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CHEMISTRY (601 journals)                  1 2 3 4 | Last

Showing 1 - 200 of 735 Journals sorted alphabetically
2D Materials     Hybrid Journal   (Followers: 11)
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: 39)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 19)
ACS Combinatorial Science     Full-text available via subscription   (Followers: 23)
ACS Macro Letters     Full-text available via subscription   (Followers: 24)
ACS Medicinal Chemistry Letters     Full-text available via subscription   (Followers: 40)
ACS Nano     Full-text available via subscription   (Followers: 255)
ACS Photonics     Full-text available via subscription   (Followers: 12)
ACS Synthetic Biology     Full-text available via subscription   (Followers: 24)
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 Chimica Slovenica     Open Access  
Acta Chromatographica     Full-text available via subscription   (Followers: 9)
Acta Facultatis Medicae Naissensis     Open Access  
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 5)
Acta Scientifica Naturalis     Open Access   (Followers: 2)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 5)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 8)
Adsorption Science & Technology     Full-text available via subscription   (Followers: 5)
Advanced Functional Materials     Hybrid Journal   (Followers: 51)
Advanced Science Focus     Free   (Followers: 3)
Advances in Chemical Engineering and Science     Open Access   (Followers: 58)
Advances in Chemical Science     Open Access   (Followers: 13)
Advances in Chemistry     Open Access   (Followers: 15)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 18)
Advances in Drug Research     Full-text available via subscription   (Followers: 23)
Advances in Enzyme Research     Open Access   (Followers: 9)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 16)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 9)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 23)
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: 20)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 6)
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)
Al-Kimia : Jurnal Penelitian Sains Kimia     Open Access  
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 3)
AMB Express     Open Access   (Followers: 1)
Ambix     Hybrid Journal   (Followers: 3)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 67)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 15)
American Journal of Chemistry     Open Access   (Followers: 28)
American Journal of Plant Physiology     Open Access   (Followers: 14)
American Mineralogist     Hybrid Journal   (Followers: 15)
Analyst     Full-text available via subscription   (Followers: 39)
Angewandte Chemie     Hybrid Journal   (Followers: 166)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 235)
Annales UMCS, Chemia     Open Access   (Followers: 1)
Annals of Clinical Chemistry and Laboratory Medicine     Open Access   (Followers: 4)
Annual Reports in Computational Chemistry     Full-text available via subscription   (Followers: 3)
Annual Reports Section A (Inorganic Chemistry)     Full-text available via subscription   (Followers: 4)
Annual Reports Section B (Organic Chemistry)     Full-text available via subscription   (Followers: 9)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 12)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 16)
Anti-Infective Agents     Hybrid Journal   (Followers: 3)
Antiviral Chemistry and Chemotherapy     Hybrid Journal   (Followers: 1)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 7)
Applied Spectroscopy     Full-text available via subscription   (Followers: 22)
Applied Surface Science     Hybrid Journal   (Followers: 28)
Arabian Journal of Chemistry     Open Access   (Followers: 6)
ARKIVOC     Open Access   (Followers: 2)
Asian Journal of Biochemistry     Open Access   (Followers: 1)
Atomization and Sprays     Full-text available via subscription   (Followers: 4)
Australian Journal of Chemistry     Hybrid Journal   (Followers: 7)
Autophagy     Hybrid Journal   (Followers: 2)
Avances en Quimica     Open Access   (Followers: 1)
Biochemical Pharmacology     Hybrid Journal   (Followers: 10)
Biochemistry     Full-text available via subscription   (Followers: 337)
Biochemistry Insights     Open Access   (Followers: 6)
Biochemistry Research International     Open Access   (Followers: 6)
BioChip Journal     Hybrid Journal  
Bioinorganic Chemistry and Applications     Open Access   (Followers: 9)
Bioinspired Materials     Open Access   (Followers: 5)
Biointerface Research in Applied Chemistry     Open Access   (Followers: 2)
Biointerphases     Open Access   (Followers: 1)
Biology, Medicine, & Natural Product Chemistry     Open Access   (Followers: 1)
Biomacromolecules     Full-text available via subscription   (Followers: 19)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 10)
Biomedical Chromatography     Hybrid Journal   (Followers: 6)
Biomolecular NMR Assignments     Hybrid Journal   (Followers: 3)
BioNanoScience     Partially Free   (Followers: 5)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 121)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 85)
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: 6)
Carbohydrate Research     Hybrid Journal   (Followers: 26)
Carbon     Hybrid Journal   (Followers: 68)
Catalysis for Sustainable Energy     Open Access   (Followers: 7)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 8)
Catalysis Science and Technology     Free   (Followers: 8)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysts     Open Access   (Followers: 8)
Cellulose     Hybrid Journal   (Followers: 7)
Cereal Chemistry     Full-text available via subscription   (Followers: 5)
ChemBioEng Reviews     Full-text available via subscription   (Followers: 1)
ChemCatChem     Hybrid Journal   (Followers: 8)
Chemical and Engineering News     Free   (Followers: 16)
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: 25)
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 3)
Chemical Research in Toxicology     Full-text available via subscription   (Followers: 22)
Chemical Reviews     Full-text available via subscription   (Followers: 184)
Chemical Science     Open Access   (Followers: 23)
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: 56)
Chemie-Ingenieur-Technik (Cit)     Hybrid Journal   (Followers: 24)
ChemInform     Hybrid Journal   (Followers: 8)
Chemistry & Biodiversity     Hybrid Journal   (Followers: 7)
Chemistry & Biology     Full-text available via subscription   (Followers: 31)
Chemistry & Industry     Hybrid Journal   (Followers: 5)
Chemistry - A European Journal     Hybrid Journal   (Followers: 149)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 16)
Chemistry and Materials Research     Open Access   (Followers: 20)
Chemistry Central Journal     Open Access   (Followers: 4)
Chemistry Education Research and Practice     Free   (Followers: 5)
Chemistry in Education     Open Access   (Followers: 9)
Chemistry International     Hybrid Journal   (Followers: 2)
Chemistry Letters     Full-text available via subscription   (Followers: 42)
Chemistry of Materials     Full-text available via subscription   (Followers: 241)
Chemistry of Natural Compounds     Hybrid Journal   (Followers: 9)
Chemistry World     Full-text available via subscription   (Followers: 22)
Chemistry-Didactics-Ecology-Metrology     Open Access   (Followers: 1)
ChemistryOpen     Open Access   (Followers: 2)
Chemkon - Chemie Konkret, Forum Fuer Unterricht Und Didaktik     Hybrid Journal  
Chemoecology     Hybrid Journal   (Followers: 4)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 14)
Chemosensors     Open Access  
ChemPhysChem     Hybrid Journal   (Followers: 11)
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)
Chromatography     Open Access   (Followers: 2)
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 Interfaces     Open Access  
Colloids and Surfaces B: Biointerfaces     Hybrid Journal   (Followers: 6)
Combinatorial Chemistry & High Throughput Screening     Hybrid Journal   (Followers: 4)
Combustion Science and Technology     Hybrid Journal   (Followers: 22)
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: 11)
Computational Chemistry     Open Access   (Followers: 2)
Computers & Chemical Engineering     Hybrid Journal   (Followers: 9)
Coordination Chemistry Reviews     Full-text available via subscription   (Followers: 3)
Copernican Letters     Open Access   (Followers: 1)
Corrosion Series     Full-text available via subscription   (Followers: 6)
Critical Reviews in Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 5)
Croatica Chemica Acta     Open Access  
Crystal Structure Theory and Applications     Open Access   (Followers: 4)
CrystEngComm     Full-text available via subscription   (Followers: 13)
Current Catalysis     Hybrid Journal   (Followers: 2)
Current Chromatography     Hybrid Journal  
Current Green Chemistry     Hybrid Journal  
Current Metabolomics     Hybrid Journal   (Followers: 5)
Current Microwave Chemistry     Hybrid Journal  
Current Opinion in Colloid & Interface Science     Hybrid Journal   (Followers: 9)
Current Opinion in Molecular Therapeutics     Full-text available via subscription   (Followers: 18)
Current Research in Chemistry     Open Access   (Followers: 8)
Current Science     Open Access   (Followers: 64)
Dalton Transactions     Full-text available via subscription   (Followers: 23)
Detection     Open Access   (Followers: 2)
Developments in Geochemistry     Full-text available via subscription   (Followers: 2)
Diamond and Related Materials     Hybrid Journal   (Followers: 12)
Dislocations in Solids     Full-text available via subscription  
Doklady Chemistry     Hybrid Journal  
Drying Technology: An International Journal     Hybrid Journal   (Followers: 4)
Eclética Química     Open Access   (Followers: 1)
Ecological Chemistry and Engineering S     Open Access   (Followers: 3)

        1 2 3 4 | Last

Journal Cover Angewandte Chemie
  [166 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  [1592 journals]
  • Tailored microstructured hyperpolarizing matrices for optimal magnetic
           resonance imaging
    • Authors: Matthieu Cavaillès; Aurélien bornet, Xavier Jaurand, Basile Vuichoud, David Baudouin, Mathieu Baudin, Laurent Veyre, Geoffrey Baudenhausen, Jean-Nicolas Dumez, Sami Jannin, Christophe Copéret, Chloé Thieuleux
      Abstract: Tailoring the physical features and the porous network architecture of silica-based hyperpolarizing solids containing TEMPO radicals, known as HYPSO (HYbrid Polarizing SOlids), enable unprecedented performance of dissolution Dynamic Nuclear Polarization (d-DNP). High polarization values up to P(1H) = 99 % were reached for samples impregnated with a mixture of H2O:D2O and loaded in a 6.7 T polarizer at temperatures around 1.2 K. These HYPSO materials combine the best performance of homogeneous DNP formulations with the advantages of solid polarizing matrices which provide hyperpolarized solutions free of any - potentially toxic - additives (radicals and glass-forming agents). The hyperpolarized solutions can be expelled from the porous solids, filtered and rapidly transferred either to a Nuclear Magnetic Resonance (NMR) spectrometer or to a Magnetic Resonance Imaging (MRI) system.
      PubDate: 2018-02-19T05:22:46.761196-05:
      DOI: 10.1002/ange.201801009
  • The Dewar isomer of 1,2-dihydro-1,2-azaborinines: Isolation,
           fragmentation, and energy storage
    • Authors: Holger Bettinger; Klara Edel, Xinyu Xinyu, Jacob Ishibashi, Ashley Lamm, Cäcilia Maichle-Mössmer, Zachary Giustra, Shih-Yuan Liu
      Abstract: The photochemistry of 1,2-dihydro-1,2-azaborinine derivatives was studied under matrix isolation conditions and in solution. Photoisomerization occurs exclusively to the Dewar valence isomers upon irradiation with UV light (> 280 nm) with high quantum yield (46 %). Further photolysis with UV light (254 nm) results in the formation of cyclobutadiene and iminoborane. The thermal electrocyclic ring opening reaction of the Dewar valence isomer back to the 1,2-dihydro-1-tert-butyldimethylsilyl-2-mesityl-1,2-azaborinine has an activation barrier of 27.0 ± 1.2 kcal·mol-1. In the presence of Wilkinson's catalyst, the ring opening occurs rapidly and exothermically (H = -48 ± 1 kcal·mol-1) at room temperature.
      PubDate: 2018-02-19T05:21:44.147391-05:
      DOI: 10.1002/ange.201712683
  • Frontispiz: Enantio- and Diastereoselective Cyclopropanation of
           1-Alkenylboronates: Synthesis of 1-Boryl-2,3-Disubstituted Cyclopropanes
    • Authors: Javier Carreras; Ana Caballero, Pedro J. Pérez
      Abstract: Asymmetrische Cyclopropanierung A. Caballero, P. Pérez et al. stellen in ihrer Zuschrift auf S. 2358 eine Methode für die hoch selektive Umwandlung von endständigen Alkinen in 2,3-disubstituierte 1-Borylcyclopropane vor.
      PubDate: 2018-02-19T05:11:32.102675-05:
      DOI: 10.1002/ange.201880961
  • Über Oxidationszahl-Obergrenzen in der Chemie
    • Authors: Shu-Xian Hu; Wan-Lu Li, Jun-Bo Lu, Junwei Lucas Bao, Haoyu S. Yu, Donald G. Truhlar, John K. Gibson, Joaquim Marçalo, Mingfei Zhou, Sebastian Riedel, W. H. Eugen Schwarz, Jun Li
      Abstract: Der Begriff Oxidationszahl (OS) ist auf der Basis des Lewis-Elektronenpaar-Bildes definiert, wobei Bindungselektronen dem jeweils elektronegativeren Element zugeordnet werden. Der Begriff ist hilfreich zur “Buchhaltung” der Elektronen, zur Vorhersage von chemischen Trends und zur Planung von Synthesewegen. Experimentelle und quantenchemische Befunde legen eine obere Grenze von etwa +8 für die OS in stabilen (neutralen) chemischen Substanzen unter normalen Bedingungen nahe. OS=+9 wurde für das isolierte [IrO4]+-Kation in der Gasphase beobachtet. Vorhergesagte OS=+10 für das isolierte [PtO4]2+-Kation wird hier theoretisch nur für tiefe Temperaturen bestätigt, konnte aber noch nicht experimentell verifiziert werden. Verbindungen mit hoher OS tendieren zur spontanen Reduktion des zentralen Metallatoms unter Oxidation der Liganden, etwa von O−2 unter Bildung von .O−1 und O-O-Bindungen, wobei nicht-Lewis-konforme Strukturen gebildet werden können.Die höchste Oxidationszahl (OS) von Elementen in Verbindungen ist nicht nur durch Anzahl und Ionisationsenergien ihrer Valenzelektronen begrenzt, sondern auch durch die elektronischen Eigenschaften der Liganden. Spontane Liganden-Oxidation und Metall-Reduktion führt zu korrelierten, offenschaligen und mehrzentrigen Bindungen. Eine gemeinsame theoretisch-experimentelle Fallstudie an PtO42+-Isomeren liefert eine OS-Obergrenze für Substanzen unter normalen Bedingungen um +8.
