T06:13:09.628078-05:
      DOI: 10.1002/anie.201708327
       
  • Generalized Self-Doping Engineering towards Ultrathin and Large-Sized
           Two-Dimensional Homologous Perovskites
    • Authors: Junnian Chen; Yaguang Wang, Lin Gan, Yunbin He, Huiqiao Li, Tianyou Zhai
      Pages: 14893 - 14897
      Abstract: Two-dimensional (2D) homologous perovskites are arousing intense interest in photovoltaics and light-emitting fields, attributing to significantly improved stability and increasing optoelectronic performance. However, investigations on 2D homologous perovskites with ultrathin thickness and large lateral dimension have been seldom reported, being mainly hindered by challenges in synthesis. A generalized self-doping directed synthesis of ultrathin 2D homologous (BA)2(MA)n−1PbnBr3n+1 (1
      PubDate: 2017-10-20T01:56:20.727686-05:
      DOI: 10.1002/anie.201708434
       
  • Organoiridium Photosensitizers Induce Specific Oxidative Attack on
           Proteins within Cancer Cells
    • Authors: Pingyu Zhang; Cookson K. C. Chiu, Huaiyi Huang, Yuko P. Y. Lam, Abraha Habtemariam, Thomas Malcomson, Martin J. Paterson, Guy J. Clarkson, Peter B. O'Connor, Hui Chao, Peter J. Sadler
      Pages: 14898 - 14902
      Abstract: Strongly luminescent iridium(III) complexes, [Ir(C,N)2(S,S)]+ (1) and [Ir(C,N)2(O,O)] (2), containing C,N (phenylquinoline), O,O (diketonate), or S,S (dithione) chelating ligands, have been characterized by X-ray crystallography and DFT calculations. Their long phosphorescence lifetimes in living cancer cells give rise to high quantum yields for the generation of 1O2, with large 2-photon absorption cross-sections. 2 is nontoxic to cells, but potently cytotoxic to cancer cells upon brief irradiation with low doses of visible light, and potent at sub-micromolar doses towards 3D multicellular tumor spheroids with 2-photon red light. Photoactivation causes oxidative damage to specific histidine residues in the key proteins in aldose reductase and heat-shock protein-70 within living cancer cells. The oxidative stress induced by iridium photosensitizers during photoactivation can increase the levels of enzymes involved in the glycolytic pathway.In for a shock: A highly luminescent organoiridium complex generates 1O2 efficiently and oxidizes specific residues of heat-shock protein-70 and aldose reductase within cancer cells. The oxidative stress induced by iridium photosensitizers during photoactivation can increase the levels of the enzymes involved in the glycolytic pathway.
      PubDate: 2017-10-19T02:07:01.788775-05:
      DOI: 10.1002/anie.201709082
       
  • Experimental and Computational Exploration of para-Selective Silylation
           with a Hydrogen-Bonded Template
    • Authors: Arun Maji; Srimanta Guin, Sheng Feng, Amit Dahiya, Vikas Kumar Singh, Peng Liu, Debabrata Maiti
      Pages: 14903 - 14907
      Abstract: The regioselective conversion of C−H bonds into C−Si bonds is extremely important owing to the natural abundance and non-toxicity of silicon. Classical silylation reactions often suffer from poor functional group compatibility, low atom economy, and insufficient regioselectivity. Herein, we disclose a template-assisted method for the regioselective para silylation of toluene derivatives. A new template was designed, and the origin of selectivity was analyzed experimentally and computationally. An interesting substrate–solvent hydrogen-bonding interaction was observed. Kinetic, spectroscopic, and computational studies shed light on the reaction mechanism. The synthetic significance of this strategy was highlighted by the generation of a precursor of a potential lipophilic bioisostere of γ-aminobutyric acid (GABA), various late-stage diversifications, and by mimicking enzymatic transformations.A template-assisted method for the regioselective para silylation of toluene derivatives is described. The origin of selectivity was analyzed both experimentally and computationally, and an interesting substrate–solvent hydrogen-bonding interaction was observed.
      PubDate: 2017-10-25T02:41:46.139141-05:
      DOI: 10.1002/anie.201708449
       
  • Lanthanide-Coordinated Semiconducting Polymer Dots Used for Flow Cytometry
           and Mass Cytometry
    • Authors: Xu Wu; Quinn DeGottardi, I-Che Wu, Jiangbo Yu, Li Wu, Fangmao Ye, Chun-Ting Kuo, William W. Kwok, Daniel T. Chiu
      Pages: 14908 - 14912
      Abstract: Simultaneous monitoring of biomarkers as well as single-cell analyses based on flow cytometry and mass cytometry are important for investigations of disease mechanisms, drug discovery, and signaling-network studies. Flow cytometry and mass cytometry are complementary to each other; however, probes that can satisfy all the requirements for these two advanced technologies are limited. In this study, we report a probe of lanthanide-coordinated semiconducting polymer dots (Pdots), which possess fluorescence and mass signals. We demonstrated the usage of this dual-functionality probe for both flow cytometry and mass cytometry in a mimetic cell mixture and human peripheral blood mononuclear cells as model systems. The probes not only offer high fluorescence signal for use in flow cytometry, but also show better performance in mass cytometry than the commercially available counterparts.Lanthanide-coordinated semiconducting polymer nanoparticles with bright fluorescence show outstanding performances in both flow cytometry and mass cytometry for cell analyses.
      PubDate: 2017-10-12T06:20:40.818779-05:
      DOI: 10.1002/anie.201708463
       
  • Structure and Mechanism of the Monoterpene Cyclolavandulyl Diphosphate
           Synthase that Catalyzes Consecutive Condensation and Cyclization
    • Authors: Takeo Tomita; Masaya Kobayashi, Yuma Karita, Yoko Yasuno, Tetsuro Shinada, Makoto Nishiyama, Tomohisa Kuzuyama
      Pages: 14913 - 14917
      Abstract: We report the three-dimensional structure of cyclolavandulyl diphosphate (CLPP) synthase (CLDS), which consecutively catalyzes the condensation of two molecules of dimethylallyl diphosphate (DMAPP) followed by cyclization to form a cyclic monoterpene, CLPP. The structures of apo-CLDS and CLDS in complex with Tris, pyrophosphate, and Mg2+ ion were refined at 2.00 Å resolution and 1.73 Å resolution, respectively. CLDS adopts a typical fold for cis-prenyl synthases and forms a homo-dimeric structure. An in vitro reaction using a regiospecifically 2H-substituted DMAPP substrate revealed the intramolecular proton transfer mechanism of the CLDS reaction. The CLDS structure and structure-based mutagenesis provide mechanistic insights into this unprecedented terpene synthase. The combination of structural and mechanistic insights advances the knowledge of intricate terpene synthase-catalyzed reactions.A synthase that can do both: Cyclolavandulyl diphosphate (CLPP) synthase (CLDS) catalyzes “head-to-middle” condensation of two molecules of dimethylallyl diphosphate (DMAPP) and subsequent cyclization to produce CLPP. The crystal structure of CLDS in complex with Tris, pyrophosphate, and Mg2+ ion was refined at 1.73 Å resolution. An in vitro reaction using a regiospecifically deuterated DMAPP, the CLDS structure, and mutagenesis provide mechanistic insights into this unique terpene synthase.
      PubDate: 2017-10-11T06:21:14.299235-05:
      DOI: 10.1002/anie.201708474
       
  • Fluorine Effects on Group Migration via a Rhodium(V) Nitrenoid
           Intermediate
    • Authors: Cheng-Qiang Wang; Yu Zhang, Chao Feng
      Pages: 14918 - 14922
      Abstract: An unprecedented rhodium(III)-catalyzed hydroarylation of α,α-difluoromethylene alkynes with N-pivaloxyl aroylamides through sequential C−H activation and aryl migration is detailed herein. A large array of α,α-difluoromethylene alkynes and N-pivaloxyl aryl amides were amenable to this transformation, thus providing a novel synthetic protocol for the construction of difluorinated 2-alkenyl aniline derivatives in high yields and with excellent regioselectivity. Notably, unique fluorine effects were found to underlie the thus unconventional reaction manifold.Exploring new avenues: Rhodium(III)-catalyzed hydroarylation of α,α-difluoromethylene alkynes with N-pivaloyloxy aryl amides enabled the efficient regiospecific synthesis of difluorinated 2-alkenyl aniline derivatives (see scheme). The fluorine substituents in the alkyne substrates diverted the course of the reaction from the conventional annulation pathway to promote the hydroarylation process involving Lossen rearrangement.
      PubDate: 2017-10-09T04:56:16.31659-05:0
      DOI: 10.1002/anie.201708505
       
  • Compartmentalizing Supramolecular Hydrogels Using Aqueous Multi-phase
           Systems
    • Authors: Serhii Mytnyk; Alexandre G. L. Olive, Frank Versluis, Jos M. Poolman, Eduardo Mendes, Rienk Eelkema, Jan H. van Esch
      Pages: 14923 - 14927
      Abstract: A generic method is used for compartmentalization of supramolecular hydrogels by using water-in-water emulsions based on aqueous multi-phase systems (AMPS). By forming the low-molecular-weight hydrogel throughout all phases of all-aqueous emulsions, distinct, micro-compartmentalized materials were created. This structuring approach offers control over the composition of each type of the compartments by directing the partitioning of objects to be encapsulated. Moreover, this method allows for barrier-less, dynamic exchange of even large hydrophilic solutes (MW≈60 kDa) between separate aqueous compartments. These features are expected to find use in the fields of, for instance, micro-structured catalysts, templating, and tissue engineering.Hydrogel compartments: A versatile approach is used to create aqueous microcompartments inside low-molecular-weight hydrogels using polymer phase separation. Distinct micrometer-sized domains are thus created with controlled composition and unrestricted exchange of even large polar solutes. The method may potentially find use for templating porous soft materials or in the fabrication of tissue engineering scaffolds.
      PubDate: 2017-09-12T01:45:59.444409-05:
      DOI: 10.1002/anie.201706272
       
