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  Subjects -> CHEMISTRY (Total: 842 journals)
    - ANALYTICAL CHEMISTRY (50 journals)
    - CHEMISTRY (594 journals)
    - CRYSTALLOGRAPHY (21 journals)
    - ELECTROCHEMISTRY (25 journals)
    - INORGANIC CHEMISTRY (41 journals)
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    - PHYSICAL CHEMISTRY (67 journals)

CHEMISTRY (594 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: 17)
ACS Combinatorial Science     Full-text available via subscription   (Followers: 23)
ACS Macro Letters     Full-text available via subscription   (Followers: 23)
ACS Medicinal Chemistry Letters     Full-text available via subscription   (Followers: 39)
ACS Nano     Full-text available via subscription   (Followers: 230)
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: 7)
Adsorption Science & Technology     Full-text available via subscription   (Followers: 5)
Advanced Functional Materials     Hybrid Journal   (Followers: 50)
Advanced Science Focus     Free   (Followers: 3)
Advances in Chemical Engineering and Science     Open Access   (Followers: 53)
Advances in Chemical Science     Open Access   (Followers: 13)
Advances in Chemistry     Open Access   (Followers: 14)
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: 15)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 8)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 19)
Advances in Nanoparticles     Open Access   (Followers: 14)
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: 18)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 19)
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: 68)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 14)
American Journal of Chemistry     Open Access   (Followers: 26)
American Journal of Plant Physiology     Open Access   (Followers: 13)
American Mineralogist     Hybrid Journal   (Followers: 14)
Analyst     Full-text available via subscription   (Followers: 38)
Angewandte Chemie     Hybrid Journal   (Followers: 160)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 212)
Annales UMCS, Chemia     Open Access   (Followers: 1)
Annals of Clinical Chemistry and Laboratory Medicine     Open Access   (Followers: 1)
Annual Reports in Computational Chemistry     Full-text available via subscription   (Followers: 3)
Annual Reports Section A (Inorganic Chemistry)     Full-text available via subscription   (Followers: 3)
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: 13)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 14)
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: 3)
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: 290)
Biochemistry Insights     Open Access   (Followers: 5)
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: 4)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 114)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 94)
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: 2)
Canadian Journal of Chemistry     Hybrid Journal   (Followers: 10)
Canadian Mineralogist     Full-text available via subscription   (Followers: 3)
Carbohydrate Research     Hybrid Journal   (Followers: 26)
Carbon     Hybrid Journal   (Followers: 66)
Catalysis for Sustainable Energy     Open Access   (Followers: 6)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 8)
Catalysis Science and Technology     Free   (Followers: 6)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysts     Open Access   (Followers: 7)
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: 12)
Chemical Bulletin of Kazakh National University     Open Access  
Chemical Communications     Full-text available via subscription   (Followers: 71)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 23)
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 3)
Chemical Research in Toxicology     Full-text available via subscription   (Followers: 19)
Chemical Reviews     Full-text available via subscription   (Followers: 178)
Chemical Science     Open Access   (Followers: 21)
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: 55)
Chemie-Ingenieur-Technik (Cit)     Hybrid Journal   (Followers: 25)
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: 142)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 15)
Chemistry and Materials Research     Open Access   (Followers: 18)
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: 45)
Chemistry of Materials     Full-text available via subscription   (Followers: 253)
Chemistry of Natural Compounds     Hybrid Journal   (Followers: 9)
Chemistry World     Full-text available via subscription   (Followers: 22)
Chemistry-Didactics-Ecology-Metrology     Open Access  
ChemistryOpen     Open Access   (Followers: 2)
Chemkon - Chemie Konkret, Forum Fuer Unterricht Und Didaktik     Hybrid Journal  
Chemoecology     Hybrid Journal   (Followers: 2)
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: 3)
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: 2)
Copernican Letters     Open Access  
Critical Reviews in Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 5)
Crystal Structure Theory and Applications     Open Access   (Followers: 3)
CrystEngComm     Full-text available via subscription   (Followers: 12)
Current Catalysis     Hybrid Journal   (Followers: 2)
Current Metabolomics     Hybrid Journal   (Followers: 5)
Current Opinion in Colloid & Interface Science     Hybrid Journal   (Followers: 9)
Current Research in Chemistry     Open Access   (Followers: 8)
Current Science     Open Access   (Followers: 58)
Dalton Transactions     Full-text available via subscription   (Followers: 22)
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: 4)
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: 2)
Environmental Chemistry     Hybrid Journal   (Followers: 9)
Environmental Chemistry Letters     Hybrid Journal   (Followers: 4)
Environmental Science & Technology Letters     Full-text available via subscription   (Followers: 5)
Environmental Science : Nano     Partially Free   (Followers: 1)

        1 2 3 | Last

Journal Cover Angewandte Chemie
  [160 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0044-8249 - ISSN (Online) 1521-3757
   Published by John Wiley and Sons Homepage  [1577 journals]
  • Versatile Tri(pyrazolyl)phosphanes - Application as phosphorus precursors
           for the synthesis of highly emitting InP/ZnS quantum dots
    • Authors: Jan J. Weigand; Alexander Eychmüller, Rene Panzer, Chris Guhrenz, Rene Hübner, Nikolai Gaponik, Danny Haubold
      Abstract: Tri(pyrazolyl)phosphanes (5R1,R2) are utilized as an alternative, cheap and low-toxic phosphorus source for the convenient synthesis of InP/ZnS quantum dots (QDs). From these precursors, remarkably long-term stable stock solutions (>6 months) of P(OLA)3 (OLAH = oleylamine) are generated from which the respective pyrazoles are conveniently recovered. P(OLA)3 acts simultaneously as phosphorus source and reducing agent in the synthesis of highly emitting InP/ZnS core/shell QDs. These QDs are characterized by a spectral range between 530-620 nm and photoluminescence quantum yields (PL QYs) between 51-62%. A proof-of-concept white light-emitting diode (LED) applying the InP/ZnS QDs as color conversion layer was built to demonstrate their applicability and processibility.
      PubDate: 2017-08-22T04:00:47.464019-05:
      DOI: 10.1002/ange.201705650
       
  • Mechanochemistry Induced Using Force Exerted by a Functionalized
           Microscope Tip
    • Authors: Yajie Zhang; Yongfeng Wang, Jing-Tao Lü, Mads Brandbyge, Richard Berndt
      Abstract: Atomic-scale mechanochemistry is realized from force exerted by a C60-functionalized scanning tunneling microscope tip. Two conformers of tin phthalocyanine can be prepared on coinage-metal surfaces. A transition between these conformers is induced on Cu(111) and Ag(100). Density-functional calculations reveal details of this reaction. Because of the large energy barrier of the reaction and the strong interaction of SnPc with Cu(111), the process cannot be achieved by electrical means.Das war (die) Spitze! Mechanochemie auf der Ebene einzelner Atome wird durch Kräfte von einer C60-funktionalisierten Rastertunnelmikroskop-Spitze ausgelöst. Zwei Konformere von Zinnphthalocyanin wurden auf Münzmetalloberflächen erzeugt, und ein Übergang zwischen diesen Konformeren konnte auf Cu(111) und Ag(100) induziert werden.
      PubDate: 2017-08-22T02:20:48.567425-05:
      DOI: 10.1002/ange.201704940
       
  • Highly Efficient Nondoped OLEDs with Negligible Efficiency Roll-Off
           Fabricated from Aggregation-Induced Delayed Fluorescence Luminogens
    • Authors: Jian Huang; Han Nie, Jiajie Zeng, Zeyan Zhuang, Shifeng Gan, Yuanjing Cai, Jingjing Guo, Shi-Jian Su, Zujin Zhao, Ben Zhong Tang
      Abstract: Pure organic emitters that can efficiently utilize triplet excitons are highly desired to cut cost of organic light-emitting diodes (OLEDs), but most of them require complicated doping technique and suffer from severe efficiency roll-off. Herein, we develop novel luminogens exhibiting weak emissions with inconspicuous and negligible delayed fluorescence in solutions but strong emissions with prominent delayed components in aggregates, presenting intriguing aggregation-induced delayed fluorescence (AIDF) feature. The concentration-caused emission quenching and exciton annihilation are well-suppressed, rendering high emission efficiencies and efficient exciton utilization in neat films. Their nondoped OLEDs provide excellent electroluminescence efficiencies of 59.1 cd A‒1, 65.7 lm W‒1 and 18.4%, and negligible current efficiency roll-off of 1.2% at 1000 cd m‒2. Exploring AIDF luminogens to construct nondoped OLEDs could be a promising strategy to advance device efficiency and stability.
      PubDate: 2017-08-21T22:00:33.132814-05:
      DOI: 10.1002/ange.201706752
       
  • A molecular design of bisphosphonates to adjust the reactivity to metal
           sources for obtaining surfactant-assisted mesoporous films
    • Authors: Tatsuo Kimura
      Abstract: The precise control of primary reactions in solutions is one of the most significant steps for the nanoscale design of inorganic solids in the multidisciplinary fields. However, further growth of the inorganic species to bulkier ones disturbs such designs. From the viewpoint, the surfactant-assisted synthesis of mesoporous materials is the good candidate for considering the above concerns because supramolecular-mediated pores are surrounded by nanometer-sized continuous frameworks. Although lots of experiments are generally conducted for optimizing the synthetic conditions for obtaining highly ordered mesostructures, I have here proposed a new and practical concept to minimize such try-and-error efforts for the precise design of porous materials. In this study, I have succeeded in adjusting the reactivity between bisphosphonates and metal sources by molecular design of the starting chemical (bisphosphonate) and then provided unique compositions of surfactant-assisted mesoporous films.
      PubDate: 2017-08-21T21:06:54.263697-05:
      DOI: 10.1002/ange.201707225
       
  • Evolution of the ligand-shell morphology during ligand-exchange reaction
           on gold nanoparticles
    • Authors: Zhi Luo; Jing Hou, Laure Menin, Quy Khac Ong, Francesco Stellacci
      Abstract: Ligand exchange reactions are used to achieve nanoparticles coated with a mixture of ligand molecules. Currently, nothing is known on the evolution of the morphology of the ligand shell during the reaction. Here, we use a recently developed method (based on MALDI-TOF) to follow the evolution of the ligand shell composition and morphology during the reaction. We observe the expected evolution in composition and we find that the ligand shell starts as a random mixture and gradually evolves towards a patchy morphology. When the composition has reached a plateau (reaction is generally assumed to be finished), the ligand shell morphology keeps evolving for days, slowly approaching its equilibrium configuration.
      PubDate: 2017-08-21T21:06:41.787939-05:
      DOI: 10.1002/ange.201708190
       
  • Three-dimensional architectures constructed from transition metal
           dichalcogenide nanomaterials for electrochemical energy storage and
           conversion
    • Authors: Hua Zhang; Qinbai Yun, Qipeng Lu, Xiao Zhang, Chaoliang Tan
      Abstract: Transition metal dichalcogenides (TMDs) have attracted considerable attention in recent years due to their unique properties and promising applications in electrochemical energy storage and conversion. However, the limited number of active sites and blocked ion and mass transport severely impair the electrochemical performance of TMDs. Construction of three-dimensional (3D) architectures from TMD nanomaterials has been proven an effective strategy to solve the aforementioned problems due to their large specific surface area and short ion and mass transport distance. Here, we summarize the commonly used routes to build 3D TMD architectures and highlight their applications in electrochemical energy storage and conversion, including batteries, supercapacitors, and electrocatalytic hydrogen evolution. Moreover, the challenges and outlooks in this research area are also discussed.
      PubDate: 2017-08-21T21:00:44.523307-05:
      DOI: 10.1002/ange.201706426
       
  • Universal Janus Filters for the Separation of Oil from Emulsions
           Stabilized by Ionic or Nonionic Surfactants
    • Authors: Guojun Liu; Zijie Wang, Morgan Lehtinen
      Abstract: Existing Janus filters cannot separate oil from emulsions stabilized by non-ionic surfactants. Reported here are universal Janus filters that separate oil from emulsions stabilized by not only ionic but also non-ionic surfactants. To prepare such a filter, poly(dimethyl siloxane) (PDMS) is grafted onto one side of a fabric. The other side is then grafted with a copolymer polysoap bearing pendant oligo(ethylene glycol) monolaurate (EL) chains. Upon contact with an emulsion, the grafted polysoap competes with free surfactants, ionic or nonionic, for adsorption onto the emulsified droplets, drawing them to the surfaces of the fabric fibers, and causes them to coalesce locally. The coalesced oil then migrates to the PDMS-coated side of the fabric and selectively permeates it. These novel filters possess enhanced versatility and showcase a new application for polysoaps.
      PubDate: 2017-08-21T14:00:31.590994-05:
      DOI: 10.1002/ange.201706158
       
  • Precursor Powders-to-CsPbX3 Perovksite Nanowires: One-pot Synthesis,
           Growth Mechanism and Oriented Self-assemblies
    • Authors: Lakshminarayana Polavarapu; Yu Tong, Bernhard J Bohn, Eva Bladt, Kun Wang, Peter Müller-Buschbaum, Sara Bals, Alexander S Urban, Jochen Feldmann
      Abstract: Colloidal synthesis and assembly of semiconductor nanowires continue to attract a great deal of research attention. Here, we demonstrate a single-step ligand-mediated synthesis of single-crystalline CsPbBr3 perovskite NWs directly from precursor powders. Shedding light on the reaction process and morphological evolution reveals that the initially formed CsPbBr3 nanocubes transform into NWs through an oriented attachment mechanism. The optical properties of the NWs can be tuned across the entire visible range by varying the halide (Cl, Br and I) composition through a subsequent halide ion exchange. Single particle studies show that these NWs exhibit strong polarized emission with a polarization anisotropy of 0.36. More importantly, we show that the NWs can self-assemble in a quasi-oriented fashion at an air/liquid interface. This process should also be easily applicable to perovskite nanocrystals of varying morphology for their integration into future nanoscale optoelectronic devices.
      PubDate: 2017-08-21T12:00:31.644458-05:
      DOI: 10.1002/ange.201707224
       
  • α-Carbonyl Cations in Sulfoxide-Driven, Oxidative Cyclizations
    • Authors: Tobias Stopka; Meike Niggemann, Nuno Maulide
      Abstract: A selective, metal-free generation of α-carbonyl cations from simple internal alkynes was accomplished by addition of a sulfoxide to a congested vinyl cation. The high reactivity of the thus generated α-carbonyl cations was found to efficiently induce hydrogen- and even carbon shift reactions with unusual selecivities. Thereby, complex and highly congested tertiary and quartenary, all-carbon-substituted centers are accessed in a single step from simple precursors. Mechanistic analysis strongly supports the intermediacy of the title species and provides a simple predictive scheme for the migratory aptitude of different substituents.
      PubDate: 2017-08-21T11:00:31.895646-05:
      DOI: 10.1002/ange.201705964
       
  • Synthesis of Diverse Phenalenyl-Fused Pyrylium Cations via Divergent
           Cascade C-H Activation/Annulations of Naphthalene Aldehydes with Alkynes
    • Authors: Jingsong You; Jiangliang Yin, Meiling Tan, Di Wu, Ruyong Jiang, Chengming Li
      Abstract: Herein we establish, for the first time, a straightforward access to stable oxonium-doped polycyclic aromatic hydrocarbons (PAHs) through the rhodium-catalyzed cascade C-H activation/annulations of naphthalene-type aldehydes with internal alkynes. This protocol provides four divergent reaction types (categorized as IA, IB, IIA and IIB), including two unexpected annulations with an oxygen transposition process, which lead to diverse types of phenalenyl-fused pyrylium cations comprising a four, five or six-ring-fused π-conjugated core. The annulations exhibit an exquisite regioselectivity and a high tolerance of sensitive functional groups. These PAHs feature the intriguing photophysical properties such as full-color tunable fluorescence emission, high quantum yield and positively charged core, and can be reduced easily to the phenalenyl radicals.
      PubDate: 2017-08-21T09:01:20.294923-05:
      DOI: 10.1002/ange.201708127
       
  • Aptamer/AuNP Biosensor for Colorimetric Profiling of Exosomal Proteins
    • Authors: Ying Jiang; Muling Shi, Yuan Liu, Shuo Wan, Cheng Cui, Liqin Zhang, Weihong Tan
      Abstract: Exosomes constitute an emerging biomarker for cancer diagnosis because they carry multiple proteins that reflect the origins of parent cells. Assessing exosome surface proteins provides a powerful means of identifying a combination of biomarkers for cancer diagnosis. We report a sensor platform that profiles exosome surface proteins in minutes by the naked eye. The sensor consists of a gold nanoparticle (AuNP) complexed with a panel of aptamers. The complexation of aptamers with AuNPs protects the nanoparticles from aggregating in a high-salt solution. In the presence of exosomes, the non-specific and weaker binding between aptamers and the AuNP is broken, and the specific and stronger binding between exosome surface protein and the aptamer displaces aptamers from the AuNP surface and results in AuNP aggregation. This aggregation results in a color change and generates patterns for the identification of multiple proteins on the exosome surface.Farbenspiel: Ein Goldnanopartikel-Aptamer-Biosensor (AuNP/AptX) ermöglicht die schnelle und parallelisierte kolorimetrische Analyse von Proteinen in Exosomen.
      PubDate: 2017-08-21T07:45:58.276171-05:
      DOI: 10.1002/ange.201703807
       
  • Ultrathin Cell-Membrane-Mimic Phosphorylcholine Polymer Film Coating
           Enables Large Improvement for In Vivo Electrochemical Detection
    • Authors: Xiaomeng Liu; Tongfang Xiao, Fei Wu, Mo-Yuan Shen, Meining Zhang, Hsiao-hua Yu, Lanqun Mao
      Abstract: Resisting biomolecule adsorption onto the surface of brain-implanted microelectrodes is a key issue for in vivo monitoring of neurochemicals. Herein, we demonstrate that an ultrathin cell-membrane-mimic film of ethylenedioxythiophene tailored with zwitterionic phosphorylcholine (EDOT-PC) electropolymerized onto the surface of a carbon fiber microelectrode (CFE) not only resists protein adsorption but also maintains the sensitivity and time response for in vivo monitoring of dopamine (DA). As a consequence, the as-prepared PEDOT-PC/CFEs could be used as a new reliable platform for tracking DA in vivo and would help understand the physiological and pathological functions of DA.Ein dünner zellmembranartiger Film aus Ethylendioxythiophen und einem zwitterionischen Phosphorylcholin (EDOT-PC) wurde elektrochemisch auf der Oberfläche einer Kohlefaser-Mikroelektrode (CFE) polymerisiert. Dieser Film erschwert die Proteinadsorption, ohne die Empfindlichkeit und zeitliche Auflösung für die In-vivo-Dopamin-Bestimmung zu beeinträchtigen.
      PubDate: 2017-08-21T07:35:34.309444-05:
      DOI: 10.1002/ange.201705900
       
  • Pot Economy in the Total Synthesis of Estradiol Methyl Ether by Using an
           Organocatalyst
    • Authors: Yujiro Hayashi; Seitaro Koshino, Kanna Ojima, Eunsang Kwon
      Abstract: Enantioselective total synthesis of estradiol methyl ether has been accomplished in a pot-economical manner using five reaction vessels and four purifications. The key reaction is a diphenylprolinol silyl ether mediated domino Michael/aldol reaction to afford bicyclo[4.3.0]nonane derivatives, containing the A, C, and D rings of steroids, as a single isomer with excellent enantioselectivity. Six reactions such as oxidation, hydrogenation, formation of acid chloride, Friedel–Crafts reaction, deprotection, and reduction can be carried out in the last one-pot sequence.Totalsynthese auf Steroiden: Östradiolmethylether wurde unter Verwendung von nur fünf Reaktionsgefäßen und vier Reinigungsschritten synthetisiert. Der Schlüsselschritt ist eine Diphenylprolinolsilylether-vermittelte Michael-Reaktion, und die abschließende Eintopfsequenz umfasst sechs Reaktionen. TMS=Trimethylsilyl.
      PubDate: 2017-08-21T07:30:55.158836-05:
      DOI: 10.1002/ange.201706046
       
  • Synthesis, Isolation, and Trifluoromethylation of Two Isomers of C84-Based
           Monometallic Cyanide Clusterfullerenes: Interplay between the Endohedral
           Cluster and the Exohedral Addends
    • Authors: Fei Jin; Song Wang, Nadezhda B. Tamm, Shangfeng Yang, Sergey I. Troyanov
      Abstract: As an emerging member of endohedral fullerenes, metal cyanide clusterfullerenes (CYCF) are unique in terms of the encapsulation of a monometallic cluster. To date the reported carbon cages of CYCFs are limited to C82 and C76, and little is known about the chemical reactivity of CYCFs. Herein, two isomers of the first C84-based CYCFs, YCN@C84, were isolated as trifluoromethyl derivatives, including YCN@C84(23)(CF3)18 and three isomers of YCN@C84(13)(CF3)16, which are based on a unique chiral C2-C84(13) cage. As a common feature of the CF3 addition patterns, the YCN@C84(CF3)16/18 compounds are stabilized by the formation of isolated C=C bonds and benzenoid rings on the carbon cages. The interplay between the endohedral YCN cluster and the exhohedral CF3 addends was unveiled according to single-crystal X-ray diffraction studies, thus offering new insight into the chemical reactivity of CYCFs.Zwei Isomere des C84-Metallcyanid- Clusterfullerens (CYCF) YCN@C84 wurden in Form der Trifluormethylderivate YCN@C84(CF3)16/18 synthetisiert, isoliert und identifiziert. Das Zusammenspiel der eingeschlossenen YCN-Spezies mit den äußeren CF3-Addenden wird in Einkristall-Röntgen-Strukturanalysen ersichtlich.
      PubDate: 2017-08-21T07:30:33.417127-05:
      DOI: 10.1002/ange.201707298
       
  • Selective Palladium(II)-Catalyzed Carbonylation of Methylene β-C−H
           Bonds in Aliphatic Amines
    • Authors: Jaime R. Cabrera-Pardo; Aaron Trowbridge, Manuel Nappi, Kyohei Ozaki, Matthew J. Gaunt
      Abstract: Palladium(II)-catalyzed C−H carbonylation reactions of methylene C−H bonds in secondary aliphatic amines lead to the formation of trans-disubstituted β-lactams in excellent yields and selectivities. The generality of the C−H carbonylation process is aided by the action of xantphos-based ligands and is important in securing good yields for the β-lactam products.Der Ligand ist der Schlüssel: Palladium(II)-katalysierte C-H-Carbonylierungen von Methylen-C-H-Bindungen in sekundären aliphatischen Aminen ermöglichen die Synthese von trans-disubstituierten β-Lactamen in hervorragenden Ausbeuten und Selektivitäten. Der Xantphos-basierte Ligand ist für die große Substratbreite der C-H-Carbonylierung entscheidend.
      PubDate: 2017-08-21T07:25:55.630493-05:
      DOI: 10.1002/ange.201706303
       
  • Highly Oriented Growth of Catalytically Active Zeolite ZSM-5 Films with a
           Broad Range of Si/Al Ratios
    • Authors: Donglong Fu; Joel E. Schmidt, Zoran Ristanović, Abhishek Dutta Chowdhury, Florian Meirer, Bert M. Weckhuysen
      Abstract: Katalytisch aktives Aluminium kann unter Einsatz kostengünstiger Alkohole in perfekt orientierte Zeolithfilme eingebaut werden. In ihrer Zuschrift (10.1002/ange.201704846) demonstrieren B. M. Weckhuysen und Mitarbeiter diesen Prozess, der durch die Windmühlen, die Al in die Kanäle pumpen, veranschaulicht wird. Der homogene Al-Einbau wird durch polarisierte Fluoreszenzmikroskopie mit reaktiven fluoreszierenden Sondenmolekülen bestätigt, symbolisiert durch die Sonne, die die „Fluoreszenz des Kanals” verursacht.
      PubDate: 2017-08-21T07:25:19.132884-05:
      DOI: 10.1002/ange.201708258
       
  • Photosalient Phenomena that Mimic Impatiens in Hollow Crystals of a
           Diarylethene
    • Authors: Kingo Uchida; Eri Hatano, Masakazu Morimoto, Takahito Imai, Kengo Hyodo, Ayako Fujimoto, Ryo Nishimura, Akiko Sekine, Nobuhiro Yasuda, Satoshi Yokojima, Shinichiro Nakamura
      Abstract: A diarylethene with a perfluorocyclohexene ring formed hollow crystals by sublimation under normal pressure. Upon UV irradiation to the crystals, they showed remarkable photosalient phenomena and scattered into small pieces. The speed of flying debris broken from the crystal by UV irradiation exceeded several meters per second. In order to investigate through visualization of these phenomena of artificially mimicking impatiens, small fluorescent beads with a 1-micro meter diameter were inserted in the hollow. Consequently, the scattering of fluorescent beads was observed upon UV irradiation with deformation and scattering of the hollow structure. This example shows how artificial light can replicate the activity of natually triggered impatiens.
      PubDate: 2017-08-21T04:00:32.41424-05:0
      DOI: 10.1002/ange.201706684
       
  • Sono-RAFT Polymerization in Aqueous Medium
    • Authors: Thomas George McKenzie; Enrico Colombo, Qiang Fu, Muthupandian Ashokkumar, Greg G. Qiao
      Abstract: The ultrasonic irradiation of aqueous solution is demonstrated to be a suitable source of initiating radicals for a controlled radical polymerization when conducted in the presence of a thiocarbonylthio-containing reversible addition-fragmentation chain transfer (RAFT) agent. This allows for a highly "green" method of externally-regulated/controlled polymerization with a potentially broad scope for polymerizable monomers and/or polymer structures.
      PubDate: 2017-08-21T03:06:54.920796-05:
      DOI: 10.1002/ange.201706771
       
  • The N-terminal domain of ALS-linked TDP-43 assembles without misfolding
    • Authors: Phoebe S. Tsoi; Kyoung-Jae Choi, Paul G. Leonard, Antons Sizovs, Mahdi Muhammad Moosa, Kevin R. MacKenzie, Josephine C. Ferreon, Allan Chris M. Ferreon
      Abstract: Transactivation response element (TAR) DNA-binding protein 43 (TDP-43) protein misfolding is implicated in several neurodegenerative diseases characterized by aggregated protein inclusions. Misfolding is believed to be mediated by both the N- and C-terminus of TDP-43; however, the mechanistic basis of the contribution of individual domains in the process remained elusive. Here, using single-molecule fluorescence and ensemble biophysical techniques, and a wide range of pH and temperature conditions, we show that TDP-43NTD is thermodynamically stable, well-folded and undergoes reversible oligomerization. We propose that, in full-length TDP-43, association between folded N-terminal domains enhances the propensity of the intrinsically unfolded C-terminal domains to drive pathological aggregation.
      PubDate: 2017-08-21T03:06:40.570295-05:
      DOI: 10.1002/ange.201706769
       
  • Carboxylation of Aromatic and Aliphatic Bromides and Triflates with CO2 by
           Dual Visible Light - Nickel Catalysis
    • Authors: Qing-Yuan Meng; Shun Wang, Burkhard König
      Abstract: We report the efficient carboxylation of bromides and triflates with K₂CO₃ as the source of CO₂ using an organic photocatalyst in combination with a nickel complex under visible light irradiation at room temperature. The reaction is compatible with a variety of functional groups and has been successfully applied to the synthesis and derivatization of biologically active molecules. Particularly, the carboxylation of unactivated cyclic bromides proceeds well under our protocol extending the scope of this transformation. Spectroscopic and spectroelectrochemical investigations indicate the generation of a Ni(0) species as catalytic reactive intermediate.
      PubDate: 2017-08-21T03:06:35.130833-05:
      DOI: 10.1002/ange.201706724
       
  • Gate-Voltage Control of Borophene Structure Formation
    • Authors: Zhuhua Zhang; Sharmila N. Shirodkar, Yang Yang, Boris I. Yakobson
      Abstract: Boron nanostructures are easily charged but how charge carriers affect their structural stability is unknown. We combine cluster expansion method with first-principles calculations to analyze the dependence of preferred structures of two-dimensional (2D) boron—borophene—on charge doping controlled by a gate voltage. At a reasonable doping level of 3.12×1014 cm-2, the ground state of 2D boron has its hollow hexagon concentration increased from 1/8 in charge-neutral state to 1/7. The numerical result for the dependence of hexagon concentration on doping level is well described by an analytics based on an electron-counting rule. Aside from in-plane electronic bonding, the hybridization among out-of-plane boron orbitals is revealed to be crucial for determining the relative stability of different sheets at a given doping level. Our results offer new insight into the stability mechanism of 2D boron and open a new ways for the control of their lattice structures in the course of formation.
      PubDate: 2017-08-21T03:06:19.890827-05:
      DOI: 10.1002/ange.201705459
       
  • Protonation of Ferrocene - Low-Temperature X-Ray Diffraction Study of
           [Cp2FeH](PF6) Reveals an Iron-Bound Hydrido Ligand
    • Authors: Karsten Meyer; Moritz Malischewski, Konrad Seppelt, Jörg Sutter, Frank W. Heinemann, Birger Dittrich
      Abstract: Ferrocene, Cp2Fe, is quantitatively protonated in a mixture of liquid HF/PF5 to yield [Cp2FeH](PF6), which was characterized by 1H and 13C NMR, 57Fe Mößbauer spectroscopy, and single-crystal X-ray diffraction analysis. The X-ray diffraction analysis at 100 K revealed a disordered, iron-coordinated hydrido ligand that was unambiguously located by aspherical atom refinement at 100 K and by analyzing the non-disordered crystal structure at 30 K, revealing a non-agostic structure.
      PubDate: 2017-08-21T03:06:17.430375-05:
      DOI: 10.1002/ange.201704854
       
  • Chemical Synthesis of the Highly Hydrophobic Antiviral Membrane Associated
           Protein IFITM3 and Modified Variants
    • Authors: Thibault J Harmand; Vijaya R Pattabiraman, Jeffrey W. Bode
      Abstract: Interferon-induced transmembrane protein 3 (IFITM3) is an antiviral transmembrane protein thought to serve as the primary factor for inhibiting replication of a large number of viruses, including the West Nile virus, the Dengue virus, the Ebola virus, and the Zika virus. Production of this 14.5 kDa, 133-residue, transmembrane protein, especially with essential posttranslational modifications by recombinant expression is challenging. In this report, we document the chemical synthesis of IFTIM3 in multimilligram quantities (>15 mg) and the preparation of phosphorylated and fluorescent variants. The synthesis was accomplished by KAHA ligations, which operate under acidic aqueous/organic mixtures that excel at solubilizing even the exceptionally hydrophobic C-terminal region of IFITM3. The synthetic material readily incorporates in model vesicles and forms the basis for using synthetic, homogenous IFITM3 and its derivatives for further studying its structure and biological mode of action.
      PubDate: 2017-08-21T03:05:50.273063-05:
      DOI: 10.1002/ange.201707554
       