      PubDate: 2018-02-19T02:57:28.910552-05:
      DOI: 10.1002/ange.201711450
  • Confined Self-Assembly in Two-Dimensional Interlayer Space: Monolayered
           Mesoporous Carbon Nanosheets with In-Plane Orderly Arranged Mesopores and
           a Highly Graphitized Framework
    • Authors: Jie Wang; Yunling Xu, Bing Ding, Zhi Chang, Xiaogang Zhang, Yusuke Yamauchi, Kevin C.-W. Wu
      Abstract: Mesoporöse Kohlenstoffnanoblätter werden über Einlagerung einer Kohlenstoffquelle und eines Blockcopolymers zwischen den Schichten von Montmorillonit hergestellt. X. Zhang, K. C.-W. Wu und Mitarbeiter stellen das Verfahren in ihrer Zuschrift (
      DOI : 10.1002/ange.201712959) vor. Der eingeschränkte Raum bei der Synthese begünstigt die Bildung von hoch graphitischem Kohlenstoff, einem schnellen Elektronenleiter. Durch die geordneten Mesoporen der Kohlenstoffnanoblätter können Gastmoleküle diffundieren.
      PubDate: 2018-02-19T02:57:14.214129-05:
  • A Non-Heme Iron Photocatalyst for Light-Driven Aerobic Oxidation of
    • Authors: Juan Chen; Stepan Stepanovic, Apparao Draksharapu, Maja Gruden, Wesley R. Browne
      Abstract: Non-heme (L)FeIII and (L)FeIII-O-FeIII(L) complexes (L=1,1-di(pyridin-2-yl)-N,N-bis(pyridin-2-ylmethyl)ethan-1-amine) underwent reduction under irradiation to the FeII state with concomitant oxidation of methanol to methanal, without the need for a secondary photosensitizer. Spectroscopic and DFT studies support a mechanism in which irradiation results in charge-transfer excitation of a FeIII−μ-O−FeIII complex to generate [(L)FeIV=O]2+ (observed transiently during irradiation in acetonitrile), and an equivalent of (L)FeII. Under aerobic conditions, irradiation accelerates reoxidation from the FeII to the FeIII state with O2, thus closing the cycle of methanol oxidation to methanal.Blitzschnelle Reaktion: (L)FeIII- und (L)FeIII-O-FeIII(L)-Nicht-Häm-Komplexe wurden unter Bestrahlung und ohne Photosensibilisator in den FeII-Zustand reduziert (siehe Schema), begleitet von der Oxidation von Methanol zu Methanal. Spektroskopische und DFT-Studien stützen einen Mechanismus mit Ladungstransferanregung eines FeIII-μ-O-FeIII-Komplexes zu [(L)FeIV=O]2+ und (L)FeII. Bestrahlung beschleunigt die Reoxidation von FeII mit O2, die den Katalysezyklus schließt.
      PubDate: 2018-02-19T02:57:02.831768-05:
      DOI: 10.1002/ange.201712678
  • IR Spectrum and Structure of Protonated Monosilanol: Dative Bonding
           between Water and the Silylium Ion
    • Authors: Martin Andreas Robert George; Nguyen Xuan Truong, Marco Savoca, Otto Dopfer
      Abstract: Die dative Bindung zwischen dem hochreaktiven Silylkation und Wasser in protoniertem Silanol wurde von O. Dopfer und Mitarbeitern in ihrer Zuschrift (
      DOI : 10.1002/ange.201712999) mithilfe von Infrarotspektroskopie und Dichtefunktionalrechnungen untersucht. Die Ergebnisse bezüglich Struktur und Bindungsverhältnissen und die Infrarotsignatur dieses einfachsten Silanol-Kations könnten seine Identifizierung erleichtern, sowohl im Weltraum als auch in Silan-Plasmen, die bei der Herstellung von Mikroelektronik genutzt werden.
      PubDate: 2018-02-19T02:56:56.386484-05:
  • Dynamic Interconversion between Boroxine Cages Based on Pyridine Ligation
    • Authors: Kosuke Ono; Shunsuke Shimo, Kohei Takahashi, Nobuhiro Yasuda, Hidehiro Uekusa, Nobuharu Iwasawa
      Abstract: Die dynamische Umwandlung großer kovalenter organischer Käfige gelang durch Erwärmen oder Behandlung mit einer Säure/Base. In ihrer Zuschrift (
      DOI : 10.1002/ange.201713221) zeigen N. Iwasawa et al., dass eine Mischung aus den Boroxin-Käfigverbindungen 12-mer und 15-mer mit Pyridin in ein Pyridin-Addukt des Boroxin-Käfigs 9-mer überführt werden kann. Dabei ändert sich die Geometrie der N-koordinierten Boratome von trigonal zu tetraedrisch. Somit konnten kovalente organische Käfigverbindungen reversibel ineinander überführt werden.
      PubDate: 2018-02-19T02:56:54.192937-05:
  • A New Portal to SuFEx Click Chemistry: A Stable Fluorosulfuryl Imidazolium
           Salt Emerging as an “F−SO2+” Donor of Unprecedented Reactivity,
           Selectivity, and Scope
    • Authors: Taijie Guo; Genyi Meng, Xiongjie Zhan, Qian Yang, Tiancheng Ma, Long Xu, K. Barry Sharpless, Jiajia Dong
      Abstract: Ein Fluorsulfurylimidazoliumsalz überträgt „F−SO2+”-Einheiten hoch effizient auf Phenole und Amine. In ihrer Zuschrift (
      DOI : 10.1002/ange.201712429) beschreiben K. B. Sharpless, J. Dong et al. die praktikable Synthese dieses stabilen Reagens im Mol-Maßstab, welches die Synthese von „klickbaren” RNHSO2F-Verbindungen ermöglicht, die Breite an SuFEx-Produkten deutlich erweitert und eine Alternative zur Verwendung von SO2F2-Gas darstellt.
      PubDate: 2018-02-19T02:56:51.682868-05:
  • Tailored Organic Electrode Material Compatible with Sulfide Electrolyte
           for Stable All-Solid-State Sodium Batteries
    • Authors: Xiaowei Chi; Yanliang Liang, Fang Hao, Ye Zhang, Justin Whiteley, Hui Dong, Pu Hu, Sehee Lee, Yan Yao
      Abstract: Natrium-Festkörperbatterien benötigen für eine gute Zyklenstabilität chemisch und elektrochemisch mit Natriumionen-Festkörperelektrolyten kompatible Kathodenmaterialien. In ihrer Zuschrift (
      DOI : 10.1002/ange.201712895) berichten Y. Yao et al. über eine Na-Festkörperbatterie mit beispielloser Zyklenstabilität und einer der höchsten spezifischen Energien. Die Batterie beruht auf dem organischen Chinon (Na4C6O6) als einem mit Sulfid-Elektrolyten kompatiblen Kathodenmaterial.
      PubDate: 2018-02-19T02:56:49.415754-05:
  • Palladium-Catalyzed C−H Silylation through Palladacycles Generated
           from Aryl Halides
    • Authors: Ailan Lu; Xiaoming Ji, Bo Zhou, Zhuo Wu, Yanghui Zhang
      Abstract: A highly efficient palladium-catalyzed disilylation reaction of aryl halides through C−H activation has been developed for the first time. The reaction has broad substrate scope. A variety of aryl halides can be disilylated by three types of C−H activation, including C(sp2)−H, C(sp3)−H, and remote C−H activation. In particular, the reactions are also unusually efficient. The yields are essentially quantitative in many cases, even in the presence of less than 1 mol % catalyst and 1 equivalent of the silylating reagent under relatively mild conditions. The disilylated biphenyls can be converted into disiloxane-bridged biphenyls.Drei zur Auswahl: Eine palladiumkatalysierte Disilylierung von Arylhalogeniden unter C-H-Aktivierung beeindruckt durch ein großes Substratspektrum und eine außergewöhnliche Effizienz. Verschiedene Arylhalogenide werden nach dreierlei C-H-Aktivierungsmodi – C(sp2)-H-, C(sp3)-H- und entfernte C-H-Aktivierung – in hervorragenden Ausbeuten disilyliert. Die Methode ist sehr atomökonomisch und für den größeren Maßstab geeignet.
      PubDate: 2018-02-19T02:56:46.600049-05:
      DOI: 10.1002/ange.201800330
  • From Linear to Angular Isomers: Achieving Tunable Charge Transport in
           Single Crystal Indolocarbazoles via Delicate Synergetic CH/NH···Pi
    • Authors: Hui Jiang; Peng Hu, Jun Ye, Apoorva Chaturvedi, Keke K. Zhang, Yongxin Li, Yi Long, Denis Fichou, Christian Kloc, Wenping Hu
      Abstract: Four five fused-ring isomers were rationally designed and synthesized to investigate the isomeric influence of linear and angular shapes in affecting their molecular packing and resultant electronic properties. Single-crystal field-effect transistors showed mobility order of 5,7-ICZ (3.61 cm2 V-1 s-1)> 5,11-ICZ (0.55 cm2 V-1 s-1)> 5,12-ICZ (~10-5 cm2 V-1 s-1) and 11,12-ICZ (~10-6 cm2 V-1 s-1). Theoretical calculations based on density functional theory (DFT) and polaron transport model revealed that 5, 7-ICZ can reach higher mobilities than the others thanks to relatively higher hole transfer integral that links to stronger intermolecular interaction due to the presence of multiple NH···pi and CH···pi(py) interactions with energy close to common NH···N hydrogen bonds, as well as overall lower hole-vibrational coupling owing to the absence of coupling of holes to low frequency modes due to better pi conjugation.
      PubDate: 2018-02-18T23:47:12.032536-05:
      DOI: 10.1002/ange.201713288
  • Electrochemical Exfoliation of Pillared-layer Metal-Organic Framework for
           Boosting the Oxygen Evolution Reaction
    • Authors: Jin Huang; Yu Li, Rui-Kang Huang, Chun-Ting He, Li Gong, Qiong Hu, Lishi Wang, Yan-Tong Xu, Xiao-Yun Tian, Si-Yang Liu, Zi-Ming Ye, Fuxin Wang, Dong-Dong Zhou, Wei-Xiong Zhang, Jie-Peng Zhang
      Abstract: Having high surface areas and fully exposed active sites, two-dimensional (2D) materials and ultrathin nanosheets are advantageous for elevating the catalysis performance and elucidating the catalysis mechanism. 2D materials are mostly restricted to inorganic or organic materials based on covalent bonds, because strong bonding within two dimensions and weak interactions in the third dimension are beneficial to stabilize the 2D structure. Here, we report an electrochemical exfoliation strategy for synthesizing metal-organic 2D materials based on coordination bonds. A catechol functionalized ligand is used as the redox active pillar to construct a pillared-layer framework. As an electrocatalyst for water oxidation, the pillar ligand can be in-situ oxidized and removed to yield ultrathin (2 nm) nanosheets, giving extraordinary catalytic activity at pH = 13 with overpotential as low as 211 mV at 10 mA cm^-2 and turnover frequency as high as 34 s^-1 at an overpotential of 300 mV.
      PubDate: 2018-02-18T21:50:35.630931-05:
      DOI: 10.1002/ange.201801029
  • Tracking the Dynamic Folding and Unfolding of RNA G-Quadruplexes in Live
    • Authors: Xiu-Cai Chen; Shuo-Bin Chen, Jing Dai, Jia-Hao Yuan, Tian-Miao Ou, Zhi-Shu Huang, Jia-Heng Tan
      Abstract: Due to the absence of methods for tracking RNA G-quadruplex dynamics, especially the folding and unfolding of this attractive structure in live cells, understanding of the biological roles of RNA G-quadruplexes is so far limited. Here we reported a new red-emitting fluorescent probe, QUMA-1, for a selective, continuous and real-time visualization of RNA G-quadruplexes in live cells. The applications of QUMA-1 in several previously intractable applications, including live-cell imaging of the dynamic folding, unfolding and movement of RNA G-quadruplexes and visualizing the unwinding of RNA G-quadruplexes by RNA helicase have been demonstrated. Notably, our real-time results revealed the complexity of the dynamics of RNA G-quadruplexes in live cells. We anticipate that the further application of QUMA-1 in combination with appropriate biological and imaging methods to explore the dynamics of RNA G-quadruplexes will uncover more information about the biological roles of RNA G-quadruplexes.
      PubDate: 2018-02-17T10:40:28.654417-05:
      DOI: 10.1002/ange.201801999
  • Lewis Acid Catalyzed Stereoselective Dearomative Coupling of Indolylboron
           Ate Complexes with D-A Cyclopropanes and Alkyl Halides
    • Authors: Saikat Das; Constantin Gabriel Daniliuc, Armido Studer
      Abstract: Indolylboron ate complexes readily generated from 2-lithio indoles and boronic esters undergo multicomponent dearomative coupling with D-A cyclopropanes and alkyl halides in the presence of Sc(OTf)3 as a catalyst. Reactions proceed with complete diastereoselectivity and excellent stereospecificity to provide indolines bearing three contiguous stereocenters. The valuable boronic ester moiety remains in the product and allows for subsequent functionalization.