  • Photoluminescence Lifetime Imaging of Synthesized Proteins in Living Cells
           Using an Iridium–Alkyne Probe
    • Authors: Jinyu Wang; Jie Xue, Zihe Yan, Sichun Zhang, Juan Qiao, Xinrong Zhang
      Pages: 14928 - 14932
      Abstract: Designing probes for real-time imaging of dynamic processes in living cells is a continuous challenge. Herein, a novel near-infrared (NIR) photoluminescence probe having a long lifetime was exploited for photoluminescence lifetime imaging (PLIM) using an iridium-alkyne complex. This probe offers the benefits of deep-red to NIR emission, a long Stokes shift, excellent cell penetration, low cytotoxicity, and good resistance to photobleaching. This example is the first PLIM probe applicable to the click reaction of copper(I)-catalyzed azide–alkyne cycloaddition (CuAAC) with remarkable lifetime shifts of 414 ns, before and after click reaction. The approach fully eliminates the background interference and distinguishes the reacted probes from the unreacted probes, thus enabling the wash-free imaging of the newly synthesized proteins within single living cells. Based on the unique properties of the iridium complexes, it is anticipated to have applications for imaging other processes within living cells.It takes a lifetime: A novel bioorthogonal probe, an Ir-alkyne complex, was designed and synthesized. It showed deep-red to near-IR emission and unexpected large lifetime shifts of 414 ns before and after click reaction. This probe enabled the wash-free imaging of the newly synthesized proteins within living cells. NP=nanoparticle.
      PubDate: 2017-10-13T06:20:31.600647-05:
      DOI: 10.1002/anie.201708566
       
  • Enzyme Encapsulation by a Ferritin Cage
    • Authors: Stephan Tetter; Donald Hilvert
      Pages: 14933 - 14936
      Abstract: Ferritins, conserved across all kingdoms of life, are protein nanocages that evolved to mineralize iron. The last several decades have shown that these cages have considerable technological and medical potential owing to their stability and tolerance to modification, as well as their ability to template nanoparticle synthesis and incorporate small molecules. Here we show that it is possible to encapsulate proteins in a ferritin cage by exploiting electrostatic interactions with its negatively charged interior. Positively supercharged green fluorescent protein is efficiently taken up by Archaeoglobus fulgidus ferritin in a tunable fashion. Moreover, several enzymes were readily incorporated when genetically tethered to this fluorescent protein. These fusion proteins retained high catalytic activity and showed increased tolerance to proteolysis and heat. Equipping ferritins with enzymatic activity paves the way for many new nanotechnological and pharmacological applications.The caged bird sings: The natural ferritin nanocage from Archaeoglobus fulgidus can encapsulate positively charged proteins (green) within its lumenal cavity through electrostatic interactions. Enzymes (gray) attached to such charged guests retain their activity [substrate (S)product (P)], thus equipping the ferritin cages with new catalytic functions and opening new avenues for their use in nanotechnology and pharmacology.
      PubDate: 2017-10-12T08:11:19.442953-05:
      DOI: 10.1002/anie.201708530
       
  • One-Pot, Three-Component Sulfonimidamide Synthesis Exploiting the
           Sulfinylamine Reagent N-Sulfinyltritylamine, TrNSO
    • Authors: Thomas Q. Davies; Adrian Hall, Michael C. Willis
      Pages: 14937 - 14941
      Abstract: Sulfonimidamides are increasingly important molecules in medicinal chemistry and agrochemistry, but their preparation requires lengthy synthetic sequences, which has likely limited their use. We describe a one-pot de novo synthesis of sulfonimidamides from widely available organometallic reagents and amines. This convenient and efficient process uses a stable sulfinylamine reagent, N-sulfinyltritylamine (TrNSO), available in one step on 10 gram scale, as a linchpin. In contrast to classical approaches starting from thiols or their derivatives, our TrNSO-based approach facilitates the rapid assembly of the three reaction components into a variety of differentially substituted sulfonimidamides containing medicinally relevant moieties, including pyridines and indoles. Analogues of the sulfonamide-containing COX-2 inhibitor Celecoxib were prepared and evaluated.Come and join us: The stable, readily prepared sulfinylamine reagent TrNSO is exploited as a linchpin to join organometallic reagents and amines to provide sulfonimidamides in a high yielding one-pot process. Good variation of both reaction components is possible.
      PubDate: 2017-10-10T07:08:15.884506-05:
      DOI: 10.1002/anie.201708590
       
  • Transient Behavior of the Metal Interface in Lithium Metal–Garnet
           Batteries
    • Authors: Kun (Kelvin) Fu; Yunhui Gong, Zhezhen Fu, Hua Xie, Yonggang Yao, Boyang Liu, Marcus Carter, Eric Wachsman, Liangbing Hu
      Pages: 14942 - 14947
      Abstract: The interface between solid electrolytes and Li metal is a primary issue for solid-state batteries. Introducing a metal interlayer to conformally coat solid electrolytes can improve the interface wettability of Li metal and reduce the interfacial resistance, but the mechanism of the metal interlayer is unknown. In this work, we used magnesium (Mg) as a model to investigate the effect of a metal coating on the interfacial resistance of a solid electrolyte and Li metal anode. The Li–Mg alloy has low overpotential, leading to a lower interfacial resistance. Our motivation is to understand how the metal interlayer behaves at the interface to promote increased Li-metal wettability of the solid electrolyte surface and reduce interfacial resistance. Surprisingly, we found that the metal coating dissolved in the molten piece of Li and diffused into the bulk Li metal, leading to a small and stable interfacial resistance between the garnet solid electrolyte and the Li metal. We also found that the interfacial resistance did not change with increase in the thickness of the metal coating (5, 10, and 100 nm), due to the transient behavior of the metal interface layer.Resistance is futile: Magnesium was used as a model material to investigate the effect of a metal coating on the interfacial resistance between the garnet (Li7La3Zr2O12) solid electrolyte and the Li metal anode in a Li–garnet solid-state battery. Surprisingly, the metal coating dissolves and diffuses into the bulk Li metal, leading to a small and stable interfacial resistance.
      PubDate: 2017-10-19T08:10:44.796778-05:
      DOI: 10.1002/anie.201708637
       
  • Synthesis of Arylamines via Aminium Radicals
    • Authors: Thomas D. Svejstrup; Alessandro Ruffoni, Fabio Juliá, Valentin M. Aubert, Daniele Leonori
      Pages: 14948 - 14952
      Abstract: Arylamines constitute the core structure of many therapeutic agents, agrochemicals, and organic materials. The development of methods for the efficient and selective construction of these structural motifs from simple building blocks is desirable but still challenging. We demonstrate that protonated electron-poor O-aryl hydroxylamines give aminium radicals in the presence of Ru(bpy)3Cl2. These highly electrophilic species undergo polarized radical addition to aromatic compounds in high yield and selectivity. We successfully applied this method to the late-stage modification of chiral catalyst templates, therapeutic agents, and natural products.A radical solution: Protonated electron-poor O-aryl hydroxylamines give aminium radicals in the presence of Ru(bpy)3Cl2. These highly electrophilic species undergo polarized radical addition to aromatic compounds to give arylamines in high yield and selectivity. This method has a broad reaction scope and was successfully applied to the late-stage modification of chiral catalyst templates, therapeutic agents, and natural products.
      PubDate: 2017-10-24T11:42:57.563471-05:
      DOI: 10.1002/anie.201708693
       
  • A Low-Cost Neutral Zinc–Iron Flow Battery with High Energy Density for
           Stationary Energy Storage
    • Authors: Congxin Xie; Yinqi Duan, Wenbin Xu, Huamin Zhang, Xianfeng Li
      Pages: 14953 - 14957
      Abstract: Flow batteries (FBs) are one of the most promising stationary energy-storage devices for storing renewable energy. However, commercial progress of FBs is limited by their high cost and low energy density. A neutral zinc–iron FB with very low cost and high energy density is presented. By using highly soluble FeCl2/ZnBr2 species, a charge energy density of 56.30 Wh L−1 can be achieved. DFT calculations demonstrated that glycine can combine with iron to suppress hydrolysis and crossover of Fe3+/Fe2+. The results indicated that an energy efficiency of 86.66 % can be obtained at 40 mA cm−2 and the battery can run stably for more than 100 cycles. Furthermore, a low-cost porous membrane was employed to lower the capital cost to less than $ 50 per kWh, which was the lowest value that has ever been reported. Combining the features of low cost, high energy density and high energy efficiency, the neutral zinc–iron FB is a promising candidate for stationary energy-storage applications.Even flow: A neutral zinc–iron flow battery with very low cost and high energy density is presented. By using highly soluble FeCl2/ZnBr2 species, a charge energy density of 56.30 Wh L−1 can be achieved. DFT calculations demonstrated that glycine can combine with iron to suppress hydrolysis and crossover of Fe3+/Fe2+. An energy efficiency of 86.66 % can be obtained at 40 mA cm−2 and the battery can run stably for more than 100 cycles.
      PubDate: 2017-10-20T01:35:29.16625-05:0
      DOI: 10.1002/anie.201708664
       
  • Electrostatic-Assisted Liquefaction of Porous Carbons
    • Authors: Peipei Li; Jennifer A. Schott, Jinshui Zhang, Shannon M. Mahurin, Yujie Sheng, Zhen-An Qiao, Xunxiang Hu, Guokai Cui, Dongdong Yao, Suree Brown, Yaping Zheng, Sheng Dai
      Pages: 14958 - 14962
      Abstract: Porous liquids are a newly developed porous material that combine unique fluidity with permanent porosity, which exhibit promising functionalities for a variety of applications. However, the apparent incompatibility between fluidity and permanent porosity makes the stabilization of porous nanoparticle with still empty pores in the dense liquid phase a significant challenging. Herein, by exploiting the electrostatic interaction between carbon networks and polymerized ionic liquids, we demonstrate that carbon-based porous nanoarchitectures can be well stabilized in liquids to afford permanent porosity, and thus opens up a new approach to prepare porous carbon liquids. Furthermore, we hope this facile synthesis strategy can be widely applicated to fabricate other types of porous liquids, such as those (e.g., carbon nitride, boron nitride, metal–organic frameworks, covalent organic frameworks etc.) also having the electrostatic interaction with polymerized ionic liquids, evidently advancing the development and understanding of porous liquids.Porous carbon liquids: By exploiting the electrostatic interaction between carbon networks and polymerized ionic liquids, hollow carbon spheres can be stabilized in liquids to afford permanent porosity. Porous carbon liquids (HCS-liquid) are promising for a variety of applications, such as CO2 separation and storage.
      PubDate: 2017-10-23T01:25:46.035077-05:
      DOI: 10.1002/anie.201708843
       