  • Between Localization and Delocalization: Ru(cod)2+ Units in the Zintl
           Clusters [Bi9{Ru(cod)}2]3- and [Tl2Bi6{Ru(cod)}]2-
    • Authors: Stefanie Dehnen; Niels Lichtenberger, Nils Spang, Andreas Eichhöfer
      Abstract: Reactions of [K(crypt-222)]2(TlBi3)·0.5en (1b) with [Ru(cod)(H2CC(Me)CH2)2] (A) in 1,2-diaminoethane (en) led to the formation of two compounds with new Bi-rich cluster anions, [K(crypt-222)]3[Bi9{Ru(cod)}2]·1.5en (2), and [K(crypt-222)]3[Tl2Bi6{Ru(cod)}]·2tol (3), alongside the salt of a binary nido cluster, [K(crypt-222)]3(Tl4Bi5)·2en (4). The anions in 2 and 3 are two further examples of the rare family of heterometallic clusters containing Ru atoms. As the cod ligand is retained on the Ru atoms in both clusters, the anions may be viewed as intermediates on the way towards larger, ligand-free intermetalloid clusters. Quantum chemical studies were undertaken to gain insight in the bonding situation of the clusters. According to these studies, 2 combines electron-precise with electron-deficient parts. Electrospray ionization mass spectrometry (ESI-MS) indicates a stepwise fragmentation.
      PubDate: 2017-08-21T03:05:30.513351-05:
      DOI: 10.1002/ange.201707632
       
  • Fractal MTW Zeolite Crystals: Hidden Dimensions in Nanoporous Materials
    • Authors: Lei Wang; Sheng-cai Zhu, Mei-kun Shen, Hai-wen Tian, Song-hai Xie, Hong-bin Zhang, Ya-hong Zhang, Yi Tang
      Abstract: Screw dislocation structures in crystals are an origin of symmetry breaking in a wide range of dense-phase crystals. Preparation of such analogous structures in framework-phase crystals is of great importance in zeolites but is still a challenge. On the basis of crystal-structure solving and model building, it was found that the two specific intergrowths in MTW zeolite produce this complex fractal and spiral structure. With the structurally determined parameters (spiral pitch h, screw angle θ, and spatial angle ψ) of Burgers circuit, the screw dislocation structure can be constructed by two different dimensional intergrowth sections. Thus the reported complexity of various dimensions in diverse crystals can be unified.Versteckte Dimensionen: Die experimentell beobachtete versetzte Schraubenstruktur von MTW-Zeolith entsteht durch Verwachsung als Folge zweier spezifischer rationaler Prozesse entlang verschiedener Raumrichtungen.
      PubDate: 2017-08-21T02:51:38.162876-05:
      DOI: 10.1002/ange.201704499
       
  • Enantioselective Construction of Trifluoromethoxylated Stereogenic Centers
           by a Nickel-Catalyzed Asymmetric Suzuki–Miyaura Coupling of Secondary
           Benzyl Bromides
    • Authors: Weichen Huang; Xiaolong Wan, Qilong Shen
      Abstract: Trifluoromethoxy-substituted stereogenic centers can be constructed with high enantioselectivity by a nickel-catalyzed Suzuki–Miyaura coupling of readily available α-bromobenzyl trifluoromethyl ethers with a variety of aryl pinacol boronates. The coupling proceeds under mild reaction conditions, and a variety of common functional groups, such as fluoride, chloride, bromide, ester, enolizable ketone, nitro, cyano, amino, and vinyl moieties, were well tolerated. Furthermore, the reaction can be easily scaled up to gram quantities without a decrease in enantioselectivity.Trifluormethoxy-substituierte Stereozentren wurden durch Nickel-katalysierte Suzuki-Miyaura-Kupplungen von (α-Brombenzyl)trifluormethylethern mit Arylpinakolboronaten mit hoher Enantioselektivität aufgebaut. Die Kupplung verläuft unter milden Reaktionsbedingungen, und verschiedenste funktionelle Gruppen werden gut toleriert.
      PubDate: 2017-08-21T02:51:05.890708-05:
      DOI: 10.1002/ange.201706868
       
  • Hoch fluoreszierende Pyridiniumbetaine für die Lichtsammlung
    • Authors: Jingjing Xu; Bolong Zhang, Marina Jansen, Lars Goerigk, Wallace W. H. Wong, Chris Ritchie
      Abstract: Die Ergebnisse experimenteller und theoretischer Untersuchungen der Eigenschaften von Pyridiniumenolaten werden vorgestellt, und ihre potenzielle Nutzbarkeit in Lichtsammelanwendungen, insbesondere lumineszierenden Solarkonzentratoren (LSCs), wird demonstriert. Synthesen, Strukturen, photophysikalische Charakterisierung und wellenfunktionsbasierte quantenchemische Studien für fünf Cyclobetaine werden präsentiert und die Leistungsfähigkeit einer LSC-Apparatur, die eines dieser Cyclobetaine enthält, wird mit dem aktuellen Stand der Technik verglichen.Experiment und Theorie: Pyridiniumenolate und ihre mögliche Anwendung in Lichtsammelsystemen, z. B. in lumineszierenden Solarkonzentratoren, wurden experimentell und theoretisch untersucht. Die Synthesen, Strukturen, photophysikalischen Eigenschaften und wellenfunktionsbasierte quantenchemische Studien von fünf Cyclobetainen werden beschrieben.
      PubDate: 2017-08-21T02:50:46.517998-05:
      DOI: 10.1002/ange.201704832
       
  • Nickel-Catalyzed Reductive Allylation of Tertiary Alkyl Halides with
           Allylic Carbonates
    • Authors: Hegui Gong; Haifeng Chen, Xiao Jia, Yingying Yu, Qun Qian
      Abstract: The construction of all C(sp3)-quaternary centers has been successfully achieved under Ni-catalyzed cross-electrophile coupling of allylic carbonates with unactivated tertiary alkyl halides. For allylic carbonates bearing C1- or C3-substituents, the reaction affords excellent regioselectivities by addition of alkyl groups to the unsubstituted allylic carbon terminus. The allylic alkylation method also exhibits excellent functional group compatibility, and delivers the products with high E-selectivities.
      PubDate: 2017-08-18T09:10:57.724578-05:
      DOI: 10.1002/ange.201705521
       
  • Homo- and heteroleptic phototoxic dinuclear metallo-intercalators based on
           RuII(dppn) intercalating moieties: synthesis, optical and biological
           studies
    • Authors: Hiwa Saeed; Paul Jarman, Stuart Archer, Sreejesh Sreedharan, Ibrahim Saeed, Luke Mckenzie, Julia Weinstein, Niklaas Buurma, Carl Smythe, Jim Antony Thomas
      Abstract: Using a new mononuclear "building block," for the first time, a dinuclear RuII(dppn) complex and a heteroleptic system containing both RuII(dppz) and RuII(dppn) moieties are reported. The complexes, including the mixed dppz/dppn system, are 1O2 sensitizers. However, unlike the homoleptic dppn systems, the mixed dppz/dppn complex also displays a luminescence "switch on" DNA light-switch effect. In both cisplatin sensitive and resistant human ovarian carcinoma lines the dinuclear complexes show enhanced uptake compared to their mononuclear analogue. Thanks to a favorable combination of singlet oxygen generation and cellular uptake properties all three of the new complexes are phototoxic and display potent activity against chemotherapeutically resistant cells.
      PubDate: 2017-08-18T08:01:03.63549-05:0
      DOI: 10.1002/ange.201707350
       
  • Control of Ice Propagation by Using Polyelectrolyte Multilayer Coatings
    • Authors: Yuankai Jin; Zhiyuan He, Qian Guo, Jianjun Wang
      Abstract: Ice propagation is of great importance to the accumulation of ice/frost on solid surfaces. However, no investigation has been reported on the tuning of ice propagation through a simple coating process. Herein, we study the ice propagation behavior on polyelectrolyte multilayer (PEM) surfaces coated with the layer-by-layer (LBL) deposition approach. We discover that ice propagation is strongly dependent on the amount of water in the outermost layer of PEMs, that is, the ice propagation rate increases with the amount of water in the outermost layer. The ice propagation rate can be tuned by up to three orders of magnitude by changing the polyelectrolyte pairs, counterions of the outermost polymer layer, or the salt concentration during the preparation of PEMs. Because the simple, versatile, and inexpensive LBL deposition approach is generally applicable to almost all available surfaces, the PEM coatings can tune ice propagation on a wide range of substrates.Eisfrei dank Polymer: Vielschichtige Polyelektrolytüberzüge (PEM) fangen Wassermoleküle an der äußersten Schicht deutlich unterschiedlich gut ein. Daher lässt sich mit solchen Überzügen die Vereisungsgeschwindigkeit auf fast allen Oberflächenarten über einen Bereich von drei Größenordnungen variieren.
      PubDate: 2017-08-18T06:26:18.013471-05:
      DOI: 10.1002/ange.201705190
       
  • The Effect of Additives on the Early Stages of Growth of Calcite Single
           Crystals
    • Authors: Yi-Yeoun Kim; Colin L. Freeman, Xiuqing Gong, Mark A. Levenstein, Yunwei Wang, Alexander Kulak, Clara Anduix-Canto, Phillip A. Lee, Shunbo Li, Li Chen, Hugo K. Christenson, Fiona C. Meldrum
      Abstract: As crystallization processes are often rapid, it can be difficult to monitor their growth mechanisms. In this study, we made use of the fact that crystallization proceeds more slowly in small volumes than in bulk solution to investigate the effects of the soluble additives Mg2+ and poly(styrene sulfonate) (PSS) on the early stages of growth of calcite crystals. Using a “Crystal Hotel” microfluidic device to provide well-defined, nanoliter volumes, we observed that calcite crystals form via an amorphous precursor phase. Surprisingly, the first calcite crystals formed are perfect rhombohedra, and the soluble additives have no influence on the morphology until the crystals reach sizes of 0.1–0.5 μm for Mg2+ and 1–2 μm for PSS. The crystals then continue to grow to develop morphologies characteristic of these additives. These results can be rationalized by considering additive binding to kink sites, which is consistent with crystal growth by a classical mechanism.Im Kristall-Hotel: Beim Ausfällen von Calcit-Kristallen in begrenzten Volumina, wo deren Wachstum langsamer verläuft, beeinflussen Additive die Kristallform erst, wenn die Kristalle mindestens 100 nm groß sind. Mit dem Kristallwachstum erhöht sich die Dichte an Knickstellen („kinks”), an die die Additive binden. Erst bei genügend hoher Dichte beginnt sich die Kristallform zu ändern.
      PubDate: 2017-08-18T06:11:24.630907-05:
      DOI: 10.1002/ange.201706800
       
  • RadH: A Versatile Halogenase for Integration into Synthetic Pathways
    • Authors: Binuraj R. K. Menon; Eileen Brandenburger, Humera H. Sharif, Ulrike Klemstein, Sarah A. Shepherd, Michael F. Greaney, Jason Micklefield
      Abstract: Flavin-dependent halogenases are useful enzymes for providing halogenated molecules with improved biological activity, or intermediates for synthetic derivatization. We demonstrate how the fungal halogenase RadH can be used to regioselectively halogenate a range of bioactive aromatic scaffolds. Site-directed mutagenesis of RadH was used to identify catalytic residues and provide insight into the mechanism of fungal halogenases. A high-throughput fluorescence screen was also developed, which enabled a RadH mutant to be evolved with improved properties. Finally we demonstrate how biosynthetic genes from fungi, bacteria, and plants can be combined to encode a new pathway to generate a novel chlorinated coumarin “non-natural” product in E. coli.Die pilzliche Halogenase RadH halogeniert regioselektiv eine Reihe biologisch aktiver Molekülgerüste. Strukturbasierte Mutagenese beleuchtet die Selektivität und den Mechanismus von RadH und verwandten Halogenasen. Ein Fluoreszenz-Hochdurchsatzscreening ergab eine RadH-Mutante mit verbesserter Aktivität, die mit anderen Enzymen aus unterschiedlichen Quellen in E. coli vereint wurde, um eine nichtnatürliche chlorierte Verbindung aufzubauen.
      PubDate: 2017-08-18T06:11:16.286148-05:
      DOI: 10.1002/ange.201706342
       
  • Pnictogen (As, Sb, Bi) Nanosheets for Electrochemical Applications Are
           Produced by Shear Exfoliation Using Kitchen Blenders
    • Authors: Rui Gusmão; Zdeněk Sofer, Daniel Bouša, Martin Pumera
      Abstract: Layered materials are of high importance because of their anisotropy and as a source of 2D materials. Whilst there is a plethora of multi-elemental 2D materials, the number mono-elemental 2D materials is rather limited. Herein, we demonstrate that aqueous shear exfoliation can be used to obtain As, Sb, and Bi exfoliated nanosheets. Morphological and chemical characterization of the exfoliated materials shows a decrease in thickness, sheet-to-nanosheet scale, and partial oxidation owing to a higher surface area. The electrochemical performance is tested in terms of inherent electrochemistry, electron transfer, and sensing applications as demonstrated with ascorbic acid. Potential energy-related applications are evaluated in the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR), with shear-exfoliated Sb having the best electrochemical performance overall. These findings will have a profound impact on the preparation and application of 2D mono-elemental materials.Gerührt, nicht geschüttelt: Das Abblättern von Pniktogenen in wässrigem Medium durch Scherung unter Einwirkung eines Küchenrührstabs erzeugt As-, Sb- und Bi-Nanoblätter mit verbesserten elektrochemischen Eigenschaften. Sb-Nanoblätter zeigten die höchste elektrokatalytische Leistungsfähigkeit.
      PubDate: 2017-08-18T06:10:45.74329-05:0
      DOI: 10.1002/ange.201706389
       
  • Manganese(I)-Catalyzed Enantioselective Hydrogenation of Ketones Using a
           Defined Chiral PNP Pincer Ligand
    • Authors: Marcel Garbe; Kathrin Junge, Svenja Walker, Zhihong Wei, Haijun Jiao, Anke Spannenberg, Stephan Bachmann, Michelangelo Scalone, Matthias Beller
      Abstract: A new chiral manganese PNP pincer complex is described. The asymmetric hydrogenation of several prochiral ketones with molecular hydrogen in the presence of this complex proceeds under mild conditions (30–40 °C, 4 h, 30 bar H2). Besides high catalytic activity for aromatic substrates, aliphatic ketones are hydrogenated with remarkable selectivity (e.r. up to 92:8). DFT calculations support an outer sphere hydrogenation mechanism as well as the experimentally determined stereochemistry.Asymmetrisch mit Mangan: Ein chiraler Mangan-„Pincer”-Komplex (C grau, H weiß, Mn blau, N grün, O rot, P magenta) wurde in der Reduktion aromatischer und aliphatischer Ketone angewendet. Asymmetrische Keton-Hydrierungen mit molekularem Wasserstoff verliefen mit diesem Katalysator unter milden Bedingungen (30–40 °C, 4 h, 30 bar H2).
      PubDate: 2017-08-18T06:10:36.932039-05:
      DOI: 10.1002/ange.201705471
       
  • Selective Ring-Opening Polymerization of None-Strained γ-Butyrolactone
           Catalyzed by Cyclic Trimeric Phosphazene Base
    • Authors: Na Zhao; Chuanli Ren, Huaike Li, Yunxin Li, Shaofeng Liu, Zhibo Li
      Abstract: A new superbase, cyclic trimeric phosphazene base (CTPB), was prepared with high yield and purity. In the presence of alcohol, the CTPB can serve as highly efficient organocatalyst for ring-opening polymerization (ROP) of "non-polymerizable" γ-butyrolactone to offer well-defined poly(γ-butyrolactone) with high conversions (up to 98%) at -60 °C. The produced polymers have high molecular weights (up to 22.9 kg·mol-1) and low polydensity distributions (1.27-1.50). NMR analysis of initiation process and the structural analysis of resulted polymers by MALDI-TOF suggest an activating initiator mechanism that is responsive for linear polymer as only product with designed BnO/H chain ends.
      PubDate: 2017-08-18T06:01:10.748189-05:
      DOI: 10.1002/ange.201707122
       
  • Branched Aramid Nanofibers
    • Authors: Jian Zhu; Ming Yang, Ahmet Emre, Joong Hwan Bahng, Lizhi Xu, Jihyeon Yeom, Bongjun Yeom, Yoonseob Kim, Kyle Johnson, Peter Green, Nicholas A. Kotov
      Abstract: Interconnectivity of components in three-dimensional networks (3DNs) is essential for stress transfer in hydrogels, aerogels, and composites. Entanglement of nanoscale components in the network relies on weak short-range intermolecular interactions. The intrinsic stiffness and rod-like geometry of nanoscale components limit the cohesive energy of the physical crosslinks in 3DN materials. Nature realizes networked gels differently using components with extensive branching. Branched aramid nanofibers (BANFs) mimicking polymeric components of biological gels were synthesized to produce 3DNs with high efficiency stress transfer. Individual BANFs are flexible, with the number of branches controlled by base strength in the hydrolysis process. The extensive connectivity of the BANFs allows them to form hydro- and aerogel monoliths with an order of magnitude less solid content than rod-like nanocomponents. Branching of nanofibers also leads to improved mechanics of gels and nanocomposites.3D-Gerüste mit effizienter Spannungsübertragung können mithilfe von verzweigten Aramid-Nanofasern (BANFs) hergestellt werden. Die starke Verknüpfung der BANFs führt zu Hydrogel- und Aerogel-Monolithen mit viel geringerem Feststoffgehalt als bei Verwendung stabförmiger Nanokomponenten. Die Verzweigung verbessert zudem die Gelmechanik, sodass kontinuierliche lumineszierende Mikrofasern und hochleistungsfähige Nanokomposite erhalten werden können.
      PubDate: 2017-08-18T05:06:24.365541-05:
      DOI: 10.1002/ange.201703766
       
  • Hochdimensionale neuronale Netze für Potentialhyperflächen großer
           molekularer und kondensierter Systeme
    • Authors: Jörg Behler
      Abstract: Moderne Simulationstechniken haben heute ein Niveau erreicht, das es ermöglicht, ein breites Spektrum von Problemen in der Chemie und in den Materialwissenschaften zu untersuchen. Trotz der Entwicklung immer leistungsfähigerer Hardware ist die Anwendung von Elektronenstrukturmethoden, die Vorhersagen ohne Rückgriff auf experimentelle Daten ermöglichen, jedoch noch immer auf kleine Systeme begrenzt, und in absehbarer Zukunft ist keine Besserung dieser Situation zu erwarten. Um auch komplexe Systeme auf atomarer Ebene verstehen zu können, ist die Entwicklung von effizienteren und gleichzeitig zuverlässigen atomistischen Potentialen in den letzten Jahren immer mehr in den Fokus gerückt. Ein vielversprechender neuer Ansatz ist die Nutzung von maschinellem Lernen (ML) zur Beschreibung der atomaren Wechselwirkungen. Nach einem Trainingsprozess mit Elektronstrukturdaten können solche ML-Potentiale Computersimulationen um mehrere Größenordnungen beschleunigen, während die quantenmechanische Genauigkeit erhalten bleibt. Anhand einer wichtigen Klasse von ML-Potentialen, die auf künstlichen neuronalen Netzen basiert, werden in diesem Aufsatz die Grundideen, die Anwendbarkeit und die offenen Fragen dieses Ansatzes diskutiert.Eine neue Klasse atomistischer Potentiale, die auf maschinellem Lernen (ML) basiert, kombiniert die Genauigkeit von Elektronenstrukturverfahren mit der Effizienz einfacher Kraftfelder. In diesem Aufsatz wird die Methodik einer speziellen Klasse von ML-Potentialen, in der künstliche neuronale Netze zum Einsatz kommen und die für sehr große molekulare und kondensierte Systeme einsetzbar ist, diskutiert.
      PubDate: 2017-08-18T04:30:54.703529-05:
      DOI: 10.1002/ange.201703114
       
  • Base-Free Asymmetric Transfer Hydrogenation of 1,2-Di- and Monoketones
           Catalyzed by a (NH)2P2-Macrocyclic Iron(II) Hydride
    • Authors: Lorena De Luca; Antonio Mezzetti
      Abstract: The hydride isonitrile complex [FeH(CNCEt3)(1 a)]BF4 (2) containing a chiral P2(NH)2 macrocycle (1 a), in the presence of 2-propanol as hydrogen donor, catalyzes the base-free asymmetric transfer hydrogenation (ATH) of prostereogenic ketones to alcohols and the hemihydrogenation of benzils to benzoins, which contain a base-labile stereocenter. Benzoins are formed in up to 83 % isolated yield with enantioselectivity reaching 95 % ee. Ketones give the same enantioselectivity observed with the parent catalytic system [Fe(CNCEt3)2(1 a)] (3 a) that operates with added NaOtBu.Base' Nein Danke! Ein Hydrid-Isonitril-Eisen(II)-Komplex mit einem C2-symmetrischen makrocyclischen (NH)2P2-Diaminoliganden katalysiert die asymmetrische Transferhydrierung von Ketonen unter basefreien Bedingungen mit exzellenter Enantioselektivität (bis zu 99 % ee). Baselabile Benzoine werden aus den entsprechenden Benzilen mit bis zu 95 % ee gebildet.
      PubDate: 2017-08-18T04:11:44.401646-05:
      DOI: 10.1002/ange.201706261
       
  • Precisely Assembled Cyclic Gold Nanoparticle Frames by 2D Polymer
           Single-Crystal Templating
    • Authors: Shan Mei; Hao Qi, Tian Zhou, Christopher Y. Li
      Abstract: In recent decades, extensive studies have been devoted to assembling nanoparticles (NPs) into various ordered structures to achieve novel optical properties. However, it still remains a challenging task to assemble NPs into cyclic one-dimensional (1D) shapes, such as rings and frames. Herein, we report a directed assembly method to precisely assemble NPs into well-defined, free-standing frames using polymer single crystals (PSCs) as the template. Preformed poly(ethylene oxide) (PEO) single crystals were used as the template to direct the crystallization of block copolymer (BCP) poly(ethylene oxide)-b-poly(4-vinylpyridine) (PEO-b-P4VP), which directs the gold NPs (AuNPs) to form AuNP frames. By controlling the PSC growth, we were able to, for the first time, precisely tune both the size and width of the AuNP frame. These novel AuNP frames topologically resemble NP nanorings and cyclic polymer chains, and show unique surface plasmon resonance (SPR) behaviors.Noch im Rahmen: Freie Goldnanopartikel(AuNP)-Rahmenstrukturen entstehen direkt durch Anlagerung von AuNPs an Polymer-Einkristall-Template. Größe und Dicke der Strukturen lassen sich präzise vorgeben. Diese Rahmen entsprechen NP-Nanoringen und cyclischen 1D-Polymer-Ketten; bezüglich ihrer optischen Eigenschaften erinnern sie an Au-Nanostäbe.
      PubDate: 2017-08-18T04:10:57.475304-05:
      DOI: 10.1002/ange.201706180
       
  • Forging Fluorine-Containing Quaternary Stereocenters by a Light-Driven
           Organocatalytic Aldol Desymmetrization Process
    • Authors: Sara Cuadros; Luca Dell'Amico, Paolo Melchiorre
      Abstract: Reported herein is a light-triggered organocatalytic strategy for the desymmetrization of achiral 2-fluoro-substituted cyclopentane-1,3-diketones. The chemistry is based on an intermolecular aldol reaction of photochemically generated hydroxy-o-quinodimethanes and simultaneously forges two adjacent fully substituted carbon stereocenters, with one bearing a stereogenic carbon–fluorine unit. The method uses readily available substrates, a simple chiral organocatalyst, and mild reaction conditions to afford an array of highly functionalized chiral 2-fluoro-3-hydroxycyclopentanones.Die Desymmetrisierung achiraler 2-fluorierter Cyclopentan-1,3-diketone (1) führt zu Produkten mit fluorsubstituierten quartären Stereozentren. Der leicht zugängliche Amidothioharnstoff-Katalysator aktiviert dabei selektiv eine der enantiotopen Carbonylgruppen von 1 und setzt eine intermolekulare Aldolreaktion mit Hydroxy-o-chinodimethanen in Gang, die zu diesem Zweck photochemisch aus 2 erzeugt werden.
      PubDate: 2017-08-18T04:05:48.817124-05:
      DOI: 10.1002/ange.201706763
       
  • Preise der Société Chimique de France 2017
    • PubDate: 2017-08-18T04:05:24.699234-05:
      DOI: 10.1002/ange.201707662
       
  • Oxygenation of Simple Olefins through Selective Allylic C−C Bond
           Cleavage: A Direct Approach to Cinnamyl Aldehydes
    • Authors: Jianzhong Liu; Xiaojin Wen, Chong Qin, Xinyao Li, Xiao Luo, Ao Sun, Bencong Zhu, Song Song, Ning Jiao
      Abstract: A novel metal-free allylic C−C σ-bond cleavage of simple olefins to give valuable cinnamyl aldehydes is reported. 1,2-Aryl or alkyl migration through allylic C−C bond cleavage occurs in this transformation, which is assisted by an alkyl azide reagent. This method enables O-atom incorporation into simple unfunctionalized olefins to construct cinnamyl aldehydes. The reaction features simple hydrocarbon substrates, metal-free conditions, and high regio- and stereoselectivity.E-selektiv: Eine metallfreie allylische C-C-Bindungsspaltung nichtfunktionalisierter Olefine liefert Zimtaldehyd-Derivate mit hohen Regio- und Stereoselektivitäten. Die Methode erweitert das Anwendungsspektrum von Alkylaziden und Olefinrekombination in der organischen Synthese.
      PubDate: 2017-08-18T04:01:25.597087-05:
      DOI: 10.1002/ange.201705671
       
  • NOAH: NMR Supersequences for Small Molecule Analysis and Structure
           Elucidation
    • Authors: Ēriks Kupče; Tim D. W. Claridge
      Abstract: Nested NMR experiments combining up to five conventional NMR pulse sequences into one supersequence are introduced. The core 2D NMR techniques routinely employed in small molecule NMR spectroscopy, such as HSQC, HMQC, HMBC, COSY, NOESY, TOCSY, and similar, can be recorded in a single measurement. In this way the data collection time may be dramatically reduced and sample throughput increased for basic NMR applications, such as structure elucidation and verification in synthetic, medicinal, and natural product chemistry.Eine NOAH-Supersequenz bietet Platz für bis zu fünf herkömmliche NMR-Pulssequenzen mit einer einzigen Erholungsphase, sodass viel Zeit bei der Datensammlung für Kleinmolekülanalysen gespart wird. Für diese Experimente benötigen die Spektrometer keinerlei Spezialausrüstung.
      PubDate: 2017-08-18T04:01:16.655522-05:
      DOI: 10.1002/ange.201705506
       
  • Enhanced Photophosphorylation of Chloroplast Entrapping Long-lived
           Photoacid
    • Authors: Youqian Xu; Jinbo Fei, Guangle Li, Tingting Yuan, Yue Li, Chenlei Wang, Xianbao Li, Junbai Li
      Abstract: Enhancing solar energy conversion efficiency is very important for developing renewable energy, protecting the environment and producing agricultural products. We demonstrate here that photophosphorylation is enhanced efficiently by coupling artificial photoacid generators (PAGs) with chloroplasts. The encapsulation of small-molecule long-lived PAGs in the thylakoid lumen is improved greatly by ultrasonication. Under visible light irradiation, a fast intramolecular photoreaction of the PAG occurs and produces many protons, remarkably enhancing the proton gradient in situ. Consequently, compared to pure chloroplasts, the assembled natural-artificial hybrid demonstrated approximately 3.9 times greater adenosine triphosphate (ATP) production. This work will provide new opportunities for constructing enhanced solar energy conversion systems.
      PubDate: 2017-08-18T04:01:12.252805-05:
      DOI: 10.1002/ange.201706368
       
  • Crystalline π-Stack Containing Five Stereoisomers: Insights into
           Conformational Isomorphism, Chirality Inversion, and Disorder
    • Authors: Agnieszka Nowak-Król; Merle I. S. Röhr, David Schmidt, Frank Würthner
      Abstract: An unprecedented crystal-packing arrangement of a tetramethoxy-bay-substituted perylene bisimide (PBI) consists of three crystallographically independent molecules, that is, an achiral (AC) PBI of saddle-shaped geometry along with two pairs of propeller-like twisted (P)- and (M)-enantiomeric PBI frameworks. All these five conformations are observed within a single π-stack revealing an intriguing packing sequence with an inversion of chirality from P to M via AC. Nudged elastic band calculations for the isolated molecule show that AC is a local minimum of the P to M interconversion path. In addition, two minor conformations were observed in the crystal, one of which resembles a transition-state molecule. Theoretical studies of dimeric and trimeric stacks reveal that the coexistence of all these structures in the crystal lattice is aided by the strong dispersion interactions between PBI cores and perfectly interdigitated dodecyl chains which stabilize energetically higher conformations.Von Hand zu Hand: Die Kristallpackung von Perylenbisimiden mit „Bay”-Substituenten umfasst propellerartig verdrehte und achirale Stereoisomere. In ein und demselbem regulären π-Stapel liegen alle Konformationen vor, wobei Chiralitätsinversion von P zu M über ein achirales Molekül zu beobachten ist. Die Koexistenz dieser Konformationen im Kristallgitter wird auf starke Dispersionskräfte zurückgeführt.
      PubDate: 2017-08-18T04:01:06.783996-05:
      DOI: 10.1002/ange.201705445
       
  • Stöchiometrische und katalytische C-C- und C-H-Bindungsbildung mit
           B(C6F5)3 über kationische Zwischenstufen
    • Authors: Yashar Soltani; Lewis C. Wilkins, Rebecca L. Melen
      Abstract: Diese Arbeit beschreibt eine neuartige katalytische Cyclisierung unter Verwendung eines stark Lewis-sauren Borans mit einhergehender C-H- oder C-C-Bindungsbildung. Die Aktivierung von Molekülen mit C-C-Dreifachbindungen unter Verwendung von B(C6F5)3 ermöglicht erstmals eine entsprechende Lewis-Säure-katalysierte, intramolekulare Cyclisierung von Carbonsäuren. Darüber hinaus zeigen die Ester dieser Carbonsäuren mit katalytischen Mengen B(C6F5)3 eine formale 1,5-Migration der Estergruppen unter Knüpfung einer C-C-Bindung. Unter Verwendung dieser neuen metallfreien Methode konnten anspruchsvolle Dihydropyrone und Isocumarine in hohen Ausbeuten unter milden Bedingungen sowie mit hoher Atomökonomie synthetisiert werden.Lewis-Säure-vermittelte Aktivierung von Alkinen führt zu einer intramolekularen Cyclisierung von Carbonsäuren. Die analogen Carbonsäure-Ester konnten unter C-C-Bindungsbildung mit katalytischen Mengen an B(C6F5)3 intramolekular cyclisiert werden. Dabei kommt es zu einer 1,5-Verschiebung der Estergruppe und zur Bildung eines ungesättigten Kohlenstoffgerüstes, wobei ausgezeichnete Ausbeuten erzielt werden.
      PubDate: 2017-08-18T03:50:51.077111-05:
      DOI: 10.1002/ange.201704789
       
  • Intramolecular π-π-interactions in flexibly linked partially fluorinated
           bis(arenes) in the gas phase
    • Authors: Norbert Werner Mitzel
      Abstract: Using hydrosilylation and C-C coupling reactions, three compounds with phenyl and perfluoro¬phenyl rings bridged by (CH2)3 and (CH2)2SiMe2 units were synthesized. Their solid-state structures are domi¬nated by intermolecular π-stacking interactions, primarily leading to dimeric or chain-type aggregates. Structures of the free molecules de¬termined by gas-phase electron diffraction reveal the most abun¬dant conformer to be significantly stabilized by intra¬mole¬cular π-π-interactions. For the silicon compounds structures charac¬te¬ri¬-zed by σ-π inter¬actions between a methyl and (perfluoro)-phenyl groups are next higher in energy and cannot be excluded completely by the GED experiments. C6H6(CH2)3C6F5 in contrast is composed of a single conformer. The gas-phase structures serve as reference for the evaluation of a series of (dis¬persion-corrected) quantum-chemi¬cal methods.
      PubDate: 2017-08-18T02:00:58.437001-05:
      DOI: 10.1002/ange.201707716
       