      PubDate: 2018-02-17T04:40:34.367473-05:
      DOI: 10.1002/ange.201711923
  • N-Heterocyclic Carbene-Treated Gold Surfaces in Pentacene Organic
    • Authors: Aifeng Lv; Matthias Freitag, Kathryn M. Chepiga, Andreas H. Schäfer, Frank Glorius, Lifeng Chi
      Abstract: N-Heterocyclic carbene (NHC) molecules, which reacted with the surface of Au electrodes, have been successfully applied in the pentacene transistors. With the application of NHCs, the charge carrier mobility of pentacene transistors increased by five times, while the contact resistance at the pentacene-Au interface reduced down to 85%. Even after annealing the NHC-Au electrodes at 200 oC for two hours before pentacene deposition, the charge carrier mobility of the pentacene transistors did not decrease. The distinguished performance renders the NHCs as excellent alternatives to thiols as metal modifiers for the application in organic field-effect transistors (OFETs).
      PubDate: 2018-02-16T21:40:26.077642-05:
      DOI: 10.1002/ange.201713415
  • Nucleopeptide Assemblies Selectively Sequester ATP in Cells
    • Authors: Huaimin Wang; Zhaoqianqi Feng, Yanan Qin, Jiaqing Wang, Bing Xu
      Abstract: Here we report that assemblies of nucleopeptides selectively sequestrate ATP in complex conditions (e.g., serum and cytosol). We develop assemblies of nucleopeptides that selectively sequester ATP over ADP. Counteracting enzymes interconvert ATP and ADP to modulate the nanostructures formed by the nucleopeptides and the nucleotides. The nucleopeptides, sequestering ATP effectively in cells, slow down efflux pumps in multidrug resistance cancer cells, thus boosting the efficacy of an anticancer drug. Examining additional 11 nucleopeptides (including D- and L-enantiomers) yields five more nucleopeptides that differentiate ATP and ADP via either precipitation or gelation. As the first example of using assemblies of nucleopeptides for interacting with ATP and disrupting intracellular ATP dynamics, this work illustrates the use of supramolecular assemblies to interact with small and essential biological molecules for controlling cell behaviors
      PubDate: 2018-02-16T15:40:28.700099-05:
      DOI: 10.1002/ange.201712834
  • One-Step Synthesis of Hybrid Core-Shell Metal-Organic Frameworks
    • Authors: Xinyu Yang; Shuai Yuan, Lanfang Zou, Hannah Drake, Yingmu Zhang, Junsheng Qin, Ali Alsalme, Hongcai Zhou
      Abstract: Epitaxial growth of MOF-on-MOF composite is an evolving research topic. In current methods, the core-shell MOFs are synthesized via a stepwise strategy which involves growing the shell-MOFs on top of the preformed core-MOFs with matched lattice parameters. However, the inconvenient stepwise synthesis and the strict lattice-matching requirement have limited the development of core-shell MOFs. Herein, we demonstrate that hybrid core-shell MOFs with mismatching lattices can be synthesized under the guidance of nucleation kinetics. A series of MOF composites with mesoporous core and microporous shell were constructed and characterized by optical microscopy, powder X-ray diffraction, gas sorption measurement, and scanning electron microscopy. Isoreticular expansion of microporous shells and orthogonal modification of the core was realized to produce multifunctional MOF composites, which acted as size selective catalysts for olefin epoxidation with high activity and selectivity.
      PubDate: 2018-02-16T15:10:24.744237-05:
      DOI: 10.1002/ange.201710019
  • Rational tuning of fluorobenzene probes for cysteine-selective protein
    • Authors: Ahmed M. Embaby; Sanne Schoffelen, Christian Kofoed, Meldal Morten, Frederik Diness
      Abstract: Fluorobenzene probes for protein profiling through selective cysteine labeling have been developed by rational reactivity tuning. Tuning was achieved by selecting an electron-withdrawing para-substituent combined with variation of the number of fluorine substituents. Optimized probes chemo-selectively arylated cysteine residues in proteins under aqueous conditions. Probes linked to azide, biotin or a fluorophore were applicable to labeling of eGFP and albumin. Selective inhibition of cysteine proteases was also demonstrated with the probes. Additionally, probes were tuned for site selective labeling among cysteine residues and for activity based protein profiling in cell lysates.
      PubDate: 2018-02-16T13:40:48.628007-05:
      DOI: 10.1002/ange.201712589
  • Direct Measurement of Charge Regulation in Metalloprotein Electron
    • Authors: Collin T. Zahler; Hongyu Zhou, Alireza Abdolvahabi, Rebecca L. Holden, Sanaz Rasouli, Peng Tao, Bryan Shaw
      Abstract: Quantifying how a protein regulates its net electrostatic charge during electron transfer (ET) is a means of directly measuring factors that contribute to either redox potential and/or reorganization energy. Charge regulation by proteins during ET has never been measured because few tools exist to measure the net charge of a folded protein in solution at different oxidation states. Here, by using protein charge ladders and capillary electrophoresis, we determined that the net charge of myoglobin, cytochrome c, and azurin changed by 0.62 ± 0.06, 1.19 ± 0.02, and 0.51 ± 0.04 units upon single ET. Computational analysis predicts that these fluctuations in charge arise from changes in the pKa of multiple non-coordinating residues (predominantly histidine) and require between 0.42-0.90 eV. These results suggest that ionizable residues can tune the reactivity of redox centers via charge regulation.
      PubDate: 2018-02-16T13:40:30.435301-05:
      DOI: 10.1002/ange.201712306
  • Enhanced Photodynamic Therapy by Reduced Intracellular Glutathione Levels
           Employing Nano-MOF with Cu (II) as Active Center
    • Authors: Wei Zhang; Jun Lu, Xiaonan Gao, Ping Li, Wen Zhang, Yu Ma, Hui Wang, Bo Tang
      Abstract: In photodynamic therapy (PDT), the level of reactive oxygen species (ROS) produced in the cell directly determines therapeutic effect. Therefore, the development of photosensitizers combining the ability of reducing GSH levels through synergisticallyimproving ROS concentration to strengthen the efficacy of PDT for tumor is important. We report a nano-metal-organic framework based on Cu (II) as active center for PDT. This MOF-2 is readily uptaken by breast cancer cells, and high-level ROS is generated under light irradiation. Meanwhile, intracellular GSH is considerably decreased owing to absorption on MOF-2, synergistically increasing ROS concentration and accelerating apoptosis, thereby enhancing the effect of PDT. Notably, through the direct adsorption of GSH, MOF-2 showed comparable effect with commercial antitumor drug camptothecin in mouse breast cancer treatment. This work provides strong evidence for MOF-2 as a promising new PDT candidate and anti-cancer drug.
      PubDate: 2018-02-16T10:40:27.005198-05:
      DOI: 10.1002/ange.201710800
  • Selective sp3 C-H Aerobic Oxidation enabled by Deca-tungstate
           Photocatalysis in Flow
    • Authors: Gabriele Laudadio; Sebastian Govaerts, Ying Wang, Davide Ravelli, Hannes Koolman, Maurizio Fagnoni, Stevan Djuric, Timothy Noel
      Abstract: A mild and selective sp3 C-H aerobic oxidation enabled by deca-tungstate photocatalysis has been developed. The reaction can be significantly improved in a microflow reactor enabling the safe use of oxygen and the enhanced irradiation of the reaction mixture. Our method allows for the oxidation of both activated and unactivated C-H bonds (30 examples). The ability to selectively oxidize natural scaffolds, such as (-)-ambroxide, pregnenolone acetate, (+)-sclareolide and artemisinin exemplifies the utility of this new method.
      PubDate: 2018-02-16T10:05:41.409409-05:
      DOI: 10.1002/ange.201800818
  • Phosphinic Acid Based Linkers: New Building Block in MOF Chemistry
    • Authors: Jan Hynek; Petr Brázda, Jan Rohlíček, Michael G.S. Londesborough, Jan Demel
      Abstract: Metal-organic frameworks (MOFs) are a chemically and topologically diverse family of materials composed of inorganic nodes and organic linkers bound together by coordination bonds. In this contribution we present two significant innovations in this field. The first is the use of a new coordination group in phenylene-1,4-bis(methylphosphinic acid) (PBPA), a phosphinic acid analogue of commonly-used terephtalic acid. We show that the use of this new linker group leads to the formation of a hydrothermally stable permanently porous MOF structure. The second innovation is the application of electron diffraction tomography (EDT), coupled with dynamical refinement of the EDT data, to the elucidation of the structure of the new material including the localization of hydrogen atoms.
      PubDate: 2018-02-16T09:10:25.351856-05:
      DOI: 10.1002/ange.201800884
  • Polyvalent Display of Biomolecules on Live Cells
    • Authors: Peng Shi; Nan Zhao, Jinping Lai, James Coyne, Erin R. Gaddes, Yong Wang
      Abstract: Surface display of biomolecules on live cells offers new opportunities to treat human diseases and perform basic studies. Existing methods are primarily focused on monovalent functionalization, that is, the display of single biomolecules across the cell surface. Here we show that the surface of live cells can be functionalized to display polyvalent biomolecular structures through two-step reactions under physiological conditions. This polyvalent functionalization enables the cell surface to recognize the microenvironment one order of magnitude more effectively than with monovalent functionalization. Thus, polyvalent display of biomolecules on live cells holds great potential for various biological and biomedical applications.Viel hilft viel: Biomoleküle auf lebenden Zellen bestimmen, wie die Zellen ihre Umgebung erkennen. Die Oberfläche lebender Zellen kann mit polyvalenten biomolekularen Strukturen funktionalisiert werden, um eine bessere molekulare Erkennung zu gewährleisten als mit monovalenter Funktionalisierung.
      PubDate: 2018-02-16T07:01:06.922382-05:
      DOI: 10.1002/ange.201712596
  • Kallol Ray
    • PubDate: 2018-02-16T06:47:19.114163-05:
      DOI: 10.1002/ange.201801205
  • Dynamic Covalent Chemistry. Principles, Reactions, and Applications
           Herausgegeben von Wei Zhang und Yinghua Jin.
    • Authors: Stefan Kubik
      Abstract: John Wiley and Sons, Hoboken 2018. 464 S., geb., 182.00 €.—ISBN 978-1119075639
      PubDate: 2018-02-16T06:47:17.163799-05:
      DOI: 10.1002/ange.201801152
  • Phosphine-Catalyzed anti-Carboboration of Alkynoates with 9-BBN-Based
           1,1-Diborylalkanes: Synthesis and Use of Multisubstituted
    • Authors: Ayaka Yamazaki; Kazunori Nagao, Tomohiro Iwai, Hirohisa Ohmiya, Masaya Sawamura
      Abstract: Trialkylphosphine organocatalysis has enabled the regioselective anti-carboboration of alkynoates with 9-BBN-based 1,1-diborylalkanes to produce secondary allylboranes with β-alkoxycarbonyl and γ-boryl substituents. The utility of the densely functionalized allylboranes was demonstrated by the highly diastereoselective allylation of N-(trimethylsilyl)aldimines to produce homoallylamines containing tertiary allylborane and acrylate moieties.Organokatalyse mit einem Trialkylphosphin ermöglichte die regioselektive anti-Carboborierung von Alkinoaten mit 1,1-Diborylalkanen zu sekundären Allylboranen mit β-Alkoxycarbonyl- und γ-Borylsubstituenten (siehe Schema). Die dicht funktionalisierten Allylborane bewirken eine hoch diastereoselektive Allylierung von N-(Trimethylsilyl)aldiminen, die Homoallylamine mit tertiären Allylboran- und Acrylateinheiten liefert.
      PubDate: 2018-02-16T06:47:03.793491-05:
      DOI: 10.1002/ange.201712351
  • Supramolecular Modulation of Structural Polymorphism in Pathogenic
           α-Synuclein Fibrils Using Copper(II) Coordination
    • Authors: Tae Su Choi; Jeeyoung Lee, Jong Yoon Han, Byung Chul Jung, Piriya Wongkongkathep, Joseph A. Loo, Min Jae Lee, Hugh I. Kim
      Abstract: Structural variation of α-synuclein (αSyn) fibrils has been linked to the diverse etiologies of synucleinopathies. However, little is known about what specific mechanism provides αSyn fibrils with pathologic features. Herein, we demonstrate Cu(II)-based supramolecular approach for unraveling the formation process of pathogenic αSyn fibrils and its application in a neurotoxic mechanism study. The conformation of αSyn monomer was strained by macrochelation with Cu(II), thereby disrupting the fibril elongation while promoting its nucleation. This non-canonical process formed shortened, β-sheet enriched αSyn fibrils (
      PubDate: 2018-02-16T06:46:55.367394-05:
      DOI: 10.1002/ange.201712286
  • Unsymmetrical, Cyclic Diborenes and Thermal Rearrangement to a
    • Authors: Tom Stennett; James Mattock, Ivonne Vollert, Alfredo Vargas, Holger Braunschweig
      Abstract: Cyclic diboranes(4) based on a chelating monoanionic benzylphosphine linker were prepared by boron-silicon exchange between arylsilanes and B2Br4. Coordination of Lewis bases to the remaining sp2 boron atom yielded unsymmetrical sp3-sp3 diboranes, which were reduced with KC8 to their corresponding trans-diborenes. These compounds were studied by a combination of spectroscopic methods, X-ray diffraction and DFT calculations. PMe3-stabilized diborene 6 was found to undergo thermal rearrangement to gem-diborene 8. DFT calculations on 8 reveal a polar boron-boron bond, and indicate that the compound is best described as a borylborylene.