  • Oxetane Grafts Installed Site-Selectively on Native Disulfides to Enhance
           Protein Stability and Activity In Vivo
    • Authors: Nuria Martínez-Sáez; Shuang Sun, Davide Oldrini, Pietro Sormanni, Omar Boutureira, Filippo Carboni, Ismael Compañón, Michael J. Deery, Michele Vendruscolo, Francisco Corzana, Roberto Adamo, Gonçalo J. L. Bernardes
      Pages: 14963 - 14967
      Abstract: A four-membered oxygen ring (oxetane) can be readily grafted into native peptides and proteins through site-selective bis-alkylation of cysteine residues present as disulfides under mild and biocompatible conditions. The selective installation of the oxetane graft enhances stability and activity, as demonstrated for a range of biologically relevant cyclic peptides, including somatostatin, proteins, and antibodies, such as a Fab arm of the antibody Herceptin and a designed antibody DesAb-Aβ against the human Amyloid-β peptide. Oxetane grafting of the genetically detoxified diphtheria toxin CRM197 improves significantly the immunogenicity of this protein in mice, which illustrates the general utility of this strategy to modulate the stability and biological activity of therapeutic proteins containing disulfides in their structures.Graft to stabilize: An efficient one-pot method introduces oxetane grafts on native disulfides of peptides and proteins under biocompatible aqueous conditions. This method allows stabilization of folded structures (four examples shown) and enhancement of their biological activity in vitro and in vivo.
      PubDate: 2017-10-20T01:55:40.461872-05:
      DOI: 10.1002/anie.201708847
       
  • Oxidative Rearrangement Coupling Reaction for the Functionalization of
           Tetrahydro-β-carbolines with Aromatic Amines
    • Authors: Jinxiang Ye; Jianlei Wu, Tingting Lv, Guolin Wu, Yu Gao, Haijun Chen
      Pages: 14968 - 14972
      Abstract: The observation of an unexpected oxidative rearrangement coupling reaction led to the development of a novel method for the efficient functionalization of tetrahydro-β-carbolines (THβCs). The treatment of THβCs with photogenerated singlet oxygen (1O2) afforded unstable dioxetanes, which underwent further transformation to form new bonds in the presence of trifluoroacetic acid. This operationally simple protocol exhibits broad functional-group tolerance and is suitable for the late-stage functionalization of complex druglike molecules.All rearrange please: The treatment of tetrahydro-β-carbolines with photogenerated singlet oxygen led to unstable dioxetanes, which underwent ring opening to give synthetic intermediates with a nine-membered ring. These products reacted with amines in the presence of an acid to form a variety of amino-substituted dihydropyrroloquinolines (see scheme). This simple method is suitable for the late-stage functionalization of complex druglike molecules.
      PubDate: 2017-10-19T02:06:44.24434-05:0
      DOI: 10.1002/anie.201708893
       
  • Conotoxin Φ-MiXXVIIA from the Superfamily G2 Employs a Novel Cysteine
           Framework that Mimics Granulin and Displays Anti-Apoptotic Activity
    • Authors: Ai-Hua Jin; Zoltan Dekan, Michael J. Smout, David Wilson, Sébastien Dutertre, Irina Vetter, Richard J. Lewis, Alex Loukas, Norelle L. Daly, Paul F. Alewood
      Pages: 14973 - 14976
      Abstract: Conotoxins are a large family of disulfide-rich peptides that contain unique cysteine frameworks that target a broad range of ion channels and receptors. We recently discovered the 33-residue conotoxin Φ-MiXXVIIA from Conus miles with a novel cysteine framework comprising three consecutive cysteine residues and four disulfide bonds. Regioselective chemical synthesis helped decipher the disulfide bond connectivity and the structure of Φ-MiXXVIIA was determined by NMR spectroscopy. The 3D structure displays a unique topology containing two β-hairpins that resemble the N-terminal domain of granulin. Similar to granulin, Φ-MiXXVIIA promotes cell proliferation (EC50 17.85 μm) while inhibiting apoptosis (EC50 2.2 μm). Additional framework XXVII sequences were discovered with homologous signal peptides that define the new conotoxin superfamily G2. The novel structure and biological activity of Φ-MiXXVIIA expands the repertoire of disulfide-rich conotoxins that recognize mammalian receptors.Like structure, like activity: Conotoxin Φ-MiXXVIIA contains a novel cysteine framework comprising three consecutive cysteines and four disulfide bonds. NMR and regioselective chemical synthesis assigned the disulfide bond connectivity. Φ-MiXXVIIA displays a unique structure and novel proliferative and anti-apoptotic activity.
      PubDate: 2017-10-24T06:12:38.299618-05:
      DOI: 10.1002/anie.201708927
       
  • Mass-Production of Mesoporous MnCo2O4 Spinels with Manganese(IV)- and
           Cobalt(II)-Rich Surfaces for Superior Bifunctional Oxygen Electrocatalysis
           
    • Authors: Wenhai Wang; Long Kuai, Wei Cao, Marko Huttula, Sami Ollikkala, Taru Ahopelto, Ari-Pekka Honkanen, Simo Huotari, Mengkang Yu, Baoyou Geng
      Pages: 14977 - 14981
      Abstract: A mesoporous MnCo2O4 electrode material is made for bifunctional oxygen electrocatalysis. The MnCo2O4 exhibits both Co3O4-like activity for oxygen evolution reaction (OER) and Mn2O3-like performance for oxygen reduction reaction (ORR). The potential difference between the ORR and OER of MnCo2O4 is as low as 0.83 V. By XANES and XPS investigation, the notable activity results from the preferred MnIV- and CoII-rich surface. The electrode material can be obtained on large-scale with the precise chemical control of the components at relatively low temperature. The surface state engineering may open a new avenue to optimize the electrocatalysis performance of electrode materials. The prominent bifunctional activity shows that MnCo2O4 could be used in metal–air batteries and/or other energy devices.ORR and, not or, OER: Mass-production of mesoporous MnCo2O4 spinel with superior electrocatalysis for both the oxygen reduction (ORR) and oxygen evolution reaction (OER) is possible. The obtained MnCo2O4 has a unique MnIV- and CoII-rich surface, which stimulates the excellent bifunctional electrocatalytic performance.
      PubDate: 2017-10-23T01:25:08.963926-05:
      DOI: 10.1002/anie.201708765
       
  • Guest-Switchable Multi-Step Spin Transitions in an Amine-Functionalized
           Metal–Organic Framework
    • Authors: Wei Liu; Yuan-Yuan Peng, Si-Guo Wu, Yan-Cong Chen, Md. Najbul Hoque, Zhao-Ping Ni, Xiao-Ming Chen, Ming-Liang Tong
      Pages: 14982 - 14986
      Abstract: Materials with hysteretic multi-step spin-crossover (SCO) have potential application in high-order data storage. Here, an unprecedented hysteretic four-step SCO behavior with the sequence of LSHS0.25LS0.75HS0.5LS0.5 HS0.75LS0.25HS is found in a three-dimensional (3D) Hofmann-type metal–organic framework (MOF), which is evidenced by magnetic, differential scanning calorimetry, and crystal data. Further experiments involving guest exchange leads to the first reversible modulation of four-, two-, and one-stepped SCO behaviors, which provides a new strategy for developing multi-step SCO materials.Hysteretic four-step SCO behavior, LSHS0.25LS0.75HS0.5LS0.5HS0.75LS0.25HS, is evidenced by magnetic, differential scanning calorimetry, and crystal data. Furthermore, reversible modulation of four-, two-, and one-stepped SCO behaviors is realized through guest exchange.
      PubDate: 2017-10-24T06:12:32.439807-05:
      DOI: 10.1002/anie.201708973
       
  • Breaking the Limits in Analyzing Carbohydrate Recognition by NMR
           Spectroscopy: Resolving Branch-Selective Interaction of a Tetra-Antennary
           N-Glycan with Lectins
    • Authors: Angeles Canales; Irene Boos, Lukas Perkams, Lukas Karst, Thomas Luber, Theodoros Karagiannis, Gemma Domínguez, F. Javier Cañada, Javier Pérez-Castells, Daniel Häussinger, Carlo Unverzagt, Jesus Jiménez-Barbero
      Pages: 14987 - 14991
      Abstract: The biological recognition of complex-type N-glycans is part of many key physiological and pathological events. Despite their importance, the structural characterization of these events remains unsolved. The inherent flexibility of N-glycans hampers crystallization and the chemical equivalence of individual branches precludes their NMR characterization. By using a chemoenzymatically synthesized tetra-antennary N-glycan conjugated to a lanthanide binding tag, the NMR signals under paramagnetic conditions discriminated all four N-acetyl lactosamine antennae with unprecedented resolution. The NMR data revealed the conformation of the N-glycan and permitted for the first time the direct identification of individual branches involved in the recognition by two N-acetyllactosamine-binding lectins, Datura stramonium seed lectin (DSL) and Ricinus Communis agglutinin (RCA120).Finally resolved: For the first time, the direct identification of all four branches of a complex tetra-antennary N-glycan by paramagnetic NMR spectroscopy is possible. The unprecedented resolution allowed an in-depth characterization of the conformations and molecular recognition patterns of this complex oligosaccharide.
      PubDate: 2017-10-24T06:12:24.267571-05:
      DOI: 10.1002/anie.201709130
       
  • Direct Synthesis of Amides by Dehydrogenative Coupling of Amines with
           either Alcohols or Esters: Manganese Pincer Complex as Catalyst
    • Authors: Amit Kumar; Noel Angel Espinosa-Jalapa, Gregory Leitus, Yael Diskin-Posner, Liat Avram, David Milstein
      Pages: 14992 - 14996
      Abstract: The first example of base-metal-catalysed synthesis of amides from the coupling of primary amines with either alcohols or esters is reported. The reactions are catalysed by a new manganese pincer complex and generate hydrogen gas as the sole byproduct, thus making the overall process atom-economical and sustainable.Just a pinc(h): The first example of base-metal-catalysed synthesis of amides from the coupling of primary amines with either alcohols or esters is reported. The reactions are catalysed by a new manganese pincer complex and generate hydrogen gas as the sole byproduct, thus making the overall process atom-economical and sustainable.
      PubDate: 2017-10-20T01:56:26.286553-05:
      DOI: 10.1002/anie.201709180
       