  • Titanocene-Catalyzed Radical Opening of N-Acylated Aziridines
    • Authors: Andreas Gansäuer; Yong-Qiang Zhang, Elisabeth Vogelsang, Zheng-Wang Qu, Stefan Grimme
      Abstract: Abstract: Aziridines activated by N-acylation are opened to the higher substituted radicals through electron transfer from titanocene(III) complexes in a novel catalytic reaction. It is applicable in conjugate additions, reductions, and cyclizations and suited for the constructions of quaternary carbon centers. The concerted mechanism of ring-opening was established by DFT-methods.
      PubDate: 2017-08-18T02:00:30.804784-05:
      DOI: 10.1002/ange.201707673
       
  • Typ-B-GPCR-Strukturen verdeutlichen Aktivierungsmechanismus
    • Authors: Felix Hausch
      Abstract: Aktive GPCRs im Fokus: Typ-B-G-Protein-gekoppelte Rezeptoren erkennen Peptidhormone und spielen eine Schlüsselrolle bei Krankheiten wie Diabetes und Fettleibigkeit. Die Entwicklung von Wirkstoffen, speziell Agonisten, für diese GPCRs ist jedoch schwierig. Nun wurden die ersten Strukturen von vollständig aktivierten Typ-B-GPCRs gelöst, die den Aktivierungsmechanismus klären und die strukturbasierte Wirkstoffforschung beschleunigen werden.
      PubDate: 2017-08-18T01:17:14.768986-05:
      DOI: 10.1002/ange.201707200
       
  • Große gesellschaftliche Herausforderungen und die Wissenschaft
    • Authors: Jürgen Kaube
      Abstract: „… Was ist der Sinn von Wissenschaft' Sie ist nicht nur ein Verfahren zur Lösung, sondern auch eines zur Identifikation von Problemen und sollte daher nicht einfach zum Dienstleister unserer Zivilisation erklärt werden. Sie ist vielmehr einer der Träger dieser Zivilisation, weil sie die Institutionalisierung von Lernbereitschaft darstellt …” Lesen Sie mehr im Editorial von Jürgen Kaube.
      PubDate: 2017-08-18T01:17:09.184306-05:
      DOI: 10.1002/ange.201707561
       
  • Lewis Base Catalysis in Organic Synthesis. 3 Bände. Herausgegeben von
           Edwin Vedejs und Scott E. Denmark.
    • Authors: Marialuisa Aufiero; Ryan Gilmour
      Abstract: Wiley-VCH, Weinheim 2016. 1488 S., geb., € 449.00.—ISBN 978-3527336180
      PubDate: 2017-08-18T01:17:04.434191-05:
      DOI: 10.1002/ange.201707836
       
  • Structural Revision and Biomimetic Synthesis of Goupiolone B
    • Authors: Yosuke Matsuo; Ayane Yoshida, Yoshinori Saito, Takashi Tanaka
      Abstract: Goupiolones A and B are unique phenolic compounds with significant DNA-damaging activity. In this study, the structure of goupiolone B was revised on the basis of DFT calculations of the 13C NMR chemical shifts and biosynthetic considerations. The dibenzobicyclo[3.2.2]nonane skeleton of the revised structure suggested that goupiolone B was produced by oxidative coupling between catechol and goupiolone A, which was strongly supported by biomimetic synthesis. Furthermore, racemization of goupiolone B was observed during the attempted resolution of its racemic mixture. A plausible racemization mechanism involving α-ketol rearrangement is proposed.Welche sind echt' Die Goupiolone A und B sind charakteristische phenolische Verbindungen mit DNA-schädigender Wirkung. Ihre Strukturen wurden nun basierend auf DFT-Rechnungen der 13C-NMR-chemischen Verschiebungen und biosynthetischer Betrachtungen revidiert. Das Dibenzobicyclo[3.2.2]nonan-Gerüst der revidierten Struktur lässt vermuten, dass Goupiolon B durch oxidative Kupplung zwischen Catechol und Goupiolon A produziert wird.
      PubDate: 2017-08-18T01:17:02.932129-05:
      DOI: 10.1002/ange.201706532
       
  • Surfactant-Assisted Phase-Selective Synthesis of New Cobalt MOFs and Their
           Efficient Electrocatalytic Hydrogen Evolution Reaction
    • Authors: Ya-Pan Wu; Wei Zhou, Jun Zhao, Wen-Wen Dong, Ya-Qian Lan, Dong-Sheng Li, Chenghua Sun, Xianhui Bu
      Abstract: Reported herein are two new polymorphic Co-MOFs (CTGU-5 and -6) that can be selectively crystallized into the pure 2D or 3D net using an anionic or neutral surfactant, respectively. Each polymorph contains a H2O molecule, but differs dramatically in its bonding to the framework, which in turn affects the crystal structure and electrocatalytic performance for hydrogen evolution reaction (HER). Both experimental and computational studies find that 2D CTGU-5 which has coordinates water and more open access to the cobalt site has higher electrocatalytic activity than CTGU-6 with the lattice water. The integration with co-catalysts, such as acetylene black (AB) leads to a composite material, AB&CTGU-5 (1:4) with very efficient HER catalytic properties among reported MOFs. It exhibits superior HER properties including a very positive onset potential of 18 mV, low Tafel slope of 45 mV dec−1, higher exchange current density of 8.6×10−4 A cm−2, and long-term stability.Zwei Co-MOFs wurden durch Phasenselektion durch anionische und neutrale Tenside erzeugt. Ihre unterschiedliche Affinität für eingeschlossene Wassermoleküle resultiert in verschieden gut zugänglichen aktiven Metallzentren. Ein Komposit aus diesen Co-MOFs überzeugte in der elektrokatalytischen Wasserstoffentwicklung durch Leistung und Langzeitstabilität.
      PubDate: 2017-08-18T01:15:52.102566-05:
      DOI: 10.1002/ange.201707238
       
  • A Doubly Boron-Doped Perylene by N-Heterocylic Carbene–Borenium
           Hydroboration–C−H Borylation–Dehydrogenation
    • Authors: Jeffrey M. Farrell; David Schmidt, Vincenzo Grande, Frank Würthner
      Abstract: Reaction of an N-heterocyclic carbene (NHC)–borenium ion with 9,10-distyrylanthracene forms four B−C bonds through two selective, tandem hydroboration–electrophilic C−H borylations to yield an isolable, crystallographically characterizable polycyclic diborenium ion as its [NTf2]− salt (1). Dehydrogenation of 1 with TEMPO radical followed by acidic workup yields a 3,9-diboraperylene as its corresponding borinic acid (2). This sequence can be performed in one pot to allow the facile, metal-free conversion of an alkene into a small molecule containing a boron-doped graphene substructure. Doubly boron-doped perylene 2 exhibits visible range absorbance and fluorescence in chloroform solution (Φ=0.63) and undergoes two reversible one-electron reductions at moderate potentials of −1.30 and −1.64 eV vs. ferrocenium/ferrocene in DMSO. Despite sterically accessible boron centers and facile electrochemical reductions, compound 2 is air-, moisture-, and silica gel-stable.Perylen mit B: Ein Eintopfverfahren führt von einem nichtfunktionalisierten Alken zu einem stabilen elektronendefizienten, doppelt bordotierten Perylen. Entscheidend ist dabei eine hoch selektive Sequenz aus Hydroborierungen mit einem N-heterocyclischen Carben-Borenium-Addukt und elektrophilen C-H-Borylierungen. Der Ansatz ergänzt andere Routen zu B-dotierten Graphen-Substrukturen.
      PubDate: 2017-08-18T01:15:37.5158-05:00
      DOI: 10.1002/ange.201706346
       
  • Ligand-Controlled Regiodivergent and Enantioselective Copper-Catalyzed
           Hydroallylation of Alkynes
    • Authors: Guoxing Xu; Haiyan Zhao, Bin Fu, Aijie Cang, Ge Zhang, Qian Zhang, Tao Xiong, Qian Zhang
      Abstract: A ligand-controlled regiodivergent and enantioselective copper-catalyzed intermolecular hydroallylation of alkynes with allylic phosphates and hydrosilanes has been achieved for the first time. The chiral bidentate sulfonate-containing N-heterocyclic carbene (NHC)-ligated CuCl complex guides enantioenriched SN2′-type products, whereas the use of IMesCuCl catalyst affords SN2-type products. Thus a range of chiral branched and achiral linear 1,4-dienes could be facilely synthesized from readily available alkynes in a regiodivergent manner.
      PubDate: 2017-08-17T21:26:33.133236-05:
      DOI: 10.1002/ange.201707070
       
  • Stereospecific Electrophilic Fluorination of Alkylcarbastannatrane
           Reagents
    • Authors: Xinghua Ma; Mohamed Diane, Glenn Ralph, Christine Chen, Mark R Biscoe
      Abstract: We report the use of isolable primary and secondary alkylcarbastannatrane nucleophiles in site-specific fluorination reactions. These reactions occur without the need for transition metal catalysis or in situ activation of the nucleophile. In the absence of the carbastannatrane backbone, alkyltin nucleophiles exhibit no activity towards fluorination. When enantioenriched alkylcarbastannatranes are employed, fluorination occurs predominately via a stereoinvertive mechanism to generate highly enantioenriched alkyl fluoride compounds. These conditions can also be extended to stereospecific chlorination, bromination, and iodination reactions.
      PubDate: 2017-08-17T21:26:22.009575-05:
      DOI: 10.1002/ange.201704672
       
  • A Stereoselective [3+1] Ring Expansion for the Synthesis of
           Highly-Substituted Methylene Azetidines
    • Authors: Steven C. Schmid; Ilia A. Guzei, Jennifer M. Schomaker
      Abstract: The reaction of rhodium-bound carbenes with strained bicyclic methylene aziridines results in a formal [3+1] ring expansion to yield highly-substituted methylene azetidines with excellent regio- and stereoselectivity. The reaction appears to proceed through an ylide-type mechanism, where the unique strain and structure of the methylene aziridine promotes a ring-opening/ring-closing cascade that efficiently transfers chirality from substrate to product. The resultant products can be elaborated into new azetidine scaffolds containing vicinal tertiary-quaternary and even quaternary-quaternary stereocenters.
      PubDate: 2017-08-17T12:20:48.076676-05:
      DOI: 10.1002/ange.201705202
       
  • Molecular dynamics of hexamethylbenzene at low temperatures; evidence of
           unconventional magnetism based on rotational motion of protons
    • Authors: Fei Yen; Zhen Zheng Zhao, Si Xia Hu, Lang Chen
      Abstract: The types of magnetism known to date are all mainly based on contributions from electron motion. We show how rotational motion of protons (H+) within the methyl groups in hexamethylbenzene (C6(CH3)6) also contribute significantly to the magnetic susceptibility. Starting from below 118 K, as the rotational motion of the methyl groups set in, an associated magnetic moment positive in nature due to charge of the protons renders the susceptibility to become anomalously dependent on temperature. Starting from 20 K, the susceptibility diverges with decreasing temperature indicative of spin-spin interactions between methyl groups aligned in a previously unclassified type of anti-ferromagnetic configuration. Complementary dielectric constant measurements also show the existence of magneto-dielectric coupling. Our findings allow for the study of strongly correlated systems that are based on a species that possesses much slower dynamics.
      PubDate: 2017-08-17T12:20:24.087691-05:
      DOI: 10.1002/ange.201707024
       
  • Electroless Formation of Hybrid Lithium Anodes for Fast Interfacial Ion
           Transport
    • Authors: Snehashis Choudhury; Zhengyuan Tu, Sanjuna Stalin, Dylan Vu, Kristen Fawole, Deniz Gunceler, Ravishankar Sundararaman, Lynden Archer
      Abstract: Rechargeable batteries based on metallic anodes are of interest for fundamental and applications-focused studies of chemical and physical kinetics of liquids at solid interfaces. Approaches that allow facile creation of uniform coatings on these metals to prevent physical contact with liquid electrolytes, while enabling fast ion-transport, are essential to address chemical instability of the anodes. Here, we report a simple electroless ion-exchange chemistry for creating coatings of the metal Indium on lithium. By means of Joint-Density Functional theory and interfacial characterization experiments, we show that In coatings stabilize Li by multiple processes, including enabling exceptionally fast surface diffusion of lithium ions and high chemical resistance to liquid electrolytes. Indium coatings also undergo reversible alloying reactions with lithium ions, facilitating design of high-capacity hybrid In-Li anodes that utilize both alloying and plating chemistries for charge storage.
      PubDate: 2017-08-17T11:20:59.099542-05:
      DOI: 10.1002/ange.201707754
       
  • Enzymatic C-H Amidation in the Production of Natural and Unnatural
           Thiotetronate Antibiotics with Potentiated Bioactivity
    • Authors: Jie Li; Xiaoyu Tang, Takayoshi Awakawa, Bradley S. Moore
      Abstract: The selective activation of unreactive hydrocarbons by biosynthetic enzymes has inspired new synthetic methods in C-H bond activation. Herein, we report the unprecedented two-step biosynthetic conversion of thiotetromycin to thiotetroamide C involving the tandem carboxylation and amidation of an unreactive ethyl group. We detail the genetic and biochemical basis for the terminal amidation in thiotetroamide C biosynthesis, which involves a uniquely adapted cytochrome P450-amidotransferase enzyme pair and highlights the first carboxylation-amidation enzymatic cascade reaction leading to the selective formation of a primary amide group from a chemically inert alkyl group. Motivated by the ten-fold increase in antibiotic potency of thiotetroamide C ascribed to the acetamide group and the unusual enzymology involved, we enzymatically interrogated diverse thiolactomycin analogues and prepared an unnatural thiotetroamide C analogue with potentiated bioactivity compared to the parent molecule.
      PubDate: 2017-08-17T11:20:33.751668-05:
      DOI: 10.1002/ange.201705239
       
  • Anionic Palladium(0) and Palladium(II) Ate Complexes
    • Authors: Marlene Kolter; Katharina Böck, Konstantin Karaghiosoff, Konrad Koszinowski
      Abstract: Palladium ate complexes are frequently invoked as important intermediates in Heck and cross-coupling reactions, but so far have largely eluded a characterization at the molecular level. Here, we use electrospray-ionization mass spectrometry, electrical conductivity measurements, and NMR spectroscopy to show that the electron-poor catalyst [L₃Pd] (L = tris[3,5-bis(trifluoromethyl)-phenyl]phosphine) readily reacts with Br− ions to afford the anionic, zero-valent ate complex [L₃PdBr]−. In contrast, more electron-rich Pd catalysts display lower tendencies toward the formation of ate complexes. Combining [L₃Pd] with LiI and an aryl iodide substrate ArI results in the observation of the Pd(II) ate complex [L₂Pd(Ar)I₂]−.
      PubDate: 2017-08-17T10:20:46.667879-05:
      DOI: 10.1002/ange.201707362
       
  • Efficient Photoelectrochemical Reduction of Carbon Dioxide to Formic Acid:
           Functionalized Ionic Liquid as an Absorbent and Electrolyte
    • Authors: Weiwei Lu; Bo Jia, Beilei Cui, Yuan Zhang, Kaisheng Yao, Yuling Zhao, Jianji Wang
      Abstract: Photoelectrochemical (PEC) reduction of carbon dioxide (CO2) is a potential method for production of fuels and chemicals from a C1 feedstock accumulated in the atmosphere. However, the low solubility of CO2 in water, and complicated processes associated with capture and conversion, render CO2 conversion inefficient. A new concept is proposed in which a PEC system is used to capture and convert CO2 into formic acid. The process is assisted by an ionic liquid (1-aminopropyl-3-methylimidazolium bromide) aqueous solution, which functions as an absorbent and electrolyte at ambient temperature and pressure. Within this PEC reduction strategy, the ionic liquid plays a critical role in promoting the conversion of CO2 to formic acid and suppressing the reduction of H2O to H2. At an applied voltage of 1.7 V, the Faradaic efficiency for formic acid production is as high as 94.1 % and the electro-to-chemical efficiency is 86.2 %.Einfangen und umwandeln: Eine funktionalisierte ionische Flüssigkeit (IL) dient als Absorber und Elektrolyt bei der photoelektrokatalytischen Reduktion von CO2 zu Ameisensäure, um die Reduktion von H2O zu H2 zu vermeiden. Ameisensäure konnte mit einem Faraday-Wirkungsgrad von 94.1 % und einer 86.2 %igen Übertragung von elektrischer in chemische Energie bei 1.7 V hergestellt. PEM=Protonenaustauschmembran.
      PubDate: 2017-08-17T08:46:28.776489-05:
      DOI: 10.1002/ange.201703977
       
  • Controlled Supramolecular Self-Assembly of Super-charged β-Lactoglobulin
           A–PEG Conjugates into Nanocapsules
    • Authors: Amit Kumar Khan; Sushanth Gudlur, Hans-Peter M. de Hoog, Winna Siti, Bo Liedberg, Madhavan Nallani
      Abstract: The synthesis and characterization of a new protein–polymer conjugate composed of β lactoglobulin A (βLG A) and poly(ethylene glycol) PEG is described. βLG A was selectively modified to self-assemble by super-charging via amination or succinylation followed by conjugation with PEG. An equimolar mixture of the oppositely charged protein–polymer conjugates self-assemble into spherical capsules of 80–100 nm in diameter. The self-assembly proceeds by taking simultaneous advantage of the amphiphilicity and polyelectrolyte nature of the protein–polymer conjugate. These protein–polymer capsules or proteinosomes are reminiscent of protein capsids, and are capable of encapsulating solutes in their interior. We envisage this approach to be applicable to other globular proteins.Eine runde Sache: Das Protein β-Lactoglobulin A (βLG A) wurde durch Aminierung oder Succinylierung und nachfolgende Konjugation mit Polyethylenglycol (PEG) selektiv für die Selbstorganisation modifiziert. Eine äquimolare Mischung der gegensätzlich geladenen Protein-Polymer-Konjugate aggregiert zu kugelförmigen Kapseln mit 80–100 nm Durchmesser.
      PubDate: 2017-08-17T08:46:05.898147-05:
      DOI: 10.1002/ange.201704298
       
  • Mineralized State of the Avian Influenza Virus in the Environment
    • Authors: Hangyu Zhou; Guangchuan Wang, Xiaoyu Wang, Zhiyong Song, Ruikang Tang
      Abstract: Although the circulation of avian influenza viruses in humans is limited, they can be transmitted from Aves (birds) to humans, representing a great challenge. Herein, we suggest that influenza viruses from Aves might exist in a mineralized state owing to the high calcium concentrations in the avian intestine. Using two typical influenza viruses as examples, we demonstrate that these viruses can self-mineralize in simulated avian intestinal fluid, resulting in egg-like virus–mineral structured composites. The mineralized viruses are more robust, with enhanced infectivity and thermostability. More importantly, the mineral exterior of mineralized viruses can alter their cell internalization, expanding the possible tropisms. The discovery of a mineralized state of influenza viruses highlights the integration of nanomaterials and viruses in the environment, which provides a new understanding of avian influenza infection and its control.Man sollte wissen, wie das Vogelgrippe-Virus über Speziesschranken hinweg auch Menschen infizieren kann. Eine Analyse des Virus in seiner Umgebung zeigt, dass es in Vögeln im mineralisierten Zustand vorliegen könnte. Die Tatsache, dass das mineralisierte Virus in rezeptorunabhängiger Weise in Wirtzellen gelangt, könnte seine Infektiosität für Menschen erklären.
      PubDate: 2017-08-17T08:45:44.337792-05:
      DOI: 10.1002/ange.201705769
       
  • Jubiläumsheft 150 Jahre GDCh
    • Authors: Peter Gölitz
      Abstract: Berlin war 1867 ein großes Dorf zumindest in August Wilhelm von Hofmanns Augen, allerdings mit einer so stimulierenden intellektuellen Atmosphäre, dass er von London nach Berlin zurückgekehrt war und hier nun rasch seine vielfältigen Tätigkeiten aufnahm; darunter war auch die Organisation der Chemiker in Berlin und „ganz Deutschland”, das sich ja erst am Vorabend der Gründung des Deutschen Reiches befand. Den Aufstieg und Niedergang der Deutschen Chemischen Gesellschaft (DChG) schildert in diesem Heft J. A. Johnson in einem Aufsatz (
      DOI : 10.1002/ange.201702487). Die DChG lag moralisch und organisatorisch 1945 in Trümmern, und erst 1949 gründete sich die Gesellschaft Deutscher Chemiker, die die positive Tradition gerade der frühen DChG aufnahm und damit 2017 ein 150-Jahre-Jubiläum feiert, das seinen Höhepunkt in einem Festakt am 10. September in Berlin hat. Am darauffolgenden Tag findet ein Angewandte-Fest-Symposium statt, und viele der Redner sowie Kuratoren und Beiräte der Zeitschrift sind mit Beiträgen in diesem Festheft vertreten. Grün ist die Farbe der GDCh, grün ist die Farbe der Hoffnung: Mögen Chemiker in Zukunft noch mehr zum Wohle der Menschheit und unseres Planeten beitragen als in der Vergangenheit - dieser Hoffnung Ausdruck zu geben ist ein Anliegen des Jubiläums-Wissenschaftsforums der GDCh in Berlin und dieses besonderen Heftes.
      PubDate: 2017-08-17T08:40:25.8267-05:00
       
  • Heavily Substituted Atropisomeric Diarylamines by Unactivated Smiles
           Rearrangement of N-Aryl Anthranilamides
    • Authors: Romain Costil; Harvey Dale, Natalie Fey, George Whitcombe, Johnathan Matlock, Jonathan Clayden
      Abstract: Diarylamines find use as metal ligands and as structural components of drug molecules, and are commonly made by metal catalyzed C-N coupling. However, the limited tolerance to steric hindrance of these couplings restricts the synthetic availability of more substituted diarylamines. Here we report a remarkable variant of the Smiles rearrangement that employs readily accessible N-aryl anthranilamides as precursors to diarylamines. Conformational predisposition of the anthranilamide starting material brings the aryl rings into proximity and allows the rearrangement to take place despite the absence of electron-withdrawing substituents, and even with sterically encumbered doubly ortho-substituted substrates. Some of the diarylamine products are resolvable into atropisomeric enantiomers, and are the first simple diarylamines to display atropisomerism.
      PubDate: 2017-08-17T08:21:27.207518-05:
      DOI: 10.1002/ange.201706341
       
  • Regio- and Stereoselective Chlorocyanation of Alkynes
    • Authors: Manuel Alcarazo; Alejandro G Barrado, Richard Goddard, Adam Zielinski
      Abstract: The regio- and stereoselective conversion of alkynes into (Z)-3-chloroacrylonitriles was achieved by treatment of a variety of terminal as well as internal alkynes with BCl3 in the presence of stoichiometric amounts of imidazolium thiocyanates. These products can be easily functionalized into useful building blocks, demonstrating the synthetic value of the method. Preliminary mechanistic studies suggest initial activation of the cationic thiocyanate by the Lewis acid followed by electrophilic attack of the alkyne. syn-Addition of a chloride to the vinyl cation intermediate and final elimination of the thiourea unit afford the desired chloroacrylonitriles.
      PubDate: 2017-08-17T08:21:24.718861-05:
      DOI: 10.1002/ange.201705851
       
  • Osmium-mediated 4sU-to-C transformation as key to study RNA dynamics by
           sequencing (TUC-seq)
    • Authors: Christian Riml; Thomas Amort, Dietmar Rieder, Catherina Gasser, Alexandra Lusser, Ronald Micura
      Abstract: To understand the functional roles of RNA in the cell, it is essential to elucidate the dynamics of their production, processing and decay. A recent method for assessing mRNA dynamics is metabolic labeling with 4-thiouridine (4sU), followed by thio-selective attachment of affinity tags. Detection of labeled transcripts by affinity purification and hybridization to microarrays or by deep sequencing then reveals RNA expression levels. Here, we present a novel sequencing method that eliminates affinity purification and allows for direct assessment of 4sU labeled RNA. It employs an OsO4 transformation to convert 4sU into cytosine. We exemplify the utility of the new method for verification of endogenous 4sU in tRNAs and for the detection of pulse-labeled mRNA of seven selected genes in mammalian cells to determine the relative abundance of the new transcripts. The results prove TUC-seq as a straight-forward and highly versatile method for studies of cellular RNA dynamics.
      PubDate: 2017-08-17T08:20:44.856689-05:
      DOI: 10.1002/ange.201707465
       
  • Takahiro Nishimura
    • PubDate: 2017-08-17T07:51:02.997336-05:
      DOI: 10.1002/ange.201707583
       
  • Tomoya Miura
    • PubDate: 2017-08-17T07:50:46.655973-05:
      DOI: 10.1002/ange.201707581
       
  • Unified Total Synthesis of Polyoxin J, L, and Fluorinated Analogues on
           the Basis of Decarbonylative Radical Coupling Reactions
    • Authors: Haruka Fujino; Masanori Nagatomo, Atmika Paudel, Suresh Panthee, Hiroshi Hamamoto, Kazuhisa Sekimizu, Masayuki Inoue
      Abstract: Polyoxins J (1 a) and L (1 b) are important nucleoside antibiotics. The complex and densely functionalized dipeptide structures of 1 a and 1 b contain thymine and uracil nucleobases, respectively. Herein we report the unified total synthesis of 1 a, 1 b, and their artificial analogues 1 c and 1 d with trifluorothymine and fluorouracil structures. Decarbonylative radical coupling between α-alkoxyacyl tellurides and a chiral glyoxylic oxime ether led to chemo- and stereoselective construction of the ribonucleoside α-amino acid structures of 1 a–d without damaging the preinstalled nucleobases. The high applicability of the radical-based methodology was further demonstrated by preparation of the trihydroxynorvaline moiety of 1 a–d. The two amino acid fragments were connected and elaborated into 1 a–d (longest linear sequence: 11 steps). Compounds 1 a and 1 b assembled in this way exhibited potent activity against true fungi, while only 1 d was active against Gram-positive bacteria.Alles anders mit Fluor: Die Nukleosid-Antibiotika Polyoxin J und L sowie zwei fluorierte Analoga wurden mithilfe einer radikalischen Strategie synthetisiert. Eine erste biologische Evaluierung belegt die charakteristischen antimikrobiellen Wirkspektren der synthetisierten Polyoxine.
      PubDate: 2017-08-17T07:46:13.051832-05:
      DOI: 10.1002/ange.201706671
       
  • Chemotaxis-Guided Hybrid Neutrophil Micromotor for Actively Targeted Drug
           Transport
    • Authors: Jingxin Shao; Mingjun Xuan, Hongyue Zhang, Xiankun Lin, Zhiguang Wu, Qiang He
      Abstract: Engineering self-propelled micromotors with good biocompatibility and biodegradability for actively seeking sites of diseases and targeted drug transport remains a huge challenge. Here we demonstrate that neutrophils with intrinsic chemotaxis ability could be transformed into self-guided biohybrid motors through integrating mesoporous silica nanoparticles (MSNs) with high loading capability. To realize the compatibility of neutrophil cells with drug-loaded MSNs, bacteria membranes derived from E. coli were coated onto MSNs in advance by using a camouflaging strategy. The resulting biohybrid micromotors successfully inherit the characteristic chemotaxis capability of native neutrophils and could move along the chemoattractant gradients produced by E.coli. Our studies suggest that the camouflaging approaches, which favor the uptake of MSNs into neutrophils without losing cellular activity and motility, could be used to construct biohybrid micromotors for advanced biomedical applications.
      PubDate: 2017-08-17T07:21:25.902046-05:
      DOI: 10.1002/ange.201706570
       
  • Intracellular Delivery of Functional Native Antibodies under Hypoxic
           Conditions by Using a Biodegradable Silica Nanoquencher
    • Authors: Shao Q. Yao; Peiyan Yuan, Hailong Zhang, Linghui Qian, Xin Mao, Shubo Du, Changmin Yu, Bo Peng
      Abstract: Antibodies are important biopharmaceuticals, but almost all antibody-based drugs are limited to targeting antigens located at the cell exterior due to their inability to enter the cell interior. Available methods for intracellular delivery of antibodies have major shortcomings. Herein we report an approach to encapsulate native antibodies in a biodegradable silica nanoquencher (BS-qNP) which could undergo efficient cellular uptake and intracellular degradation to release antibodies under hypoxic conditions. By coating the surface of BS-qNP with cell-penetrating poly(disulfide)s (CPD), the delivered antibodies (or other proteins) avoided endolysosomal trapping. Doping of the silica coating with a fluorescent dye and a dark hole quencher further endowed BS-qNP with hypoxia-responsive fluorescence Turn-ON property. Our antibody delivery system thus provides the first platform capable of stable encapsulation, efficient uptake, on-demand antibody release and imaging of release/cell state.
      PubDate: 2017-08-17T07:21:19.936407-05:
      DOI: 10.1002/ange.201705578
       
  • The Hydrophobic Gap at High Hydrostatic Pressures
    • Authors: Florian J Wirkert; Christoph Hölzl, Michael Paulus, Paul Salmen, Metin Tolan, Dominik Horinek, Julia Nase
      Abstract: We gain new insight into the so-called hydrophobic gap, a molecularly thin region of decreased electron density at the interface between water and a solid hydrophobic surface, by X-ray reflectivity experiments and molecular dynamics simulations at different hydrostatic pressures. Pressure variation shows that the hydrophobic gap persists up to a pressure of 5 kbar. The depletion in the interfacial region is strongly decreasing with rising pressure, indicating that the interfacial region is compressed more strongly than bulk water. The decrease is most significant up to 2 kbar, beyond that, the pressure response of the depletion is less pronounced.
      PubDate: 2017-08-17T07:20:40.709631-05:
      DOI: 10.1002/ange.201706662
       
  • Reductive Decarboxylative Alkynylation of N-Hydroxyphthalimide Esters with
           Bromoalkynes
    • Authors: Liangbin Huang; Astrid M. Olivares, Daniel J. Weix
      Abstract: A new method for the synthesis of terminal and internal alkynes from the nickel-catalyzed decarboxylative coupling of N-hydroxyphthalimide esters and bromoalkynes is presented. This reductive cross-electrophile coupling is the first to use a C(sp)−X electrophile, and appears to proceed via an alkynylnickel intermediate. The internal alkyne products are obtained in yields of 41–95 % without the need for a photocatalyst, light, or a strong oxidant. The reaction displays a broad scope of carboxylic acid and alkyne coupling partners, and can tolerate an array of functional groups, including carbamate NH, halogen, nitrile, olefin, ketone, and ester moieties. Mechanistic studies suggest that this process does not involve an alkynylmanganese reagent and instead proceeds through nickel-mediated bond formation.Terminale und interne Alkine wurden durch die Nickel-katalysierte decarboxylierende Kupplung von N-Hydroxyphthalimidestern und Bromalkinen erhalten. Diese Umsetzung zeichnet sich durch eine große Substratbreite aus, und verschiedene funktionelle Gruppen wie Carbamate, Halogenide, Nitrile, Olefin, Ketone und Ester werden toleriert.
      PubDate: 2017-08-17T07:08:51.909064-05:
      DOI: 10.1002/ange.201706781
       