      PubDate: 2018-02-16T06:42:30.835248-05:
      DOI: 10.1002/ange.201800671
  • Synthesis of Biaryls via Hypervalent Iodine-Tethered Sigmatropic
    • Authors: Mitsuki Hori; Jing-Dong Guo, Tomoyuki Yanagi, Keisuke Nogi, Takahiro Sasamori, Hideki Yorimitsu
      Abstract: Metal-free dehydrogenative coupling of aryliodanes with phenols to afford 2-hydroxy-2'-iodobiaryls has been developed. This reaction proceeds via ligand exchange on the hypervalent iodine atom, followed by [3,3] sigmatropic rearrangement, to realize exclusive regioselectivity. This coupling, in combination with in situ oxidation by mCPBA, facilitates the convenient conversion of iodoarenes into the desired biaryls. The obtained biaryls have convertible iodo and hydroxy groups in close proximity, and are thus synthetically useful, as exemplified by the controlled syntheses of π-expanded furans and a substituted [5] helicene. DFT calculations clearly revealed that the rearrangement is sigmatropic and involves C-C bond formation and I-O bond cleavage in a concerted manner. Acetic acid, which was found to be the best solvent for this protocol, would make the iodine atom more cationic and thus accelerate the sigmatropic rearrangement.
      PubDate: 2018-02-16T06:41:38.075016-05:
      DOI: 10.1002/ange.201801132
  • Helicenophyrins - expanded carbaporphyrins incorporating aza[5]helicene
           and heptacyclic S-shaped aza[5]helicene motifs
    • Authors: Bartosz Szyszko; Monika Przewoznik, Michal J. Bialek, Agata Bialonska, Piotr J. Chmielewski, Jakub Cichos, Lechoslaw Latos-Grazynski
      Abstract: Incorporation of phenanthrene into a hexaphyrin( frame resulted in the intramolecular fusion giving rise to chiral helicenophyrins, i.e. molecules which convolute helicene and porphyrin features incorporating aza[5]helicene or heptacyclic S-shaped aza[5]helicene.
      PubDate: 2018-02-16T05:40:34.641269-05:
      DOI: 10.1002/ange.201800879
  • N-Functionalized Ferrocenes. Subvalent Group XIV Element Chlorides and an
           tButyl Lithium-Induced C─C Bond Cleavage Under Mild Conditions
    • Authors: Bastian Nayyar; Hazem Alnasr, Wolf Hiller, Klaus Jurkschat
      Abstract: The ferrocene derivative η5-CpFeη5-C5H3-1-(ArNCH)-2-(CH2NMe2) (1, Ar = 2,6-iPr2C6H3)) reacts diastereoselectively with LiR under carbolithiation and subsequent hydrolysis to give η5-CpFeη5-C5H3-1-(ArHNCHR)-2-(CH2NMe2) (3, R = tBu; 4, R = Ph; 5, R = Me) in high yields. For R = tBu the organolithium derivative η5-CpFeη5-C5H3-1-(ArLiNCHR)-2-(CH2NMe2) (2) was isolated. Compound 2 reacts with GeCl2∙dioxane and SnCl2, respectively, giving the metallylene amide chlorides η5-CpFeη5-C5H3-1-(ArMNCHtBu)-2-(CH2NMe2) (6, M = GeCl; 7, M = SnCl) containing each three stereogenic centres. The potential of 7 as ligand in transition metal chemistry is demonstrated by formation of its complex η5-CpFeη5-C5H3-1-(ArMNCHtBu)-2-(CH2NMe2) [9, M = Sn(Cl)W(CO)5]. Treatment at room temperature of 3 with tert-butyllithium causes an unprecedented carbon-carbon bond cleavage while under kinetic control lithiation at the Cp-3 position takes place allowing the isolation of η5-CpFeη5-C5H3-1-(ArHNCHtBu)-2-(CH2NMe2)-3-SiMe3 (10).
      PubDate: 2018-02-16T04:40:39.623891-05:
      DOI: 10.1002/ange.201800128
  • ADUC-Preise / Carl-Duisberg-Gedächtnispreis für Bill Morandi / Neue
           Mitglieder der Académie des Sciences / Max-Delbrück-Nachwuchspreis für
           Sabrina Disch / Novartis Early Career Award
    • PubDate: 2018-02-16T04:03:08.905872-05:
      DOI: 10.1002/ange.201801006
  • Organometallic-Mediated Radical Polymerization of Vinylidene Fluoride
    • Authors: Sanjib Banerjee; Vincent Ladmiral, Antoine Debuigne, Christophe Detrembleur, Rinaldo Poli, Bruno Améduri
      Abstract: An unprecedented level of control for the radical polymerization of vinylidene fluoride (VDF), yielding well-defined PVDF (at least up to 14 500 g mol−1) with low dispersity (≤1.32), was achieved using organometallic-mediated radical polymerization (OMRP) with an organocobalt compound as initiator. The high chain-end fidelity was demonstrated by the synthesis of PVDF- and PVAc-containing di-and triblock copolymers. DFT calculations rationalize the efficient reactivation of both head and tail chain end dormant species.Kein Ende absehbar: Eine Organocobaltverbindung vermittelt die metallorganische radikalische Polymerisation (OMRP) von Vinylidenfluorid (VDF) zu definiertem PVDF (bis 14 500 g mol−1 und darüber) mit niedriger Dispersität (≤1.32). Dichtefunktionalrechnungen belegen, dass so erhaltenes PVDF an beiden Enden reaktiviert werden kann.
      PubDate: 2018-02-16T04:02:53.006454-05:
      DOI: 10.1002/ange.201712347
  • Bildgebung von Nano-Bio-Interaktionen in der Niere: Für ein besseres
           Verständnis der Nanopartikel-Clearance
    • Authors: Junqing Wang; Gang Liu
      Abstract: Alles klar! Jüngste Studien haben zu einem besseren Verständnis der Wechselwirkungen zwischen biologischen Strukturen und Nanopartikeln geführt und zum rationalen Design renal eliminierbarer Nanopartikel in erkrankten Nieren beigetragen. Die renale Clearance von Goldnanopartikeln (AuNPs) hängt nicht nur von den Choi-Kriterien ab, sondern wird auch von der Mikrostruktur der glomerulären Barriere sowie von pathophysiologischen Veränderungen im Nephron beeinflusst.
      PubDate: 2018-02-16T04:02:30.416759-05:
      DOI: 10.1002/ange.201711705
  • A Versatile Ligand Platform for Palladium- and Nickel-Catalyzed Ethylene
           Copolymerization with Polar Monomers
    • Authors: Min Chen; Changle Chen
      Abstract: The ability to carry out transition-metal-catalyzed copolymerizations of olefins with polar monomers is a great challenge in the field of olefin polymerization. Palladium has been the dominant player in this field, while its low-cost nickel counterpart has only achieved very limited success. We report the synthesis and evaluation of a highly versatile platform based on diphosphazane monoxide ligands. Both palladium and nickel catalysts bearing these ligands mediate the copolymerization of ethylene with a number of fundamental polar monomers.Polymerisationsplattform: Eine vielseitige Plattform auf Basis von Diphosphazanmonoxid-Liganden wurde entworfen und untersucht. Palladium- und Nickelkatalysatoren mit diesen Liganden vermitteln die Copolymerisation von Ethylen mit einer Reihe von polaren Monomeren.
      PubDate: 2018-02-16T04:01:40.003188-05:
      DOI: 10.1002/ange.201711753
  • Two Chiral Events in a Single C-H Activation Step: a route towards
           terphenyl ligands with two atropisomeric axes.
    • Authors: Françoise Colobert; Quentin Dherbassy, Jean-Pierre Djukic, Joanna Wencel-Delord
      Abstract: Herein we disclose the synthesis of original chiral scaffolds - ortho-orientated terphenyls presenting two atropisomeric Ar-Ar axes. These unusual structures are built up using the C-H activation approach and remarkably both chiral axes are controlled with excellent stereoselectivities in a single transformation. During the reaction, not only atroposelective functionalization of the biaryl precursor occurs imposing one chiral axis, but also an unprecedented atropo-stereoselective C-H arylation takes place generating the second chiral element. These functionalized enantiopure ortho-terphenyls present an original tridimensional structure and thus constitute a unique ground to build-up rapidly and efficiently a library of enantiopure mono- and bicoordinating ligands such as new S/N-Biax and diphosphine Biax-Phos ligands.
      PubDate: 2018-02-16T03:10:59.787586-05:
      DOI: 10.1002/ange.201801130
  • An Organic Mixed-Valence Ligand for Multistate Redox-Active Coordination
    • Authors: Joo yeon Ha; Jin young Koo, Hiroyoshi Ohtsu, Yumi Yakiyama, Kimoon Kim, Daisuke Hashizume, Masaki Kawano
      Abstract: The multi-redox-active/multi-interactive ligand 5,5',8,8'-tetra(4-pyridyl)-2,2'-(1,4-phenylene)bis-1H-perimidine (H2TPP) was designed and synthesized. H2TPP exhibits four one-electron oxidation steps, and was subsequently used for the preparation of a multi-redox-active coordination network via a solid-liquid interface reaction using molten Cd2+ cations. The multiple redox states of H2TPP were confirmed spectroscopically by a stepwise four-electron oxidation. The spectroscopic analysis indicated that the mixed-valence states of the ligand are Class II on the UV-vis-NIR time scale and borderline Class II/Class III on the ESR time scale.
      PubDate: 2018-02-16T01:10:28.521374-05:
      DOI: 10.1002/ange.201713035
  • Synthesis of a Helical Bilayer Nanographene
    • Authors: Paul Jameson Evans; Jiangkun Ouyang, Ludovic Favereau, Jeanne Crassous, Israel Fernández, Josefina Perles Hernáez, Nazario Martin
      Abstract: A rigid, inherently chiral bilayer nanographene has been synthesized as both the racemate and enantioenriched M isomer (with an ee of 93%) in three steps from precedented helicenes. This folded nanographene is comprised of two hexa-peri-hexabenzocoronene layers fused to a [10]helicene, with an interlayer distance of 3.6Å as determined by X-ray crystallography. The rigidity of the helicene linker forces the layers to adopt a nearly-aligned AA-stacked conformation rarely observed in few-layer graphene. By combining the advantages of nanographenes and helicenes, we have constructed a bilayer system of 30 fused benzene rings that is also chiral, rigid, and remains soluble in common organic solvents. We present this as a molecular model system of bilayer graphene, with properties of interest in a variety of potential applications.
      PubDate: 2018-02-15T13:10:52.69762-05:0
      DOI: 10.1002/ange.201800798
  • Ni-catalyzed Umpolung Arylation of Ambiphilic a-Bromo Boronic Esters
    • Authors: Ruben Martin; Shang-Zheng Sun
      Abstract: A Ni-catalyzed reductive arylation of ambiphilic a-bromo boronic esters with aryl halides is described. This platform provides an unrecognized opportunity to promote catalytic umpolung reactivity of ambiphilic reagents with aryl halides, thus unlocking a new cross-coupling strategy that complements existing technologies for the preparation of densely functionalized alkyl organometallic reagents from simple and accessible precursors
      PubDate: 2018-02-15T11:40:57.955535-05:
      DOI: 10.1002/ange.201712428
  • The Amyloid Polymorphism in the Protein Folding and Aggregation Energy
    • Authors: Raffaele Mezzenga; Jozef Adamcik
      Abstract: Protein folding (and misfolding) is of paramount importance to an extraordinary vast class of fields, spanning from biochemistry to biology, medicine, biophysics and statistical thermodynamics. The folding process involves a large number of steps and conformations in which the folding protein samples different thermodynamic states characterized by local minima and activation energies in between. The kinetically trapped on- or off-pathway intermediates identifying the relative minima are metastable folding intermediates towards the lowest absolute energy minima, which have been postulated to be the natively folded state for the regime in which the intramolecular interactions dominate, and the amyloid status for the regime where intermolecular interactions rule. This view, however, has largely neglected the rich polymorphism characterizing the various amyloid species. In this article, we review the protein folding energy landscape in view of recent findings identifying specific transition routes among different amyloid polymorphs. Observed transitions such as twisted ribboncrystal or helical ribbonnanotube or forbidden transitions such helical ribbon crystal, are discussed and precisely positioned within the protein folding and aggregation energy landscape. In particular, because these transitions occur without an unfolding/refolding process, the various energetic states can be navigated by relying on continuous mechanic concepts, which concur, together with experimental evidence, to identify amyloid crystals as the ground state of the protein folding and aggregation energy landscape.
      PubDate: 2018-02-15T11:26:35.179117-05:
      DOI: 10.1002/ange.201713416
  • Confinement effects on the benzene orientational structure
    • Authors: Marta Falkowska; Daniel T. Bowron, Haresh Manyar, Tristan G. A. Youngs, Christopher Hardacre
      Abstract: Liquids under confinement exhibit different properties compared with their corresponding bulk phases, for example miscibility, phase transitions, and diffusion. The underlying cause is the local ordering of molecules which is usually only studied using pure simulation methods. Herein, we derive experimentally the structure of benzene confined in MCM-41 using total neutron scattering measurements. The study reveals a layering of molecules across a pore, and four concentric cylindrical shells can be distinguished for a pore with the radius of 18 Å. The nanoscale confinement of the liquid has a major effect on the spatial and orientational correlations observed between the molecules, when compared with the structure of the bulk liquid. These differences are most marked for the molecules in the parallel configurations, and this suggests differences in chemical reactivity between the confined and bulk liquids.