  • Characterization of the Conjugation Pattern in Large
           Polysaccharide–Protein Conjugates by NMR Spectroscopy
    • Authors: Stefano Giuntini; Evita Balducci, Linda Cerofolini, Enrico Ravera, Marco Fragai, Francesco Berti, Claudio Luchinat
      Pages: 14997 - 15001
      Abstract: Carbohydrate-based vaccines are among the safest and most effective vaccines and represent potent tools for prevention of life-threatening bacterial infectious diseases, like meningitis and pneumonia. The chemical conjugation of a weak antigen to protein as a source of T-cell epitopes generates a glycoconjugate vaccine that results more immunogenic. Several methods have been used so far to characterize the resulting polysaccharide–protein conjugates. However, a reduced number of methodologies has been proposed for measuring the degree of saccharide conjugation at the possible protein sites. Here we show that detailed information on large proteins conjugated with large polysaccharides can be achieved by a combination of solution and solid-state NMR spectroscopy. As a test case, a large protein assembly, l-asparaginase II, has been conjugated with Neisseria meningitidis serogroup C capsular polysaccharide and the pattern and degree of conjugation were determined.Solid-state NMR spectra of highly glycosylated proteins (E. coli l-Asparaginase-II) have been obtained showing a remarkable quality. Based on this observation, a protocol that combines solution and solid-state NMR methods was developed to obtain a semi-quantitative evaluation of the conjugation degree and pattern in glycoconjugate vaccines.
      PubDate: 2017-10-19T02:07:11.178782-05:
      DOI: 10.1002/anie.201709274
       
  • Changing the Mechanism for CO2 Hydrogenation Using Solvent-Dependent
           Thermodynamics
    • Authors: Samantha A. Burgess; Aaron M. Appel, John C. Linehan, Eric S. Wiedner
      Pages: 15002 - 15005
      Abstract: A critical scientific challenge for utilization of CO2 is the development of catalyst systems that function in water and use inexpensive and environmentally friendly reagents. We have used thermodynamic insights to predict and demonstrate that the HCoI(dmpe)2 catalyst system, previously described for use in organic solvents, can hydrogenate CO2 to formate in water with bicarbonate as the only added reagent. Replacing tetrahydrofuran as the solvent with water changes the mechanism for catalysis by altering the thermodynamics for hydride transfer to CO2 from a key dihydride intermediate. The need for a strong organic base was eliminated by performing catalysis in water owing to the change in mechanism. These studies demonstrate that the solvent plays a pivotal role in determining the reaction thermodynamics and thereby catalytic mechanism and activity.Charting a new path: Switching from organic solvent to water alters the mechanism of catalytic CO2 hydrogenation by a cobalt phosphine complex. The mechanism change is attributed to the favorable impact of water on the hydride donor ability of a key catalytic intermediate. Kinetic studies indicate that this catalyst is among the most active base-metal catalysts for CO2 hydrogenation in water.
      PubDate: 2017-10-23T06:45:23.298122-05:
      DOI: 10.1002/anie.201709319
       
  • Combining Charge-Transfer Pathways to Achieve Unique Thermally Activated
           Delayed Fluorescence Emitters for High-Performance Solution-Processed,
           Non-doped Blue OLEDs
    • Authors: Xu-Lin Chen; Ji-Hui Jia, Rongmin Yu, Jian-Zhen Liao, Ming-Xue Yang, Can-Zhong Lu
      Pages: 15006 - 15009
      Abstract: Two efficient blue thermally activated delayed fluorescence compounds, B-oCz and B-oTC, composed of ortho-donor (D)–acceptor (A) arrangement were designed and synthesized. The significant intramolecular D–A interactions induce a combined charge transfer pathway and thus achieve small ΔEST and high efficiencies. The concentration quenching can be effectively inhibited in films of these compounds. The blue non-doped organic light emitting diodes (OLEDs) based on B-oTC prepared from solution processes shows record-high external quantum efficiency (EQE) of 19.1 %.Blue note: Highly efficient blue thermally activated delayed fluorescent (TADF) materials have been developed by using a new design strategy. Solution-processed, non-doped blue organic light-emitting diodes based on these emitters realized record-high external quantum efficiency of 19.1 %.
      PubDate: 2017-10-24T11:41:26.961483-05:
      DOI: 10.1002/anie.201709125
       
  • Synthesis of Octaaryl Naphthalenes and Anthracenes with Different
           Substituents
    • Authors: Shin Suzuki; Kenichiro Itami, Junichiro Yamaguchi
      Pages: 15010 - 15013
      Abstract: A synthesis of multiply arylated naphthalenes and anthracenes with eight different substituents has been accomplished. The key intermediates are tetraarylthiophene S-oxides, which are synthesized through a method involving sequential C−H arylation and cross-coupling from 3-methoxythiophene, followed by oxidation of the sulfur atom. The resulting tetraarylthiophene S-oxides can be converted into a tetraaryl benzynes or naphthalynes and then merged through [4+2] cycloaddition reaction with another tetraarylthiophene S-oxide, thereby resulting in the programmed synthesis of octaarylnaphthalenes and octaarylanthracenes.Straight to eight: A novel method is presented that enables the synthesis of octaarylnaphthalenes (OANs) and octaarylanthracenes (OAAs) with eight different aryl substituents through [4+2] cycloaddition of tetraarylthiophene S-oxides with multiply arylated arynes.
      PubDate: 2017-10-19T02:07:21.421346-05:
      DOI: 10.1002/anie.201709332
       
  • Sequence-Mandated, Distinct Assembly of Giant Molecules
    • Authors: Wei Zhang; Xinlin Lu, Jialin Mao, Chih-Hao Hsu, Gaoyan Mu, Mingjun Huang, Qingyun Guo, Hao Liu, Chrys Wesdemiotis, Tao Li, Wen-Bin Zhang, Yiwen Li, Stephen Z. D. Cheng
      Pages: 15014 - 15019
      Abstract: Although controlling the primary structure of synthetic polymers is itself a great challenge, the potential of sequence control for tailoring hierarchical structures remains to be exploited, especially in the creation of new and unconventional phases. A series of model amphiphilic chain-like giant molecules was designed and synthesized by interconnecting both hydrophobic and hydrophilic molecular nanoparticles in precisely defined sequence and composition to investigate their sequence-dependent phase structures. Not only compositional variation changed the self-assembled supramolecular phases, but also specific sequences induce unconventional phase formation, including Frank–Kasper phases. The formation mechanism was attributed to the conformational change driven by the collective hydrogen bonding and the sequence-mandated topology of the molecules. These results show that sequence control in synthetic polymers can have a dramatic impact on polymer properties and self-assembly.Molecular nanoparticles (NPs) can be precisely connected into chain-like macromolecules as sequence-controlled polymers. The sequence, along with the composition of the synthetic polymers, can be specifically designed to mandate their supramolecular phase structures. POSS=polyhedral oligomeric silsesquioxane (POSS); B hydrophobic, D hydrophilic.
      PubDate: 2017-10-24T06:11:58.05062-05:0
      DOI: 10.1002/anie.201709354
       
  • Assembly, Thermodynamics, and Structure of a Two-Wheeled Composite of a
           Dumbbell-Shaped Molecule and Cylindrical Molecules with Different Edges
    • Authors: Taisuke Matsuno; Sho Kamata, Sota Sato, Atsutoshi Yokoyama, Parantap Sarkar, Hiroyuki Isobe
      Pages: 15020 - 15024
      Abstract: A carbonaceous dumbbell was able to spontaneously glue two tubular receptors to form a unique two-wheeled composite through van der Waals interactions, thus forcing the wheel components into contact with each other at the edges. In the present study, two tubular receptors with enantiomeric carbon networks were assembled on the dumbbell joint, and the handedness of the receptors was discriminated, thus leading to the self-sorting of homomeric receptors from a mixture of enantiomeric tubes. The crystal structures of the composites revealed the structural origins of the molecular recognition driven by van der Waals forces as well as the presence of a columnar array of C120 molecules in a 1:1 composite.Leave them to sort themselves out: C120 acts as a dumbbell-shaped joint for the assembly of two tubular receptors (see picture). Enantiomeric receptor carbon networks can be discriminated on the basis of the structures of the contacting edges, thus leading to the self-sorting of homomeric receptors from a mixture of enantiomeric tubes.
      PubDate: 2017-10-23T06:45:58.62633-05:0
      DOI: 10.1002/anie.201709442
       
  • Co-adsorption of Cations as the Cause of the Apparent pH Dependence of
           Hydrogen Adsorption on a Stepped Platinum Single-Crystal Electrode
    • Authors: Xiaoting Chen; Ian T. McCrum, Kathleen A. Schwarz, Michael J. Janik, Marc T. M. Koper
      Pages: 15025 - 15029
      Abstract: The successful deployment of advanced energy-conversion systems depends critically on our understanding of the fundamental interactions of the key adsorbed intermediates (hydrogen *H and hydroxyl *OH) at electrified metal–aqueous electrolyte interfaces. The effect of alkali metal cations (Li+, Na+, K+, Cs+) on the non-Nernstian pH shift of the step-related voltammetric peak of the Pt(553) electrode is investigated over a wide pH window (1 to 13) by means of experimental and computational methods. The co-adsorbed alkali cations along the step weaken the OH adsorption at the step sites, causing a positive shift of the potential of the step-related peak on Pt(553). Density functional calculations explain the observations on the identity and concentration of alkali cations on the non-Nernstian pH shift, and demonstrate that cation–hydroxyl co-adsorption causes the apparent pH dependence of “hydrogen” adsorption in the step sites of platinum electrodes.Keeping in step: A combination of experiment and computations shows that the apparent pH dependence of hydrogen adsorption in step and defect sites of platinum electrodes is due to the co-adsorption of cations with hydroxyl. A model for this effect, which is of key importance for interpreting the electrocatalytic activity of platinum, is outlined.
      PubDate: 2017-10-23T01:55:40.940204-05:
      DOI: 10.1002/anie.201709455
       