  • Paolo Samorì
    • PubDate: 2017-08-17T07:08:38.57472-05:0
      DOI: 10.1002/ange.201707626
       
  • Nickel-Catalyzed Enantioselective Conjunctive Cross-Coupling of 9-BBN
           Borates
    • Authors: Matteo Chierchia; Chunyin Law, James P. Morken
      Abstract: Catalytic enantioselective conjunctive cross-coupling between 9-BBN borate complexes and aryl electrophiles can be accomplished with Ni salts in the presence of a chiral diamine ligand. The reactions furnish chiral 9-BBN derivatives in an enantioselective fashion and these are converted to chiral alcohols and amines, or engaged in other stereospecific C−C bond forming reactions.Konjunktive Kupplung: Ni-katalysierte konjunktive Kupplungen liefern in enantioselektiver Weise chirale 9-BBN-Derivate, die anschließend in chirale Alkohole und Amine umgewandelt oder in anderen stereospezifischen C-C-Kupplungen eingesetzt werden können.
      PubDate: 2017-08-17T07:07:29.453023-05:
      DOI: 10.1002/ange.201706719
       
  • A 2-O-Methylriboside Unknown Outside the RNA World Contains Arsenic
    • Authors: Ronald A. Glabonjat; Georg Raber, Kenneth B. Jensen, Nikolaus Guttenberger, Klaus Zangger, Kevin A. Francesconi
      Abstract: Lipid-soluble arsenic compounds, also called arsenolipids, are ubiquitous marine natural products of currently unknown origin and function. In our search for clues about the possible biological roles of these compounds, we investigated arsenic metabolism in the unicellular green alga Dunaliella tertiolecta, and discovered an arsenolipid fundamentally different from all those previously identified; namely, a phytyl 5-dimethylarsinoyl-2-O-methyl-ribofuranoside. The discovery is of particular interest because 2-O-methylribosides have, until now, only been found in RNA. We briefly discuss the significance of the new lipid in biosynthesis and arsenic biogeochemical cycling.Ein kleiner Fremdling: Studien des Arsenmetabolismus in der einzelligen Grünalge Dunaliella tertiolecta offenbarten ein Arsenolipid, das sich von allen bisher identifizierten Vertretern unterscheidet, nämlich ein Phytyl-5-dimethylarsinoyl-2-O-methylribofuranosid (siehe Bild). Die Entdeckung ist vor allem deshalb interessant, weil 2-O-Methylriboside bisher nur in RNA gefunden wurden.
      PubDate: 2017-08-17T06:47:01.034641-05:
      DOI: 10.1002/ange.201706310
       
  • Enzymatic Synthesis of Homogeneous Chondroitin Sulfate Oligosaccharides
    • Authors: Jine Li; Guowei Su, Jian Liu
      Abstract: Chondroitin sulfate (CS) is a sulfated polysaccharide that plays essential physiological roles. Here, we report an enzyme-based method for the synthesis of a library of 15 different CS oligosaccharides. This library covers 4-O-sulfated and 6-O-sulfated oligosaccharides ranging from trisaccharides to nonasaccharides. We also describe the synthesis of unnatural 6-O-sulfated CS pentasaccharides containing either a 6-O-sulfo-2-azidogalactosamine or a 6-O-sulfogalactosamine residue. The availability of structurally defined CS oligosaccharides offers a novel approach to investigate the biological functions of CS.Eine Enzym-basierte Methode ermöglichte die Synthese von 15 Chondroitinsulfat(CS)-Oligosacchariden, darunter 4-O- und 6-O-sulfatierte Oligosaccharide von Tri- bis Nonasacchariden. Nichtnatürliche 6-O-sulfatierte CS-Pentasaccharide mit einer 6-O-Sulfo-2-azidogalactosamin- oder einer 6-O-Sulfogalactosamin-Einheit wurden ebenfalls synthetisiert.
      PubDate: 2017-08-17T06:46:53.623794-05:
      DOI: 10.1002/ange.201705638
       
  • How Understanding the Role of an Additive Can Lead to an Improved
           Synthetic Protocol without an Additive: Organocatalytic Synthesis of
           Chiral Diarylmethyl Alkynes
    • Authors: Min Chen; Jianwei Sun
      Abstract: The use of additives for organic synthesis has become a common tactic to improve the outcome of organic reactions. Herein, by using an organocatalytic process for the synthesis of chiral diarylmethyl alkynes as a platform, we describe how an additive is involved in the improvement of the process. The evolution of an excellent synthetic protocol has been achieved in three stages, from 1) initially no catalyst turnover, to 2) good conversion and enantioselectivity with a superior additive, and eventually 3) even better efficiency and selectivity without an additive. This study is an important and rare demonstration that understanding the role of additive can be so beneficial as to obviate the need for the additive.Additiv subtrahiert: Anhand eines organokatalytischen Prozesses wird gezeigt, wie eine Reaktion zunächst in eine hoch effiziente und enantioselektive katalytische Variante mit Additiv, und schließlich auch ohne Additiv, entwickelt werden kann. Durch Aufklärung der Funktion eines Additivs ist es möglich, Synthesevorschriften grundlegend zu verbessern.
      PubDate: 2017-08-17T06:46:40.888812-05:
      DOI: 10.1002/ange.201706579
       
  • DNA-Hydrogele aus Plasmid-DNA
    • Authors: Tanja Nöll; Sabine Wenderhold-Reeb, Holger Schönherr, Gilbert Nöll
      Abstract: DNA-Hydrogele sind aufgrund ihrer Biokompatibilität und ihrer biologischen Abbaubarkeit für verschiedene biomedizinische Anwendungen von großem Interesse. Bisher werden DNA-Hydrogele aus synthetischen Bausteinen hergestellt, was mit hohen Kosten verbunden ist. Als Alternative wird hier die Herstellung von DNA-Hydrogelen aus Plasmid-DNA beschrieben. Plasmid-DNA kann durch Fermentation in großem Maßstab hergestellt werden. Die gewünschten linearen DNA-Bausteine werden dann durch enzymatischen Verdau erhalten. Die Gelierung erfolgt durch die Ausbildung kovalenter Bindungen zwischen einzelnen Bausteinen durch enzymatische Ligation. Hier wird zum ersten Mal die Herstellung reiner DNA-Hydrogele aus Plasmid-DNA vorgestellt. Rheologische Untersuchungen bestätigen, dass die so hergestellten DNA-Hydrogele Speichermoduli von G′>100 Pa besitzen.Ab- und Aufbau: Reine DNA-Hydrogele wurden aus biotechnologisch gewonnener Plasmid-DNA durch Ligation verschieden langer Fragmente ohne Verwendung synthetisch hergestellter DNA-Bausteine hergestellt. Die rheologischen Eigenschaften der Hydrogele können durch Variieren von Länge und Sequenz der verwendeten Fragmente kontrolliert werden.
      PubDate: 2017-08-17T06:40:36.497421-05:
      DOI: 10.1002/ange.201705001
       
  • Phosphine-catalyzed Enantioselective Formal [4+4] Annulation of
           alpha,beta-Unsaturated Imines and Allene Ketones: Construction of
           Eight-membered Rings
    • Authors: Yixin Lu; Huanzhen Ni, Xiaodong Tang, Wenrui Zheng, Weijun Yao, Nisar Ullah
      Abstract: The first highly enantioselective phosphine-catalyzed formal[4+4] annulation has been developed. In the presence of amino acid-derived phosphines, the unprecedented formal [4+4] annulations between benzofuran/indole derived α,β-unsaturated imines and allene ketones proceeded smoothly, affording azocines bearing a benzofuran or an indole moiety in excellent yields and with nearly perfect enantioselectivities (≥98% ee in most cases). This work marks the first efficient asymmetric construction of optically enriched eight-membered rings via phosphine catalysis
      PubDate: 2017-08-17T06:26:54.98198-05:0
      DOI: 10.1002/ange.201707183
       
  • Direct and Stereospecific [3+2] Synthesis of Pyrrolidines from Simple
           Unactivated Alkenes
    • Authors: Jorge Otero-Fraga; Samuel Suárez-Pantiga, Marc Montesinos-Magraner, Dennis Rhein, Abraham Mendoza
      Abstract: Pyrrolidines are central heterocyclic compounds with endless applications in organic synthesis, metal- and organocatalysis. In particular, their potential as ligands for first-row transition-metal catalysts has inspired a new method to access complex poly-heterocyclic pyrrolidines in one-step from available materials. This fundamental step forward is grounded on the discovery of an essential organoaluminum promoter that engages unactivated and electron-rich olefins in intermolecular [3+2] cycloadditions for the first time.
      PubDate: 2017-08-17T06:26:46.481554-05:
      DOI: 10.1002/ange.201706682
       
  • Decacene: On-Surface Generation
    • Authors: Justus Krüger; Fátima García, Frank Eisenhut, Dmitry Skidin, José M. Alonso, Enrique Guitián, Dolores Pérez, Gianaurelio Cuniberti, Francesca Moresco, Diego Peña
      Abstract: Acenes are intriguing molecules with unique electronic properties. The difficulties in their preparation owing to low stability under ambient conditions are apparent because successful syntheses of long unsubstituted acenes are still scarce, in spite of the great attention they have attracted. Only unsubstituted acenes up to heptacene have been isolated in bulk, with nonacene being the largest acene detected to date. Herein we use on-surface assisted reduction of tetraepoxy decacene precursors on Au(111) as the key step to generate unprecedented decacene which is visualized and its electronic resonances studied by scanning tunneling microscopy (STM) and spectroscopy (STS).Zehnerreihe: Durch eine Kombination aus organischer Synthese und Chemie auf Oberflächen konnte Decacen erstmals synthetisiert werden. Iterative Arin-Cycloadditionen führten zu stabilen Tetraepoxy-Vorstufen, die auf Au(111) zum gewünschten Produkt reduziert wurden. Das so erhaltene Decacen konnte durch Rastertunnelmikroskopie visualisiert werden.
      PubDate: 2017-08-17T04:51:57.444234-05:
      DOI: 10.1002/ange.201706156
       
  • Two-Dimensional Seeded Self-Assembly of a Complex Hierarchical
           Perylene-Based Heterostructure
    • Authors: Yin Liu; Cheng Peng, Wei Xiong, Yifan Zhang, Yanjun Gong, Yanke Che, Jincai Zhao
      Abstract: A complex two-dimensional (2D) hierarchical heterostructure was fabricated by a sequential two-dimensional seeded self-assembly, which consisted of laterally grown nanotubes from one perylene monomer and terminally elongated nanocoils from a similar perylene monomer on microribbon seeds from a third perylene. Because the nanotube and nanocoil monomers can form kinetically trapped off-pathway aggregates to prevent self-nucleation and have similar molecular organizations to different facets of the seeds, the nanotube and nanocoil monomers preferentially nucleate and grow on the seed sides and terminal ends, respectively, to form a complex 2D hierarchical heterostructure. The strategy used in this work can be extended to fabricate other complex nanoarchitectures from small molecules.Eine komplexe hierarchische 2D-Heterostruktur wurde durch sequenzielle keimgestützte Selbstorganisation aufgebaut. Sie besteht aus lateral gewachsenen Nanoröhren aus einem Perylenderivat (blau) und terminal verlängerten Nanoknäueln aus einem ähnlichen Perylen (gelb) auf einem Mikrobandkeim (rot) aus einem dritten Perylen.
      PubDate: 2017-08-17T04:51:23.12307-05:0
      DOI: 10.1002/ange.201704015
       
  • Targeting the genome stability hub Ctf4 by stapled-peptide design
    • Authors: Yuteng Wu; Fabrizio Villa, Joseph Maman, Lina Dobnikar, Yu H Lau, Aline C Simon, Karim Labib, David R Spring, Luca Pellegrini
      Abstract: Exploitation of synthetic lethality by small-molecule targeting of pathways that maintain genomic stability is an attractive chemotherapeutic approach. The Ctf4/AND-1 protein hub that links DNA replication, repair and chromosome segregation, represents a novel target for the synthetic lethality approach. Here we report the design, optimization, and validation of double-click stapled peptides encoding the Ctf4-interacting peptide (CIP) of the replicative helicase subunit Sld5. Screening stapling positions in the Sld5 CIP, we identified an unorthodox i,i+6 stapled peptide with improved, sub-micromolar binding to Ctf4. The mode of interaction with Ctf4 was confirmed by a crystal structure of the stapled Sld5 peptide bound to Ctf4. The stapled Sld5 peptide was able to displace the Ctf4-partner DNA polymerase alpha from the replisome in yeast extracts. Our study provides proof-of-principle evidence for the development of small-molecule inhibitors of the human-CTF4 orthologue AND-1.
      PubDate: 2017-08-17T03:20:30.790115-05:
      DOI: 10.1002/ange.201705611
       
  • Palladium-Catalyzed Synthesis of Heteroarene-Fused Cyclooctatetraenes via
           Dehydrogenative Cyclodimerization
    • Authors: Masahiro Miura; Keita Fukuzumi, Yuji Nishii
      Abstract: Arene-fused cyclooctatetraenes (COTs) possess unique structural and electronic properties originated from their saddle-shaped -conjugated architectures. Considerable attention has been paid for the transition-metal-mediated synthesis of these cyclic compounds; however, limited achievements have been represented to date in the efficient construction of heteroarene-fused COTs. In this contribution, we report a novel Pd-catalyzed dehydrogenative cyclodimerization of biheteroarenes via four-fold C-H activation toward the synthesis of a series of heteroarene-fused COTs. A set of mechanistic examinations indicated the involvement of high-valent Pd species prior to the dimerization event in the catalytic cycle. The redox behavior of the obtained COTs is also described briefly.
      PubDate: 2017-08-17T00:21:12.790052-05:
      DOI: 10.1002/ange.201707515
       
  • Degradable Vanadium Disulfide Nanostructures with Unique Optical and
           Magnetic Functions for Cancer Theranostics
    • Authors: Yuyan Chen; Liang Cheng, Ziliang Dong, Yu Chao, Huali Lei, He Zhao, Jian Wang, Zhuang Liu
      Abstract: Multifunctional biodegradable inorganic theranostic nano-agents are of great interests to the field of nanomedicine. Herein, VS2 nanosheets upon lipid modification could be converted into ultra-small VS2 nanodots encapsulated inside polyethylene glycol (PEG) modified lipid micelles. Owing to the paramagnetic property, high near-infrared (NIR) absorbance, and chelator-free 99mTc4+ labeling of VS2, such VS2@lipid-PEG nanoparticles could be used for T1-weighted magnetic resonance (MR), photoacoustic (PA),and single photon emission computed tomography (SPECT) tri-modal imaging guided photothermal ablation of tumors. Importantly, along with the gradual degradation of VS2, our VS2@lipid-PEG nanoparticles exhibit effective body excretion without appreciable toxicity. Our work presents the unique advantages of VS2 nanostructures with highly integrated functionalities and biodegradable behaviors, promising for applications in cancer theranostics.
      PubDate: 2017-08-16T23:21:04.626218-05:
      DOI: 10.1002/ange.201707128
       
  • Wacker-Type Oxidation Using an Iron Catalyst and Ambient Air and Its
           Application to Late-Stage Oxidation of Complex Molecules
    • Authors: Wei Han; Binbin Liu, Fengli Jin, Tianjiao Wang, Xiaorong Yuan
      Abstract: We present a practical and general iron-catalyzed Wacker-type oxidation of olefins to ketones which uses ambient air as the sole oxidant. The mild oxidation conditions enable exceptional functional group tolerance, which has not been demonstrated for any other Wacker-type reaction to date. The inexpensive and nontoxic reagents [iron(II) chloride, PMHS (polymethylhydrosiloxane), and air] can, therefore, also be employed to oxidize complex natural-product derived and polyfunctionalized molecules.
      PubDate: 2017-08-16T21:25:37.897415-05:
      DOI: 10.1002/ange.201707006
       
  • Determinants of the Inhibition of DprE1 and CYP2C9 by Antitubercular
           Thiophenes
    • Authors: Renhe Liu; Xiaoxuan Lyu, Mei-Hui Hsu, Catherine Vilcheze, Scott G. Franzblau, William R. Jacobs, Gurdyal S. Besra, Eric F. Johnson, Klaus Fütterer, Feng Wang
      Abstract: Mycobacterium tuberculosis (Mtb) DprE1, an essential isomerase for the biosynthesis of the mycobacterial cell wall, is a validated target for tuberculosis (TB) drug development. Here we report the X-ray crystal structures of DprE1 and the DprE1 resistant mutant (Y314C) in complexes with TCA1 derivatives to elucidate the molecular basis of their inhibitory activities and an unconventional resistance mechanism, which enabled us to optimize the potency of the analogs. The selected lead compound showed excellent in vitro and in vivo activities, and low risk of toxicity profile except for the inhibition of CYP2C9. A crystal structure of CYP2C9 in complex with a TCA1 analog revealed the similar interaction patterns to the DprE1-TCA1 complex. Guided by the structures, an optimized molecule was generated with differential inhibitory activities against DprE1 and CYP2C9, which provides insights for development of a clinical candidate to treat TB.
      PubDate: 2017-08-16T21:20:38.488884-05:
      DOI: 10.1002/ange.201707324
       
  • Synthesis of Bicyclo[n.1.0]alkanes via Cobalt-Catalyzed Multiple C(sp3)-H
           Activation Strategy
    • Authors: Zhuo-Zhuo Zhang; Ye-Qiang Han, Bei-Bei Zhan, Sai Wang, Bing-Feng Shi
      Abstract: A cobalt-catalyzed dual C(sp3)-H activation strategy has been developed, providing a novel strategy for the synthesis of bicyclo[4.1.0]heptanes and bicyclo[3.1.0]hexanes. A key to the success of this reaction is the conformation-induced methylene C(sp3)-H activation of the resulting cobaltabicyclo[4.n.1] intermediate. In addition, the synthesis of bicyclo[3.1.0]hexane from pivalamide via triple C(sp3)-H activation has also been demonstrated.
      PubDate: 2017-08-16T13:20:32.542836-05:
      DOI: 10.1002/ange.201707638
       
  • A semi-synthetic glycoconjugate vaccine candidate for carbapenem-resistant
           Klebsiella pneumoniae
    • Authors: Peter H. Seeberger; Claney L. Pereira, Naeem Khan, Guozhi Xiao, Elizabeth Diago-Navarro, Katrin Reppe, Bastian Opitz, Bettina C. Fries, Martin Witzenrath
      Abstract: Hospital acquired infections are an increasingly serious health concern. Infections caused by carpabenem-resistant Klebsiella pneumoniae (CR-Kp) are especially problematic, with a 50% average survival rate. CR-Kp are isolated from patients with ever greater frequency: 7% within the EU but 62% in Greece. At a time when antibiotics are becoming less effective, no vaccines to protect from this severe bacterial infection exist. Here, we describe the convergent [3+3] synthesis of the hexasaccharide repeating unit from its capsular polysaccharide and related sequences. Immunization with the synthetic hexasaccharide 1 glycoconjugate resulted in high titers of cross-reactive antibodies against CR-Kp CPS in mice and rabbits. Whole cell ELISA was used to establish the surface staining of CR-Kp strains. The antibodies raised were found to promote phagocytosis. Thus, this semi-synthetic glycoconjugate is a lead for the development of a vaccine against a rapidly progressing, deadly bacterium.
      PubDate: 2017-08-16T11:20:46.24286-05:0
      DOI: 10.1002/ange.201700964
       
  • Synthesis and Characterization of Iridium(V) Coordination Complexes With
           an N,O-Donor Organic Ligand
    • Authors: Liam Sharninghausen; Shashi Bhushan Sinha, Dimitar Y. Shopov, Brandon Q. Mercado, David Balcells, Gary W. Brudvig, Robert H. Crabtree
      Abstract: We have prepared and fully characterized two isomers of [IrIV(dpyp)2] (dpyp = meso-2,4-di(2-pyridynyl)-2,4-pentanediolate). These complexes can be cleanly oxidized to [IrV(dpyp)2]+, which to our knowledge represent the first coordination complexes of Ir(V) in an N,O-donor environment. One isomer has been fully characterized in the Ir(V) state, including by x-ray crystallography, XPS, and DFT calculations, all of which support metal-centered oxidation. The unprecedented stability of these Ir(V) complexes is ascribed to the exceptional donor strength of the ligands, their resistance to oxidative degradation, and the presence of four highly donor alkoxide groups in a plane, which breaks the degeneracy of the d-orbitals and favors oxidation.
      PubDate: 2017-08-16T11:20:31.41392-05:0
      DOI: 10.1002/ange.201707593
       
  • 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
      Abstract: We present a generic method 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, we created distinct, micro-compartmentalized materials. This structuring approach offers control over the composition of each type of the compartments by directing the partitioning of objects to be encapsulated. Moreover, our method allows for barrier-less, dynamic exchange of even large hydrophilic solutes (MW ~ 60 kDa) between separate aqueous compartments. We expect these features to find use in the fields of, for instance, micro-structured catalysts, templating, and tissue engineering.
      PubDate: 2017-08-16T09:21:23.6841-05:00
      DOI: 10.1002/ange.201706272
       
  • Colossal Stability of Gas-Phase Trianions: Super-Pnictogens
    • Authors: Tianshan Zhao; Jian Zhou, Qian Wang, Puru Jena
      Abstract: Multiply charged negative ions are ubiquitous in nature. They are stable as crystals because of charge compensating cations; while in solutions, solvent molecules protect them. However, they are rarely stable in the gas phase because of strong electrostatic repulsion between the extra electrons. Therefore, understanding their stability without the influence of the environment has been of great interest to scientists for decades. While much of the past work has focused on dianions, work on triply charged negative ions is sparse and the search for the smallest trianion that is stable against spontaneous electron emission or fragmentation continues. Stability of BeB11(X)123− (X=CN, SCN, BO) trianions is demonstrated in the gas phase, with BeB11(CN)123− exhibiting colossal stability against electron emission by 2.65 eV and against its neutral adduct by 15.85 eV. The unusual stability of these trianions opens the door to a new class of super-pnictogens with potential applications in aluminum-ion batteries.Die ungewöhnlich stabilen Trianionen BeB11(CN)123−, BeB11(BO)123− und BeB11(SCN)123− wurden auf der Grundlage der Oktett- und Wade-Mingos-Regeln entworfen. In der Gasphase sind sie gegenüber spontaner Elektronenabgabe um 2.65, 1.30 bzw. 0.59 eV stabilisiert. Bezüglich ihrer chemischen Eigenschaften ähneln die Trianionen den Gruppe-15-Elementen.
      PubDate: 2017-08-16T08:56:29.457924-05:
      DOI: 10.1002/ange.201706764
       
  • Nucleophilic Amination of Methoxy Arenes Promoted by a Sodium
           Hydride/Iodide Composite
    • Authors: Atsushi Kaga; Hirohito Hayashi, Hiroyuki Hakamata, Miku Oi, Masanobu Uchiyama, Ryo Takita, Shunsuke Chiba
      Abstract: A method for the nucleophilic amination of methoxy arenes was established by using sodium hydride (NaH) in the presence of lithium iodide (LiI). This method offers an efficient route to benzannulated nitrogen heterocycles. Mechanistic studies showed that the reaction proceeds through an unusual concerted nucleophilic aromatic substitution.Konzertiert cyclisiert: Die nucleophile Aminierung von Methoxyarenen mit Natriumhydrid (NaH) in Gegenwart von Lithiumiodid (LiI) bietet einen effizienten Zugang zu benzanellierten Stickstoffheterocyclen. Mechanistischen Studien zufolge verläuft die Reaktion als ungewöhnliche konzertierte nucleophile aromatische Substitution.
      PubDate: 2017-08-16T08:56:14.337492-05:
      DOI: 10.1002/ange.201705916
       
  • Molekulare Knoten
    • Authors: Stephen D. P. Fielden; David A. Leigh, Steffen L. Woltering
      Abstract: Der erste synthetische Kleeblattknoten wurde in den späten 1980er Jahren hergestellt. Kompliziertere Knotentopologien wurden jedoch erst in den letzten Jahren in molekularer Form erhalten. Die Verknotung molekularer Stränge erzeugt sterische Einschränkungen und kann so wichtige physikalische und chemische Eigenschaften verleihen, unter anderem Chiralität, starkes und selektives Binden von Ionen und katalytische Aktivität. Da die Anzahl und Komplexität molekularer Knoten steigt, wird es für Chemiker immer wichtiger, die Knotennomenklatur anderer Disziplinen zu verwenden. Hier geben wir einen Überblick über die Synthesestrategien für molekulare Knoten und beschreiben die Grundlagen der Knoten-, Zopf- und Tangle-Theorie in einem für Chemiker und molekulare Strukturen angemessenen Umfang.Thou shalt knot …: Dieser Aufsatz gibt einen Überblick über das Feld der aus geschlossenen Ringen bestehenden molekularen Knoten. Ihre Synthesen und die für Chemiker und molekulare Struktur angemessenen Grundlagen der Knoten-, Zopf- und Tangletheorie werden behandelt. Die durch Verknotung erzeugten sterischen Einschränkungen können bedeutsame physikalische und chemische Eigenschaften verleihen, unter anderem Chiralität, starkes und selektives Binden von Ionen sowie katalytische Aktivität.
      PubDate: 2017-08-16T08:46:21.353595-05:
      DOI: 10.1002/ange.201702531
       
  • Switchable Stereoselectivity in Bromoaminocyclization of Olefins: Using
           Brønsted Acids of Anionic Chiral Cobalt(III) Complexes
    • Authors: Hua-Jie Jiang; Kun Liu, Jie Yu, Ling Zhang, Liu-Zhu Gong
      Abstract: Brønsted acids of anionic chiral CoIII complexes act as bifunctional phase-transfer catalysts to shuttle the substrates across the solvent interface and control stereoselectivity. The diastereomeric chiral CoIII-templated Brønsted acids, with the same chiral ligands, enabled a switch in the enantioselective bromoaminocyclization of olefins to afford the two enantiomers of 2-substituted pyrrolidines with high enantioselectivities (up to 99:1 e.r.).Links oder rechts: Brønsted-Säuren von anionischen chiralen CoIII-Komplexen wurden als difunktionelle Phasentransferkatalysatoren identifiziert, die Substrate über die Lösungsgrenzfläche transportieren und die Stereoselektivität ihrer Umsetzung steuern. Diastereomere CoIII-basierte Brønsted-Säuren mit denselben chiralen Liganden ermöglichen Bromaminocyclisierungen von Olefinen unter hoch stereoselektiver Bildung beider Enantiomere der 2-substituierten Pyrrolidine.
      PubDate: 2017-08-16T08:45:41.728514-05:
      DOI: 10.1002/ange.201705066
       
  • Control of Redox Events by Dye Encapsulation Applied to Light-Driven
           Splitting of Hydrogen Sulfide
    • Authors: Xu Jing; Yang Yang, Cheng He, Zhiduo Chang, Joost N. H. Reek, Chunying Duan
      Abstract: Solar production of hydrogen by consuming low-value waste products is an attractive pathway that has both economic and environmental benefits. Inspired by the reactive pocket of enzymes, a synthetic platform to combine photocatalytic hydrogen evolution with sulfide oxidation in a one-pot process via control over the location of the electron-transfer steps is developed. The redox-active coordination vessel Ni-TFT, which has an octahedral pocket, encapsulates an organic dye to pre-organize for photocatalytic proton reduction via an oxidative quenching pathway using the nickel corners as catalysts, generating molecular hydrogen and the oxidized dye. The oxidized dye is displaced by a neutral dye and oxidizes sulfide once outside the pocket to give element sulfur. The overall reaction constitutes hydrogen sulfide splitting, forming molecular hydrogen and elemental sulfur, which is analogous to the water-splitting reaction.Ein supramolekularer Käfig ermöglicht die photokatalytische Wasserstoffbildung in Kombination mit Sulfidoxidation in einem Eintopfprozess durch Präorganisation des Farbstoffs, der die entscheidenden Elektronentransferschritte steuert. Die Gesamtreaktion ist eine Schwefelwasserstoffspaltung unter Bildung von molekularem Wasserstoff und elementarem Schwefel, analog zur Wasserspaltung.
      PubDate: 2017-08-16T08:45:31.650021-05:
      DOI: 10.1002/ange.201704327
       
  • Reagent-Free C-H/N-H Cross-Coupling: Regioselective Synthesis of
           N-Heteroaromatics from Biaryl Aldehydes and NH₃
    • Authors: Huai-Bo Zhao; Zhan-Jiang Liu, Jinshuai Song, Hai-Chao Xu
      Abstract: An unprecedented synthesis of N-heteroaromatics from biaryl aldehydes and NH3 through reagent-free C-H/N-H cross-coupling has been developed. The electrosynthesis uses NH3 as an inexpensive and atom-economic nitrogen donor, requires no oxidizing agents, and allows efficient and regioselective access to a wide range of phenanthridines and structurally related polycyclic N-heteroaromatic products.
      PubDate: 2017-08-16T08:21:27.415465-05:
      DOI: 10.1002/ange.201707192
       
  • An Esterase-Sensitive Prodrug Approach for Controllable Delivery of
           Persulfide Species
    • Authors: Yueqin Zheng; Bingchen Yu, Zhen Li, Zhengnan Yuan, Chelsea L. Organ, Rishi K. Trivedi, Siming Wang, David J. Lefer, Binghe Wang
      Abstract: A strategy to deliver a well-defined persulfide species in a biological medium is described. Under near physiological conditions, the persulfide prodrug can be activated by an esterase to generate a “hydroxymethyl persulfide” intermediate, which rapidly collapses to form a defined persulfide. Such persulfide prodrugs can be used either as chemical tools to study persulfide chemistry and biology or for future development as H2S-based therapeutic reagents. Using the persulfide prodrugs developed in this study, the reactivity between S-methyl methanethiosulfonate (MMTS) with persulfide was unambiguously demonstrated. Furthermore, a representative prodrug exhibited potent cardioprotective effects in a murine model of myocardial ischemia-reperfusion (MI/R) injury with a bell shape therapeutic profile.Definierte Persulfide können gezielt in biologische Medien transportiert werden. Unter nahezu physiologischen Bedingungen wird eine Persulfid-Vorstufe durch eine Esterase aktiviert. Dadurch entsteht ein Hydroxymethylpersulfid-Intermediat, das schnell unter Freisetzung des Persulfids zerfällt. Anhand solcher Prodrugs können chemische und biologische Aspekte von Persulfiden und ihre Entwicklung zu H2S-basierten Wirkstoffen studiert werden.
      PubDate: 2017-08-16T07:47:43.906689-05:
      DOI: 10.1002/ange.201704117
       
  • Mechanisch verzahnte Moleküle (MIMs) – molekulare Shuttle, Schalter und
           Maschinen (Nobel-Aufsatz)
    • Authors: J. Fraser Stoddart
      Abstract: Die Chemie begrüßt eine neue Bindung: Die mechanische Bindung stattet Moleküle mit Komponenten aus, deren Bewegung gesteuert und verfolgt werden kann. J. F. Stoddart beschreibt in seinem Nobelaufsatz, wie die Fähigkeit zum gezielten Aufbau mechanisch verzahnter Moleküle zum Design und der Synthese von Shuttles, Schaltern und Maschinen auf der Nanoskala geführt hat.
      PubDate: 2017-08-16T07:47:38.017126-05:
      DOI: 10.1002/ange.201703216
       