      PubDate: 2018-02-15T09:40:26.962274-05:
      DOI: 10.1002/ange.201713115
  • Epoxides as Alkylating Reagents for the Catellani Reaction
    • Authors: Hong-Gang Cheng; Chenggui Wu, Han Chen, Ruiming Chen, Guangyin Qian, Zhi Geng, Qiang Wei, Yuanyuan Xia, Jingyang Zhang, Yuming Zhang, Qianghui Zhou
      Abstract: We report a cooperative catalytic system comprising a PdII complex, XPhos, and the potassium salt of 5-norbornene-2-carboxylic acid that enables the use of epoxides as alkylating reagents in the Catellani reaction, thereby expanding the existing paradigm of this powerful transformation. The potassium salt of inexpensive 5-norbornene-2-carboxylic acid acts as both mediator and base in the process. This mild, chemoselective, scalable, and atom-economical protocol is compatible with a wide variety of readily available functionalized aryl iodides and epoxides, as well as terminating olefins. The resulting products undergo facile oxa-Michael addition to furnish ubiquitous isochroman scaffolds.Ein kooperatives katalytisches System aus einem PdII/XPhos-Komplex und dem Kaliumsalz von 5-Norbornen-2-carbonsäure, das als Reaktionsvermittler und Base zugleich fungiert, ermöglichte die Verwendung von Epoxiden als Alkylierungsreagentien in der Catellani-Reaktion (siehe Schema). Die Produkte können durch Oxa-Michael-Addition in Isochroman-Gerüste umgewandelt werden.
      PubDate: 2018-02-15T09:15:33.519167-05:
      DOI: 10.1002/ange.201800573
  • Formation of NiCo2V2O8 Yolk–Double Shell Spheres with Enhanced
           Lithium Storage Properties
    • Authors: Yan Lu; Jianwei Nai, Xiong Wen (David) Lou
      Abstract: Complex nanostructures with multi-components and intricate architectures hold great potential in developing high-performance electrode materials for lithium-ion batteries (LIBs). Herein, we demonstrate a facile self-templating strategy for the synthesis of metal vanadate nanomaterials with complex chemical composition of NiCo2V2O8 and a unique yolk–double shell structure. Starting with the Ni-Co glycerate spheres, NiCo2V2O8 yolk–double shell spheres are synthesized through an anion-exchange reaction of Ni-Co glycerate templates with VO3− ions, followed by an annealing treatment. By virtue of compositional and structural advantages, these NiCo2V2O8 yolk–double shell spheres manifest outstanding lithium storage properties when evaluated as anodes for LIBs. Impressively, an extra-high reversible capacity of 1228 mAh g−1 can be retained after 500 cycles at a high current density of 1.0 Ag−1.NiCo2V2O8-Kugeln mit einer Dotter-Zweischalen-Struktur wurden mit einer einfachen Templat-Technik unter Verwendung einer Ionenaustauschreaktion zwischen Ni-Co-Glycerat-Kugeln und NH4VO3 unter Rückflussbedingungen synthetisiert, gefolgt von einer Wärmebehandlung an Luft. Die synthetisierten NiCo2V2O8-Verbindungen zeigen hervorragende elektrochemische Eigenschaften, wenn sie als Anodenmaterial in Lithiumionenbatterien verwendet werden.
      PubDate: 2018-02-15T09:10:42.724171-05:
      DOI: 10.1002/ange.201800363
  • Bioorthogonal Catalytic Activation of Platinum and Ruthenium Anticancer
           Complexes by FAD and Flavoproteins
    • Authors: Silvia Alonso-de Castro; Aitziber L. Cortajarena, Fernando López-Gallego, Luca Salassa
      Abstract: Recent advances in bioorthogonal catalysis promise to deliver new chemical tools for performing chemoselective transformations in complex biological environments. Herein, we report how FAD (flavin adenine dinucleotide), FMN (flavin mononucleotide), and four flavoproteins act as unconventional photocatalysts capable of converting PtIV and RuII complexes into potentially toxic PtII or RuII−OH2 species. In the presence of electron donors and low doses of visible light, the flavoproteins mini singlet oxygen generator (miniSOG) and NADH oxidase (NOX) catalytically activate PtIV prodrugs with bioorthogonal selectivity. In the presence of NADH, NOX catalyzes PtIV activation in the dark as well, indicating for the first time that flavoenzymes may contribute to initiating the activity of PtIV chemotherapeutic agents.Substrat statt Katalysator: Flavine agieren als selektive Photokatalysatoren für die Aktivierung Metall-basierter Prodrugs in biologischer Umgebung. Anders als in der gewöhnlichen Katalyse sind Metallkomplexe die Substrate, und nicht die Katalysatoren dieser Reaktionen.
      PubDate: 2018-02-15T09:05:59.744289-05:
      DOI: 10.1002/ange.201800288
  • Kinetic Resolution of sec-Thiols by Enantioselective Oxidation with
           Rationally Engineered 5-(Hydroxymethyl)furfural Oxidase
    • Authors: Mathias Pickl; Alexander Swoboda, Elvira Romero, Christoph K. Winkler, Claudia Binda, Andrea Mattevi, Kurt Faber, Marco W. Fraaije
      Abstract: Various flavoprotein oxidases were recently shown to oxidize primary thiols. Herein, this reactivity is extended to sec-thiols by using structure-guided engineering of 5-(hydroxymethyl)furfural oxidase (HMFO). The variants obtained were employed for the oxidative kinetic resolution of racemic sec-thiols, thus yielding the corresponding thioketones and nonreacted R-configured thiols with excellent enantioselectivities (E≥200). The engineering strategy applied went beyond the classic approach of replacing bulky amino acid residues with smaller ones, as the active site was additionally enlarged by a newly introduced Thr residue. This residue established a hydrogen-bonding interaction with the substrates, as verified in the crystal structure of the variant. These strategies unlocked HMFO variants for the enantioselective oxidation of a range of sec-thiols.Passend gemacht: Gezielt entworfene Varianten der 5-(Hydroxymethyl)furfural(HMF)-Oxidase katalysieren die enantioselektive Oxidation von 1-Phenylethanthiolen und erreichen dabei eine kinetische Racematspaltung mit besipiellosen Selektivitäten. Dieses Ergebnis wird anhand der Kristallstruktur einer solchen Variante erklärt.
      PubDate: 2018-02-15T09:01:17.966651-05:
      DOI: 10.1002/ange.201713189
  • Base-Free Generation of Organic Electron Donors from Air-Stable Precursors
    • Authors: Guillaume Tintori; Pierre Nabokoff, Ruqaya Buhaibeh, David Bergé-Lefranc, Sébastien Redon, Julie Broggi, Patrice Vanelle
      Abstract: Organic electron donors (OEDs) are powerful reducing agents recognized for their potential in the reduction of challenging substrates and in original applications. Nonetheless, their low stability in atmospheric oxygen or over time complicates their manipulation and storage. To overcome these constraints and enhance OED practicality, new air- and moisture-stable aminopyridinium carboxylate and carbonate precursors were synthesized and thermally activated to generate the potent electron donor in situ. Carboxylate adducts proved to be excellent latent OED systems, enabling the facile and efficient reduction of challenging substrates. Their reduction properties were correlated to their structural characteristics by thermogravimetric and spectroscopic analysis.Um die Praktikabilität organischer Elektronendonoren (OEDs) zu verbessern, wurden neue luft- und feuchtigkeitsstabile Carboxylat- und Carbonat-Vorstufen synthetisiert. Diese wurden in situ durch thermische Aktivierung in potente Elektronendonoren überführt und ermöglichen so die effiziente Reduktion anspruchsvoller Substrate (ET=Elektronentransfer).
      PubDate: 2018-02-15T09:01:12.17506-05:0
      DOI: 10.1002/ange.201713079
  • Total Synthesis of Astellatol
    • Authors: Nan Zhao; Shuqiang Yin, Shengling Xie, Hao Yan, Pan Ren, Gui Chen, Fang Chen, Jing Xu
      Abstract: A nearly-30-year-old unanswered synthetic puzzle, astellatol, has been solved in an enantiospecific manner. The highly congested pentacyclic skeleton of this rare sesterterpenoid, which possesses a unique bicyclo[4.1.1]octane motif, ten stereocenters, a cyclobutane that contains two quaternary centers, an exo-methylene group, and a sterically encumbered isopropyl trans-hydrindane motif, makes astellatol arguably one of the most challenging targets for sesterterpenoid synthesis. An intramolecular Pauson–Khand reaction was exploited to construct the right-hand side scaffold of this sesterterpenoid. An unprecedented reductive radical 1,6-addition, mediated by SmI2, forged the cyclobutane motif. Last, a strategic oxidation/reduction step provided not only the decisive solution for the remarkably challenging late-stage transformations, but also a highly valuable unravelling of the notorious issue of trans-hydrindane synthesis. Importantly, the synthesis of astellatol showcases a rapid, scalable strategy to access diverse complex isopropyl trans-hydrindane sesterterpenoids.Ein pentacyclisches Sesterterpenoid – Astellatol – wurde enantiospezifisch synthetisiert. Eine Pauson-Khand-Reaktion erzeugte die rechte Seite des Produkts, und eine reduktive radikalische 1,6-Addition unter Verwendung von SmI2 lieferte die Bicyclo[4.1.1]octan-Einheit. Durch strategische Oxidation/Reduktion gegen Ende der Syntheseroute wurde das hoch substituierte trans-Hydrindan fertiggestellt.
      PubDate: 2018-02-15T09:01:04.368077-05:
      DOI: 10.1002/ange.201800167
  • Catalytic Gas-Phase Production of Lactide from Renewable Alkyl Lactates
    • Authors: Rik De Clercq; Michiel Dusselier, Ekaterina Makshina, Bert F. Sels
      Abstract: A new route to lactide, which is a key building block of the bioplastic polylactic acid, is proposed involving a continuous catalytic gas-phase transesterification of renewable alkyl lactates in a scalable fixed-bed setup. Supported TiO2/SiO2 catalysts are highly selective to lactide, with only minimal lactide racemization. The solvent-free process allows for easy product separation and recycling of unconverted alkyl lactates and recyclable lactyl intermediates. The catalytic activity of TiO2/SiO2 catalysts was strongly correlated to their optical properties by DR UV/Vis spectroscopy. Catalysts with high band-gap energy of the supported TiO2 phase, indicative of a high surface spreading of isolated Ti centers, show the highest turnover frequency per Ti site.Ein effizientes Herstellungsverfahren für Lactid – einen cyclischen Baustein für Biokunststoffe – beruht auf der Umesterung von Alkyllactaten in der Gasphase. TiO2/SiO2-Trägerkatalysatoren erzielen dabei hohe Lactid-Selektivitäten. Die Aktivität der Katalysatoren korreliert mit ihrer Bandlücke und nimmt bei Reduktion des Ti-Polymerisationsgrads stark zu.
      PubDate: 2018-02-15T09:00:35.671495-05:
      DOI: 10.1002/ange.201711446
  • Ge14Br8(PEt3)4: A Subhalide Cluster of Germanium - First Step into a Novel
           Field in Germanium Chemistry
    • Authors: Andreas Bernd Schnepf; Claudio Schrenk, Tanja Kunz
      Abstract: Heating a metastable solution of Ge(I)Br to room temperature leads to the first structurally characterized metalloid subhalide cluster Ge14Br8(PEt3)4 (1). Furthermore 1 can be seen as the first isolated binary halide cluster on the way from Ge(I)Br to elemental germanium, giving insight into the complex reaction mechanism of its disproportionation reaction. Quantum chemical calculations further indicate that within 1 a classical bonding situation is realized and that the last step of the formation of 1 might include the trapping of GeBr2 units.
      PubDate: 2018-02-15T07:41:09.561008-05:
      DOI: 10.1002/ange.201712247
  • Coumarin Photocages Modified with an Electron-Rich Styryl Moiety at the
           3-Position: Long Wavelength Excitation, Rapid Photolysis and
    • Authors: Linyong Zhu; Qiuning Lin, Lipeng Yang, Zhiqiang Wang, Yujie Hua, Dasheng Zhang, Bingkun Bao, Chunyan Bao, Xueqing Gong
      Abstract: A new class of coumarin photocages modified with an electron-rich styryl moiety at the 3-position was constructed. The large π-conjugated structure and stabilization of the carbocation intermediates by electron-donors endowed the new photocages excellent long wavelength absorption, large two-photon absorption cross-sections and high uncaging quantum yields. Moreover, the new photocages displayed unique photobleaching property after photocleavage as a result of the intramolecular cyclization rearrangement of carbocation intermediate to form five-membered ring byproducts and block the styryl conjugation at the 3-position. These superior properties of the new photocages are extremely beneficial for high concentration samples and thick specimens, thus extending the application of photocages in many fields.
      PubDate: 2018-02-15T06:11:12.85484-05:0
      DOI: 10.1002/ange.201800713
  • Co-assembly of Polyoxometalates and Zwitterionic Amphiphiles into
           Supramolecular Hydrogels: From Crystalline Fibrillar to Amorphous Micellar
    • Authors: Aoli Wu; Xinpei Gao, Panpan Sun, Fei Lu, Liqiang Zheng
      Abstract: Gelation mechanism is of utmost importance to the rational design of supramolecular hydrogelators. Although both kinetic and thermodynamic controlling self-assembly processes have been widely studied in hydrogels, the evolution relationship between crystalline and amorphous gel networks still remains ambiguous. Herein, a gelation transformation from kinetic to thermodynamic process was achieved by balancing the rigidity and flexibility of the inorganic-organic co-assemblies. And for the first time, the transition morphologies between crystalline and amorphous hydrogel networks were evidenced as ordered wormlike micelles. Given the versatile applications of hydrogels in biological systems and material science, we expect our findings may highlight the potential of inorganic-organic binary supramolecular hydrogelators and fill in the blank between kinetic and thermodynamic controlling gelation processes.