  • Diastereoselective Construction of Densely Functionalized
           1-Halocyclopentenes Using an Alkynyl Halo-Prins/Halo-Nazarov Cyclization
           Strategy
    • Authors: Georgios Alachouzos; Alison J. Frontier
      Pages: 15030 - 15034
      Abstract: A diastereoselective two-step strategy for the synthesis of densely functionalized 1-halocyclopentenes with several chiral centers has been developed. In the first step, a multicomponent alkynyl halo-Prins reaction joins an enyne, a carbonyl derivative, and either a chloride, bromide, or iodide to produce a cyclic ether intermediate. In the subsequent step, the intermediate is ionized to generate a halopentadienyl cation, which undergoes an interrupted halo-Nazarov cyclization. The products contain three new contiguous stereogenic centers, generated with a high level of stereocontrol, as well as a vinyl halide allowing for additional functionalization. The strategy creates two new carbon–carbon bonds, one carbon–halide bond, and one carbon–oxygen bond.A two-step strategy has been developed for the synthesis of densely functionalized 1-halocyclopentenes with a high level of stereocontrol. First, a multicomponent alkynyl halo-Prins reaction joins an enyne, a carbonyl derivative, and either chloride, bromide, or iodide to produce a cyclic ether intermediate. Then, the intermediate is ionized to generate a halopentadienyl cation, which undergoes an interrupted halo-Nazarov cyclization.
      PubDate: 2017-10-24T11:40:36.379209-05:
      DOI: 10.1002/anie.201709482
       
  • Copper-Catalyzed Synthesis of γ-Amino Acids Featuring Quaternary
           Stereocenters
    • Authors: José Enrique Gómez; Wusheng Guo, Silvia Gaspa, Arjan W. Kleij
      Pages: 15035 - 15038
      Abstract: The first general asymmetric synthesis of γ,γ-disubstituted γ-amino acids by copper-catalyzed ring opening of nonstrained lactones with amines is reported. This approach features ample scope, operational simplicity, and wide functional-group diversity. The catalytic process allows access to a series of highly functionalized enantioenriched γ-amino acids featuring quaternary stereocenters with excellent enantiomeric ratios of up to 98:2 and excellent yields of up to 98 %.Open sesame: The first general asymmetric synthesis of γ,γ-disubstituted γ-amino acids by copper-catalyzed ring opening of nonstrained lactones with amines is reported. This catalytic system allows the synthesis of a series of highly functionalized γ-amino acids, featuring quaternary stereocenters, with excellent enantiomeric ratios of up to 98:2 and yields of up to 98 %.
      PubDate: 2017-10-24T11:38:03.114346-05:
      DOI: 10.1002/anie.201709511
       
  • Radical-Based C−C Bond-Forming Processes Enabled by the Photoexcitation
           of 4-Alkyl-1,4-dihydropyridines
    • Authors: Luca Buzzetti; Alexis Prieto, Sudipta Raha Roy, Paolo Melchiorre
      Pages: 15039 - 15043
      Abstract: We report herein that 4-alkyl-1,4-dihydropyridines (alkyl-DHPs) can directly reach an electronically excited state upon light absorption and trigger the generation of C(sp3)-centered radicals without the need for an external photocatalyst. Selective excitation with a violet-light-emitting diode turns alkyl-DHPs into strong reducing agents that can activate reagents through single-electron transfer manifolds while undergoing homolytic cleavage to generate radicals. We used this photochemical dual-reactivity profile to trigger radical-based carbon–carbon bond-forming processes, including nickel-catalyzed cross-coupling reactions.Powered by light: 4-alkyl-1,4-dihydropyridines 1 are primarily understood as hydride sources in their ground state. Excitation with a violet-light-emitting diode transforms them into strong reducing agents that can activate reagents through single-electron transfer while undergoing homolytic cleavage to generate alkyl radicals. This process was used to trigger radical-based C−C bond-forming processes, including nickel-catalyzed cross-coupling reactions.
      PubDate: 2017-10-24T06:11:20.665842-05:
      DOI: 10.1002/anie.201709571
       
  • Tetrazole-Based Probes for Integrated Phenotypic Screening, Affinity-Based
           Proteome Profiling, and Sensitive Detection of a Cancer Biomarker
    • Authors: Ke Cheng; Jun-Seok Lee, Piliang Hao, Shao Q. Yao, Ke Ding, Zhengqiu Li
      Pages: 15044 - 15048
      Abstract: Target-identification phenotypic screening has been a powerful approach in drug discovery; however, it is hindered by difficulties in identifying the underlying cellular targets. To address this challenge, we have combined phenotypic screening of a fully functionalized small-molecule library with competitive affinity-based proteome profiling to map and functionally characterize the targets of screening hits. Using this approach, we identified ANXA2, PDIA3/4, FLAD1, and NOS2 as primary cellular targets of two bioactive molecules that inhibit cancer cell proliferation. We further demonstrated that a panel of probes can label and/or image annexin A2 (a cancer biomarker) from different cancer cell lines, thus providing opportunities for potential cancer diagnosis and therapy.Tetrazole-based probes bearing an alkyne handle are suitable for phenotypic screening and affinity-based proteome profiling, especially Tz6, which can sensitively detect a cancer biomarker by both protein labeling and bioimaging.
      PubDate: 2017-10-23T01:56:30.494915-05:
      DOI: 10.1002/anie.201709584
       
  • Total Synthesis of Lycoricidine and Narciclasine by Chemical
           Dearomatization of Bromobenzene
    • Authors: Emma H. Southgate; Daniel R. Holycross, David Sarlah
      Pages: 15049 - 15052
      Abstract: The total synthesis of lycoricidine and narciclasine is enabled by an arenophile-mediated dearomative dihydroxylation of bromobenzene. Subsequent transpositive Suzuki coupling and cycloreversion deliver a key biaryl dihydrodiol intermediate, which is rapidly converted into lycoricidine through site-selective syn-1,4-hydroxyamination and deprotection. The total synthesis of narciclasine is accomplished by the late-stage, amide-directed C−H hydroxylation of a lycoricidine intermediate. Moreover, the general applicability of this strategy to access dihydroxylated biphenyls is demonstrated with several examples.The dearomative dihydroxylation of bromobenzene and a subsequent transpositive Suzuki coupling provide rapid and controlled access to the potent anticancer natural products narciclasine and lycoricidine. The generality of this sequence was demonstrated by the preparation of several cis-dihydroxylated biphenyls.
      PubDate: 2017-10-23T01:55:30.26743-05:0
      DOI: 10.1002/anie.201709712
       
  • Enantioselective Light Harvesting with Perylenediimide Guests on
           Self-Assembled Chiral Naphthalenediimide Nanofibers
    • Authors: Ramarani Sethy; Jatish Kumar, Rémi Métivier, Marine Louis, Keitaro Nakatani, Nila Mohan Thazhe Mecheri, Akhila Subhakumari, K. George Thomas, Tsuyoshi Kawai, Takuya Nakashima
      Pages: 15053 - 15057
      Abstract: Self-assembling molecular systems often display amplified chirality compared to the monomeric state, which makes the molecular recognition more sensitive to chiral analytes. Herein, we report the almost absolute enantioselective recognition of a chiral perylenediimide (PDI) molecule by chiral supramolecular nanofibers of a bichromophoric naphthalenediimide (NDI) derivative. The chiral recognition was evaluated through the Förster resonance energy transfer (FRET) from the NDI-based host nanofibers to the guest PDI molecules. The excitation energy was successfully transferred to the guest molecule through efficient energy migration along the host nanofiber, thus demonstrating the light-harvesting capability of these hybrid systems. Furthermore, circularly polarized luminescence (CPL) was enantioselectively sensitized by the guest molecule as the wavelength band and sign of the CPL signal were switched in response to the chiral guest molecule.The enantioselective recognition of a chiral perylenediimide (PDI) molecule by chiral supramolecular nanofibers of a bichromophoric naphthalenediimide (NDI) derivative is described. The chiral recognition was evaluated through the Förster resonance energy transfer (FRET) from the NDI nanofibers to the PDI molecules, which demonstrated the light-harvesting capability of these hybrid systems.
      PubDate: 2017-09-14T06:25:35.342029-05:
      DOI: 10.1002/anie.201707160
       
  • A Triple Salting-Out Effect is Required for the Formation of
           Ionic-Liquid-Based Aqueous Multiphase Systems
    • Authors: Helena Passos; Sara H. Costa, Ana M. Fernandes, Mara G. Freire, Robin D. Rogers, João A. P. Coutinho
      Pages: 15058 - 15062
      Abstract: Novel aqueous multiphase systems (MuPSs) formed by quaternary mixtures composed of cholinium-based ionic liquids (ILs), polymers, inorganic salts, and water are reported herein. The influence of several ILs, polymers, and salts was studied, demonstrating that a triple salting-out is a required phenomenon to prepare MuPSs. The respective phase diagrams and “tie-surfaces” were determined, followed by the evaluation of the effect of temperature. Finally, the remarkable ability of IL-based MuPSs to selectively separate mixtures of textile dyes is shown.Three's a crowd: A simultaneous, triple salting-out effect is required to form ionic-liquid-based three-phase aqueous systems. These novel aqueous multiphase systems (MuPSs) were used for the selective separation of textile dyes, demonstrating their great potential in environmental and industrial applications.
      PubDate: 2017-10-19T02:05:27.095825-05:
      DOI: 10.1002/anie.201705704
       
  • Synergistic Manganese(I) C−H Activation Catalysis in Continuous Flow:
           Chemoselective Hydroarylation
    • Authors: Hui Wang; Fabio Pesciaioli, João C. A. Oliveira, Svenja Warratz, Lutz Ackermann
      Pages: 15063 - 15067
      Abstract: Chemoselective hydroarylations were accomplished by a novel synergistic Brønsted acid/manganese(I)-catalyzed C−H activation manifold. Thus, alkynes bearing O-leaving groups could, for the first time, be employed for C−H alkenylations without concurrent β-O elimination, thereby setting the stage for versatile late-stage diversifications. Also described is the first manganese-catalyzed C−H activation in continuous flow, thus enabling efficient hydroarylations within only 20 minutes.Mn with the flow: Synergistic Brønsted acid/manganese(I) catalysis enables chemoselective hydroarylations, in flow, within 1 to 20 minutes, and sets the stage for versatile late-stage modifications. The reaction features facile C−H cleavage and the use of nontoxic sustainable manganese.
      PubDate: 2017-10-24T06:34:11.242019-05:
      DOI: 10.1002/anie.201708271
       