  • Frontispiz: Direct Hydroxylation of Benzene to Phenol by Cytochrome
           P450BM3 Triggered by Amino Acid Derivatives
    • Authors: Osami Shoji; Sota Yanagisawa, Joshua Kyle Stanfield, Kazuto Suzuki, Zhiqi Cong, Hiroshi Sugimoto, Yoshitsugu Shiro, Yoshihito Watanabe
      Abstract: Hydroxylierung In der Zuschrift auf S. 10460 beschreiben O. Shoji, Y. Watanabe et al. die Verwendung von bestimmten Aminosäurederivaten für die Aktivierung von Cytochrom P450BM3 zur direkten Hydroxylierung von Benzol zu Phenol.
      PubDate: 2017-08-16T06:27:06.726378-05:
      DOI: 10.1002/ange.201783561
       
  • Processable and Moldable Sodium-Metal Anodes
    • Authors: Aoxuan Wang; Xianfei Hu, Haoqing Tang, Chanyuan Zhang, Shan Liu, Ying-Wei Yang, Quan-Hong Yang, Jiayan Luo
      Abstract: Sodium-ion batteries are similar in concept and function to lithium-ion batteries, but their development and commercialization lag far behind. One obstacle is the lack of a standard reference electrode. Unlike Li foil reference electrodes, sodium is not easily processable or moldable and it deforms easily. Herein we fabricate a processable and moldable composite Na metal anode made from Na and reduced graphene oxide (r-GO). With only 4.5 % percent r-GO, the composite anodes had improved hardness, strength, and stability to corrosion compared to Na metal, and can be engineered to various shapes and sizes. The plating/stripping cycling of the composite anode was significantly extended in both ether and carbonate electrolytes giving less dendrite formation. We used the composite anode in both Na-O2 and Na-Na3V2(PO4)3 full cells.Formstabiles Natrium: Ein Hindernis auf dem Weg zu natriumbasierten Energiesystemen ist das Fehlen einer Standard-Bezugselektrode. Natrium verformt sich leicht, und falls es für die Anwendung als Bezugselektrode zu einem Film ausgerollt wird, sind dessen Form und Dicke schwer zu steuern. Zusatz von 4.5 % reduziertem Graphenoxid (r-GO) ergibt ein Na@r-GO-Komposit, das geformt und zu Anoden mit verbesserten elektrochemischen Eigenschaften verarbeitet werden kann.
      PubDate: 2017-08-16T06:01:23.976583-05:
      DOI: 10.1002/ange.201703937
       
  • Fluorous Phase-Directed Peptide Assembly Affords Nano-Peptisomes Capable
           of Ultrasound-Triggered Cellular Delivery
    • Authors: Scott H. Medina; Megan S. Michie, Stephen E. Miller, Martin J. Schnermann, Joel P. Schneider
      Abstract: Here, we report the design, synthesis and efficacy of a new class of ultrasound (US)-sensitive self-assembled peptide-based nanoparticle. Peptisomes are prepared via templated assembly of a de novo designed peptide at the interface of fluorinated nanodroplets. Utilizing peptide assembly allows for facile particle synthesis, direct incorporation of bioactive sequences displayed from the particle corona, and the ability to easily encapsulate biologics during particle preparation using a mild solvent exchange procedure. Further, nano-peptisome size can be precisely controlled by simply modulating the starting peptide and fluorinated solvent concentrations during synthesis. Biomolecular cargo encapsulated within the particle core can be directly delivered to the cytoplasm of cells upon US-mediated rupture of the carrier. Thus, nano-peptisomes represent a novel class of US-activated carriers that can shuttle cell-impermeable biomacromolecules into cells with spatial and temporal precision.Lass die Blase zerplatzen: Die templatgestützte Anordnung eines de novo entworfenen Peptids an der Grenzfläche fluoriger Nanotröpfchen ergibt ultraschallempfindliche Nanopeptisome. Akustisches Aufbrechen der Tröpfchen an der Zelloberfläche führt zum direkten Transfer der verkapselten membranimpermeablen biomolekularen Fracht in die Zellen mit räumlicher und zeitlicher Präzision.
      PubDate: 2017-08-16T06:01:12.317594-05:
      DOI: 10.1002/ange.201704649
       
  • Geometry-Retentive C-Alkenylation of Lithiated α-Aminonitriles:
           Quaternary α-Alkenyl Amino Acids and Hydantoins
    • Authors: Josep Mas-Roselló; Shuji Hachisu, Jonathan Clayden
      Abstract: α-Amino nitriles tethered to alkenes through a urea linkage undergo intramolecular C-alkenylation on treatment with base by attack of the lithionitrile derivatives on the N′-alkenyl group. A geometry-retentive alkene shift affords stereospecifically the E or Z isomer of the 5-alkenyl-4-iminohydantoin products from the corresponding starting E- or Z-N′-alkenyl urea, each of which may be formed from the same N-allyl precursor by stereodivergent alkene isomerization. The reaction, formally a nucleophilic substitution at an sp2 carbon atom, allows the direct regioselective incorporation of mono-, di-, tri-, and tetrasubstituted olefins at the α-carbon of amino acid derivatives. The initially formed 5-alkenyl iminohydantoins may be hydrolyzed and oxidatively deprotected to yield hydantoins and unsaturated α-quaternary amino acids.E- oder Z-Alkenylharnstoff-Derivate von Aminonitrilen gehen bei Behandlung mit einer Base eine stereospezifische N-zu-C-Alkenylverschiebung ein. Alkenylhydantoine oder (nach Hydrolyse) Alkenylaminosäuren von biologischem und pharmazeutischem Nutzen sind auf diese Weise zugänglich.
      PubDate: 2017-08-16T04:20:59.34817-05:0
      DOI: 10.1002/ange.201704908
       
  • Macroscopic Polarization Enhancement Promoting Photo- and
           Piezoelectric-Induced Charge Separation and Molecular Oxygen Activation
    • Authors: Hongwei Huang; Shuchen Tu, Chao Zeng, Tierui Zhang, Ali H. Reshak, Yihe Zhang
      Abstract: Efficient photo- and piezoelectric-induced molecular oxygen activation are both achieved by macroscopic polarization enhancement on a noncentrosymmetric piezoelectric semiconductor BiOIO3. The replacement of V5+ ions for I5+ in IO3 polyhedra gives rise to strengthened macroscopic polarization of BiOIO3, which facilitates the charge separation in the photocatalytic and piezoelectric catalytic process, and renders largely promoted photo- and piezoelectric induced reactive oxygen species (ROS) evolution, such as superoxide radicals (.O2−) and hydroxyl radicals (.OH). This work advances piezoelectricity as a new route to efficient ROS generation, and also discloses macroscopic polarization engineering on improvement of multi-responsive catalysis.Die verstärkte makroskopische Polarisation durch Einführung von V5+ in den piezoelektrischen Halbleiter BiOIO3 erleichtert die Ladungstrennung und ermöglicht die effiziente photo- und piezoelektrisch induzierte Aktivierung von molekularem Sauerstoff, um Superoxid- und Hydroxyl-Radikale zu erzeugen.
      PubDate: 2017-08-16T03:51:12.568471-05:
      DOI: 10.1002/ange.201706549
       
  • C-H Bond Trifluoromethylation of Arenes Enabled by a Robust, High-Valent
           NiIV-Complex.
    • Authors: Florian D'Accriscio; Pilar Borja, Nathalie Saffon-Merceron, Marie Fustier-Boutignon, Nicolas Mézailles, Noel Nebra
      Abstract: The robust, high-valent NiIV complex [(Py)2NiIVF2(CF3)2] 3, is reported. The structure of 3 was fully characterized by NMR, XRD and EA. 3 reacts with aromatics at 25°C to form the corresponding benzotrifluorides in nearly quantitative yield. Monomeric and dimeric NiIIICF3 complexes 2.Py and 2 were identified as key intermediates, and their structures were unambiguously assigned by EPR and XRD analysis. Preliminary kinetic study coupled to experimental isolation of reaction intermediates proves that the C-H bond breaking/C-CF3 bond forming sequence can occur both with the NiIVCF3 and NiIIICF3 centers.
      PubDate: 2017-08-16T03:20:50.219536-05:
      DOI: 10.1002/ange.201706237
       
  • An Ionophore-Based Anion-Selective Optode Printed on Cellulose Paper
    • Authors: Xuewei Wang; Qi Zhang, Changwoo Nam, Michael Hickner, Mollie Mahoney, Mark E. Meyerhoff
      Abstract: A general anion-sensing platform is reported based on a portable and cost-effective ion-selective optode and a smartphone detector equipped with a color analysis app. In contrast to traditional anion-selective optodes using a hydrophobic polymer and/or plasticizer to dissolve hydrophobic sensing elements, the new optode relies on hydrophilic cellulose paper. The anion ionophore and a lipophilic pH indicator are inkjet-printed and adsorbed on paper and form a “dry” hydrophobic sensing layer. Porous cellulose sheets also allow the sensing site to be modified with dried buffer that prevents any sample pH dependence of the observed color change. A highly selective fluoride optode using an AlIII-porphyrin ionophore is examined as an initial example of this new anion sensing platform for measurements of fluoride levels in drinking water samples. Apart from Lewis acid–base recognition, hydrogen bonding recognition is also compatible with this sensing platform.Auf Cellulose-Papier als Substrat wurden ein lipophiler Anionophor und ein pH-Indikatorfarbstoff adsorbiert, um einen heterogenen Anionensensor mit Anion-Proton-Coextraktionsmechanismus zu erhalten. Dieses System eignet sich auch für die Adsorption eines Puffersalzes zur Einstellung des pH-Werts der Probe, um pH-abhängige optische Antworten auszuschließen.
      PubDate: 2017-08-16T02:26:41.026843-05:
      DOI: 10.1002/ange.201706147
       
  • Shaping Antiaromatic π-Systems by Metalation: Synthesis of a Bowl-Shaped
           Antiaromatic Palladium Norcorrole
    • Authors: Tsubasa Yonezawa; Siham A. Shafie, Satoru Hiroto, Hiroshi Shinokubo
      Abstract: The synthesis of a bowl-shaped antiaromatic molecule was achieved through the deformation of a planar antiaromatic porphyrinic π-conjugation system by insertion of palladium into the small cavity of a metal-free norcorrole. The bowl-to-bowl inversion dynamics of the antiaromatic Pd-coordinated norcorrole was determined by variable-temperature 1H NMR spectroscopy. The metal-free norcorrole was prepared from acid-induced demetalation of a copper norcorrole, which was obtained from the intramolecular coupling of a bis(diiododipyrrin) copper complex with copper thiophenecarboxylate.Schalenförmig und antiaromatisch ist das Produkt der Deformierung eines planaren antiaromatischen konjugierten π-Systems nach Koordination von Palladium in den kleinen Hohlraum eines metallfreien Norcorrols. Letzteres wurde durch Demetallierung eines Kupfernorcorrols erhalten, das bei der intramolekularen Kupplung eines Bis(diioddipyrrin)-Kupfer-Komplexes mit Kupferthiophencarboxylat entsteht.
      PubDate: 2017-08-16T02:26:36.464603-05:
      DOI: 10.1002/ange.201706134
       
  • Hydrogen Isotope Exchange - The Foundation of C-H activation and Isotope
           Science in Drug Discovery
    • Authors: Jens Atzrodt; Volker Derdau, William J. Kerr, Marc Reid
      Abstract: The wide range of applications involving hydrogen isotopes in drug discovery and beyond dictates that their selective and efficient installation continues to present an important and continuing challenge to synthetic chemists. In this review advances in the field of hydrogen isotope exchange over the last ten years and related hydrogen isotope applications in a broad spectrum of disciplinary areas are brought together.
      PubDate: 2017-08-16T02:20:26.352239-05:
      DOI: 10.1002/ange.201704146
       
  • Solvation Accounts for the Counter-Intuitive Nucleophilicity Ordering of
           Peroxide Anions
    • Authors: Robert Mayer; Takahiro Tokuyasu, Peter Mayer, Jérôme Gomar, Stéphane Sabelle, Benedetta Mennucci, Herbert Mayr, Armin R. Ofial
      Abstract: The nucleophilic reactivities (N, sN) of peroxide anions (generated from aromatic and aliphatic peroxyacids or alkyl hydroperoxides) were investigated by following the kinetics of their reactions with a series of benzhydrylium ions (Ar2CH+) in alkaline aqueous solutions at 20 °C. The second-order rate constants revealed that deprotonated peroxyacids (RCO3-), though being the considerably weaker Brønsted bases, react much faster than anions of aliphatic hydroperoxides (ROO-). Substitution of the rate constants of their reactions with benzhydrylium ions into the linear free energy relationship lg k = sN(N + E) furnished nucleophilicity parameters (N, sN) of peroxide anions, which were successfully applied to predict the rates of Weitz-Scheffer epoxidations. DFT calculations with inclusion of solvent effects by means of the Integral Equation Formalism (IFM) version of the Polarizable Continuum Model (PCM) were performed to rationalize the observed reactivities.
      PubDate: 2017-08-16T01:22:02.797979-05:
      DOI: 10.1002/ange.201707086
       
  • Acid Labile Acyclic Cucurbit[n]uril Molecular Containers for Controlled
           Release
    • Authors: Dake Mao; Yajun Liang, Yamin Liu, Xianhao Zhou, Jiaqi Ma, Jia Liu, Biao Jiang, Da Ma
      Abstract: Stimuli responsive molecular containers are of great importance for controlled drug delivery and other biomedical applications. Here, we report a new type of acid labile acyclic cucurbit[n]uril (CB[n]) molecular containers, which can degrade and release the encapsulated cargo with accelerated rates under mildly acidic conditions (pH 5.5-6.5). These containers retain the excellent recognition property of CB[n] type hosts. Cell culture study demonstrated that the cellular uptake of cargos could be fine-tuned by complexation with different containers. The release and cell uptake of cargo dye was promoted by acidic pH.
      PubDate: 2017-08-15T21:21:45.164529-05:
      DOI: 10.1002/ange.201707164
       
  • A Synthesis of Crocagin A
    • Authors: Filip Bihelovic; Desiree Stichnoth, Rolf Müller, Dirk Trauner, Frank Surup
      Abstract: Crocagin A (1) combines an attractive molecular structure with an unusual biosynthesis and bioactivity. Here, we present an efficient synthesis of crocagin A that hinges on an early formation of its heterotricyclic core, an electrophilic amination, and a stereoselective hydrogenation of a tetrasubstituted double bond. Our synthesis confirms the absolute configuration of crocagin A and provides access to the natural product and derivatives thereof for further biological testing.
      PubDate: 2017-08-15T21:21:28.149482-05:
      DOI: 10.1002/ange.201612641
       
  • In situ Investigation of Methane Dry Reforming on M-CeO2(111) {M= Co, Ni,
           Cu} Surfaces: Metal-Support Interactions and the activation of C-H bonds
           at Low Temperature
    • Authors: Jose A Rodriguez; Zongyuan Liu, Pablo Lustemberg, Ramon Gutierrez, John Carey, Robert Palomino, Mykhailo Vorohta, David Grinter, Pedro Ramirez, Vladimir Matolin, Michael Nolan, M. Veronica Ganduglia-Pirovano, Sanjaya Senanayake
      Abstract: Studies with a series of M-CeO2(111) {M= Co, Ni, Cu} surfaces indicate that metal-oxide interactions can play a very important role for the activation of methane and its reforming with CO2 at relatively low temperatures (600-700 K). Among the systems examined, Co-CeO2(111) exhibits the best performance and Cu-CeO2(111) has negligible activity. Experiments using ambient pressure XPS indicate that methane dissociates on Co-CeO2(111), at temperatures as low as 300 K, generating CHx and COx species on the catalyst surface. The results of density-functional calculations show a reduction in the methane activation barrier from 1.07 eV on Co(0001) to 0.87 eV on Co2+/CeO2(111), and to only 0.05 eV on Co0/CeO2-x(111). At 700 K, under methane dry reforming conditions, CO2 dissociates on the oxide surface and a catalytic cycle is established without coke deposition. A significant part of the CHx formed on the Co0/CeO2-x (111) catalyst recombines to yield ethane or ethylene.
      PubDate: 2017-08-15T15:40:33.449357-05:
      DOI: 10.1002/ange.201707538
       
  • Discovery of Key Physicochemical, Structural, and Spatial Properties of
           RNA-targeted Bioactive Ligands
    • Authors: Brittany S Morgan; Jordan E Forte, Rebecca N Culver, Yuqi Zhang, Amanda E Hargrove
      Abstract: While myriad non-coding RNAs are known to be essential in cellular processes and misregulated in diseases, the development of RNA-targeted small molecule probes has met with limited success. To elucidate guiding principles for selective small molecule:RNA recognition, we analyzed cheminformatic and shape-based descriptors for 104 RNA-targeted ligands with demonstrated biological activity (RNA-targeted BIoactive ligaNd Database, RBIND). We then compared R-BIND to both FDA-approved small molecule drugs and RNA ligands without reported bioactivity. Several striking trends emerged for bioactive RNA ligands, including: i) compliance to medicinal chemistry rules; ii) distinctive structural features; and iii) enrichment in "rod-like" over other shapes. This work provides unique insights that directly facilitate the selection and synthesis of RNA-targeted libraries with the goal of efficiently identifying selective small molecule ligands for therapeutically relevant RNAs.
      PubDate: 2017-08-15T13:15:43.96706-05:0
      DOI: 10.1002/ange.201707641
       
  • Quasi-Dual-Packed-Kernelled Au49(2,4-DMBT)27 Nanoclusters and the
           Influence of Kernel Packing on the Electrochemical Gap
    • Authors: Zhikun Wu
      Abstract: Although face-centered cubic (fcc), body-centered cubic (bcc), hexagonal close-packed (hcp) and other structured gold nanoclusters have been reported, it is still unclear if gold nanoclusters with mix-packed (e.g., fcc and non-fcc) kernels exist, and the correlation between kernel packing and the properties of gold nanoclusters is unknown. Herein, a novel Au49(2,4-DMBT)27 nanocluster with shell electron count of 22 has been synthesized and structurally resolved by single-crystal X-ray crystallography, which revealed that Au49(2,4-DMBT)27 contained a unique Au34 kernel consisting of one quasi-fcc-structured Au21 and one non-fcc-structured Au13 unit (where 2,4-DMBTH = 2,4-dimethylbenzenethiol). Such a quasi-dual-packed structure has not been previously reported. Interestingly, further experiments revealed that the kernel packing greatly influenced the electrochemical gap (EG) and that the fcc structure possessed a larger EG than the investigated non-fcc structure.
      PubDate: 2017-08-15T07:20:59.946627-05:
      DOI: 10.1002/ange.201707582
       
  • Real-Time Intracellular Measurements of ROS and RNS in Living Cells with
           Single Core-Shell Nanowire Electrodes
    • Authors: Xin-Wei Zhang; Quan-Fa Qiu, Hong Jiang, Fu-Li Zhang, Yan-Ling Liu, Christian Amatore, Wei-Hua Huang
      Abstract: Nanoelectrodes allow precise and quantitative measurements of important biological processes at the single living cell level in real time. Cylindrical nanowires electrodes (NWEs) required for intracellular measurements create a great challenge for keeping excellent electrochemical and mechanical performances. Herein, we disclose a facile and robust solution to this problem based on a SiC-core-shell unique design to produce cylindrical NWEs with superior mechanical toughness provided by the SiC nano-core and excellent electrochemical performances brought by the ultrathin carbon shell that can be used as such or platinized. The biological interest of such NWEs is illustrated by the first time quantitative measurement of ROS/RNS in individual phagolysosomes of living macrophages. Since the shell material can be varied to meet any specific detection purpose, this work opens up new opportunities to track quantitatively biological functions occurring inside cells and their organelles.
      PubDate: 2017-08-15T07:20:55.501847-05:
      DOI: 10.1002/ange.201707187
       
  • Palladium-Catalysed Carbon-Fluorine and Carbon-Hydrogen Bond Alumination
           of Fluoroarenes and Heteroarenes
    • Authors: Mark Richard Crimmin; Wenyi Chen, Thomas Hooper, Andrew White, Jamues Ng
      Abstract: Through serendipitous discovery, a palladium bis(phosphine) complex was identified as a catalyst for the selective transformation of sp2C-F and sp2C-H bonds of fluoroarenes and heteroarenes to sp2C-Al bonds (19 examples, 1 mol% Pd loading). The carbon-fluorine bond functionalization reaction is highly selective for the formation of organoaluminum products in preference to hydrodefluorination products (selectivity = 4.4:1 to 27:1). Evidence is presented for a two step mechanism in which hydrodefluorination is followed by sp2C-H alumination.
      PubDate: 2017-08-15T07:20:50.057597-05:
      DOI: 10.1002/ange.201706378
       
  • Redox-Neutral Manganese(I)-Catalyzed C-H Activation: Traceless Directing
           Group Enabled Regioselective Annulation
    • Authors: Qingquan Lu; Steffen Greßies, Sara Cembellín, Felix Klauck, Constantin Daniliuc, Frank Glorius
      Abstract: An unprecedented strategy using traceless directing groups (TDG) to promote the redox-neutral Mn(I)-catalyzed regioselective synthesis of N-heterocycles is reported. Alkyne coupling partners bearing traceless directing group, which serve as both chelator and internal oxidant, were used to control the regioselectivity of the annulation reactions. This operationally simple approach is highly effective with previously challenging unsymmetrical alkyne systems, including unbiased dialkyl alkynes, featuring switchable regioselectivity, simple conditions, and gram-scale synthesis. The application of this strategy in the concise synthesis of bioactive compound PK11209 and pharmaceutical moxaverine is also described.
      PubDate: 2017-08-15T06:20:38.570304-05:
      DOI: 10.1002/ange.201707396
       
  • Donor-Acceptor Complex Enables Alkoxyl Radical Generation for Metal-Free
           C(sp3)-C(sp3) Cleavage and Allylation/Alkenylation
    • Authors: Jing Zhang; Yang Li, Ruoyu Xu, Yiyun Chen
      Abstract: The alkoxyl radical is an essential and prevalent reactive intermediate for chemical and biological studies. Here we report the first donor-acceptor complex-enabled alkoxyl radical generation under metal-free reaction conditions induced by visible light. Hantzsch ester forms the key donor-acceptor complex with N-alkoxyl derivatives, which is elucidated by a series of spectrometry and mechanistic experiments. Selective C(sp3)-C(sp3) bond cleavage and allylation/alkenylation is demonstrated for the first time using this photocatalyst-free approach with linear primary, secondary, and tertiary alkoxyl radicals.
      PubDate: 2017-08-15T03:15:57.581891-05:
      DOI: 10.1002/ange.201707171
       
  • Peptide-Directed Binding for the Discovery of Modulators of
           α-Helix-Mediated Protein–Protein Interactions: Proof-of-Concept Studies
           with the Apoptosis Regulator Mcl-1
    • Authors: Andrew Michael Beekman; Maria Anne O'Connell, Lesley Ann Howell
      Abstract: Targeting PPIs with small molecules can be challenging owing to large, hydrophobic binding surfaces. Herein, we describe a strategy that exploits selective α-helical PPIs, transferring these characteristics to small molecules. The proof of concept is demonstrated with the apoptosis regulator Mcl-1, commonly exploited by cancers to avoid cell death. Peptide-directed binding uses few synthetic transformations, requires the production of a small number of compounds, and generates a high percentage of hits. In this example, about 50 % of the small molecules prepared showed an IC50 value of less than 100 μm, and approximately 25 % had IC50 values below 1 μm to Mcl-1. Compounds show selectivity for Mcl-1 over other anti-apoptotic proteins, possess cytotoxicity to cancer cell lines, and induce hallmarks of apoptosis. This approach represents a novel and economic process for the rapid discovery of new α-helical PPI modulators.Selektive α-helikale Protein-Protein-Wechselwirkungen wurden ausgenutzt, um niedermolekulare Inhibitoren dieser Wechselwirkungen zu entwickeln. Machbarkeitsstudien mit dem Apoptoseregulator Mcl-1 führten zur Identifizierung von Verbindungen, die selektiv an Mcl-1 gegenüber anderen Antiapoptoseproteinen binden, zytotoxisch für mehrere Krebszelllinien sind und Apoptosemarker induzieren.
      PubDate: 2017-08-09T03:11:34.046161-05:
      DOI: 10.1002/ange.201705008
       
  • Titelbild: Competition between Arene–Perfluoroarene and Charge-Transfer
           Interactions in Organic Light-Harvesting Systems (Angew. Chem. 35/2017)
    • Authors: Yanqiu Sun; Yilong Lei, Liangsheng Liao, Wenping Hu
      Pages: 10383 - 10383
      Abstract: Effizienter Energietransfer von einem Ladungstransfer-Wirt zu einem Aren-Perfluoraren-Dotanden führt zu Kristallen, die eine stabile weiße Strahlung abgeben. W. P. Hu et al. beschreiben in der Zuschrift auf S. 10488 konkurrierende intermolekulare Ladungstransfer- und Aren-Perfluoraren-Wechselwirkungen in blaues Licht emittierenden Pyren-Octafluornaphthalin-Cokristallen, die mit einem orangefarbenes Licht emittierenden Pyren-1,2,4,5-Tetracyanbenzol-Komplex dotiert sind.
      PubDate: 2017-07-04T06:36:20.681232-05:
      DOI: 10.1002/ange.201706512
       
  • Innentitelbild: Crystalline Hollow Microrods for Site-Selective
           Enhancement of Nonlinear Photoluminescence (Angew. Chem. 35/2017)
    • Authors: Bing Chen; Wei Kong, Yong Liu, Yunhao Lu, Mingyu Li, Xvsheng Qiao, Xianping Fan, Feng Wang
      Pages: 10384 - 10384
      Abstract: Sun Wukong, der Affenkönig, lässt hohle Mikrokristalle im Nahinfrarotlicht als räumlich aufgelöste optische Codes erstrahlen. In der Zuschrift auf S. 10519 erklären F. Wang et al., wie Lichtstreuung und -reflexion durch die Innenwände der Mikrostäbe die Lichtintensität über die Struktur hinweg moduliert. Dabei wird das elektrische Feld in der Nähe der Innenwände verstärkt, und es kommt zu hellen Lichtemissionen im Bereich der Löcher.
      PubDate: 2017-06-20T06:59:56.71875-05:0
      DOI: 10.1002/ange.201705758
       
  • Editorial: Die neuen 1.2-GHz-NMR-Spektrometer und ihr Beitrag zur
           Forschung
    • Authors: Harald Schwalbe
      Pages: 10386 - 10387
      Abstract: Warum es sinnvoll ist, Forschern die Anschaffung der neuesten Ultrahochfeld-NMR-Spektrometer zu finanzieren, begründet Harald Schwalbe in seinem Editorial, indem er an die wichtigen Impulse, die bisher von jeder neuen Generation von Hochfeld-NMR-Spektrometern ausgingen, erinnert und Themen vorstellt, bei denen die neuesten Spektrometer Hilfe versprechen.
      PubDate: 2017-07-24T15:17:32.954574-05:
      DOI: 10.1002/ange.201705936
       
  • Graphisches Inhaltsverzeichnis: Angew. Chem. 35/2017
    • Pages: 10389 - 10405
      PubDate: 2017-08-16T06:27:05.348635-05:
      DOI: 10.1002/ange.201783511
       
  • Top-Beiträge aus unseren Schwesterzeitschriften: Angew. Chem. 35/2017
    • Pages: 10408 - 10411
      PubDate: 2017-08-16T06:27:06.251031-05:
      DOI: 10.1002/ange.201783513
       
  • H. Tom Soh
    • Pages: 10412 - 10412
      Abstract: „Mein Lieblingsessen ist koreanisches BBQ. Wenn ich frustriert bin, mache ich Yoga ...“ Dies und mehr von und über H. Tom Soh finden Sie auf Seite 10412.
      PubDate: 2017-03-31T06:05:24.408679-05:
      DOI: 10.1002/ange.201702763
       
  • Wissenschaftspreis 2017: T. Beck / In die Heidelberger Akademie der
           Wissenschaften gewählt und František-Šorm-Gedenkmedaille erhalten: A.
           Marx / Ruhrpreis für Kunst und Wissenschaft: R. Schlögl /
           Karl-Ziegler-Gastprofessur: A. H. Hoveyda
    • Pages: 10413 - 10413
      PubDate: 2017-07-28T02:20:26.964431-05:
      DOI: 10.1002/ange.201707049
       
  • “Super-reduzierende” Photokatalyse: konsekutive Energie- und
           Elektronentransfers mit polycyclischen aromatischen Kohlenwasserstoffen
    • Authors: Malte Brasholz
      Pages: 10414 - 10415
      Abstract: Weniger ist mehr: Aktuelle Entwicklungen in der Photokatalyse machen zunehmend negative Reduktionspotentiale synthetisch nutzbar. Feinabgestimmte Energie- und Elektronentransfers mit polycyclischen aromatischen Kohlenwasserstoffen ermöglichen die katalytische Bildung von stark reduzierenden Aren-Radikalanionen, klassischen Ein-Elektronen-Reduktionsmitteln der organischen Synthese.
      PubDate: 2017-06-23T01:32:23.208843-05:
      DOI: 10.1002/ange.201704763
       
  • Borylene: eine aufstrebende Verbindungsklasse
    • Authors: Michele Soleilhavoup; Guy Bertrand
      Pages: 10416 - 10426
      Abstract: Freie Borylene (R-B:) konnten bislang lediglich spektroskopisch in der Gasphase oder in Tieftemperatur-Matrices charakterisiert werden. In der letzten Zeit gelang es jedoch, einige Mono- und Di(Lewis-Base)-stabilisierte Borylene zu isolieren. In beiden Verbindungen ist das Boratom durch die formale Oxidationsstufe +I gekennzeichnet, während es sich in klassischen Organoborverbindungen in der Oxidationsstufe +III befindet. Mono(Lewis-Base)-stabilisierte Borylene sind isoelektronisch zu Singulett-Carbenen, und ihre Reaktivität ähnelt teilweise der von Übergangsmetallen, etwa bei der Aktivierung kleiner Moleküle (wie H2) und der Koordination weiterer Liganden. Di(Lewis-Base)-Borylen-Addukte sind isoelektronisch zu Aminen und Phosphanen. Im Unterschied zu Boranen, die als Elektronenakzeptoren fungieren, sind diese Spezies elektronenreich und eignen sich als Liganden für Übergangsmetalle.Organoborverbindungen als Carben- und Aminanaloga: Im Gegensatz zu klassischen Organoborverbindungen, die sich als Lewis-Säuren verhalten und in denen Bor die Oxidationsstufe +III einnimmt, kennzeichnet Mono- und Di(Lewis-Base)-Borylen-Addukte ein nucleophiler Charakter, und das Boratom befindet sich in der Oxidationsstufe +I. Dieses Forschungsgebiet steckt noch in den Anfängen, verspricht aber viele Entdeckungen.
      PubDate: 2017-07-21T05:00:37.759446-05:
      DOI: 10.1002/ange.201705153
       