      PubDate: 2018-02-15T05:35:28.975243-05:
      DOI: 10.1002/ange.201800939
  • Ein auf Sulfoxid basierendes, isobares Derivatisierungsreagens für die
           präzise quantitative Massenspektrometrie
    • Authors: Michael Stadlmeier; Jana Bogena, Miriam Wallner, Martin Wühr, Thomas Carell
      Abstract: Die moderne Proteomik erfordert Reagentien für eine akkurate Quantifizierung von Peptiden in komplexen Proben. Peptide werden üblicherweise mit isobaren Markierungen versehen, die aus einem Massenausgleicher und einem Reporter bestehen, die in der Gasphase gespalten werden. Eine geschickte Verteilung der stabilen Isotope liefert mehrere Reagentien mit identischem Molekulargewicht, jedoch mit einer abweichenden Masse der Reportergruppen, was die relative Quantifizierung mehrerer Proben in einer einzigen Messung ermöglicht. Hier wird ein neues isobares Derivatisierungsreagens vorgestellt, in dem der Massenausgleicher und der Reporter über eine Sulfoxidgruppe verbunden sind, was auf Basis einer Sulfoxidpyrolyse zu einer einfachen und asymmetrischen Spaltung bei niedriger Energie führt. Das neue Reagensdesign zeigt eine signifikante Verbesserung der Spaltung, was zu intensiveren Signalen der komplementären Ionen führt und somit auch die Analyse der Komplementärionen-Cluster ermöglicht.Ein neuer Tag bricht an: Ein neues Reagens (SulfOxide Tag) für die quantitative Proteomik wurde entwickelt, das einfacher fragmentiert wird und dadurch zu höheren Reporter- und Komplementärionen-Intensitäten führt.
      PubDate: 2018-02-15T05:00:56.045293-05:
      DOI: 10.1002/ange.201708867
  • Synergistic Photoredox and Organocatalysis for Inverse Hydroboration of
    • Authors: Jin Xie
      Abstract: The first catalytic inverse hydroboration of imines with N-heterocyclic carbene boranes has been realized by means of cooperative organocatalysis and photocatalysis. This catalytic combination brings a promising platform to promote NHC-boryl radical chemistry under sustainable and radical initiator free conditions. The highly important functional group compatibility and possible application in late-stage hydroboration represent an important step-forward to an enhanced -amino organoboron lead library.
      PubDate: 2018-02-15T04:35:40.122291-05:
      DOI: 10.1002/ange.201800421
  • Stereodivergent Evolution of Artificial Enzymes for the Michael Reaction
    • Authors: Xavier Garrabou Pi; Duncan Stuart Macdonald, Basile I. M. Wicky, Donald Hilvert
      Abstract: Enzymes are valuable biocatalysts for asymmetric synthesis due to their exacting stereocontrol. Changing the selectivity of an existing catalyst for new applications is, however, challenging. Here we show that, in contrast, the stereoselectivity of an artificial enzyme created by design and directed evolution is readily tunable. We engineered a promiscuous artificial retro-aldolase into four stereocomplementary catalysts for the Michael addition of a tertiary carbanion to an unsaturated ketone. Notably, this selectivity is also preserved with alternative Michael nucleophiles. Complete stereodiversification of other designer enzymes should similarly be possible by extension of these approaches.
      PubDate: 2018-02-15T03:35:22.965779-05:
      DOI: 10.1002/ange.201712554
  • Stabilizing and Organizing Bi3Cu4 and Bi7Cu12 Nanoclusters in
           Two-Dimensional Metal-Organic Networks
    • Authors: Linghao Yan; Bowen Xia, Qiushi Zhang, Guowen Kuang, Hu Xu, Jun Liu, Pei Nian Liu, Nian Lin
      Abstract: Multinuclear heterometallic nanoclusters with controllable stoichiometry and structure are anticipated to possess promising catalytic, magnetic, and optical properties. Here we demonstrate that heterometallic nanoclusters with precise stoichiometry of Bi3Cu4 and Bi7Cu12 can be stabilized in the scaffold of two-dimensional metal-organic networks on a Cu(111) surface through on-surface metallosupramolecular self-assembly processes. The atomic structures of the nanoclusters were resolved using scanning tunnelling microscopy and density functional theory calculations. The nanoclusters feature highly symmetric planar hexagonal shapes and core-shell charge modulation. The clusters are arranged as triangular lattices with a periodicity that can be tuned by choosing molecules of different size. This work shows that on-surface metallosupramolecular self-assembly creates unique possibilities for the design and synthesis of multinuclear heterometallic nanoclusters.
      PubDate: 2018-02-15T03:11:10.490842-05:
      DOI: 10.1002/ange.201800906
  • Rh-Catalyzed Arylation of Cyclopropenes Based on Asymmetric Directed
           Functionalization of Three-Membered Carbocycles
    • Authors: Ilan Marek; Longyang Dian
      Abstract: A large variety of highly diastereo- and enantiomerically enriched arylcyclopropanes is obtained through the asymmetric Rh-catalyzed arylation reaction of achiral non-functionalized cyclopropene derivatives with commercially available aryl boronic acids and (R,S)-Josiphos
      PubDate: 2018-02-15T03:10:45.846289-05:
      DOI: 10.1002/ange.201713324
  • Entropy-Driven Diastereoselectivity Improvement in the Paternò-Büchi
           Reaction of 1-Naphthylarylethenes with Chiral Cyanobenzoate through Remote
    • Authors: Keisuke Nagasaki; Yoshihisa Inoue, Tadashi Mori
      Abstract: Precisely stereocontrolling photocycloaddition is still a significant challenge, due to mechanistic complexity and highly reactive and short-lived nature of intermediates. Attempts have hitherto been made through structural modifications, mostly by introducing steric conflicts, to increase difference in enthalpic barrier. Here, we show that entropy plays a crucial role in manipulating diastereoselectivity of Paternò-Büchi reaction. A remote meta-alkylation of donor caused nominal changes in photophysical properties as well as exciplexes derived therefrom. Nevertheless, diastereomeric excess of oxetane produced was greatly improved by ca. 40%. This enhancement without accompanying any significant photophysical property changes is difficult to rationalize by conventional enthalpic control concept based on repulsive steric and/or attractive intermolecular interactions as well as electronic perturbations. Differential activation parameters and compensatory enthalpy-entropy relationship revealed that the diastereoselectivity enhancement is not simply enthalpic but also entropic in origin.
      PubDate: 2018-02-14T21:41:17.186672-05:
      DOI: 10.1002/ange.201801330
  • The Solution of the Puzzle of Smectic-Q: The Phase Structure and the
           Origin of Spontaneous Chirality
    • Authors: Huanjun Lu; Xiangbing Zeng, Goran Ungar, Christian Dressel, Carsten Tschierske
      Abstract: Flüssigkristalle existieren in diversen Strukturen, die viele Möglichkeiten für nanotechnologische Anwendungen bieten. Die Struktur einer bestimmten flüssigkristallinen Phase, der Smektisch-Q-Phase, konnte allerdings über 35 Jahre nicht aufgeklärt werden. Jetzt ist es soweit: X. B. Zeng, G. Ungar, C. Tschierske et al. beschreiben in ihrer Zuschrift (
      DOI : 10.1002/ange.201712812) die verwirrende Anordnung orthogonaler helikaler Säulen, die nicht aus chiralen Molekülen aufgebaut ist und doch homochiral.
      PubDate: 2018-02-14T08:45:47.758373-05:
  • Identification of Tumor Initiating Cells with a Small-Molecule Fluorescent
           Probe by Using Vimentin as a Biomarker
    • Authors: Yong-An Lee; Jong-Jin Kim, Jungyeol Lee, Jia Hui Jane Lee, Srikanta Sahu, Haw-Young Kwon, Sung-Jin Park, Se-Young Jang, Jun-Seok Lee, Zhenxun Wang, Wai Leong Tam, Bing Lim, Nam-Young Kang, Young-Tae Chang
      Abstract: Tumor initiating cells (TICs) have been implicated in clinical relapse and metastasis of a variety of epithelial cancers, including lung cancer. While efforts toward the development of specific probes for TIC detection and targeting are ongoing, a universal TIC probe has yet to be developed. We report the first TIC-specific fluorescent chemical probe, TiY, with identification of the molecular target as vimentin, a marker for epithelial-to-mesenchymal transition (EMT). TiY selectively stains TICs over differentiated tumor cells or normal cells, and facilitates the visualization and enrichment of functionally active TICs from patient tumors. At high concentration, TiY also shows anti-TIC activity with low toxicity to non-TICs. With the unexplored target vimentin, TiY shows potential as a first universal probe for TIC detection in different cancers.Eine selektive Sonde für Tumor-initiierende Zellen (TICs) – TiY – nutzt Vimentin als Zielmolekül. TiY erleichtert die Verfolgung und Anreicherung funktionsfähiger TICs aus Tumoren von Patienten und allen anderen untersuchten Krebszelllinien. In hohen Konzentrationen war TiY auch gegen TICs wirksam.
      PubDate: 2018-02-14T08:21:17.6794-05:00
      DOI: 10.1002/ange.201712920
  • CO2-ausgelöste schaltbare Hydrophilie von heterogen konjugierten
           Polymerphotokatalysatoren für verbesserte katalytische Aktivität in
    • Authors: Jeehye Byun; Wei Huang, Di Wang, Run Li, Kai A. I. Zhang
      Abstract: Zahlreiche aktuelle Studien befassen sich mit wasserlöslichen, heterogenen Photokatalysatoren für Energie- und Umweltanwendungen. Ein Problem dieser Systeme ist jedoch, dass normalerweise ein Kompromiss zwischen der Hydrophilie und der Wiederverwendbarkeit der Photokatalysatoren eingegangen werden muss. In dieser Studie stellen wir konjugierte Polymerphotokatalysatoren mit tertiären terminalen Aminen vor, die reversibel CO2 binden und somit eine veränderbare Hydrophilie aufweisen können. Die durch die CO2-Bindung ausgelöste Hydrophilie verstärkt die photokatalytische Effizienz des Polymerphotokatalysators in wässrigen Lösungen. Wird CO2 desorbiert, kann der Photokatalysator unter einfachsten Bedingungen aus dem Reaktionsmedium regeneriert werden, wodurch der Katalysator wiederverwendbar wird. Die Kontrolle über die hydrophilen/hydrophoben Eigenschaften des Katalysators wurde anhand verschiedener organischer Photoredox-Reaktionen, die durch Bestrahlung mit sichtbarem Licht ausgelöst werden, in wässrigem Medium demonstriert.An/Aus-Hydrophilie des Photokatalysators: Die Hydrophilie eines konjugierten Polymerphotokatalysators mit tertiären Aminseitengruppen kann durch einfachen CO2/N2-Austausch geschaltet werden. Diese Hydrophilieumschaltung ermöglicht eine Verbesserung der katalytischen Effizienz und Wiederverwendbarkeit des heterogenen Polymerphotokatalysators in organischen Photoredox-Reaktionen in Wasser.
      PubDate: 2018-02-14T08:16:18.548389-05:
      DOI: 10.1002/ange.201711773
  • Nucleophile Promiscuity of Engineered Class II Pyruvate Aldolase
           YfaU from E. Coli
    • Authors: Karel Hernández; Jesús Joglar, Jordi Bujons, Teodor Parella, Pere Clapés
      Abstract: Pyruvate-dependent aldolases exhibit a stringent selectivity for pyruvate, limiting application of their synthetic potential, which is a drawback shared with other existing aldolases. Structure-guided rational protein engineering rendered a 2-keto-3-deoxy-l-rhamnonate aldolase variant, fused with a maltose-binding protein (MBP-YfaU W23V/L216A), capable of efficiently converting larger pyruvate analogues, for example, those with linear and branched aliphatic chains, in aldol addition reactions. Combination of these nucleophiles with N-Cbz-alaninal (Cbz=benzyloxycarbonyl) and N-Cbz-prolinal electrophiles gave access to chiral building blocks, for example, derivatives of (2S,3S,4R)-4-amino-3-hydroxy-2-methylpentanoic acid (68 %, d.r. 90:10) and the enantiomer of dolaproine (33 %, d.r. 94:6) as well as a collection of unprecedented α-amino acid derivatives of the proline and pyrrolizidine type. Conversions varied between 6–93 % and diastereomeric ratios from 50:50 to 95:5 depending on the nucleophilic and electrophilic components.Leichte Vielfalt: Strukturgeleitete rationale Proteinveränderungen resultierten in einer Fusion aus 2-Keto-3-deoxy-l-rhamnonat-Aldolase-Variante und Maltose-bindendem Protein (MBP-YfaU W23V/L216A), die chirale Bausteine sowie eine Reihe beispielloser Prolin- und Pyrrolizidin-α-Aminosäurederivate liefern kann.
      PubDate: 2018-02-14T08:15:39.746438-05:
      DOI: 10.1002/ange.201711289
  • Übergangsmetall-katalysierte selektive Funktionalisierung von
           C(sp3)-H-Bindungen in Naturstoffen
    • Authors: Rashad R. Karimov; John F. Hartwig
      Abstract: Die direkte Funktionalisierung von Naturstoffen ist wichtig für die Untersuchung von Struktur-Aktivitäts- und Struktur-Eigenschafts-Beziehungen dieser Moleküle. Jüngste Fortschritte bei Übergangsmetall-katalysierten Funktionalisierungen von C(sp3)-H-Bindungen, den zwar häufigsten, aber inerten Bindungen in Naturstoffen, haben gezeigt, dass selektiv Derivate dieser Naturstoffe hergestellt werden können. Strategien, um eine solche Transformation zu realisieren, werden diskutiert.Direkt derivatisiert: Die direkte Funktionalisierung von Naturstoffen ist wichtig zum Studium ihrer Struktur-Aktivitäts- und Struktur-Eigenschafts-Beziehungen. Aktuelle Fortschritte bei Übergangsmetall-katalysierten Funktionalisierungen von C(sp3)-H-Bindungen haben gezeigt, dass sich selektiv Derivate dieser Naturstoffe synthetisieren lassen. Dieser Kurzaufsatz erörtert Strategien für die Realisierung einer solchen Transformation.