  • Catalytic Asymmetric [8+2] Annulation Reactions Promoted by a Recyclable
           Immobilized Isothiourea
    • Authors: Shoulei Wang; Carles Rodríguez-Escrich, Miquel A. Pericàs
      Pages: 15068 - 15072
      Abstract: Higher-order cycloaddition reactions constitute an efficient approach towards the construction of medium to large ring systems. However, enantioselective versions of these transformations remain scarce, which hampers their deployment in medicinal chemistry, or any other discipline in which homochirality is deemed crucial. Herein, we report a novel method for the production of enantiomerically enriched cycloheptatrienes fused to a pyrrolidone ring on the basis of an isothiourea-catalyzed periselective [8+2] cycloaddition reaction between chiral ammonium enolates (generated in situ from carboxylic acids) and azaheptafulvenes. The resulting bicyclic compounds can be hydrogenated, but, most remarkably, they can also undergo completely regioselective [4+2] cycloaddition with active dienophiles to give architecturally complex polycyclic compounds in a straightforward manner.Always ready for more: A periselective [8+2] cycloaddition between chiral ammonium enolates and azaheptafulvenes with a recyclable isothiourea catalyst provided enantiomerically enriched cycloheptatrienes fused to a pyrrolidone ring (see scheme). Derivatization of these versatile cycloadducts through a further regio- and diastereoselective cycloaddition reaction led to architecturally complex polycyclic compounds.
      PubDate: 2017-10-23T06:51:26.522565-05:
      DOI: 10.1002/anie.201707341
       
  • Photoredox Generation of Carbon-Centered Radicals Enables the Construction
           of 1,1-Difluoroalkene Carbonyl Mimics
    • Authors: Simon B. Lang; Rebecca J. Wiles, Christopher B. Kelly, Gary A. Molander
      Pages: 15073 - 15077
      Abstract: Described is a facile, scalable route to access functional-group-rich gem-difluoroalkenes. Using visible-light-activated catalysts in conjunction with an arsenal of carbon-radical precursors, an array of trifluoromethyl-substituted alkenes undergoes radical defluorinative alkylation. Nonstabilized primary, secondary, and tertiary radicals can be used to install functional groups in a convergent manner, which would otherwise be challenging by two-electron pathways. The process readily extends to other perfluoroalkyl-substituted alkenes. In addition, we report the development of an organotrifluoroborate reagent to expedite the synthesis of the requisite trifluoromethyl-substituted alkene starting materials.CF3 today, CF2 tomorrow: Described is a facile, scalable route to access functional-group-rich gem-difluoroalkenes. Trifluoromethyl-substituted alkenes readily undergo radical defluorinative alkylation using visible-light-activated catalysts and an arsenal of C-radical precursors. Nonstabilized primary, secondary, and tertiary radicals can be used to install various functional groups. PC=photocatalyst.
      PubDate: 2017-10-24T06:11:49.338731-05:
      DOI: 10.1002/anie.201709487
       
  • Toward Cost-Effective Manufacturing of Silicon Solar Cells:
           Electrodeposition of High-Quality Si Films in a CaCl2-based Molten Salt
    • Authors: Xiao Yang; Li Ji, Xingli Zou, Taeho Lim, Ji Zhao, Edward T. Yu, Allen J. Bard
      Pages: 15078 - 15082
      Abstract: Electrodeposition of Si films from a Si-containing electrolyte is a cost-effective approach for the manufacturing of solar cells. Proposals relying on fluoride-based molten salts have suffered from low product quality due to difficulties in impurity control. Here we demonstrate the successful electrodeposition of high-quality Si films from a CaCl2-based molten salt. Soluble SiIV−O anions generated from solid SiO2 are electrodeposited onto a graphite substrate to form a dense film of crystalline Si. Impurities in the deposited Si film are controlled at low concentrations (both B and P are less than 1 ppm). In the photoelectrochemical measurements, the film shows p-type semiconductor character and large photocurrent. A p–n junction fabricated from the deposited Si film exhibits clear photovoltaic effects. This study represents the first step to the ultimate goal of developing a cost-effective manufacturing process for Si solar cells based on electrodeposition.Creating cheaper solar cells: High-quality Si films for photovoltaic applications were fabricated by electrodeposition from molten CaCl2–CaO–SiO2. Soluble SiIV−O anions generated from solid SiO2 are electrodeposited onto a graphite substrate to form a dense and thick film of p-type Si. Impurities in the deposited Si film are controlled at low concentrations. The film exhibits good photoelectrochemical properties and clear photovoltaic effects.
      PubDate: 2017-10-19T02:06:30.648713-05:
      DOI: 10.1002/anie.201707635
       
  • “On-Droplet” Chemistry: The Cycloaddition of Diethyl
           Azodicarboxylate and Quadricyclane
    • Authors: Ryan M. Bain; Shyam Sathyamoorthi, Richard N. Zare
      Pages: 15083 - 15087
      Abstract: Sharpless and co-workers previously studied the [2σ+2σ+2π] cycloaddition of diethyl azodicarboxylate (DEAD) and quadricyclane and reported that the addition of water to the neat reagents caused an acceleration in the reaction rate, giving birth to what has been called “on-water” chemistry. We have examined the same reaction in aqueous microdroplets (ca. 5 μm diameter) and find that the cycloaddition reaction is accelerated even further (by a factor of 102) compared to that of the “on-water” reaction reported previously. The trends of acceleration in solvents other than water demonstrated by Sharpless and colleagues were replicated in the corresponding microdroplet experiments. We also find that DEAD reacts with itself to form a variety of hydrazine carboxylates and intercept intermediates of this reaction in microdroplets to validate a mechanism proposed herein. We suggest that “on-droplet” chemistry, similar to “on-water” chemistry, may be a general process of synthetic interest.Accelerated reactions: The unique reactivity “on water” of [2σ+2σ+2π] cycloadditions is further enhanced “on droplet”. A further rate acceleration of the cycloaddition reaction between diethyl azodicarboxylate and quadricyclane has been observed on microdroplets generated by electrospray ionization.
      PubDate: 2017-10-24T06:33:20.247611-05:
      DOI: 10.1002/anie.201708413
       
  • Cooperative Effects between Chiral Cpx–Iridium(III) Catalysts and Chiral
           
    • Authors: Yun-Suk Jang; Michael Dieckmann, Nicolai Cramer
      Pages: 15088 - 15092
      Abstract: An enantioselective C−H amidation of phosphine oxides by using an iridium(III) catalyst bearing an atropchiral cyclopentadienyl (Cpx) ligand is reported. A very strong cooperative effect between the chiral Cpx ligand and a phthaloyl tert-leucine enabled the transformation. Matched–mismatched cases of the different acid enantiomers are shown. The amidated P-chiral arylphosphine oxides are formed in yields of up to 95 % and with excellent enantioselectivities of up to 99:1 er. Enantiospecific reduction provides access to valuable P-chiral phosphorus(III) compounds.Catalytic handshake: A cooperative effect between a chiral CpxIrIII complex and chiral carboxylic acid enables highly enantioselective C−H amidations of phosphine oxides with up to 99:1 e.r. Matched–mismatched pairs have a strong influence on the reactivity and selectivity.
      PubDate: 2017-10-06T05:42:58.321347-05:
      DOI: 10.1002/anie.201708440
       
  • Iridium-Catalyzed Asymmetric Allylic Dearomatization by a Desymmetrization
           Strategy
    • Authors: Ye Wang; Chao Zheng, Shu-Li You
      Pages: 15093 - 15097
      Abstract: A desymmetrization strategy was developed involving iridium-catalyzed allylic dearomatization of indoles. The six-membered-ring spiroindolenines contain three contiguous stereogenic centers, including an all-carbon quaternary center, and were obtained in up to 99 % yield with 99 % ee and>95:5 d.r. When treated with a catalytic amount of tosylic acid, six-membered spiroindolenine undergoes an unprecedented six-to-seven-membered ring expansion, affording the corresponding hexahydroazepino[4,5-b]indole.The Legend of Spiro: An iridium-catalyzed desymmetrization reaction involving allylic dearomatization of indoles was developed. The six-membered-ring spiroindolenines were obtained in up to 99 % yield with 99 % ee and>95:5 d.r. When treated with a catalytic amount of tosylic acid, six-membered spiroindolenine undergoes six-to-seven-membered ring expansion, yielding hexahydroazepino[4,5-b]indole.
      PubDate: 2017-10-24T06:33:44.795796-05:
      DOI: 10.1002/anie.201708419
       
  • Electronic Delocalization in Two and Three Dimensions: Differential
           Aggregation in Indium “Metalloid” Clusters
    • Authors: Andrey V. Protchenko; Juan Urbano, Joseph A. B. Abdalla, Jesús Campos, Dragoslav Vidovic, Andrew D. Schwarz, Matthew P. Blake, Philip Mountford, Cameron Jones, Simon Aldridge
      Pages: 15098 - 15102
      Abstract: Reduction of indium boryl precursors to give two- and three-dimensional M−M bonded networks is influenced by the choice of supporting ligand. While the unprecedented nanoscale cluster [In68(boryl)12]− (with an In12@In44@In12(boryl)12 concentric structure), can be isolated from the potassium reduction of a bis(boryl)indium(III) chloride precursor, analogous reduction of the corresponding (benzamidinate)InIIIBr(boryl) system gives a near-planar (and weakly aromatic) tetranuclear [In4(boryl)4]2− system.Clusters à la carte: Reduction of indium boryl complexes to give 2D and 3D aggregates can be controlled by the choice of supporting ligand. The unprecedented nanoscale cluster In12@In44@In12(boryl)12 (see picture) is isolated from the potassium reduction of a bis(boryl) precursor, while reduction of (amidinate)InIIIBr(boryl) gives a (weakly aromatic) planar tetranuclear [In4(boryl)4]2− system.
      PubDate: 2017-10-11T06:21:31.252465-05:
      DOI: 10.1002/anie.201708496
       