  • Neue Modalitäten für schwierige Zielstrukturen in der
           Wirkstoffentwicklung
    • Authors: Eric Valeur; Stéphanie M. Guéret, Hélène Adihou, Ranganath Gopalakrishnan, Malin Lemurell, Herbert Waldmann, Tom N. Grossmann, Alleyn T. Plowright
      Pages: 10428 - 10459
      Abstract: Unsere sich stetig erweiternden Kenntnisse über biologische Systeme haben eine Vielzahl an hoch interessanten neuen biologischen Zielstrukturen aufgedeckt, deren Modulation möglicherweise neuartige Therapiemöglichkeiten für viele Krankheiten erschließt. Diese Angriffspunkte umfassen insbesondere Protein-Protein- und Protein-Nukleinsäure-Wechselwirkungen, die jedoch durch klassische niedermolekulare Substanzen oftmals nicht adressierbar sind. Andere Substanzklassen oder Modalitäten werden daher benötigt, um diese Ziele anzuvisieren. Einige akademische Forschungsgruppen und pharmazeutische Unternehmen greifen daher zunehmend das Konzept der so genannten “neuen Modalitäten” auf. Dieser Aufsatz definiert erstmals diesen Begriff, der neuartige Peptidgerüststrukturen, Oligonukleotide, Hybride, molekulare Konjugate sowie auf neuartige Weise eingesetzte, klassische niedermolekulare Verbindungen berücksichtigt. Wir stellen die repräsentativsten Beispiele dieser Modalitäten vor, die auf große Bindungsoberflächen, wie sie in Protein-Protein-Wechselwirkungen vorkommen, sowie auf zentrale biologische Zellregulationsvorgänge abzielen.Eine neue Generation von Molekülen, die neuartige Peptide, Oligonukleotide, Hybride und molekulare Konjugate umfasst, ermöglicht neue Strategien, um schwierige Zielmoleküle sowie zentrale biologische Zellregulationsvorgänge anzuvisieren. Dieser Aufsatz definiert „neue Modalitäten” und beschreibt, wie der Fortschritt in diesem Bereich derzeit eine Vielzahl an neuartigen Wirkstoffen hervorbringt.
      PubDate: 2017-07-24T07:10:51.883965-05:
      DOI: 10.1002/ange.201611914
       
  • Direct Hydroxylation of Benzene to Phenol by Cytochrome P450BM3 Triggered
           by Amino Acid Derivatives
    • Authors: Osami Shoji; Sota Yanagisawa, Joshua Kyle Stanfield, Kazuto Suzuki, Zhiqi Cong, Hiroshi Sugimoto, Yoshitsugu Shiro, Yoshihito Watanabe
      Pages: 10460 - 10465
      Abstract: The selective hydroxylation of benzene to phenol, without the formation of side products resulting from overoxidation, is catalyzed by cytochrome P450BM3 with the assistance of amino acid derivatives as decoy molecules. The catalytic turnover rate and the total turnover number reached 259 min−1 P450BM3−1 and 40 200 P450BM3−1 when N-heptyl-l-proline modified with l-phenylalanine (C7-l-Pro-l-Phe) was used as the decoy molecule. This work shows that amino acid derivatives with a totally different structure from fatty acids can be used as decoy molecules for aromatic hydroxylation by wild-type P450BM3. This method for non-native substrate hydroxylation by wild-type P450BM3 has the potential to expand the utility of P450BM3 for biotransformations.Aminosäurederivate, deren Strukturen sich deutlich von Fettsäuren unterscheiden, wurden für die Aktivierung von Cytochrom P450BM3 zur direkten Hydroxylierung von Benzol zu Phenol verwendet. Auf diesem Wege wurden katalytische Umsatzgeschwindigkeiten und -zahlen von 259 min−1 P450BM3−1 bzw. 40 200 P450BM3−1 erzielt.
      PubDate: 2017-06-08T07:50:22.071789-05:
      DOI: 10.1002/ange.201703461
       
  • Catalytic Stereoselective 1,4-Addition Reactions Using CsF on Alumina as a
           Solid Base: Continuous-Flow Synthesis of Glutamic Acid Derivatives
    • Authors: Parijat Borah; Yasuhiro Yamashita, Shū Kobayashi
      Pages: 10466 - 10470
      Abstract: A novel methodology using CsF⋅Al2O3 as a highly efficient, environmentally benign, and reusable solid-base catalyst was developed to synthesize glutamic acid derivatives by stereoselective 1,4-addition of glycine derivatives to α,β-unsaturated esters. CsF⋅Al2O3 showed not only great selectivity toward 1,4-addtion reactions by suppressing the undesired formation of pyrrolidine derivations by [3+2] cycloadditions, but also offered high yields for the 1,4-adduct with excellent anti diastereoselectivities. The catalyst was well characterized by using XRD, 19F MAS-NMR and 19F NMR spectroscopy, FT-IR, CO2-TPD, and XPS. And highly basic F from Cs3AlF6 was identified as the most probable active basic site for the 1,4-addition reactions. Continuous-flow synthesis of 3-methyl glutamic acid derivative was successfully demonstrated by using this solid-base catalysis.Zwei Wege: Ein Syntheseverfahren für Glutaminsäure-Derivate beruht auf der hoch stereoselektiven 1,4-Addition von Glycin-Derivaten an α,β-ungesättigte Ester mit CsF⋅Al2O3 als wiederverwendbarem festen Basekatalysator. Für die Umsetzung wurden sowohl ein Batch- als auch ein kontinuierliches Fluss-System entwickelt. Cs3AlF6 erwies sich als aktive Base in der Reaktion.
      PubDate: 2017-08-16T06:26:58.426673-05:
      DOI: 10.1002/ange.201701789
       
  • Size Dependence of Doping by a Vacancy Formation Reaction in Copper
           Sulfide Nanocrystals
    • Authors: Orian Elimelech; Jing Liu, Anna M. Plonka, Anatoly I. Frenkel, Uri Banin
      Pages: 10471 - 10476
      Abstract: Doping of nanocrystals (NCs) is a key, yet underexplored, approach for tuning of the electronic properties of semiconductors. An important route for doping of NCs is by vacancy formation. The size and concentration dependence of doping was studied in copper(I) sulfide (Cu2S) NCs through a redox reaction with iodine molecules (I2), which formed vacancies accompanied by a localized surface plasmon response. X-ray spectroscopy and diffraction reveal transformation from Cu2S to Cu-depleted phases, along with CuI formation. Greater reaction efficiency was observed for larger NCs. This behavior is attributed to interplay of the vacancy formation energy, which decreases for smaller sized NCs, and the growth of CuI on the NC surface, which is favored on well-defined facets of larger NCs. This doping process allows tuning of the plasmonic properties of a semiconductor across a wide range of plasmonic frequencies by varying the size of NCs and the concentration of iodine. Controlled vacancy doping of NCs may be used to tune and tailor semiconductors for use in optoelectronic applications.Die Bildung von Gitterlücken und die Plasmonenreaktion wurden in I2-behandelten Cu2S-Halbleiter-Nanokristallen (NCs) analysiert. Die Redoxreaktion von Cu2S mit I2 erzeugt Gitterlücken in der Cu2S-Phase, deren Zahl mit der NC-Größe steigt. Die Plasmonenreaktion kann durch die NC-Größe oder den Löcherdotierungsgrad, der vom I/Cu-Verhältnis abhängt, gesteuert werden.
      PubDate: 2017-07-19T06:21:04.269503-05:
      DOI: 10.1002/ange.201702673
       
  • A Porphyrin Complex as a Self-Conditioned Electrode Material for
           High-Performance Energy Storage
    • Authors: Ping Gao; Zhi Chen, Zhirong Zhao-Karger, Jonathan E. Mueller, Christoph Jung, Svetlana Klyatskaya, Thomas Diemant, Olaf Fuhr, Timo Jacob, R. Jürgen Behm, Mario Ruben, Maximilian Fichtner
      Pages: 10477 - 10482
      Abstract: The novel functionalized porphyrin [5,15-bis(ethynyl)-10,20-diphenylporphinato]copper(II) (CuDEPP) was used as electrodes for rechargeable energy-storage systems with an extraordinary combination of storage capacity, rate capability, and cycling stability. The ability of CuDEPP to serve as an electron donor or acceptor supports various energy-storage applications. Combined with a lithium negative electrode, the CuDEPP electrode exhibited a long cycle life of several thousand cycles and fast charge–discharge rates up to 53 C and a specific energy density of 345 Wh kg−1 at a specific power density of 29 kW kg−1. Coupled with a graphite cathode, the CuDEPP anode delivered a specific power density of 14 kW kg−1. Whereas the capacity is in the range of that of ordinary lithium-ion batteries, the CuDEPP electrode has a power density in the range of that of supercapacitors, thus opening a pathway toward new organic electrodes with excellent rate capability and cyclic stability.Geben und nehmen: Auf einem Kupferporphyrin basierende Elektroden zeigen einen exzellenten Kapazitätsbehalt über mehrere Tausend Zyklen und sehr schnelle Lade/Entlade-Raten, was den Weg zu organischen Elektrodenmaterialien mit der Kapazität einer Lithiumionenbatterie und der Ratenkapazität eines guten Superkondensators ebnet. Die Fähigkeit des Porphyrinkomplexes, als Elektronendonor oder -akzeptor zu fungieren, bietet hier den Vorteil, verschiedene Energiespeicheranwendungen zu realisieren (siehe Bild).
      PubDate: 2017-07-19T06:21:18.877039-05:
      DOI: 10.1002/ange.201702805
       
  • Gold(Core)–Lead(Shell) Nanoparticle-Loaded Titanium(IV) Oxide Prepared
           by Underpotential Photodeposition: Plasmonic Water Oxidation
    • Authors: Ryo Negishi; Shin-ichi Naya, Hisayoshi Kobayashi, Hiroaki Tada
      Pages: 10483 - 10487
      Abstract: Underpotential photodeposition of Pb yields an ultrathin shell layer on the Au(111) surface of Au nanoparticle(NP)-loaded TiO2 (Au/TiO2) with heteroepitaxial nanojunctions. The localized surface plasmon resonance of Au/TiO2 undergoes no damping with the Pb-shell formation, and the Pb shell offers resistance to aerobic oxidation. Mesoporous films comprising the Au(core)–Pb(shell) NP-loaded TiO2 and unmodified Au/TiO2 were formed on fluorine-doped tin oxide (FTO) electrode. Using them as the photoanode, photoelectrochemical cells were fabricated, and the photocurrent was measured under illumination of simulated sunlight. The photocurrent for water splitting is dramatically enhanced by the Pb-shell formation. The photoelectrochemical measurements of the hot-electron lifetime and density functional theory calculations for model clusters indicate that the Pb-shell effect originates from the charge separation enhancement.Wirkungsvolle Verhüllung: Die Unterpotential-Photoabscheidung von Pb ergibt eine dünne Schale auf der Au(111)-Oberfläche von mit Au-Nanopartikeln beladenem TiO2 (Au/TiO2). Der Einbau dieses Systems in eine Photoanode führt zu einem drastischen Anstieg des Photostroms für die Wasserspaltung als Resultat der Bildung der Pb-Schale.
      PubDate: 2017-07-24T06:18:20.915566-05:
      DOI: 10.1002/ange.201703093
       
  • Competition between Arene–Perfluoroarene and Charge-Transfer
           Interactions in Organic Light-Harvesting Systems
    • Authors: Yanqiu Sun; Yilong Lei, Liangsheng Liao, Wenping Hu
      Pages: 10488 - 10492
      Abstract: Two typical types of luminescent organic cocrystals comprising pyrene–octafluoronaphthalene (pyrene–OFN) and pyrene–1,2,4,5-tetracyanobezene (pyrene–TCNB) were developed by a simple supramolecular assembly strategy. The cocrystals exhibit distinct optical properties because of their different intermolecular interaction modes; that is, arene–perfluoroarene (AP) and charge-transfer (CT) interactions. Unexpectedly, a pyrene–TCNB system with strong CT interactions was incorporated into a pyrene–OFN host as a robust guest to generate white-light emission (WLE). In the supramolecular cocrystal system, an efficient energy-transfer process from pyrene–OFN to pyrene–TCNB occurred because of the well-matched spectra of the constituents and a desirable energy donor/acceptor (D/A) distance. The present competitive intermolecular interaction strategy could be applied to the fabrication of more complicated organic light-harvesting systems.Leuchtschwerter: Mit Pyren-1,2,4,5-tetracyanbenzol (Pyren-TCNB) dotierte Pyren-Octafluornaphthalin(Pyren-OFN)-Kokristalle vereinen einen intermolekularen Ladungstransfer mit konkurrierenden Aren-Perfluoraren-Wechselwirkungen und geben eine stabile weiße Strahlung ab. Eine effiziente Energieübertragung vom Ladungstransferwirt auf die Aren-Perfluoraren-Dotierung ist zu beobachten.
      PubDate: 2017-05-19T02:05:58.975586-05:
      DOI: 10.1002/ange.201702084
       
  • Unique Spectral Overlap and Resonant Energy Transfer between Europium(II)
           and Ytterbium(III) Cations: No Quantum Cutting
    • Authors: Lei Zhou; Peter A. Tanner, Weijie Zhou, Yeye Ai, Lixin Ning, Mingmei M. Wu, Hongbin Liang
      Pages: 10493 - 10497
      Abstract: Samples of the Ca3Sc2Si3O12 (CSS) host singly doped with Eu2+ or Yb3+, doubly doped with Eu2+ and Yb3+, and triply doped with Ce3+, Eu2+ and Yb3+ were synthesized by a sol–gel combustion process under reducing conditions. Unlike previous reports of Eu2+Yb3+ energy transfer in other systems, the energy transfer is resonant in the CSS host and the transfer efficiency reaches 100 % for lightly doped samples. The transfer mechanism is multipolar rather than electron transfer for the sample compositions employed herein. The emission intensity of Yb3+ is further enhanced by co-doping with Ce3+ in addition to Eu2+. The quantum efficiencies of the doped materials range between 9 % and 93 %.Gewinnung von Sonnenenergie: Einfach mit Eu2+ oder Yb3+, doppelt mit Eu2+ und Yb3+ und dreifach mit Ce3+, Eu2+ und Yb3+ dotierte Ca3Sc2Si3O12(CSS)-Wirtgitter wurden in einem Sol-Gel-Verbrennungsprozess synthetisiert. Das dreifach dotierte System wandelt Sonnenenergie in eine Nahinfrarot-Emission des Yb3+-Ions um (dd=Dipol-Dipol-, dq=Dipol-Quadrupol-Wechselwirkungen; ET=Elektronentransfer).
      PubDate: 2017-07-19T07:35:26.473953-05:
      DOI: 10.1002/ange.201703331
       
  • Boronic Acid Functionalized Photosensitizers: A Strategy To Target the
           Surface of Bacteria and Implement Active Agents in Polymer Coatings
    • Authors: Anzhela Galstyan; Roswitha Schiller, Ulrich Dobrindt
      Pages: 10498 - 10502
      Abstract: Advanced methods for preventing and controlling hospital-acquired infections via eradication of free-floating bacteria and bacterial biofilms are of great interest. In this regard, the attractiveness of unconventional treatment modalities such as antimicrobial photodynamic therapy (aPDT) continues to grow. This study investigated a new and innovative strategy for targeting polysaccharides found on the bacterial cell envelope and the biofilm matrix using the boronic acid functionalized and highly effective photosensitizer (PS) silicon(IV) phthalocyanine. This strategy has been found to be successful in treating planktonic cultures and biofilms of Gram-negative E. coli. An additional advantage of boronic acid functionality is a possibility to anchor the tailor made PS to poly(vinyl alcohol) and to fabricate a self-disinfecting coating.Therapie mit und ohne Schranken: Die Boronsäure-Diol-Wechselwirkung wurde genutzt, um einen Photosensibilisator in der Bakterienzellwand und Biofilmmatrix zu verankern und die Schranke für die photodynamische Wirkung zu durchbrechen. Die gleiche funktionelle Gruppe ermöglicht die Implementierung des aktiven Wirkstoffs in eine Poly(vinylalkohol)-Beschichtung, wodurch eine photobakterizide Barriere gegen mikrobielle Adhäsion erhalten wird.
      PubDate: 2017-07-25T06:05:38.977729-05:
      DOI: 10.1002/ange.201703398
       
  • Redox-Driven Migration of Copper Ions in the Cu-CHA Zeolite as Shown by
           the In Situ PXRD/XANES Technique
    • Authors: Casper Welzel Andersen; Elisa Borfecchia, Martin Bremholm, Mads Ry Vogel Jørgensen, Peter Nicolai Ravnborg Vennestrøm, Carlo Lamberti, Lars Fahl Lundegaard, Bo Brummerstedt Iversen
      Pages: 10503 - 10508
      Abstract: Using quasi-simultaneous in situ PXRD and XANES, the direct correlation between the oxidation state of Cu ions in the commercially relevant deNOx NH3-SCR zeolite catalyst Cu-CHA and the Cu ion migration in the zeolitic pores was revealed during catalytic activation experiments. A comparison with recent reports further reveals the high sensitivity of the redox-active centers concerning heating rates, temperature, and gas environment during catalytic activation. Previously, Cu+ was confirmed present only in the 6R. Results verify a novel 8R monovalent Cu site, an eventually large Cu+ presence upon heating to high temperatures in oxidative conditions, and demonstrate the unique potential in combining in situ PXRD and XANES techniques, with which both oxidation state and structural location of the redox-active centers in the zeolite framework could be tracked.Quasisimultane In-situ-PXRD/XANES wurde verwendet, um die direkte Korrelation von Oxidationsstufe und Cu-Ionen-Migration in dem kommerziell relevanten deNOx-Zeolithkatalysator Cu-CHA aufzuzeigen. Die Ergebnisse decken eine schwerwiegende Autoreduktion von Cu unter oxidativen Bedingungen oberhalb von 400 °C auf, verifizieren eine mögliche 8R-Stelle für Cu+ und demonstrieren das Potenzial quasisimultaner PXRD- und XANES-Techniken.
      PubDate: 2017-07-24T07:32:41.325349-05:
      DOI: 10.1002/ange.201703808
       
  • Phosphorene Co-catalyst Advancing Highly Efficient Visible-Light
           Photocatalytic Hydrogen Production
    • Authors: Jingrun Ran; Bicheng Zhu, Shi-Zhang Qiao
      Pages: 10509 - 10513
      Abstract: Transitional metals are widely used as co-catalysts boosting photocatalytic H2 production. However, metal-based co-catalysts suffer from high cost, limited abundance and detrimental environment impact. To date, metal-free co-catalyst is rarely reported. Here we for the first time utilized density functional calculations to guide the application of phosphorene as a high-efficiency metal-free co-catalyst for CdS, Zn0.8Cd0.2S or ZnS. Particularly, phosphorene modified CdS shows a high apparent quantum yield of 34.7 % at 420 nm. This outstanding activity arises from the strong electronic coupling between phosphorene and CdS, as well as the favorable band structure, high charge mobility and massive active sites of phosphorene, supported by computations and advanced characterizations, for example, synchrotron-based X-ray absorption near edge spectroscopy. This work brings new opportunities to prepare highly-active, cheap and green photocatalysts.Dichtefunktionalrechnungen wurden verwendet, um die Entwicklung von Phosphoren als metallfreiem Cokatalysator für Metallsulfide in der photokatalytischen H2-Erzeugung zu steuern. Die verbesserte Leistung ist das Ergebnis der elektronischen Kopplung zwischen Metallsulfiden und Phosphoren sowie von dessen vorteilhafter Bandstruktur und exzellenter Ladungsträgerbeweglichkeit.
      PubDate: 2017-07-19T07:40:26.053191-05:
      DOI: 10.1002/ange.201703827
       
  • Full Selectivity Control in Cobalt(III)-Catalyzed C−H Alkylations by
           Switching of the C−H Activation Mechanism
    • Authors: Daniel Zell; Markus Bursch, Valentin Müller, Stefan Grimme, Lutz Ackermann
      Pages: 10514 - 10518
      Abstract: Selectivity control in hydroarylation-based C−H alkylation has been dominated by steric interactions. A conceptually distinct strategy that exploits the programmed switch in the C−H activation mechanism by means of cobalt catalysis is presented, which sets the stage for convenient C−H alkylations with unactivated alkenes. Detailed mechanistic studies provide compelling evidence for a programmable switch in the C−H activation mechanism from a linear-selective ligand-to-ligand hydrogen transfer to a branched-selective base-assisted internal electrophilic-type substitution.Sterisch gehinderte Carboxylat-Additive vermitteln die cobaltkatalysierte C-H-Alkylierung (Alkylgruppe=Alk) nichtaktivierter Alkene. Sperrige Additive schalten zu einer baseunterstützten internen elektrophilen Substitution (BIES) als C-H-Aktivierungsmechanismus, der sterisch befrachtete Markownikow-Produkte begünstigt. Ohne Additiv wirkt als Mechanismus ein linear-selektiver Ligand-zu-Ligand-Wasserstofftransfer (LLHT).
      PubDate: 2017-07-24T07:37:01.559703-05:
      DOI: 10.1002/ange.201704196
       
  • Crystalline Hollow Microrods for Site-Selective Enhancement of Nonlinear
           Photoluminescence
    • Authors: Bing Chen; Wei Kong, Yong Liu, Yunhao Lu, Mingyu Li, Xvsheng Qiao, Xianping Fan, Feng Wang
      Pages: 10519 - 10523
      Abstract: A class of one-dimensional hollow microstructure is described, which was formed by a kinetically controlled crystal growth process. A hexagonal-phase NaYbF4 microrod comprising isolated holes along the longitudinal axis was synthesized by a one-pot hydrothermal method with the assistance of citrate ligands. The structural void feature modulates light intensity across the microrods as a result of interference arising from light scattering and reflection by the inner walls. A single crystal comprising a structural void was doped with upconverting lanthanide ions. Upon near-infrared excitation of the doped crystal spatially resolvable optical codes were produced.Hohle Mikrokristalle von hexagonalem NaYbF4 erzeugen eine nichtlineare Photolumineszenz bei Bestrahlung mit Nahinfrarotlicht. Streuung und Reflexion an den Innenwänden der strukturierten Mikrostäbe modulieren die Lichtintensität in den verschiedenen Bereichen der Struktur. Durch Dotierung mit aufwärtskonvertierenden Lanthanoidionen werden räumlich aufgelöste optische Codes erhalten.
      PubDate: 2017-05-23T08:05:33.868725-05:
      DOI: 10.1002/ange.201703600
       
  • Highly Syndiotactic or Isotactic Polyhydroxyalkanoates by
           Ligand-Controlled Yttrium-Catalyzed Stereoselective Ring-Opening
           Polymerization of Functional Racemic β-Lactones
    • Authors: Romain Ligny; Mikko M. Hänninen, Sophie M. Guillaume, Jean-François Carpentier
      Pages: 10524 - 10529
      Abstract: Reported herein is the first stereoselective controlled ROP of a specific family of racemic functional β-lactones, namely 4-alkoxymethylene-β-propiolactones (BPLORs). This process is catalyzed by an yttrium complex stabilized by a nonchiral tetradentate amino alkoxy bisphenolate ligand {ONOOR′2}2−, which features both a good activity and a high degree of control over the molar masses of the resulting functional poly(3-hydroxyalkanoate)s. A simple modification of the R′ substituents in ortho and para position on the ligand platform allows for a complete reversal from virtually pure syndioselectivity (Ps up to 0.91 with R′=cumyl) to very high isoselectivity (Pi up to 0.93 with R′=Cl), as supported by DFT insights. This is the first example of a highly isoselective ROP of a racemic chiral β-lactone.Qual der Wahl: Hoch syndiotaktische oder isotaktische Polyhydroxyalkanoate wurden aus racemischen funktionalen Alkoxymethylen-β-lactonen in einer Yttrium-katalysierten Ringöffnungspolymerisation gewonnen. Die Selektivität konnte durch eine einfache Modifikation der Substituenten des Katalysatorliganden umgekehrt werden.
      PubDate: 2017-07-25T03:51:42.618521-05:
      DOI: 10.1002/ange.201704283
       
  • CO2-Sourced α-Alkylidene Cyclic Carbonates: A Step Forward in the Quest
           for Functional Regioregular Poly(urethane)s and Poly(carbonate)s
    • Authors: Sandro Gennen; Bruno Grignard, Thierry Tassaing, Christine Jérôme, Christophe Detrembleur
      Pages: 10530 - 10534
      Abstract: Described is a robust platform for the synthesis of a large diversity of novel functional CO2-sourced polymers by exploiting the regiocontrolled ring-opening of α-alkylidene carbonates by various nucleophiles. The reactivity of α-alkylidene carbonates is dictated by the exocyclic olefinic group. The polyaddition of CO2-sourced bis(α-alkylidene carbonate)s (bis-αCCs) with primary and secondary diamines provides novel regioregular functional poly(urethane)s. The reactivity of bis-αCCs is also exploited for producing new poly(β-oxo-carbonate)s by organocatalyzed polyaddition with a diol. This synthesis platform provides new functional variants of world-class leading polymer families (polyurethanes, polycarbonates) and valorizes CO2 as a chemical feedstock.Wertschöpfende Polymerisation: Die regioselektive Ringöffnung von Bis(α-alkylidencarbonaten) mit Diaminen und Diolen wird genutzt, um eine Bandbreite von funktionellen regioregulären Polymeren unter Umgebungsbedingungen herzustellen. Die robuste Syntheseplattform liefert neue funktionelle Varianten führender Polymerfamilien (Polyurethane und Polycarbonate) und verwertet CO2 als chemischen Rohstoff.
      PubDate: 2017-07-24T06:11:03.875809-05:
      DOI: 10.1002/ange.201704467
       
  • Reconstitution of Low-Density Lipoproteins with Fatty Acids for the
           Targeted Delivery of Drugs into Cancer Cells
    • Authors: Chunlei Zhu; Pallab Pradhan, Da Huo, Jiajia Xue, Song Shen, Krishnendu Roy, Younan Xia
      Pages: 10535 - 10538
      Abstract: Low-density lipoproteins (LDLs) are a class of nanocarriers for the targeted delivery of therapeutics into aberrant cells that overexpress the LDL receptor. A facile procedure is used for reconstituting the hydrophobic core of LDLs with a binary fatty acid mixture. Facilitated by the tumor targeting capability of the apolipoprotein, the reconstituted, drug-loaded LDLs can effectively target cancer cells that overexpress the LDL receptor while showing minor adverse impact on normal fibroblasts. According to a hypothesized mechanism, the reconstituted LDLs can also enable metabolism-triggered drug release while preventing the payloads from lysosomal degradation. This study demonstrates that LDLs reconstructed with fatty acids hold great promise to serve as effective and versatile nanocarriers for targeted cancer therapy.Tumorgerichtete Nanoträger: Der hydrophobe Kern nativer Lipoproteine niedriger Dichte (LDLs) kann mit natürlich vorkommenden Fettsäuren rekonstituiert werden (siehe Bild). Dieser Prozess erleichtert die metabolismusaktivierte Freisetzung von Wirkstoffen für die zielgerichtete Krebstherapie.
      PubDate: 2017-07-24T03:25:57.067513-05:
      DOI: 10.1002/ange.201704674
       
  • Integrated In Situ Characterization of a Molten Salt Catalyst Surface:
           Evidence of Sodium Peroxide and Hydroxyl Radical Formation
    • Authors: Kazuhiro Takanabe; Abdulaziz M. Khan, Yu Tang, Luan Nguyen, Ahmed Ziani, Benjamin W. Jacobs, Ayman M. Elbaz, S. Mani Sarathy, Franklin (Feng) Tao
      Pages: 10539 - 10543
      Abstract: Sodium-based catalysts (such as Na2WO4) were proposed to selectively catalyze OH radical formation from H2O and O2 at high temperatures. This reaction may proceed on molten salt state surfaces owing to the lower melting point of the used Na salts compared to the reaction temperature. This study provides direct evidence of the molten salt state of Na2WO4, which can form OH radicals, using in situ techniques including X-ray diffraction (XRD), scanning transmission electron microscopy (STEM), laser induced fluorescence (LIF) spectrometry, and ambient-pressure X-ray photoelectron spectroscopy (AP-XPS). As a result, Na2O2 species, which were hypothesized to be responsible for the formation of OH radicals, have been identified on the outer surfaces at temperatures of ≥800 °C, and these species are useful for various gas-phase hydrocarbon reactions, including the selective transformation of methane to ethane.In-situ-Charakterisierungen bei hoher Temperatur ergeben, dass der geschmolzene Zustand von Na2WO4 auf einer Oxidoberfläche eine Na2O2-reiche äußere Oberfläche bildet, die die Bildung von OH-Radikalen aus einem O2/H2O-Gemisch katalysiert. Dieser Prozess ist nützlich für die H-Abstraktion aus Kohlenwasserstoffen in der Gasphase.
      PubDate: 2017-07-24T06:10:33.670823-05:
      DOI: 10.1002/ange.201704758
       
  • Long-Term Live-Cell STED Nanoscopy of Primary and Cultured Cells with the
           Plasma Membrane HIDE Probe DiI-SiR
    • Authors: Alexander D. Thompson; Mitchell H. Omar, Felix Rivera-Molina, Zhiqun Xi, Anthony J. Koleske, Derek K. Toomre, Alanna Schepartz
      Pages: 10544 - 10548
      Abstract: Super-resolution imaging of live cells over extended time periods with high temporal resolution requires high-density labeling and extraordinary fluorophore photostability. Herein, we achieve this goal by combining the attributes of the high-density plasma membrane probe DiI-TCO and the photostable STED dye SiR-Tz. These components undergo rapid tetrazine ligation within the plasma membrane to generate the HIDE probe DiI-SiR. Using DiI-SiR, we visualized filopodia dynamics in HeLa cells over 25 min at 0.5 s temporal resolution, and visualized dynamic contact-mediated repulsion events in primary mouse hippocampal neurons over 9 min at 2 s temporal resolution. HIDE probes such as DiI-SiR are non-toxic and do not require transfection, and their apparent photostability significantly improves the ability to monitor dynamic processes in live cells at super-resolution over biologically relevant timescales.Lebende Zellen wurden mithilfe der Plasmamembransonde DiI-TCO und des photostabilen STED-Farbstoffs SiR-Tz mit hoher Auflösung und über längere Zeiträume dargestellt. Die Tetrazin-Ligation dieser Komponenten in der Plasmamembran erzeugt die HIDE-Sonde DiI-SiR (HIDE: „high-density environment-sensitive”), mit der die Filopodien-Dynamik in HeLa-Zellen über 25 min mit einer zeitlichen Auflösung von 0.5 s verfolgt wurde.
      PubDate: 2017-07-24T14:42:09.815438-05:
      DOI: 10.1002/ange.201704783
       
  • A Molecular Boroauride: A Donor–Acceptor Complex of Anionic Gold
    • Authors: Jordan W. Taylor; Alex McSkimming, Marc-Etienne Moret, W. Hill Harman
      Pages: 10549 - 10553
      Abstract: Gold is unique among the transition metals in that it is stable as an isolated anion (auride). Despite this fact, the coordination chemistry of anionic gold is virtually nonexistent, and this unique oxidation state is not readily exploited in conventional solution chemistry owing to its high reactivity. Through the use of a new molecular scaffold based on diboraanthracene (B2P2, 1), we have overcome these issues by avoiding the intermediacy of zerovalent gold and stabilizing the highly reduced gold anion through acceptor interactions. We have thus synthesized a molecular boroauride [(B2P2)Au]− ([2]−) and showed its reversible conversion between Au−I and AuI states. Through a combination of spectroscopic and computational studies, we show the neutral state to be a AuI complex with a ligand radical anion. Bonding analyses (NBO and QTAIM) and the isolobal relationship between gold and hydrogen provide support for the description of [2]− as a boroauride complex.Starke Akzeptor-Wechselwirkungen eines Diboraanthracen-Diphosphan-Liganden ermöglichen die Synthese eines anionischen Gold-Koordinationskomplexes (siehe Bild). Der Komplex kann zwischen AuI- und Au−I-Zuständen reversibel geschaltet werden, begleitet von ausgleichenden Geometrie- und Redoxänderungen am Diboraanthracenkern.
      PubDate: 2017-06-27T06:18:08.21527-05:0
      DOI: 10.1002/ange.201703235
       