      PubDate: 2018-02-14T08:10:31.210878-05:
      DOI: 10.1002/ange.201710330
  • Me3Si−SiMe2[o-CON(i-Pr)2-C6H4]: A New Unsymmetrical Disilane Reagent for
           Regio- and Stereoselective Bis-silylation of Alkynes
    • Authors: Zhen Lei Song; Peihong Xiao, Yanjun Cao, Yingying Gui, Lu Gao
      Abstract: The air-stable unsymmetrical disilane Me3Si−SiMe2[o-CON(i-Pr)2C6H4] has been developed for bis-silylation of alkynes. This reagent tolerates a range of functional groups, providing Z-vinyl disilanes in high yields. The phenyl ring-tethered amide group is proposed to direct oxidative addition of Pd(0) into the Si-Si bond, that might facilitate formation of a six-membered Pd cycle, leading to the observed good to excellent regioselectivity.
      PubDate: 2018-02-14T07:41:21.683102-05:
      DOI: 10.1002/ange.201800513
  • Synthesis of Sub-2 nm Fe-Doped NiSe2 Nanowires and Their Surface Confined
           Oxidation for Oxygen Evolution Catalysis
    • Authors: Shu-Hong Yu; Chao Gu, Shaojin Hu, Xusheng Zheng, Min-Rui Gao, Ya-Rong Zheng, Lei Shi, Qiang Gao, Xiao Zheng, Wangsheng Chu, Hong-Bin Yao, Junfa Zhu
      Abstract: Ultrathin nanostructures are attractive for diverse applications owing to their unique properties compared to their bulks. Transition metal chalcogenides are promising electrocatalysts, yet there remains difficult to make ultrathin structures (sub-2 nm), and the realization of their chemical doping is even more challenging. Here we describe a soft template mediated colloidal synthesis of Fe-doped NiSe2 ultrathin nanowires (UNWs) with diameter down to 1.7 nm. The synergistic interplay between oleylamine and 1-dodecanethiol is crucial to yield these UNWs. The in-situ formed amorphous hydroxide layers that confined on the surface of the ultrathin scaffolds enable efficient oxygen evolution electrocatalysis. The resultant UNW derivatives exhibit a very low overpotential of 268 mV at 10 mA cm-2 in 0.1 M KOH, as well as remarkable long-term stability, representing one of the most efficient noble-metal-free catalysts.
      PubDate: 2018-02-14T07:41:01.694552-05:
      DOI: 10.1002/ange.201800883
  • Electrolyte additives for lithium metal anodes and rechargeable lithium
           metal batteries: progresses and perspectives
    • Authors: Heng Zhang; Gebrekidan Gebresilassie Eshetu, Xabier Judez, Chunmei Li, Lide M. Rodriguez-Martínez, Michel Armand
      Abstract: Lithium metal (Li°) - based rechargeable batteries (LMBs), such as Li° anode vs. intercalation and/or conversion type cathode batteries, lithium-sulphur (Li-S), and lithium-oxygen (O2)/air (Li-O2/air) are becoming increasingly important for electrifying the modern transportation system, enabling sustainable mobility in the near future. Though some rechargeable LMBs batteries (e.g., Li°/LiFePO4 batteries from Bolloré Bluecar®, Li-S batteries from OXIS Energy and Sion Power) are already commercially viable in niche applications, their large-scale deployment is still hampered due to the existence of a number of formidable challenges, including lithium dendrite growth, electrolyte instability towards high voltage intercalation type cathode, poor electronic and ionic conductivities of sulphur (S8) and O2, as well as their corresponding reduction products (e.g., Li2S and Li2O), dissolution and shuttling of polysulphide (PS) intermediates etc. This ultimately results in short cycle life, low coulombic/energy efficiency, poor safety, and a high self-discharge rate. Among other mitigating strategies, the use of electrolyte additives is considered as one of the most economical, and effective approach for circumventing these dilemmas. Set out to offer an in-depth insight into the rapidly growing research on the account of electrolyte additives for rechargeable LMBs, this review presents an overview of the various functional additives, that are being applied in Li-anode/intercalation cathode-based, Li-S and Li-O2 batteries. This review is believed to assess the status quo of the research and thereby arouse new thoughts and opportunities, opening new avenues for the practical realization of these appealing devices.
      PubDate: 2018-02-14T07:12:16.976516-05:
      DOI: 10.1002/ange.201712702
  • A Benzene-1,3,5-Triaminyl Radical Fused with Zn(II)-Porphyrins: Remarkable
           Stability and High Spin Quartet Ground State
    • Authors: Atsuhiro Osuka; Daiki Shimizu
      Abstract: A benzene-1,3,5-triaminyl radical fused with three Zn(II)-porphyrins was synthesized via a three-fold oxidative fusion reaction of 1,3,5-tris(Zn(II)-porphyrinylamino)benzene followed by oxidation with PbO2 as key steps. This triaminyl radical has been proved to possess a quartet ground state with a doublet-quartet energy gap of 3.1 kJ/mol by SQUID studies. Despite the high-spin nature, this triradical is remarkably stable, allowing for its separation and recrystallization under ambient conditions. Moreover, this triradical can be stored as solids more than one year without serious deterioration. The high stability of the triradical has been attributed to effective spin delocalization over the porphyrin segments and steric protection at the nitrogen centers and the porphyrin meso-positions.
      PubDate: 2018-02-14T07:11:36.690978-05:
      DOI: 10.1002/ange.201801080
  • Rhodium(I)-Catalyzed Cycloisomerization of Homopropargylallene-Alkynes
           through C(sp3)−C(sp) Bond Activation
    • Authors: Yasuaki Kawaguchi; Kenya Yabushita, Chisato Mukai
      Abstract: Upon exposure to a catalytic amount of [RhCl(CO)2]2 in 1,4-dioxane, homopropargylallene-alkynes underwent a novel cycloisomerization accompanied by the migration of the alkyne moiety of the homopropargyl functional group to produce six/five/five tricyclic compounds in good yields. A plausible mechanism was proposed on the basis of an experiment with 13C-labeled substrate. The resulting tricyclic derivatives were further converted into the corresponding bicyclo[3.3.0] skeletons with vicinal cis dihydroxy groups.In Gegenwart von [RhCl(CO)2]2 reagieren Homopropargylallen-substituierte Alkine über C(sp3)-C(sp)-Bindungsspaltung und Migration zu tricyclischen Gerüsten mit einer Trien-Einheit. Deren Oxidation ergibt benachbarte cis-Diole in einer stereo- und regioselektiven Reaktion.
      PubDate: 2018-02-14T05:56:46.935013-05:
      DOI: 10.1002/ange.201713096
  • Densely Packed, Ultra Small SnO Nanoparticles for Enhanced Activity and
           Selectivity in Electrochemical CO2 Reduction
    • Authors: Jun Gu; Florent Héroguel, Jeremy Luterbacher, Xile Hu
      Abstract: Controlling the selectivity in electrochemical CO2 reduction is an unsolved challenge. While tin (Sn) has emerged as a promising non-precious catalyst for CO2 electroreduction, most Sn-based catalysts produce formate as the major product, which is less desirable than CO in terms of separation and further use. Tin monoxide (SnO) nanoparticles supported on carbon black were synthesized and assembled and their application in CO2 reduction was studied. Remarkably high selectivity and partial current densities for CO formation were obtained using these SnO nanoparticles compared to other Sn catalysts. The high activity is attributed to the ultra-small size of the nanoparticles (2.6 nm), while the high selectivity is attributed to a local pH effect arising from the dense packing of nanoparticles in the conductive carbon black matrix.Zinnmonoxid-Nanopartikel (SnO-NPs) auf einem Kohlenstoffträger wurden zur Reduktion von CO2 verwendet, wo sie im Vergleich zu anderen Zinnkatalysatoren hohe Partialstromdichten für die CO-Bildung ergaben. Die hohe Aktivität wird mit der geringen Größe der Nanopartikel (2.6 nm) erklärt, die hohe Selektivität mit einem pH-Effekt der dichten NP-Packung auf dem leitfähigen Kohlenstoffsubstrat.
      PubDate: 2018-02-14T05:41:43.436893-05:
      DOI: 10.1002/ange.201713003
  • Dynamic Interconversion between Boroxine Cages Based on Pyridine Ligation
    • Authors: Kosuke Ono; Shunsuke Shimo, Kohei Takahashi, Nobuhiro Yasuda, Hidehiro Uekusa, Nobuharu Iwasawa
      Abstract: Dynamic interconversion between large covalent organic cages was achieved simply by heating or acid/base treatment. A mixture of the boroxine cages 12-mer and 15-mer was cleanly converted into a pyridine adduct of the 9-mer boroxine cage upon treatment with pyridine, and the geometry of N-coordinated boron atoms changed from trigonal to tetrahedral. The reverse reaction was achieved by heating or acid treatment. In this process, the larger boroxine cages 12-mer and 15-mer were found to be entropically favored owing to the release of free pyridine molecules from 9-mer⋅6 Py.Eine Mischung aus den Boroxin-Käfigverbindungen 12-mer und 15-mer wurde mit Pyridin sauber in ein Pyridin-Addukt des Boroxin-Käfigs 9-mer überführt. Die Rückreaktion gelang durch Erwärmen oder Behandlung mit Säure. Die Bildung der größeren Boroxin-Käfige 12-mer und 15-mer ist aufgrund der Freisetzung von Pyridin-Molekülen aus 9-mer⋅6 Py entropisch begünstigt.
      PubDate: 2018-02-14T05:41:26.712195-05:
      DOI: 10.1002/ange.201713221
  • The [U2F12]2− Anion of Sr[U2F12]
    • Authors: Benjamin Scheibe; Clemens Pietzonka, Otto Mustonen, Maarit Karppinen, Antti J. Karttunen, Mihail Atanasov, Frank Neese, Matthias Conrad, Florian Kraus
      Abstract: The D2h-symmetric dinuclear complex anion [U2F12]2− of pastel green Sr[U2F12] shows a hitherto unknown structural feature: The coordination polyhedra around the U atoms are edge-linked monocapped trigonal prisms, the UV atoms are therefore seven-coordinated. This leads to a U–U distance of 3.8913(6) Å. A weak UV–UV interaction is observed for the dinuclear [U2F12]2− complex and described by the antiferromagnetic exchange Jexp of circa −29.9 cm−1. The crystalline compound can be easily prepared from SrF2 and β-UF5 in anhydrous hydrogen fluoride (aHF) at room temperature. It was studied by means of single crystal X-ray diffraction, IR, Raman and UV/VIS spectroscopy, magnetic measurements, and by molecular as well as by solid-state quantum chemical calculations.Ein zweikerniges Fluoridouranat(V) – das D2h-symmetrische [U2F12]2−-Anion – ist ein beispielloses Merkmal des neu synthetisierten Sr[U2F12]. Die spektroskopischen und magnetischen Eigenschaften des Produkts wurden in quantenchemischen Rechnungen reproduziert. Eine antiferromagnetische Kopplung der UV-Atome wird beobachtet.
      PubDate: 2018-02-14T05:40:43.431915-05:
      DOI: 10.1002/ange.201800743
  • Monitoring Dissociation Kinetics during Electrophoretic Focusing to Enable
           High-Specificity Nucleic Acid Detection
    • Authors: Tal Zeidman Kalman; Rebecca Khalandovsky, Elena Tenenbaum Gonikman, Moran Bercovici
      Abstract: A wide range of medical conditions can be diagnosed through sequence-specific analysis of nucleic acids. However, a major challenge remains in detecting a specific target in samples containing a high concentration of mismatching sequences. A single-step kinetic homogenous (free solution) assay is presented in which free sequence-specific probes are continuously separated from probe–target hybrids during electrophoretic sample focusing, allowing monitoring of dissociation kinetics. Under these conditions, the different kinetics of targets versus mismatches result in distinct patterns of the signal (for example, linear increase for target versus exponential decay for mismatch), allowing the detection of desired sequences even in the presence of high background nucleic acid content. Additionally, an analytical model provides insight into the underlying dynamics, and allows design of assays based on this mechanism.In einem Schritt und in homogener Lösung arbeitet ein Assay, das im Zuge einer elektrophoretischen Probenfokussierung freie sequenzspezifische Sonden kontinuierlich von Sonde-Analyt-Hybriden trennt. Die Methode kann gewünschte Sequenzen auch in Proben mit einem hohen Gehalt an anderen Nukleinsäuren nachweisen.
      PubDate: 2018-02-14T05:36:20.856479-05:
      DOI: 10.1002/ange.201711673
  • Cocrystals Strategy towards Novel Materials for Near-infrared Photothermal
           Conversion and Imaging
    • Authors: Wenping Hu; Yu Wang, Weigang Zhu, Wenna Du, Xinfeng Liu, Xiaotao Zhang, Huanli Dong
      Abstract: Herein, a cocrystal strategy with simple preparation process is developed to fabricate novel materials for Near-infrared photothermal (PT) conversion and imaging. Dibenzotetrathiafulvalene (DBTTF) and tetracyanobenzene (TCNB) are selected as electron-donor and electron-acceptor, which self-assemble into new cocrystals through non-covalent interactions. The strong interaction between the donors and acceptors leads to a narrow bandgap with near-infrared (NIR) absorption and that both the ground state and lowest-lying excited state are CT state. Remarkably, under the illumination of 808 nm laser (0.7 W/cm2), the temperature of cocrystal is sharply increased and reaches as high as 66.1 °C within 5 minutes. As a contrast, without cocrystals the sample rises only 3 °C, hence, the cocrystal demonstrates high performance PT conversion efficiency (η = 18.8%).