  • Construction of Discrete Pentanuclear Platinum(II) Stacks with Extended
           Metal–Metal Interactions by Using Phosphorescent Platinum(II) Tweezers
    • Authors: Fred Ka-Wai Kong; Alan Kwun-Wa Chan, Maggie Ng, Kam-Hung Low, Vivian Wing-Wah Yam
      Pages: 15103 - 15107
      Abstract: Discrete pentanuclear PtII stacks were prepared by the host-guest adduct formation between multinuclear tweezer-type PtII complexes. The formation of the PtII stacks in solution was accompanied by color changes and the turning on of near-infrared emission resulting from Pt⋅⋅⋅Pt and π–π interactions. The X-ray crystal structure revealed the formation of a discrete 1:1 adduct, in which a linear stack of five PtII centers with extended Pt⋅⋅⋅Pt interactions was observed. Additional binding affinity and stability have been achieved through a multinuclear host-guest system. The binding behaviors can be fine-tuned by varying the spacer between the two PtII moieties in the guests. This work provides important insights for the construction of discrete higher-order supramolecular metal-ligand aggregates using a tweezer-directed approach.Stack up: Discrete pentanuclear PtII stacks were prepared by the host-guest adduct formation between multinuclear tweezer-type PtII complexes, with color changes and the turning on of near-infrared emission resulting from Pt⋅⋅⋅Pt and π–π interactions. The X-ray crystal structure revealed the formation of a discrete 1:1 adduct, in which a linear stack of five PtII centers with extended Pt⋅⋅⋅Pt interactions was observed.
      PubDate: 2017-10-11T07:15:30.538746-05:
      DOI: 10.1002/anie.201708504
       
  • Synthesis and Characterization of an Eclipsed Digermylene as a Building
           Block to Construct a Cyclic Octagermylene
    • Authors: Yu-Te Wey; Fan-Shan Yang, Hsien-Cheng Yu, Ting-Shen Kuo, Yi-Chou Tsai
      Pages: 15108 - 15112
      Abstract: The preparation of an unprecedented GeI-GeI bonded digermylene [K2{Ge2(μ-κ2:η2:η4-2,6-(2,6-iPr2C6H3-N)2-4-CH3C5H2N)2}] in an eclipsed conformation stabilized by two bridging diamidopyridyl ligands is presented. Although it exhibits an eclipsed conformation, the Ge−Ge bond length is 2.5168(6) Å, which is shorter than those in the trans-bent and gauche digermylenes. In combination with two pendant amido groups, the GeI2 motif is employed as a building block to assemble the first example of octagermylene [Ge4(μ-κ2:κ1-2,6-(2,6-iPr2C6H3-N)2-4-CH3C5H2N)2]2 showing a cyclic configuration and containing three distinct types of GeI−GeI bonds.Eclipse at the heart: In contrast to many examples of trans-bent digermylenes with a staggered configuration, a digermylene with an eclipsed geometry has now been characterized. The eclipsed digermylene was employed as a building block to assemble a cyclic octagermylene containing three types of GeI−GeI bonds (see picture; Ge brown, N pink).
      PubDate: 2017-10-06T05:42:34.123953-05:
      DOI: 10.1002/anie.201708551
       
  • Single-Step Reagentless Laser Scribing Fabrication of Electrochemical
           Paper-Based Analytical Devices
    • Authors: William R. de Araujo; Carolina M. R. Frasson, Wilson A. Ameku, José R. Silva, Lúcio Angnes, Thiago R. L. C. Paixão
      Pages: 15113 - 15117
      Abstract: A single-step laser scribing process is used to pattern nanostructured electrodes on paper-based devices. The facile and low-cost technique eliminates the need for chemical reagents or controlled conditions. This process involves the use of a CO2 laser to pyrolyze the surface of the paperboard, producing a conductive porous non-graphitizing carbon material composed of graphene sheets and composites with aluminosilicate nanoparticles. The new electrode material was extensively characterized, and it exhibits high conductivity and an enhanced active/geometric area ratio; it is thus well-suited for electrochemical purposes. As a proof-of-concept, the devices were successfully employed for different analytical applications in the clinical, pharmaceutical, food, and forensic fields. The scalable and green fabrication method associated with the features of the new material is highly promising for the development of portable electrochemical devices.Electrochemistry on paperboard: A simple, scalable fabrication of nanostructured electrochemical paper-based analytical devices using a CO2 laser and paperboard is presented. The method does not require additional reagents or control of the fabrication environment.
      PubDate: 2017-10-23T01:23:38.864672-05:
      DOI: 10.1002/anie.201708527
       
  • High Sulfur Content Material with Stable Cycling in Lithium-Sulfur
           Batteries
    • Authors: Molleigh B. Preefer; Bernd Oschmann, Craig J. Hawker, Ram Seshadri, Fred Wudl
      Pages: 15118 - 15122
      Abstract: We demonstrate a novel crosslinked disulfide system as a cathode material for Li-S cells that is designed with the two criteria of having only a single point of S−S scission and maximizing the ratio of S−S to the electrochemically inactive framework. The material therefore maximizes theoretical capacity while inhibiting the formation of polysulfide intermediates that lead to parasitic shuttle. The material we report contains a 1:1 ratio of S:C with a theoretical capacity of 609 mAh g−1. The cell gains capacity through 100 cycles and has 98 % capacity retention thereafter through 200 cycles, demonstrating stable, long-term cycling. Raman spectroscopy confirms the proposed mechanism of disulfide bonds breaking to form a S−Li thiolate species upon discharge and reforming upon charge. Coulombic efficiencies near 100 % for every cycle, suggesting the suppression of polysulfide shuttle through the molecular design.Put a ring on it: A crosslinked disulfide material with high sulfur content displays stable cycling in a lithium-sulfur battery with no evidence of the detrimental polysulfide shuttle.
      PubDate: 2017-10-19T02:06:35.930522-05:
      DOI: 10.1002/anie.201708746
       
  • Catalytic Reduction of Alkyl and Aryl Bromides Using Propan-2-ol
    • Authors: Michael C. Haibach; Brian M. Stoltz, Robert H. Grubbs
      Pages: 15123 - 15126
      Abstract: Milstein's complex, (PNN)RuHCl(CO), catalyzes the efficient reduction of aryl and alkyl halides under relatively mild conditions by using propan-2-ol and a base. Sterically hindered tertiary and neopentyl substrates are reduced efficiently, as well as more functionalized aryl and alkyl bromides. The reduction process is proposed to occur by radical abstraction/hydrodehalogenation steps at ruthenium. Our research represents a safer and more sustainable alternative to typical silane, lithium aluminium hydride, and tin-based conditions for these reductions.A simple complex: Milstein's complex, (PNN)RuHCl(CO), catalyzes the efficient reduction of alkyl bromides and chlorides under relatively mild reaction conditions by using propan-2-ol and a base. Sterically hindered tertiary and neopentyl substrates are reduced efficiently, as well as more-functionalized aryl and alkyl bromides. The reaction appears to occur by a radical pathway, and provides an alternative to silane, lithium aluminium hydride, and tin-based reductions.
      PubDate: 2017-10-24T11:42:39.316244-05:
      DOI: 10.1002/anie.201708800
       
  • Selective Reduction of CO2 to a Formate Equivalent with Heterobimetallic
           Gold- - -Copper Hydride Complexes
    • Authors: Alexandra Hicken; Andrew J. P. White, Mark R. Crimmin
      Pages: 15127 - 15130
      Abstract: A series of heterobimetallic complexes containing three-center, two-electron Au−H−Cu bonds have been prepared from addition of a parent gold hydride to a bent d10 copper(I) fragment. These highly unusual heterobimetallic complexes represent a missing link in the widely investigated series of neutral and cationic coinage metal hydride complexes containing Cu−H−Cu and M−H−M+ moieties (M=Cu, Ag). The well-defined heterobimetallic hydride complexes act as precatalysts for the conversion of CO2 into HCO2Bpin with HBpin as the reductant. The selectivity of the heterobimetallic complexes for the catalytic production of a formate equivalent surpasses that of the parent monomeric Group 11 complexes.The golden touch: A series of heterobimetallic complexes containing three-center, two-electron Au−H−Cu bonds have been prepared. These unusual molecules represent a missing link in the widely investigated series of neutral and cationic coinage metal hydride complexes containing Cu−H−Cu and M−H−M+ moieties (M=Cu, Ag), and act as precatalysts for the selective reduction of CO2 to HCO2Bpin.
      PubDate: 2017-10-19T02:06:56.197588-05:
      DOI: 10.1002/anie.201709072
       
  • Ruthenium-Catalyzed para-Selective C−H Alkylation of Aniline
           Derivatives
    • Authors: Jamie A. Leitch; Claire L. McMullin, Andrew J. Paterson, Mary F. Mahon, Yunas Bhonoah, Christopher G. Frost
      Pages: 15131 - 15135
      Abstract: The para-selective C−H alkylation of aniline derivatives furnished with a pyrimidine auxiliary is herein reported. This reaction is proposed to take place via an N−H-activated cyclometalate formed in situ. Experimental and DFT mechanistic studies elucidate a dual role of the ruthenium catalyst. Here the ruthenium catalyst can undergo cyclometalation by N−H metalation (as opposed to C−H metalation in meta-selective processes) and form a redox active ruthenium species, to enable site-selective radical addition at the para position.Para-normal activity: The para-selective C−H alkylation of aniline derivatives is reported. The methodology is proposed to proceed by a dual role ruthenium process: cycloruthenation at N−H and redox radical generation. This strategy leads to para-selective alkylations using pyrimidine and quinazoline auxiliaries.
      PubDate: 2017-10-24T11:42:35.599351-05:
      DOI: 10.1002/anie.201708961
       