  • An Activatable Photosensitizer Targeted to γ-Glutamyltranspeptidase
    • Authors: Mayumi Chiba; Yuki Ichikawa, Mako Kamiya, Toru Komatsu, Tasuku Ueno, Kenjiro Hanaoka, Tetsuo Nagano, Norbert Lange, Yasuteru Urano
      Pages: 10554 - 10558
      Abstract: We adopted a spirocyclization-based strategy to design γ-glutamyl hydroxymethyl selenorhodamine green (gGlu-HMSeR) as a photo-inactive compound that would be specifically cleaved by the tumor-associated enzyme γ-glutamyltranspeptidase (GGT) to generate the potent photosensitizer HMSeR. gGlu-HMSeR has a spirocyclic structure and is colorless and does not show marked phototoxicity toward low-GGT-expressing cells or normal tissues upon irradiation with visible light. In contrast, HMSeR predominantly takes an open structure, is colored, and generates reactive oxygen species upon irradiation. The γ-glutamyl group thus serves as a tumor-targeting moiety for photodynamic therapy (PDT), switching on tumor-cell-specific phototoxicity. To validate this system, we employed chick chorioallantoic membrane (CAM), a widely used model for preliminary evaluation of drug toxicity. Photoirradiation after gGlu-HMSeR treatment resulted in selective ablation of implanted tumor spheroids without damage to healthy tissue.Ziel erfasst: Eine intramolekulare Spirocyclisierungsstrategie wurde zum Design eines zielgerichteten Photosensibilisators verfolgt, der durch γ-Glutamyltranspeptidase, die in Krebszellen überexprimiert ist, aktiviert wird. Photodynamische Therapie mit gGlu-HMSeR/Grünlicht-Bestrahlung in einem Küken-Chorioallantoismembran-Modell resultierte in selektiver Ablation implantierter Tumorsphäroide ohne Schäden an gesundem Gewebe.
      PubDate: 2017-07-28T03:50:39.728437-05:
      DOI: 10.1002/ange.201704793
       
  • Reentrant Structural Transitions and Collapse of Charge and Orbital Orders
           in Quadruple Perovskites
    • Authors: Alexei A. Belik; Yoshitaka Matsushita, Dmitry D. Khalyavin
      Pages: 10559 - 10563
      Abstract: Charge and orbital degrees of freedom determine properties of many materials, and are central to many important phenomena. At high temperatures, thermal fluctuations overcome them, and high-symmetry structures are realized. On decreasing temperature, different charge- and orbital-order transitions take place accompanied by symmetry lowering. Remarkable exceptions to this general tendency, realized in Cu-doped BiMn7O12 quadruple perovskites, are presented. Introduction of Cu2+ produces mixtures of Mn3+ and Mn4+ and charge degree of freedom. BiCuMn6O12 (and compositions in the vicinity) exhibits well-defined 1:3 charge order of Mn4+ and Mn3+ and orbital order of Mn3+ near room temperature, but both charge and orbital orders collapse below about 115 K with the reentrance of the high-temperature cubic Im3‾ phase. What is interesting the collapse can be controlled by a magnetic field even without long-range magnetic order, and the collapsed phase shows nearly zero thermal expansion.Totaler Zusammenbruch: Die Auswirkungen der Einführung von Ladungsfreiheitsgraden in die B-Stelle von BiMn7O12 bis BiCuxMn7−xO12 werden erforscht. BiCuMn6O12 zeigt nahe Raumtemperatur eine wohldefinierte 1:3-Ladungsordnung von Mn4+ und Mn3+ sowie Orbitalordnung von Mn3+, beide Ordnungen brechen aber unterhalb ca. 115 K zusammen, einhergehend mit der Wiederherstellung der kubischen Hochtemperaturphase Im3‾.
      PubDate: 2017-07-24T06:10:44.08886-05:0
      DOI: 10.1002/ange.201704798
       
  • Bromination of Cycloparaphenylenes: Strain-Induced Site-Selective
           Bis-Addition and Its Application for Late-Stage Functionalization
    • Authors: Eiichi Kayahara; Rui Qu, Shigeru Yamago
      Pages: 10564 - 10568
      Abstract: Bromination of [n]cycloparaphenylenes (CPPs) is herein reported. Small [n]CPPs (n
      PubDate: 2017-07-19T06:21:36.030523-05:
      DOI: 10.1002/ange.201704982
       
  • Heterogeneous Microtesla SABRE Enhancement of 15N NMR Signals
    • Authors: Kirill V. Kovtunov; Larisa M. Kovtunova, Max E. Gemeinhardt, Andrey V. Bukhtiyarov, Jonathan Gesiorski, Valerii I. Bukhtiyarov, Eduard Y. Chekmenev, Igor V. Koptyug, Boyd M. Goodson
      Pages: 10569 - 10573
      Abstract: The hyperpolarization of heteronuclei via signal amplification by reversible exchange (SABRE) was investigated under conditions of heterogeneous catalysis and microtesla magnetic fields. Immobilization of [IrCl(COD)(IMes)], [IMes=1,3-bis(2,4,6-trimethylphenyl), imidazole-2-ylidene; COD=cyclooctadiene] catalyst onto silica particles modified with amine linkers engenders an effective heterogeneous SABRE (HET-SABRE) catalyst that was used to demonstrate a circa 100-fold enhancement of 15N NMR signals in 15N-pyridine at 9.4 T following parahydrogen bubbling within a magnetic shield. No 15N NMR enhancement was observed from the supernatant liquid following catalyst separation, which along with XPS characterization supports the fact that the effects result from SABRE under heterogeneous catalytic conditions. The technique can be developed further for producing catalyst-free agents via SABRE with hyperpolarized heteronuclear spins, and thus is promising for biomedical NMR and MRI applications.Empfindliche Maßnahme: Ein Heterogenkatalysator für die NMR-Verstärkung wurde durch Immobilisierung eines Iridium-Katalysators auf SiO2-Mikropartikeln hergestellt. Der Zusatz von Parawasserstoff führte zu einer etwa 100fachen Verstärkung von 15N-NMR-Signalen. Die Katalysatorpartikel sind leicht abtrennbar, was die Herstellung von Substraten mit hyperpolarisierten Heterokernen ohne Katalysatorkontaminationen ermöglichen sollte.
      PubDate: 2017-07-28T01:56:42.215258-05:
      DOI: 10.1002/ange.201705014
       
  • Adapting the Glaser Reaction for Bioconjugation: Robust Access to
           Structurally Simple, Rigid Linkers
    • Authors: Anthony P. Silvestri; Philip A. Cistrone, Philip E. Dawson
      Pages: 10574 - 10578
      Abstract: Copper-mediated coupling between alkynes to generate a structurally rigid, linear 1,3-diyne linkage has been known for over a century. However, the mechanistic requirement to simultaneously maintain CuI and an oxidant has limited its practical utility, especially for complex functional molecules in aqueous solution. We find that addition of a specific bpy-diol ligand protects unprotected peptides from CuII-mediated oxidative damage through the formation of an insoluble CuII gel which solves the critical challenge of applying Glaser coupling to substrates that are degraded by CuII. The generality of this method is illustrated through the conjugation of a series of polar and nonpolar labels onto a fully unprotected GLP-1R agonist through a linear 7 Å diynyl linker.Doppelfunktion: Ein wasserlösliches Bipyridin-Diol erweist sich als optimaler Ligand in der CuI-katalysierten Glaser-Kreuzkupplung von ungeschützten Peptiden mit funktionellen Molekülen in wässrigen Medien. Dieser difunktionelle Ligand stabilisiert die benötigte CuI/II-Spezies entlang des Reaktionspfads zur gewünschten linearen 1,3-Diin-Verknüpfung und sequestriert außerdem peptidabbauende CuII-Nebenspezies in Form eines unlöslichen Gels.
      PubDate: 2017-07-21T01:50:46.001185-05:
      DOI: 10.1002/ange.201705065
       
  • Electrochemical Exfoliation of Layered Black Phosphorus into Phosphorene
    • Authors: Adriano Ambrosi; Zdeněk Sofer, Martin Pumera
      Pages: 10579 - 10581
      Abstract: Among 2D materials that recently have attracted enormous interest, black phosphorus (BP) is gaining a rising popularity due to its tunable band-gap structure, which is strongly correlated to the thickness and can enable its use in optoelectronic and electronic applications. It is therefore important to provide a facile and scalable methodology to prepare single or few-layer BP nanosheets. We propose herein a simple and fast top-down method to exfoliate a BP crystal into nanosheets of reduced thickness by using electrochemistry. The application of an anodic potential to the crystal in an acidic aqueous solution allows control over the exfoliation efficiency and quality of the nanosheets produced. X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and scanning transmission electron microscopy (STEM) have been applied to fully characterize the exfoliated material, which presented significantly reduced layer thickness compared to the starting bulk material.Ein schichtförmiger Ansatz: Eine einfache und schnelle elektrochemische Top-down-Methode zur Exfoliation eines Kristalls von schwarzem Phosphor zu Nanoschichten verringerter Dicke wird vorgeschlagen. Das Anlegen eines Anodenpotentials an den Kristall in saurer Lösung ermöglicht die Steuerung der Exfoliationseffizienz und der Qualität der erhaltenen Nanoschichten.
      PubDate: 2017-07-25T03:34:11.581181-05:
      DOI: 10.1002/ange.201705071
       
  • Controlling Regioselectivity in the Enantioselective N-Alkylation of
           Indole Analogues Catalyzed by Dinuclear Zinc-ProPhenol
    • Authors: Barry M. Trost; Elumalai Gnanamani, Chao-I (Joey) Hung
      Pages: 10587 - 10592
      Abstract: The enantioselective N-alkylation of indole and its derivatives with aldimines is efficiently catalyzed by a zinc-ProPhenol dinuclear complex under mild conditions to afford N-alkylated indole derivatives in good yield (up to 86 %) and excellent enantiomeric ratio (up to 99.5:0.5 e.r.). This method tolerates a wide array of indoles, as well as pyrrole and carbazole, to afford the corresponding N-alkylation products. The reaction can be run on a gram scale with reduced catalyst loading without impacting the efficiency. The chiral aminals were further elaborated into various chiral polyheterocyclic derivatives. The surprising stability of the chiral N-alkylation products will open new windows for asymmetric catalysis and medicinal chemistry.Die enantioselektive N-Alkylierung von Indol und seinen Derivaten mit Aldiminen wird von einem Zink-ProPhenol-Zweikernkomplex unter milden Bedingungen effizient katalysiert. Die Produkte werden in guten Ausbeuten (bis 86 %) und mit hervorragenden Enantiomerenverhältnissen (bis 99.5:0.5 e.r.) erhalten. Die Methode eignet sich für zahlreiche Indole und liefert auch mit Pyrrol und Carbazol die entsprechenden N-Alkylierungsprodukte.
      PubDate: 2017-07-19T06:11:15.079739-05:
      DOI: 10.1002/ange.201705315
       
  • Intrinsic Photoprotective Mechanisms in Chlorophylls
    • Authors: Michał Kotkowiak; Alina Dudkowiak, Leszek Fiedor
      Pages: 10593 - 10597
      Abstract: Photosynthetic energy conversion competes with the formation of chlorophyll triplet states and the generation of reactive oxygen species. These may, especially under high light stress, damage the photosynthetic apparatus. Many sophisticated photoprotective mechanisms have evolved to secure a harmless flow of excitation energy through the photosynthetic complexes. Time-resolved laser-induced optoacoustic spectroscopy was used to compare the properties of the T1 states of pheophytin a and its metallocomplexes. The lowest quantum yield of the T1 state is always observed in the Mg complex, which also shows the least efficient energy transfer to O2. Axial coordination to the central Mg further lowers the yield of both T1 and singlet oxygen. These results reveal the existence of intrinsic photoprotective mechanisms in chlorophylls, embedded in their molecular design, which substantially suppress the formation of triplet states and the efficiency of energy transfer to O2, each by 20–25 %. Such intrinsic photoprotective effects must have created a large evolutionary advantage for the Mg complexes during their evolution as the principal photoactive cofactors of photosynthetic proteins.Zeitauflösende laserinduzierte optoakustische Spektroskopie wurde verwendet, um die Eigenschaften der T1-Zustände von Pheophytin a und seinen Metallkomplexen zu vergleichen. Die niedrigste Quantenausbeute des T1-Zustands wird für den Mg-Komplex beobachtet, der außerdem den am wenigsten effizienten Energietransfer zu O2 zeigt. Eine axiale Koordination an Mg senkt weiter die Quantenausbeute sowohl von T1 als auch von Singulett-Sauerstoff.
      PubDate: 2017-07-25T06:05:43.672782-05:
      DOI: 10.1002/ange.201705357
       
  • Self-Healable Organogel Nanocomposite with Angle-Independent Structural
           Colors
    • Authors: Jinming Zhou; Peng Han, Meijin Liu, Haiyan Zhou, Yingxue Zhang, Jieke Jiang, Peng Liu, Yu Wei, Yanlin Song, Xi Yao
      Pages: 10598 - 10602
      Abstract: Structural colors have profound implications in the fields of pigments, displays and sensors, but none of the current non-iridescent photonic materials can restore their functions after mechanical damage. Herein, we report the first self-healable organogel nanocomposites with angle-independent structural colors. The organogel nanocomposites were prepared through the co-assembly of oleophilic silica nanoparticles, silicone-based supramolecular gels, and carbon black. The organogel system enables amorphous aggregation of silica nanoparticles and the angle-independent structural colors in the nanocomposites. Moreover, the hydrogen bonding in the supramolecular gel provides self-healing ability to the system, and the structural colored films obtained could heal themselves in tens of seconds to restore storage modulus, structural color, and surface slipperiness from mechanical cuts or shear failure repeatedly.Ausheilende Farben: Organogel-Nanokomposite mit der Fähigkeit zur schnellen Selbstheilung wurden hergestellt. Die Gele können Filme bilden, die winkelabhängige Strukturfarben aufweisen und wasserabweisend sind. Beide Eigenschaften sind durch Selbstheilung wiederherstellbar.
      PubDate: 2017-07-25T03:34:37.604188-05:
      DOI: 10.1002/ange.201705462
       
  • Opening a Can of Worm(-like Micelle)s: The Effect of Temperature of
           Solutions of Functionalized Dipeptides
    • Authors: Emily R. Draper; Hao Su, Christopher Brasnett, Robert J. Poole, Sarah Rogers, Honggang Cui, Annela Seddon, Dave J. Adams
      Pages: 10603 - 10606
      Abstract: A simple heat/cool cycle can be used to significantly affect the properties of a solution of a low-molecular-weight gelator at high pH. The viscosity and extensional viscosity are increased markedly, leading to materials with very different properties than when the native solution is used.Dehnen und Strecken: Ein einfacher Heiz-Kühl-Zyklus wird genutzt, um die Eigenschaften einer Lösung eines niedermolekularen Gelbildners bei hohem pH zu verändern. Die Viskosität und Dehnviskosität steigen deutlich an, sodass Materialien resultieren, die sich in ihren Eigenschaften sehr von der Ausgangslösung unterscheiden.
      PubDate: 2017-07-28T02:36:21.631439-05:
      DOI: 10.1002/ange.201705604
       
  • An Electrochemical Biosensor with Dual Signal Outputs: Toward Simultaneous
           Quantification of pH and O2 in the Brain upon Ischemia and in a Tumor
           during Cancer Starvation Therapy
    • Authors: Li Liu; Fan Zhao, Wei Liu, Tong Zhu, John Z. H. Zhang, Chen Chen, Zhihui Dai, Huisheng Peng, Jun-Long Huang, Qin Hu, Wenbo Bu, Yang Tian
      Pages: 10607 - 10611
      Abstract: Herein, we develop a novel method for designing electrochemical biosensors with both current and potential signal outputs for the simultaneous determination of two species in a living system. Oxygen (O2) and pH, simple and very important species, are employed as model molecules. By designing and synthesizing a new molecule, Hemin-aminoferrocene (Hemin-Fc), we create a single electrochemical biosensor for simultaneous detection and ratiometric quantification of O2 and pH in the brain. The reduction peak current of the hemin group increases with the concentration of O2 from 1.3 to 200.6 μm. Meanwhile, the peak potential positively shifts with decreasing pH from 8.0 to 5.5, resulting in the simultaneous determination of O2 and pH. The Fc group can serve as an internal reference for ratiometric biosensing because its current and potential signals remain almost constant with variations of O2 and pH. The developed biosensor has high temporal and spatial resolutions, as well as remarkable selectivity and accuracy, and is successfully applied in the real-time quantification of O2 and pH in the brain upon ischemia, as well as in tumor during cancer therapy.Zwei Fliegen mit einer Klappe: Eine Methode für die Entwicklung von elektrochemischen Biosensoren durch die Messung von Strom- und Spannungssignalen wird vorgestellt. Das Molekül Hämin-Fc wurde für den simultanen Nachweis und die ratiometrische Quantifizierung von O2 und des pH gezielt entworfen und für die Echtzeitquantifizierung in ischämischem Rattengehirn und in der Krebsfastentherapie eingesetzt.
      PubDate: 2017-07-24T06:11:20.538559-05:
      DOI: 10.1002/ange.201705615
       
  • Trifluoroacetic Anhydride Promoted Copper(I)-Catalyzed Interrupted Click
           Reaction: From 1,2,3-Triazoles to 3-Trifluoromethyl-Substituted
           1,2,4-Triazinones
    • Authors: Wei Wu; Junwen Wang, Yukang Wang, Yangjie Huang, Yingfei Tan, Zhiqiang Weng
      Pages: 10612 - 10616
      Abstract: A copper(I)-catalyzed interrupted click reaction in the presence of trifluoroacetic anhydride has been developed, wherein an N-trifluoroacetyl group is used to accelerate the ring-opening of the putative 5-copper(I) triazolide intermediate. Under the optimized reaction conditions, a broad range of azides and alkynes were found to participate in this transformation, thus affording 3-trifluoromethyl-substituted 1,2,4-triazinones in moderate to excellent yields. The reaction has proven to be compatible with a variety of electron-withdrawing and electron–donating groups, halogens, and nitrogen- and sulfur-containing heterocycles, as well as pharmaceutically relevant molecules.Schnell, aber nicht schmutzig: 3-Trifluormethyl-substituierte 1,2,4-Triazinone werden durch Kupfer(I)-katalysierte „unterbrochene” Klick-Reaktion von Aziden, Alkinen und Trifluoressigsäureanhydrid synthetisiert. Die Cycloaddition verläuft unter milden Bedingungen, toleriert viele funktionelle Gruppen und liefert wertvolle trifluormethylierte Triazinone direkt ausgehend von preiswerten Verbindungen.
      PubDate: 2017-07-24T14:34:44.01969-05:0
      DOI: 10.1002/ange.201705620
       
  • A Fairly Stable Crystalline Silanone
    • Authors: Isabel Alvarado-Beltran; Alfredo Rosas-Sánchez, Antoine Baceiredo, Nathalie Saffon-Merceron, Vicenç Branchadell, Tsuyoshi Kato
      Pages: 10617 - 10621
      Abstract: Silanones 2 substituted by bulky amino- and phosphonium ylide substituents have been synthesized and isolated in crystalline form. Thanks to the steric protection and the strong electron-donating ability of the substituents, silanones 2 are persistent and only slowly dimerizes at room temperature (t1/2=0.5 or 5 h). Structural and theoretical analysis of 2 indicate a short Si=O bond (1.533 Å) and an enhanced polarization toward the O atom compared to Me2Si=O owing to the strong π-electron donation from the phosphonium ylide substituent.Stabilisatoren für Silanone: Silanone mit sperrigen Amino- und Phosphoniumylid-Substituenten wurden synthetisiert und in kristalliner Form isoliert. Dank der sterischen Abschirmung und des starken Elektronendonorvermögens der Substituenten sind diese Silanone relativ stabil und dimerisieren nur langsam bei Raumtemperatur (t1/2=0.5 oder 5 h).
      PubDate: 2017-07-24T15:17:31.156724-05:
      DOI: 10.1002/ange.201705644
       
  • Synthesis of WOn-WX2 (n=2.7, 2.9; X=S, Se) Heterostructures for Highly
           Efficient Green Quantum Dot Light-Emitting Diodes
    • Authors: Shikui Han; Xuyong Yang, Yihan Zhu, Chaoliang Tan, Xiao Zhang, Junze Chen, Ying Huang, Bo Chen, Zhimin Luo, Qinglang Ma, Melinda Sindoro, Hao Zhang, Xiaoying Qi, Hai Li, Xiao Huang, Wei Huang, Xiao Wei Sun, Yu Han, Hua Zhang
      Pages: 10622 - 10626
      Abstract: Preparation of two-dimensional (2D) heterostructures is important not only fundamentally, but also technologically for applications in electronics and optoelectronics. Herein, we report a facile colloidal method for the synthesis of WOn-WX2 (n=2.7, 2.9; X=S, Se) heterostructures by sulfurization or selenization of WOn nanomaterials. The WOn-WX2 heterostructures are composed of WO2.9 nanoparticles (NPs) or WO2.7 nanowires (NWs) grown together with single- or few-layer WX2 nanosheets (NSs). As a proof-of-concept application, the WOn-WX2 heterostructures are used as the anode interfacial buffer layer for green quantum dot light-emitting diodes (QLEDs). The QLED prepared with WO2.9 NP-WSe2 NS heterostructures achieves external quantum efficiency (EQE) of 8.53 %. To our knowledge, this is the highest efficiency in the reported green QLEDs using inorganic materials as the hole injection layer.Schwefelgrün: Sulfurierung oder Selenierung von WOn-Nanomaterialien ergibt WOn-WX2-Heterostrukturen (n=2.7, 2.9; X=S, Se). Hocheffiziente grüne Quantenpunkt-Leuchtdioden (QLEDs) wurden unter Verwendung der unbehandelten WOn-WX2-Heterostrukturen als Lochinjektionsschicht hergestellt.
      PubDate: 2017-07-24T06:06:26.646446-05:
      DOI: 10.1002/ange.201705617
       
  • Direct Alkylation of Amines with Primary and Secondary Alcohols through
           Biocatalytic Hydrogen Borrowing
    • Authors: Sarah L. Montgomery; Juan Mangas-Sanchez, Matthew P. Thompson, Godwin A. Aleku, Beatriz Dominguez, Nicholas J. Turner
      Pages: 10627 - 10630
      Abstract: The reductive aminase from Aspergillus oryzae (AspRedAm) was combined with a single alcohol dehydrogenase (either metagenomic ADH-150, an ADH from Sphingobium yanoikuyae (SyADH), or a variant of the ADH from Thermoanaerobacter ethanolicus (TeSADH W110A)) in a redox-neutral cascade for the biocatalytic alkylation of amines using primary and secondary alcohols. Aliphatic and aromatic secondary amines were obtained in up to 99 % conversion, as well as chiral amines directly from the racemic alcohol precursors in up to>97 % ee, releasing water as the only byproduct.Die reduktive Aminase aus Aspergillus oryzae (AspRedAm) wurde mit einer Alkohol-Dehydrogenase (ADH-150, SyADH oder TeSADH W110A) in einer redoxneutralen Kaskade für die biokatalytische Alkylierung von Aminen mit primären und sekundären Alkoholen kombiniert. Aliphatische und aromatische sekundäre Amine wurden mit bis zu 99 % Umsatz erhalten. Chirale Amine entstanden direkt aus den racemischen Alkoholen mit Wasser als einzigem Koppelprodukt.
      PubDate: 2017-07-21T01:45:59.386684-05:
      DOI: 10.1002/ange.201705848
       
  • Crystalline Diuranium Phosphinidiide and μ-Phosphido Complexes with
           Symmetric and Asymmetric UPU Cores
    • Authors: Thomas M. Rookes; Benedict M. Gardner, Gábor Balázs, Matthew Gregson, Floriana Tuna, Ashley J. Wooles, Manfred Scheer, Stephen T. Liddle
      Pages: 10631 - 10636
      Abstract: Reaction of [U(TrenTIPS)(PH2)] (1, TrenTIPS=N(CH2CH2NSiPri3)3) with C6H5CH2K and [U(TrenTIPS)(THF)][BPh4] (2) afforded a rare diuranium parent phosphinidiide complex [{U(TrenTIPS)}2(μ-PH)] (3). Treatment of 3 with C6H5CH2K and two equivalents of benzo-15-crown-5 ether (B15C5) gave the diuranium μ-phosphido complex [{U(TrenTIPS)}2(μ-P)][K(B15C5)2] (4). Alternatively, reaction of [U(TrenTIPS)(PH)][Na(12C4)2] (5, 12C4=12-crown-4 ether) with [U{N(CH2CH2NSiMe2But)2CH2CH2NSi(Me)(CH2)(But)}] (6) produced the diuranium μ-phosphido complex [{U(TrenTIPS)}(μ-P){U(TrenDMBS)}][Na(12C4)2] [7, TrenDMBS=N(CH2CH2NSiMe2But)3]. Compounds 4 and 7 are unprecedented examples of uranium phosphido complexes outside of matrix isolation studies, and they rapidly decompose in solution underscoring the paucity of uranium phosphido complexes. Interestingly, 4 and 7 feature symmetric and asymmetric UPU cores, respectively, reflecting their differing steric profiles.Außerhalb der Matrix: Die ersten Uran-Phosphidokomplexe, die nicht durch Tieftemperatur-Matrixisolation hergestellt wurden, werden vorgestellt. Die Komplexe werden auf zwei unterschiedlichen Wegen erhalten und weisen symmetrische und unsymmetrische (hier gezeigt; U grün, P violett, N blau, Si gelb) UPU-Kerne im Festkörper auf.
      PubDate: 2017-07-24T06:06:16.619367-05:
      DOI: 10.1002/ange.201706002
       
  • Towards a Comprehensive Understanding of the Reaction Mechanisms Between
           Defective MoS2 and Thiol Molecules
    • Authors: Qiang Li; Yinghe Zhao, Chongyi Ling, Shijun Yuan, Qian Chen, Jinlan Wang
      Pages: 10637 - 10641
      Abstract: Sulfur vacancies (SVs) inherent in MoS2 are generally detrimental for carrier mobility and optical properties. Thiol chemistry has been explored for SV repair and surface functionalization. However, the resultant products and reaction mechanisms are still controversial. Herein, a comprehensive understanding on the reactions is provided by tracking potential energy surfaces and kinetic studies. The reactions are dominated by two competitive mechanisms that lead to either functionalization products or repair SVs, and the polarization effect from decorating thiol molecules and thermal effect are two determining factors. Electron-donating groups are conducive to the repairing reaction whereas electron-withdrawing groups facilitate the functionalization process. Moreover, the predominant reaction mechanism can be switched by increasing the temperature. This study fosters a way of precisely tailoring the electronic and optical properties of MoS2 by means of thiol chemistry approaches.Schwefel-Fehlstellen (SVs) in MoS2 sind im Allgemeinen abträglich für Ladungsträgerbeweglichkeit und optische Eigenschaften. Thiole wurden für die SV-Reparatur und Oberflächenfunktionalisierung untersucht: Elektronendonorgruppen am Thiol unterstützen die Reparatur, Elektronenakzeptorgruppen erleichtern die Funktionalisierung. Auch durch Erhöhen der Temperatur kann die dominante Reaktion gewechselt werden.
      PubDate: 2017-07-24T14:45:11.425145-05:
      DOI: 10.1002/ange.201706038
       
  • From a Molecular 2Fe-2Se Precursor to a Highly Efficient Iron Diselenide
           Electrocatalyst for Overall Water Splitting
    • Authors: Chakadola Panda; Prashanth W. Menezes, Carsten Walter, Shenglai Yao, Matthias E. Miehlich, Vitaly Gutkin, Karsten Meyer, Matthias Driess
      Pages: 10642 - 10646
      Abstract: A highly active FeSe2 electrocatalyst for durable overall water splitting was prepared from a molecular 2Fe-2Se precursor. The as-synthesized FeSe2 was electrophoretically deposited on nickel foam and applied to the oxygen and hydrogen evolution reactions (OER and HER, respectively) in alkaline media. When used as an oxygen-evolution electrode, a low 245 mV overpotential was achieved at a current density of 10 mA cm−2, representing outstanding catalytic activity and stability because of Fe(OH)2/FeOOH active sites formed at the surface of FeSe2. Remarkably, the system is also favorable for the HER. Moreover, an overall water-splitting setup was fabricated using a two-electrode cell, which displayed a low cell voltage and high stability. In summary, the first iron selenide material is reported that can be used as a bifunctional electrocatalyst for the OER and HER, as well as overall water splitting.Doppelfunktion: Ein hoch aktiver Eisendiselenid-Elektrokatalysator wurde aus einem bioinspirierten 2Fe-2Se-Molekülkomplex hergestellt (Dep=Diethylphenyl) und für bifunktionelle Sauerstoff- und Wasserstoffentwicklungsreaktionen sowie die Gesamtwasserspaltung eingesetzt. Die Natur der aktiven Zentren und Struktur-Aktivitäts-Beziehungen des Elektrokatalysators wurden ermittelt.
      PubDate: 2017-07-19T06:11:22.265957-05:
      DOI: 10.1002/ange.201706196
       
  • Lateral Organization of Host Heterogeneous Raft-like Membranes Altered by
           the Myristoyl Modification of Tyrosine Kinase c-Src
    • Authors: Mridula Dwivedi; Tom Mejuch, Herbert Waldmann, Roland Winter
      Pages: 10647 - 10651
      Abstract: Membrane-bound c-Src non-receptor tyrosine kinase, unlike other acyl-modified lipid-anchored proteins, anchors to the membrane by a myristoyl chain along with a polybasic residue stretch, which is shorter in chain length than its host membrane. The packing defect arising from this mismatched chain length of the host and the lipid anchor significantly affects the lateral organization of heterogeneous membranes. We reveal the mixing of phase domains and formation of novel nanoscale-clusters upon membrane binding of the Myr-Src (2–9) peptide. Fluorescence cross correlation spectroscopy was used to explore the nature of these clusters. We show that Myr-Src (2–9) is able to oligomerize, and the peptide clusters are embedded in a lipid platform generated by lipid sorting. Further, using confocal fluorescence microscopy and FRET assays we show that localized charge enrichment and membrane curvature are able to shift the partition coefficient towards the more ordered lipid phase.Lipid-Protein-Nanocluster: Die Tyrosinkinase c-Src heftet sich an die Plasmamembran mittels eines Myristoyl(Myr)-Ankers, der kürzer ist als die umgebende Lipidmatrix. Insertion des lipidierten Myr-Src-Ankers in verschiedene Biomembranmodelle verändert die Organisation der Peptide auf der Nanoskala durch die Membranbindung und führt zu einer veränderten lateralen Struktur der Wirtmembran.
      PubDate: 2017-07-24T06:06:03.832746-05:
      DOI: 10.1002/ange.201706233
       