  • A Lewis Base Catalysis Approach for the Photoredox Activation of Boronic
           Acids and Esters
    • Authors: Fabio Lima; Upendra K. Sharma, Lars Grunenberg, Debasmita Saha, Sandra Johannsen, Joerg Sedelmeier, Erik V. Van der Eycken, Steven V. Ley
      Pages: 15136 - 15140
      Abstract: We report herein the use of a dual catalytic system comprising a Lewis base catalyst such as quinuclidin-3-ol or 4-dimethylaminopyridine and a photoredox catalyst to generate carbon radicals from either boronic acids or esters. This system enabled a wide range of alkyl boronic esters and aryl or alkyl boronic acids to react with electron-deficient olefins via radical addition to efficiently form C−C coupled products in a redox-neutral fashion. The Lewis base catalyst was shown to form a redox-active complex with either the boronic esters or the trimeric form of the boronic acids (boroxines) in solution.Boronic acids turn photoactivable: A dual catalytic system comprising a Lewis base catalyst (LB) such as quinuclidin-3-ol or 4-dimethylaminopyridine and a photoredox catalyst enables the generation of carbon radicals from either boronic acids or esters. A wide range of alkyl boronic esters and aryl or alkyl boronic acids reacted with electron-deficient olefins to form C−C coupled products in a redox-neutral fashion.
      PubDate: 2017-10-24T06:11:13.032304-05:
      DOI: 10.1002/anie.201709690
       
  • A Water-Containing Organopotassium Compound Based on
           Bis(4,6-tBu-benzoxazol-2-yl)methanide and Its Unexpected Stability to
           Hydrolysis
    • Authors: Ingo Koehne; Sebastian Bachmann, Regine Herbst-Irmer, Dietmar Stalke
      Pages: 15141 - 15145
      Abstract: The bulky bis(4,6-tBu-benzoxazol-2-yl)methane ligand system enabled the synthesis of the water-containing organometallic potassium complex [(18-crown-6)K{(4,6-tBu-OCNC6H2)2CH}⋅H2O] (2), which is an unprecedented example of a water-stable reactive organopotassium compound. Furthermore, 2 is a rare example of a bis(benzoxazol-2-yl)methanide ligand displaying solely O-coordination to a metal ion. Compound 2 was fully characterized through its solid-state structure. Furthermore, its behavior in solution was investigated by NMR titration DOSY experiments. These revealed full protonation of the complex only after seven days and the addition of 114 equivalents of water.Fire and water are unified in a solely O-coordinated organopotassium complex based on the ambidentate bis(4,6-tBu-benzoxazol-2-yl)methanide ligand. The complex is fully protonated only after seven days and the addition of 114 equivalents of water, and might turn out to be a sustainable synthetic synthon in deep eutectic solvents.
      PubDate: 2017-10-23T06:51:06.360747-05:
      DOI: 10.1002/anie.201706316
       
  • Overcoming the Gas–Liquid Mass Transfer of Oxygen by Coupling
           Photosynthetic Water Oxidation with Biocatalytic Oxyfunctionalization
    • Authors: Anna Hoschek; Bruno Bühler, Andreas Schmid
      Pages: 15146 - 15149
      Abstract: Gas–liquid mass transfer of gaseous reactants is a major limitation for high space–time yields, especially for O2-dependent (bio)catalytic reactions in aqueous solutions. Herein, oxygenic photosynthesis was used for homogeneous O2 supply via in situ generation in the liquid phase to overcome this limitation. The phototrophic cyanobacterium Synechocystis sp. PCC6803 was engineered to synthesize the alkane monooxygenase AlkBGT from Pseudomonas putida GPo1. With light, but without external addition of O2, the chemo- and regioselective hydroxylation of nonanoic acid methyl ester to ω-hydroxynonanoic acid methyl ester was driven by O2 generated through photosynthetic water oxidation. Photosynthesis also delivered the necessary reduction equivalents to regenerate the Fe2+ center in AlkB for oxygen transfer to the terminal methyl group. The in situ coupling of oxygenic photosynthesis to O2-transferring enzymes now enables the design of fast hydrocarbon oxyfunctionalization reactions.Oxidation reactions often suffer from limited gas–liquid mass transfer of O2. Combining oxygenic photosynthesis with O2-transferring enzymes such as monooxygenases for chemo- and regioselective hydroxylations of hydrocarbons has the potential to overcome this limitation. Cyanobacteria as whole-cell biocatalysts homogeneously generate O2 from water, driving respective O2-dependent oxidizing enzymes.
      PubDate: 2017-10-27T02:55:24.439387-05:
      DOI: 10.1002/anie.201706886
       
  • Ethers on Si(001): A Prime Example for the Common Ground between Surface
           Science and Molecular Organic Chemistry
    • Authors: Lisa Pecher; Slimane Laref, Marc Raupach, Ralf Tonner
      Pages: 15150 - 15154
      Abstract: By using computational chemistry it has been shown that the adsorption of ether molecules on Si(001) under ultrahigh vacuum conditions can be understood with classical concepts of organic chemistry. Detailed analysis of the two-step reaction mechanism—1) formation of a dative bond between the ether oxygen atom and a Lewis acidic surface atom and 2) nucleophilic attack of a nearby Lewis basic surface atom—shows that it mirrors acid-catalyzed ether cleavage in solution. The O−Si dative bond is the strongest of its kind, and the reactivity in step 2 defies the Bell–Evans–Polanyi principle. Electron rearrangement during C−O bond cleavage has been visualized with a newly developed method for analyzing bonding, which shows that the mechanism of nucleophilic substitutions on semiconductor surfaces is identical to molecular SN2 reactions. Our findings illustrate how surface science and molecular chemistry can mutually benefit from each other and unexpected insight can be gained.The not-so-odd couple: A computational study of ethers on Si(001) has shown the commonalities of surface science and molecular chemistry. Quantitative insight into the bonding situation and reactivity demonstrates that these systems can be understood with classical reaction concepts of organic chemistry.
      PubDate: 2017-10-19T07:25:24.263594-05:
      DOI: 10.1002/anie.201707428
       
  • Dimethylamine as a Substrate in Hydroaminoalkylation Reactions
    • Authors: Jens Bielefeld; Sven Doye
      Pages: 15155 - 15158
      Abstract: Transition-metal-catalyzed hydroaminoalkylations of alkenes have made great progress over the last decade and are heading to become a viable alternative to the industrial synthesis of amines through hydroformylation of alkenes and subsequent reductive amination. In the past, one major obstacle of this progress has been an inability to apply these reactions to the most important amines, methylamine and dimethylamine. Herein, we report the first successful use of dimethylamine in catalytic hydroaminoalkylations of alkenes with good yields. We also report applicability for a variety of alkenes to show the tolerance of the reaction towards different functional groups. Additionally, we present a catalytic dihydroaminoalkylation reaction using dimethylamine, which has never been reported before.Size matters: For the first time since catalytic hydroaminoalkylation chemistry started 37 years ago, dimethylamine can efficiently be added to alkenes using an inexpensive and easily obtainable Ti catalyst. The size of the flask determines whether the reaction gives monohydroaminoalkylation or dihydroaminoalkylation.
      PubDate: 2017-10-26T08:25:56.26538-05:0
      DOI: 10.1002/anie.201708959
       
  • [SnBi3]5− —A Carbonate Analogue Comprising Exclusively
           Metal Atoms
    • Authors: Kerstin Mayer; Jasmin V. Dums, Wilhelm Klein, Thomas F. Fässler
      Pages: 15159 - 15163
      Abstract: The new [SnBi3]5− polyanion is obtained by the reaction of K3Bi2 with K4Sn9 or K12Sn17 in liquid ammonia. The anion is iso(valence)electronic with and structurally analogous to the carbonate ion. Despite the high negative charge of the anion, the Sn−Bi bond lengths range between single and double bonds. Quantum-chemical calculations at a DFT-PBE0/def2-TZVPP/COSMO level of theory reveal that the partial double bond character between the heavy main-group atoms Bi and Sn originates from a delocalized π-electronic system. The structure of the anion is determined by single-crystal X-ray diffraction analyses of the compounds K5[SnBi3] 9 NH3 (1) and K9[K(18-crown-6)][SnBi3]2⋅15 NH3 (2). The [SnBi3]5− unit is the first example of a carbonate-like anion obtained from solution, and it consists exclusively of metal atoms and completes the series of metal analogues of CO and CO2.Carbonate build up by metals: Whereas alkali metal carbonates are mostly insoluble in liquid ammonia, a carbonate analogue is formed by Bi and Sn by reaction of deeply colored solutions of polyanionc bismuthides and stannides in liquid ammonia and can be isolated as the potassium salt K5SnBi3⋅9 NH3. In contrast to carbonate, the highly charged [BiSn3]5− ion decomposes readily in the presence of traces of water.
      PubDate: 2017-10-24T06:11:00.47576-05:0
      DOI: 10.1002/anie.201709700
       
  • Inside Back Cover: Compartmentalizing Supramolecular Hydrogels Using
           Aqueous Multi-phase Systems (Angew. Chem. Int. Ed. 47/2017)
    • Authors: Serhii Mytnyk; Alexandre G. L. Olive, Frank Versluis, Jos M. Poolman, Eduardo Mendes, Rienk Eelkema, Jan H. van Esch
      Pages: 15165 - 15165
      Abstract: A hydrogel compartmentalization strategy is presented by J. H. van Esch et al. in their Communication on page 14923 ff. This method exploits the incompatibility of aqueous polymer solutions for creating distinct aqueous microdomains within a supramolecular hydrogel network. By eliminating the need for hydrophobic barriers and allowing control over domain composition, this approach offers access to a new type of structured materials.
      PubDate: 2017-10-27T05:02:18.15313-05:0
      DOI: 10.1002/anie.201710805
       
  • Back Cover: Enantioselective Light Harvesting with Perylenediimide Guests
           on Self-Assembled Chiral Naphthalenediimide Nanofibers (Angew. Chem. Int.
           Ed. 47/2017)
    • Authors: Ramarani Sethy; Jatish Kumar, Rémi Métivier, Marine Louis, Keitaro Nakatani, Nila Mohan Thazhe Mecheri, Akhila Subhakumari, K. George Thomas, Tsuyoshi Kawai, Takuya Nakashima
      Pages: 15166 - 15166
      Abstract: The enantioselective recognition of a chiral perylenediimide (PDI) molecule by chiral supramolecular nanofibers based on a naphthalenediimide (NDI) derivative is described by T. Kawai, T. Nakashima, and co-workers in their Communication on page 15053 ff. An NDI assembly with right-handed helicity selectively recognizes bichromophoric PDI derivatives with a counterclockwise arrangement.
      PubDate: 2017-10-05T03:41:48.710369-05:
      DOI: 10.1002/anie.201709986
       
 
 
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