  • Living and Conducting: Coating Individual Bacterial Cells with
           In Situ Formed Polypyrrole
    • Authors: Rong-Bin Song; YiChao Wu, Zong-Qiong Lin, Jian Xie, Chuan Hao Tan, Joachim Say Chye Loo, Bin Cao, Jian-Rong Zhang, Jun-Jie Zhu, Qichun Zhang
      Pages: 10652 - 10656
      Abstract: Coating individual bacterial cells with conjugated polymers to endow them with more functionalities is highly desirable. Here, we developed an in situ polymerization method to coat polypyrrole on the surface of individual Shewanella oneidensis MR-1, Escherichia coli, Ochrobacterium anthropic or Streptococcus thermophilus. All of these as-coated cells from different bacterial species displayed enhanced conductivities without affecting viability, suggesting the generality of our coating method. Because of their excellent conductivity, we employed polypyrrole-coated Shewanella oneidensis MR-1 as an anode in microbial fuel cells (MFCs) and found that not only direct contact-based extracellular electron transfer is dramatically enhanced, but also the viability of bacterial cells in MFCs is improved. Our results indicate that coating individual bacteria with conjugated polymers could be a promising strategy to enhance their performance or enrich them with more functionalities.Oberflächenmodifizierung von Bakterien: Einzelne Bakterienzellen wurden in situ mit Polypyrrol (PPy) als leitfähiger Schicht überzogen, um den Bakterien eine verbesserte elektrische Leitfähigkeit zu verleihen. Die PPy-Beschichtungen fördern den kontaktbasierten Elektronentransfer zwischen S. oneidensis MR-1 und der Elektrode, wodurch die Erzeugung von Bioelektrizität in mikrobiellen Brennstoffzellen (MFCs) verbessert wird.
      PubDate: 2017-06-26T02:37:54.404636-05:
      DOI: 10.1002/ange.201704729
       
  • γ-Functionalizations of Amines through Visible-Light-Mediated,
           Redox-Neutral C−C Bond Cleavage
    • Authors: Wei Shu; Alexandre Genoux, Zhaodong Li, Cristina Nevado
      Pages: 10657 - 10660
      Abstract: Cleavage of unstrained C−C bonds under mild, redox-neutral conditions represents a challenging endeavor which is accomplished here in the context of a flexible, visible-light-mediated, γ-functionalization of amines. In situ generated C-centered radicals are harvested in the presence of Michael acceptors, thiols and alkyl halides to efficiently form new C(sp3)−C(sp3), C(sp3)−H and C(sp3)−Br bonds, respectively.Sichtbares Licht ermöglicht die leichte Spaltung von spannungsfreien C-C-Bindungen und die nachfolgende ferngelenkte Funktionalisierung von in situ gebildeten C-zentrierten Radikalen in γ-Stellung zu einer Aminogruppe. In Gegenwart von Michael-Akzeptoren, Thiolen oder Alkylhalogeniden werden neue C(sp3)-C(sp3)-, C(sp3)-H- bzw. C(sp3)-Br-Bindungen effizient gebildet.
      PubDate: 2017-07-25T07:05:36.637244-05:
      DOI: 10.1002/ange.201704068
       
  • A Direct Synthesis of Highly Substituted π-Rich Aromatic Heterocycles
           from Oxetanes
    • Authors: Alexander R. White; Ryan A. Kozlowski, Shiou-Chuan Tsai, Christopher D. Vanderwal
      Pages: 10661 - 10665
      Abstract: The ubiquitous use of π-rich five-membered heterocycles has driven the development of new methods for their synthesis for more than a century. Here, we disclose a general and reliable reaction manifold for the construction of highly substituted heterocycles through a facile Lewis-acid-catalyzed oxetane rearrangement. Notably, this methodology employs a keto-oxetane motif as a 1,4-dicarbonyl surrogate, which can be synthesized using robust alkylation or alkenylation reactions, and thus obviates the need to access 1,4-dicarbonyl compounds via umpoled starting materials. We harnessed this reactivity to generate a broad range of substituted furans and pyrroles, and extended this methodology to produce benzo-fused versions thereof.Durch Alkenylierung oder Addition an die Ketofunktion von billig erhältlichem 3-Oxetanon wird der gespannte Oxetanring für eine Umlagerung vorbereitet, die in einfacher und allgemeiner Weise zu wichtigen heterocyclischen Produkten führt.
      PubDate: 2017-07-21T04:45:59.780208-05:
      DOI: 10.1002/ange.201704119
       
  • Practical Alkoxythiocarbonyl Auxiliaries for Iridium(I)-Catalyzed
           C−H Alkylation of Azacycles
    • Authors: Anh T. Tran; Jin-Quan Yu
      Pages: 10666 - 10670
      Abstract: The development of new and practical 3-pentoxythiocarbonyl auxiliaries for IrI-catalyzed C−H alkylation of azacycles is described. This method allows for the α-C−H alkylation of a variety of substituted pyrrolidines, piperidines, and tetrahydroisoquinolines through alkylation with alkenes. While the practicality of these simple carbamate-type auxiliaries is underscored by the ease of installation and removal, the method's utility is demonstrated in its ability to functionalize biologically relevant l-proline and l-trans-hydroxyproline, delivering unique 2,5-dialkylated amino acid analogues that are not accessible by other C−H functionalization methods.Feinabstimmung: Ein Carbamat-artiges 3-Pentoxythiocarbonyl-Auxiliar wurde für die α-C-H-Alkylierung vielseitig substituierter N-Heterocyclen durch die Reaktion mit Alkenen entwickelt (siehe Schema). Die Anwendung der Reaktion auf biologisch relevantes l-Prolin und l-trans-Hydroxyprolin lieferte 2,5-dialkylierte Aminosäureanaloga.
      PubDate: 2017-07-24T03:25:32.928777-05:
      DOI: 10.1002/ange.201704755
       
  • Enantioselective Oxidative (4+3) Cycloadditions between Allenamides and
           Furans through Bifunctional Hydrogen-Bonding/Ion-Pairing Interactions
    • Authors: Laura Villar; Uxue Uria, Jose I. Martínez, Liher Prieto, Efraim Reyes, Luisa Carrillo, Jose L. Vicario
      Pages: 10671 - 10674
      Abstract: BINOL-based N-trifluoromethanesulfonyl phosphoramides catalyze the enantioselective (4+3) cycloaddition between furans and oxyallyl cations, the latter being generated in situ by oxidation of allenamides. The chiral organic phosphoramide counteranion is proposed to engage in the activation of the oxyallyl cation intermediate through cooperative hydrogen-bonding and ion-pairing interactions, enabling an efficient chirality transfer that provide the final adducts with high diastereo- and enantioselectivities. Remarkably, the reaction shows a wide substrate scope that includes a variety of substituted allenamides and furans.Gegensätze ziehen sich an: Ein BINOL-basiertes N-Sulfonylphosphoramid katalysiert die (4+3)-Cycloaddition von in situ generierten Oxyallylkationen mit Furanen und liefert die entsprechenden Produkte in sehr guten Ausbeuten mit hoher Enantioselektivität. Das Oxyallylkation wird sowohl durch Wasserstoffbrücken als auch durch die Bildung eines Ionenpaares aktiviert.
      PubDate: 2017-07-26T02:45:50.930688-05:
      DOI: 10.1002/ange.201704804
       
  • Silver-Catalyzed Oxidative C(sp3)−P Bond Formation through C−C and
           P−H Bond Cleavage
    • Authors: Lili Li; Wenbin Huang, Lijin Chen, Jiaxing Dong, Xuebing Ma, Yungui Peng
      Pages: 10675 - 10680
      Abstract: The silver-catalyzed oxidative C(sp3)−H/P−H cross-coupling of 1,3-dicarbonyl compounds with H-phosphonates, followed by a chemo- and regioselective C(sp3)−C(CO) bond-cleavage step, provided heavily functionalized β-ketophosphonates. This novel method based on a readily available reaction system exhibits wide scope, high functional-group tolerance, and exclusive selectivity.Schneiden und einfügen: β-Ketophosphonate wurden durch eine Silber-katalysierte Umwandlung unter oxidativer C(sp3)-H/P-H-Kreuzkupplung von 1,3-Dicarbonylverbindungen mit H-Phosphonaten und exklusiver C(sp3)-C(CO)-Tandembindungsspaltung synthetisiert (siehe Schema). Der base-, ligand- und additivfreie Prozess bietet den zusätzlichen Vorteil eines einfachen Katalysatorsystems und guter Verträglichkeit mit funktionellen Gruppen.
      PubDate: 2017-07-21T04:41:19.698391-05:
      DOI: 10.1002/ange.201704910
       
  • Iridium-Catalyzed Enantioselective Synthesis of Pyrrole-Annulated
           Medium-Sized-Ring Compounds
    • Authors: Lin Huang; Yue Cai, Chao Zheng, Li-Xin Dai, Shu-Li You
      Pages: 10681 - 10684
      Abstract: Enantioselective synthesis of pyrrole-annulated medium-sized-ring compounds by an iridium-catalyzed allylic dearomatization/retro-Mannich/hydrolysis sequence is presented. Various substituted pyrrole-annulated seven- and eight-membered-ring products were obtained under mild reaction conditions with moderate to good yields and excellent enantioselectivity. Additionally, these products contain a scaffold widely distributed in natural products and biologically active compounds. The current method provides a convenient way for accessing such pyrrole-anuulated medium-sized-ring compounds.Die enantioselektive Synthese von Pyrrol-anellierten mittelgroßen Ringen gelingt durch eine Sequenz aus Iridium-katalysierter allylischer Dearomatisierung, Retro-Mannich-Reaktion und Hydrolyse. Vielfältig substituierte Pyrrol-anellierte sieben- und achtgliedrige Ringe wurden unter milden Bedingungen mit mäßigen bis guten Ausbeuten und exzellenten Enantioselektivitäten erhalten.
      PubDate: 2017-07-19T06:21:48.435304-05:
      DOI: 10.1002/ange.201705068
       
  • Exceptionally Strong Electron-Donating Ability of Bora-Ylide Substituent
           vis-à-vis Silylene and Silylium Ion
    • Authors: Alfredo Rosas-Sánchez; Isabel Alvarado-Beltran, Antoine Baceiredo, Nathalie Saffon-Merceron, Stéphane Massou, Vicenç Branchadell, Tsuyoshi Kato
      Pages: 10685 - 10690
      Abstract: Electropositive boron-based substituent (phosphonium bora-ylide) with an exceptionally strong π- and σ-electron donating character dramatically increases the stability of a new type of N-heterocyclic silylene 2 featuring amino- and bora-ylide-substituents. Moreover, the related silylium ion 4 and transition-metal–silylene complexes, with trigonal-planar geometries around the silicon center, are also well stabilized. Therefore, the N,B-heterocyclic silylene 2 can be used as a strongly electron-donating innocent ligand in coordination chemistry similarly to N-heterocyclic carbenes.Elektronendonor-Ligand: Ein elektropositiver Bor-basierter Substituent (Phosphoniumborylid) mit außergewöhnlich starkem π- und σ-Elektronendonorcharakter erhöht die Stabilität eines neuartigen N-heterocyclischen Silylens mit Amino- und Boraylid-Substituenten. Der Ligand stabilisiert ebenfalls das verwandte Silylium-Ion und Übergangsmetall-Silylenkomplexe, sogar solche mit trigonal-planarer Geometrie am Siliciumzentrum.
      PubDate: 2017-07-21T04:40:30.031707-05:
      DOI: 10.1002/ange.201705302
       
  • Copper-Catalyzed Three-Component Carboazidation of Alkenes with
           Acetonitrile and Sodium Azide
    • Authors: Ala Bunescu; Tu M. Ha, Qian Wang, Jieping Zhu
      Pages: 10691 - 10694
      Abstract: A copper-catalyzed three-component reaction of alkenes, acetonitrile, and sodium azide afforded γ-azido alkyl nitriles by formation of one C(sp3)−C(sp3) bond and one C(sp3)−N bond. The transformation allows concomitant introduction of two highly versatile groups (CN and N3) across the double bond. A sequence involving the copper-mediated generation of a cyanomethyl radical and its subsequent addition to an alkene, and a C(sp3)−N bond formation accounted for the reaction outcome. The resulting γ-azido alkyl nitrile can be easily converted into 1,4-diamines, γ-amino nitriles, γ-azido esters, and γ-lactams of significant synthetic value.Synthese mit höchster Disziplin: Die regioselektive Azidocyanmethylierung von Alkenen gelingt leicht in Gegenwart von Di-tert-butylperoxid (DTBP), einer katalytischen Menge an Cu(OAc)2 und MnF3, um γ-Azidoalkylnitrile als wertvolle Synthesebausteine zu erhalten. Die Reaktion umfasst die kupfervermittelte Bildung eines Cyanmethylradikals und dessen anschließende Addition an ein Alken sowie eine C(sp3)-N-Bindungsbildung.
      PubDate: 2017-07-26T02:46:00.069532-05:
      DOI: 10.1002/ange.201705353
       
  • Delineating the Mechanism of Ionic Liquids in the Synthesis of
           Quinazoline-2,4(1H,3H)-dione from 2-Aminobenzonitrile and CO2
    • Authors: Martin Hulla; Sami M. A. Chamam, Gabor Laurenczy, Shoubhik Das, Paul J. Dyson
      Pages: 10695 - 10699
      Abstract: Ionic liquids (ILs) are versatile solvents and catalysts for the synthesis of quinazoline-2,4-dione from 2-aminobenzonitrile and CO2. However, the role of the IL in this reaction is poorly understood. Consequently, we investigated this reaction and showed that the IL cation does not play a significant role in the activation of the substrates, and instead plays a secondary role in controlling the physical properties of the IL. A linear relationship between the pKa of the IL anion (conjugate acid) and the reaction rate was identified with maximum catalyst efficiency observed at a pKa of>14.7 in DMSO. The base-catalyzed reaction is limited by the acidity of the quinazoline-2,4-dione product, which is deprotonated by more basic catalysts, leading to the formation of the quinazolide anion (conjugate acid pKa 14.7). Neutralization of the original catalyst and formation of the quinazolide anion catalyst leads to the observed reaction limit.Das IL-Kation spielt keine signifikante Rolle in der Aktivierung der Substrate bei der Synthese von Chinazolin-2,4-dion aus 2-Aminobenzonitril und CO2. Stattdessen hat es eine sekundäre Funktion in der Kontrolle der physikalischen Eigenschaften der IL. Eine lineare Beziehung zwischen dem pKa des IL-Anions (konjugierte Säure) und der Reaktionsgeschwindigkeit wurde identifiziert, mit einem Maximum der Katalysatoreffizienz bei pKa>14.7 in DMSO.
      PubDate: 2017-07-26T02:46:15.901229-05:
      DOI: 10.1002/ange.201705438
       
  • Hydroformylation of Alkenes in a Planetary Ball Mill: From
           Additive-Controlled Reactivity to Supramolecular Control of
           Regioselectivity
    • Authors: Kévin Cousin; Stéphane Menuel, Eric Monflier, Frédéric Hapiot
      Pages: 10700 - 10704
      Abstract: The Rh-catalyzed hydroformylation of aromatic-substituted alkenes is performed in a planetary ball mill under CO/H2 pressure. The dispersion of the substrate molecules and the Rh-catalyst into the grinding jar is ensured by saccharides: methyl-α-d-glucopyranoside, acyclic dextrins, or cyclodextrins (CDs, cyclic oligosaccharides). The reaction affords the exclusive formation of aldehydes whatever the saccharide. Acyclic saccharides disperse the components within the solid mixture leading to high conversions of alkenes. However, they showed typical selectivity for α-aldehyde products. If CDs are the dispersing additive, the steric hindrance exerted by the CDs on the primary coordination sphere of the metal modifies the selectivity so that the β-aldehydes were also formed in non-negligible proportions. Such through-space control via hydrophobic effects over reactivity and regioselectivity reveals the potential of such solventless process for catalysis in solid state.Gemahlener Zucker: Die Rhodium-katalysierte Hydroformylierung von aromatisch substituierten Alkenen gelingt effizient in einer Planetenmühle unter CO/H2-Druck. Man erhält Aldehyde mit hoher Chemoselektivität und einer modifizierten Regioselektivität zugunsten der sonst weniger bevorzugten β-Aldehyde.
      PubDate: 2017-07-24T06:11:12.857211-05:
      DOI: 10.1002/ange.201705467
       
  • Mechanistic Insight Leads to a Ligand Which Facilitates the
           Palladium-Catalyzed Formation of 2-(Hetero)Arylaminooxazoles and
           4-(Hetero)Arylaminothiazoles
    • Authors: Esben P. K. Olsen; Pedro L. Arrechea, Stephen L. Buchwald
      Pages: 10705 - 10708
      Abstract: By using mechanistic insight, a new ligand (EPhos) for the palladium-catalyzed C−N cross-coupling between primary amines and aryl halides has been developed. Employing an isopropoxy group at the C3-position favors the C-bound isomer of the ligand-supported palladium(II) complexes and leads to significantly improved reactivity. The use of a catalyst system based on EPhos with NaOPh as a mild homogeneous base proved to be very effective in the formation of 4-arylaminothiazoles and highly functionalized 2-arylaminooxazoles. Previously, these were not readily accessible using palladium catalysis.Suche mit System: Ein neuer Ligand für palladiumkatalysierte C-N-Kreuzkupplungen, EPhos, wurde basierend auf Struktur-Aktivitäts-Beziehungen BrettPhos-ähnlicher Liganden entwickelt. EPhos wurde in der Pd-katalysierten Bildung von 2-(Hetero)arylaminoxazolen und 4-(Hetero)arylaminothiazolen eingesetzt, deren übergangsmetallkatalysierte Synthese bisher problematisch war.
      PubDate: 2017-07-25T03:34:06.142072-05:
      DOI: 10.1002/ange.201705525
       
  • Enantioselective Organocatalytic Intramolecular Aza-Diels–Alder
           Reaction
    • Authors: Lucie Jarrige; Florent Blanchard, Géraldine Masson
      Pages: 10709 - 10712
      Abstract: A highly efficient catalytic enantioselective intramolecular Povarov reaction was developed with primary anilines as 2-azadiene precursors. A wide variety of angularly fused azacycles were obtained without column chromatography in high to excellent yields and with excellent diastereo- and enantioselectivity (d.r.>99:1 and up to e.r. 99:1). Furthermore, the catalyst loading could be lowered to 1 mol %, and the obtained azacycles could be used as key intermediates for further transformations to generate additional molecular diversity.Die passende Paarung zwischen einer chiralen Phosphorsäure und Cycloadduktvorstufen ermöglichte die Entwicklung einer enantioselektiven intramolekularen Povarov-Reaktion (siehe Schema). Die effiziente Reaktion hat einen großen Substratbereich und läuft mit hoher Diastereo- und Enantioselektivität ab. Einfaches Abscheiden genügt für die Produktisolierung in exzellenter Reinheit und ohne chromatographische Trennung.
      PubDate: 2017-07-24T08:00:37.099753-05:
      DOI: 10.1002/ange.201705746
       
  • Ta(CNDipp)6: An Isocyanide Analogue of Hexacarbonyltantalum(0)
    • Authors: Khetpakorn Chakarawet; Zachary W. Davis-Gilbert, Stephanie R. Harstad, Victor G. Young, Jeffrey R. Long, John E. Ellis
      Pages: 10713 - 10717
      Abstract: Hexakis(2,6-diisopropylphenylisocyanide)tantalum is the first isocyanide analogue of the highly unstable Ta(CO)6 and represents the only well-defined zerovalent tantalum complex to be prepared by conventional laboratory methods. Two prior examples of homoleptic Ta0 complexes are known, Ta(benzene)2 and Ta(dmpe)3, dmpe=1,2-bis(dimethylphosphano)ethane, but these have only been accessed via ligand co-condensation with tantalum vapor in a sophisticated metal-atom reactor. Consistent with its 17-electron nature, Ta(CNDipp)6 undergoes facile one-electron oxidation, reduction, or disproportionation reactions. In this sense, it qualitatively resembles V(CO)6, the only paramagnetic homoleptic metal carbonyl isolable under ambient conditions.Leicht zugänglich: Mit Hexakis(2,6-diisopropylphenylisocyanid)tantal wird das paramagnetische homoleptische Metallisocyanid eines 5d-Übergangsmetalls beschrieben. Dieser bisher einzige strukturell bestätigte nullwertige Tantalkomplex, der durch konventionelle Labormethoden hergestellt wurde, ist analog zu dem hoch instabilen Hexacarbonyltantal(0). Seine Eigenschaften entsprechen denen eines 17-Elektronen-Metalloradikals.
      PubDate: 2017-07-26T02:46:26.006238-05:
      DOI: 10.1002/ange.201706323
       
  • Eisen-katalysierte intramolekulare Aminierung von C(sp3)-H-Bindungen in
           Alkylarylaziden
    • Authors: Isabel T. Alt; Claudia Guttroff, Bernd Plietker
      Pages: 10718 - 10722
      Abstract: Der nucleophile Fe-Komplex Bu4N[Fe(CO)3(NO)] (TBA[Fe]) katalysiert die direkte intramolekulare Aminierung nicht-aktivierter C(sp3)-H-Bindungen durch Aktivierung von Arylaziden. Substituierte Indolin- und Tetrahydrochinolinderivate sind so gut zugänglich.Überraschendes Produkt: Der anionische Fe-Komplex Bu4N[Fe(CO)3(NO)] katalysiert die C(sp3)-H-Aminierung einer Vielzahl von Alkylarylaziden zu den entsprechende Indolinen und, unerwarteterweise, Tetrahydrochinolinen in guten Ausbeuten.
      PubDate: 2017-07-31T07:47:32.748345-05:
      DOI: 10.1002/ange.201704260
       
  • Reaktionen von Donor-Akzeptor-Cyclopropanen mit Naphthochinonen: eine
           Kombination aus Redox- und Lewis-Säure-Katalyse
    • Authors: Alexander Lücht; Lukas J. Patalag, André U. Augustin, Peter G. Jones, Daniel B. Werz
      Pages: 10723 - 10727
      Abstract: 2-Arylcyclopropandicarboxylate werden mit Naphthochinonen zur Reaktion gebracht. Der Schlüsselschritt besteht in der Verwendung von katalytischen Mengen an SnCl2, das sowohl als Elektronendonor als auch als Lewis-Säure fungiert. Mittels einer In-situ-Umpolung wird das vormals elektrophile Naphthochinon in ein Nukleophil überführt. Dieses löst die Ringöffnung des Dreirings aus, wobei eine neue C-C-Bindung geknüpft wird. Werden die so erhaltenen Produkte mit einer Base unter oxidativen Bindungen umgesetzt, führt dies – durch Abspaltung von Methylformiat – zu cyclopentanellierten Produkten mit einem komplett konjugierten π-System, welche eine intensive Absorption im sichtbaren Bereich aufweisen.Elektronen-Power: Elektrophile Naphthochinone werden mittels katalytischer Mengen an Zinn(II) in die entsprechenden nukleophilen Spezies umgewandelt, welche imstande sind, ein Donor-Akzeptor-Cyclopropan zu öffnen. Basische oxidative Bedingungen führen über eine [3+2]-Cyclopentanellierung zu einem vollständig konjugierten π-System.
      PubDate: 2017-07-19T07:45:35.929706-05:
      DOI: 10.1002/ange.201703732
       
  • Enge molekulare Erkennung von Benzo[a]pyren durch einen hochaffinen
           Antikörper
    • Authors: Andreas Eichinger; Irmgard Neumaier, Michael Pschenitza, Reinhard Niessner, Dietmar Knopp, Arne Skerra
      Pages: 10728 - 10733
      Abstract: Benzo[a]pyren entsteht bei der unvollständigen Verbrennung von organischem Material und ist wegen seiner karzinogenen metabolischen Abbauprodukte ein verbreiteter Umweltgiftstoff. Der hochaffine (KD≈3 nm) monoklonale Antikörper 22F12 ermöglicht die einfache bioanalytische Quantifizierung von Benzo[a]pyren auch in komplexer Matrix. Hier wird über dessen funktionelle und röntgenkristallographische Analyse im Komplex mit 3-Hydroxybenzo[a]pyren nach Klonierung der V-Gene und Produktion als rekombinantes Fab-Fragment berichtet. Der polycyclische aromatische Kohlenwasserstoff wird in einer tiefen Tasche zwischen leichter und schwerer Kette gebunden, wo er hauptsächlich von aromatischen und aliphatischen Aminosäureseitenketten umgeben ist. Die Hapten/Antikörper-Grenzfläche ist weniger dicht gepackt als erwartet und weist auch polare, H-Brücken-artige Wechselwirkungen mit dem polycyclischen aromatischen π-Elektronensystem auf, die es dem Antikörper vermutlich gestatten, eine große, überwiegend hydrophobe Bindungsstelle in wässriger Umgebung aufrechtzuerhalten, die gleichzeitig genügende Komplementarität zum Liganden bietet.Gefahr erkannt: Die molekulare Erkennung von (hydroxyliertem) Benzo[a]pyren gelingt mithilfe des hochaffinen Antikörpers 22F12, eines immunchemischen Reagens, das die empfindliche bioanalytische Quantifizierung des giftigen polycyclischen aromatischen Kohlenwasserstoffs auch in komplexer Matrix ermöglicht.
      PubDate: 2017-07-21T04:15:53.28408-05:0
      DOI: 10.1002/ange.201703893
       
  • Optoelektrochemische In-situ-Beobachtung der kathodischen Abscheidung
           einzelner Cobaltnanopartikel
    • Authors: Vitor Brasiliense; Jan Clausmeyer, Alice L. Dauphin, Jean-Marc Noël, Pascal Berto, Gilles Tessier, Wolfgang Schuhmann, Fréderic Kanoufi
      Pages: 10734 - 10737
      Abstract: Die Elektrochemie einzelner Partikel auf einer Nanoelektrode wird mittels optischer Dunkelfeldmikroskopie untersucht. Die Betrachtung des gestreuten Lichts macht es möglich, die elektrochemische Abscheidung einzelner Cobaltnanopartikel mit Radien bis hinunter zu 65 nm in situ zu verfolgen. Die Dimensionen von größeren Submikropartikeln können durch Superlokalisierung der Partikelgrenzen bestimmt werden. Zusätzlich enthält das gestreute Licht ergänzende Informationen über die komplexe Redoxchemie. Mit der optoelektrochemischen Technik werden wertvolle Einblicke in elektrokatalytische Prozesse während der Abscheidung gewonnen, die durch elektrochemische Messungen an einzelnen Partikeln allein nicht zugänglich wären.Die Elektrochemie einzelner Nanopartikel auf einer Nanoelektrode wird mittels optischer Dunkelfeldmikroskopie untersucht. Durch Betrachtung des gestreuten Lichts kann die elektrochemische Abscheidung einzelner Cobaltnanopartikel mit Radien bis hinunter zu 65 nm in situ verfolgt werden. Das optische Signal liefert zudem wertvolle mechanistische Informationen, die von elektrochemischen Messungen allein nicht erfasst werden.
      PubDate: 2017-07-24T07:32:34.821437-05:
      DOI: 10.1002/ange.201704394
       
  • Kovalent gebundene, ineinander verkettete Cyclohexa-m-phenylene und ihre
           Selbstorganisation: Auf dem Weg zu supramolekularen
           3D-Kohlenstoffnanostrukturen
    • Authors: Bastian Dumslaff; Anna N. Reuss, Manfred Wagner, Xinliang Feng, Akimitsu Narita, George Fytas, Klaus Müllen
      Pages: 10738 - 10742
      Abstract: Durch den Versuch, so viele Phenylen-Einheiten wie möglich auf kleinstem Raum zu gruppieren, betreten wir die dreidimensionale Welt der benzolbasierten Moleküle. In dieser Arbeit ermöglichen wir dies durch das einzigartige, schaufelradförmige Polyphenylen 10, welches aus zwei kovalent gebundenen, ineinander verketteten Cyclohexa-m-phenylenen besteht. Es wurde ein Vorläufermolekül konzipiert, welches frei rotierende m-Chlorphenylen-Einheiten trägt, die gleichermaßen eine ausreichende Löslichkeit und die benötigte räumliche Nähe für die finalen Ringschlüsse zu Struktur 10 ermöglichen. Die Selbstorganisation der löslichen Derivate zu supramolekularen Kohlenstoffnanostrukturen wird nacheinander mittels dynamischer Lichtstreuung (DLS) und Brillouin-Lichtstreuung (BLS) untersucht, um die Dimensionen der im Anfangsstadium gebildeten Aggregate in Lösung, sowie den amorphen Charakter im Festkörper zu bestimmen.Praktisch spannungsfreie und thermisch stabile, schaufelradförmige Polyphenylene bestehend aus zwei kovalent ineinander verketteten Cyclohexa-m-phenylenen wurden synthetisiert. Durch Optimierung der Löslichkeit gelang es, die stufenweise Strukturbildung von 3D-Nanostrukturen zu beobachten.
      PubDate: 2017-07-24T06:10:53.688043-05:
      DOI: 10.1002/ange.201705403
       
  • Innenrücktitelbild: A Molecular Boroauride: A Donor–Acceptor Complex of
           Anionic Gold (Angew. Chem. 35/2017)
    • Authors: Jordan W. Taylor; Alex McSkimming, Marc-Etienne Moret, W. Hill Harman
      Pages: 10743 - 10743
      Abstract: Gold ist ungewöhnlich im Vergleich zu den anderen Übergangsmetallen, da es als Anion (Aurid) stabil ist. Unter Verwendung eines von Diboraanthracen abgeleiteten Diphosphanliganden wurde ein Donor-Akzeptor-Komplex des anionischen Golds isoliert. In ihrer Zuschrift auf S. 10549 zeigen W. H. Harman et al., dass der Aurid-Komplex eine reversible Zwei-Elektronen-Oxidation zu einem kationischen Goldkomplex eingehen kann, indem die Diboraanthracen-Einheit dissoziiert, was einen formalen Au(I/−I)-Redoxprozess ermöglicht.
      PubDate: 2017-08-02T04:00:50.795404-05:
      DOI: 10.1002/ange.201707176
       
  • Rücktitelbild: Living and Conducting: Coating Individual Bacterial Cells
           with In Situ Formed Polypyrrole (Angew. Chem. 35/2017)
    • Authors: Rong-Bin Song; YiChao Wu, Zong-Qiong Lin, Jian Xie, Chuan Hao Tan, Joachim Say Chye Loo, Bin Cao, Jian-Rong Zhang, Jun-Jie Zhu, Qichun Zhang
      Pages: 10744 - 10744
      Abstract: Die Beschichtung einzelner Bakterienzellen …… mit in situ gebildetem Polypyrrol wird von J. S. C. Loo, B. Cao, J. R. Zhang, J. J. Zhu et al. in ihrer Zuschrift auf S. 10652 beschrieben. Das Polypyrrol kann als leitfähiges Medium sowie als Schutzschicht fungieren. Ein erhöhter direkter kontaktbasierter extrazellulärer Elektronentransfer und eine bessere Lebensfähigkeit der Bakterienzellen werden beobachtet, wenn mit Polypyrrol beschichtete exoelektrogene Bakterien als Anode in mikrobiellen Brennstoffzellen eingesetzt werden.
      PubDate: 2017-07-20T04:47:15.573807-05:
      DOI: 10.1002/ange.201706568
       
 
 
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