      PubDate: 2018-02-14T05:35:34.282185-05:
      DOI: 10.1002/ange.201712949
  • Shape-Tunable Colloids from Structured Liquid Droplet Templates
    • Authors: Bing Liu; Zhang Luo
      Abstract: Shaping colloidal building units is paramount important for their self-assembly to complex objects. Continuous tuning of colloidal shapes is highly desired for understanding self-assembly, but it still remains a challenge. Here we report a new templated strategy for shape-tunable synthesis of anisotropic colloids with shapes continuously tuned from discoids (oblate spheroids) to spheres to theta shapes to dumbbells. This is realized by creating structured shape-tunable droplets with patchy colloidal discs and followed by using the droplets as templates. In particular, we find a controlled dumbbell-to-eyeball droplet transformation that can be used for the synthesis of eyeball-shaped colloids. We demonstrate the droplets transformation pathways and extend the method to synthesize colloidal molecules. These colloids provide possibilities for exploring their ordered packing structures and the method based on structured droplets can be adapted for the synthesis of other functional colloidal particles.
      PubDate: 2018-02-14T05:35:31.023221-05:
      DOI: 10.1002/ange.201800587
  • Precisely Tailoring Upconversion Dynamics via Energy Migration in
           Core–Shell Nanostructures
    • Authors: Jing Zuo; Dapeng Sun, Langping Tu, Yanni Wu, Yinghui Cao, Bin Xue, Youlin Zhang, Yulei Chang, Xiaomin Liu, Xianggui Kong, Wybren Jan Buma, Evert Jan Meijer, Hong Zhang
      Abstract: Upconversion emission dynamics have long been believed to be determined by the activator and its interaction with neighboring sensitizers. Herein this assumption is, however, shown to be invalid for nanostructures. We demonstrate that excitation energy migration greatly affects upconversion emission dynamics. “Dopant ions’ spatial separation” nanostructures are designed as model systems and the intimate link between the random nature of energy migration and upconversion emission time behavior is unraveled by theoretical modelling and confirmed spectroscopically. Based on this new fundamental insight, we have successfully realized fine control of upconversion emission time behavior (either rise or decay process) by tuning the energy migration paths in various specifically designed nanostructures. This result is significant for applications of this type of materials in super resolution spectroscopy, high-density data storage, anti-counterfeiting, and biological imaging.Der Weg nach oben: Eine aufwärtskonvertierte Emission mit maßgeschneiderter Dynamik beruht auf der Kontrolle über die Energieverlagerungspfade in Kern-Schale-Nanostrukturen. Dies setzt Strukturen voraus, in denen die dotierenden Ionen räumlich voneinander getrennt sind.
      PubDate: 2018-02-14T05:32:14.996018-05:
      DOI: 10.1002/ange.201711606
  • Functional Hydride Transfer by a Thiolate-Containing Model of Mono-Iron
           Hydrogenase featuring an Anthracene Scaffold
    • Authors: Spencer A. Kerns; Anne-Clarisse Magtaan, Pisey R. Vong, Michael J. Rose
      Abstract: We report the synthesis, X-ray structure and functional biomimetic activity of a model complex of mono-iron hydrogenase (Hmd). To achieve the desired biomimetic fac-CNS(thiolate) ligation motif, an anthracene framework is used to provide the requisite donors in a single chelate. A bulky aryl thiolate (ortho dimethylphenyl) is included to achieve mononuclearity. In addition to exhibiting structural (X-ray) and spectroscopic (NMR, IR) similarity to the enzyme, the complex is competent for H2 activation (heterolysis) and hydride transfer to a model substrate—mimicking the functional behavior of the enzyme in a biomimetic CNS coordination sphere for the first time.Spiegelbildliche Aktivität: Ein synthetisches Modell des Enzyms Monoeisenhydrogenase mit „Anthracen-Gerüst” katalysiert die biomimetische H2-Aktivierung und den Hydridtransfer auf ein Modellsubstrat. Der Modellkomplex imitiert dabei eine Enzymfunktion in einer biomimetischen CNS-Koordinationssphäre.
      PubDate: 2018-02-14T05:25:56.017171-05:
      DOI: 10.1002/ange.201712948
  • Rapid and Efficient Generation of Stable Antibody–Drug Conjugates via an
           Encoded Cyclopropene and an Inverse-Electron-Demand Diels–Alder Reaction
    • Authors: Benjamí Oller-Salvia; Gene Kym, Jason W. Chin
      Abstract: Homogeneous antibody–drug conjugates (ADCs), generated by site-specific toxin linkage, show improved therapeutic indices with respect to traditional ADCs. However, current methods to produce site-specific conjugates suffer from low protein expression, slow reaction kinetics, and low yields, or are limited to particular conjugation sites. Here we describe high yielding expression systems that efficiently incorporate a cyclopropene derivative of lysine (CypK) into antibodies through genetic-code expansion. We express trastuzumab bearing CypK and conjugate tetrazine derivatives to the antibody. We show that the dihydropyridazine linkage resulting from the conjugation reaction is stable in serum, and generate an ADC bearing monomethyl auristatin E that selectively kills cells expressing a high level of HER2. Our results demonstrate that CypK is a minimal bioorthogonal handle for the rapid production of stable therapeutic protein conjugates.Ein Cyclopropen-Derivat von Lysin, CypK, kann durch Erweiterung des genetischen Codes effizient in Antikörper eingebaut werden. Konjugation von CypK an Moleküle mit Tetrazin-Motiv ergibt eine in Serum stabile Vernetzung. Monomethyl-Auristatin E kann mit diesem Verfahren an Trastuzumab gebunden werden, um ein Antikörper-Wirkstoff-Konjugat aufzubauen, das selektiv gegen Zellen mit hohem HER2-Spiegel wirkt.
      PubDate: 2018-02-14T05:25:34.724287-05:
      DOI: 10.1002/ange.201712370
  • A Diazido Mannose Analogue as a Chemoenzymatic Synthon for Synthesizing
           Di-N-acetyllegionaminic Acid-Containing Glycosides
    • Authors: Abhishek Santra; An Xiao, Hai Yu, Wanqing Li, Yanhong Li, Linh Ngo, John B. McArthur, Xi Chen
      Abstract: A chemoenzymatic synthon was designed to expand the scope of the chemoenzymatic synthesis of carbohydrates. The synthon was enzymatically converted into carbohydrate analogues, which were readily derivatized chemically to produce the desired targets. The strategy is demonstrated for the synthesis of glycosides containing 7,9-di-N-acetyllegionaminic acid (Leg5,7Ac2), a bacterial nonulosonic acid (NulO) analogue of sialic acid. A versatile library of α2-3/6-linked Leg5,7Ac2-glycosides was built by using chemically synthesized 2,4-diazido-2,4,6-trideoxymannose as a chemoenzymatic synthon for highly efficient one-pot multienzyme (OPME) sialylation followed by downstream chemical conversion of the azido groups into acetamido groups. The syntheses required 10 steps from commercially available d-fucose and had an overall yield of 34–52 %, thus representing a significant improvement over previous methods. Free Leg5,7Ac2 monosaccharide was also synthesized by a sialic acid aldolase-catalyzed reaction.Eine Bibliothek biologisch wichtiger α2-3/6-verknüpfter Leg5,7NAc2-haltiger Glykoside wurde ausgehend von chemisch synthetisiertem 6deoxyMan2,4diN3 als chemoenzymatischem Synthon mithilfe von Eintopf-Multienzym-Sialylierungssystemen und anschließender chemischer Umwandlung der Azido- in Acetamidogruppen aufgebaut (siehe Schema). In diesem hoch effizienten chemoenzymatischen Prozess sind kommerziell erhältliche Enzyme einsetzbar.
      PubDate: 2018-02-14T05:25:27.769875-05:
      DOI: 10.1002/ange.201712022
  • Ice Melting to Release Reactants in Solution Syntheses
    • Authors: Hehe Wei; Kai Huang, Le Zhang, Binghui Ge, Dong Wang, Jialiang Lang, Jingyuan Ma, Da Wang, Shuai Zhang, Qunyang Li, Ruoyu Zhang, Naveed Hussain, Ming Lei, Li-Min Liu, Hui Wu
      Abstract: Aqueous solution syntheses are mostly based on mixing two solutions with different reactants. It is shown that freezing one solution and melting it in another solution provides a new interesting strategy to mix chemicals and to significantly change the reaction kinetics and thermodynamics. For example, a precursor solution containing a certain concentration of AgNO3 was frozen and dropped into a reductive NaBH4 solution at about 0 °C. The ultra-slow release of reactants was successfully achieved. An ice-melting process can be used to synthesize atomically dispersed metals, including cobalt, nickel, copper, rhodium, ruthenium, palladium, silver, osmium, iridium, platinum, and gold, which can be easily extended to other solution syntheses (such as precipitation, hydrolysis, and displacement reactions) and provide a generalized method to redesign the interphase reaction kinetics and ion diffusion in wet chemistry.Eine Lösung einfrieren und in einer anderen wieder auftauen bildet eine Strategie zur Mischung von Chemikalien, wodurch kinetische und thermodynamische Reaktionseigenschaften modifiziert werden können. Einfrieren einer AgNO3-Lösung und Zugabe zu einer NaBH4-Lösung bei ungefähr 0 °C lieferte beispielsweise dispergierte Metallatome. Die Methode kann aber auch auf Fällungsvorgänge, Hydrolysen und Austauschreaktionen angewendet werden.
      PubDate: 2018-02-14T05:21:01.939182-05:
      DOI: 10.1002/ange.201711128
  • Total Synthesis and Conformational Study of Callyaerin A:
           Anti-Tubercular Cyclic Peptide Bearing a Rare Rigidifying (Z)-2,3-
           Diaminoacrylamide Moiety
    • Authors: Shengping Zhang; Luis M. De Leon Rodriguez, Ivanhoe K. H. Leung, Gregory M. Cook, Paul W. R. Harris, Margaret A. Brimble
      Abstract: The first synthesis of the anti-TB cyclic peptide callyaerin A (1), containing a rare (Z)-2,3-diaminoacrylamide bridging motif, is reported. Fmoc-formylglycine-diethylacetal was used as a masked equivalent of formylglycine in the synthesis of the linear precursor to 1. Intramolecular cyclization between the formylglycine residue and the N-terminal amine in the linear peptide precursor afforded the macrocyclic natural product 1. Synthetic 1 possessed potent anti-TB activity (MIC100=32 μm) while its all-amide congener was inactive. Variable-temperature NMR studies of both the natural product and its all-amide analogue revealed the extraordinary rigidity imposed by this diaminoacrylamide unit on peptide conformation. The work reported herein pinpoints the intrinsic role that the (Z)-2,3-diaminoacrylamide moiety confers on peptide bioactivity.Starre Struktur: Callyaerin A, ein makrocyclisches Anti-Tuberkulose-Peptid mit seltener (Z)-2,3-Diaminoacrylamid-Einheit, wurde in hoher Ausbeute aus einem ungewöhnlichen Baustein – Fmoc-Formylglycindiethylacetal – synthetisiert. VT-NMR-Studien zufolge überträgt das (Z)-2,3-Diaminoacrylamid eine hohe konformative Rigidität auf die Peptidstruktur; es zeigt damit großes Potenzial als neuartiges Strukturelement zur konformativen Einschränkung.
      PubDate: 2018-02-14T05:20:33.770399-05:
      DOI: 10.1002/ange.201712792
  • A Reconfigurable DNA Accordion Rack
    • Authors: Yeongjae Choi; Hansol Choi, Amos C. Lee, Hyunung Lee, Sunghoon Kwon
      Abstract: DNA nanostructure-based mechanical systems that control the distance between elements of interest have demonstrated great potential for various applications, including nanoplasmonic systems, molecular reactors, and other nanotechnology platforms. However, previously reported systems could not collectively manipulate a 2D or 3D nanoscale network of elements to various forms in multiple stages. A reconfigurable DNA accordion rack structure is introduced that is a DNA beam lattice that changes its conformation with a small amount of short-length DNA locks as the controlling input. The lattice shape of the 2D DNA accordion rack and the diameter and the height of the 3D DNA nanotubular structure made of the DNA accordion rack could be controlled. Furthermore, by sequentially repeating the detachment and the attachment of the different DNA locks using strand displacement, the shape reconfiguration was repeatedly carried out.Ein feststellbares DNA-Scherengitter mit beweglichen Kreuzungspunkten ändert seine Konformation bei Zugabe kleiner Mengen an kurzen DNA-Knebelsequenzen. Die Gitterform sowie der Durchmesser und die Höhe von DNA-Nanoröhren, die aus den Gittern aufgebaut werden, ließen sich auf diese Weise vorgeben.
      PubDate: 2018-02-14T05:16:10.238397-05:
      DOI: 10.1002/ange.201709362
  • Light-Activated Control of Translation by Enzymatic Covalent mRNA Labeling
    • Authors: Dongyang Zhang; Cun Yu Zhou, Kayla N. Busby, Seth C. Alexander, Neal K. Devaraj
      Abstract: Activation of cellular protein expression upon visible-light photocleavage of small-molecule caging groups covalently attached to the 5′ untranslated region (5′ UTR) of an mRNA was achieved. These photocleavable caging groups are conjugated to in vitro transcribed mRNA (IVT-mRNA) through RNA transglycosylation, an enzymatic process in which a bacterial tRNA guanine transglycosylase (TGT) exchanges a guanine nucleobase in a specific 17-nucleotide motif (Tag) for synthetic pre-queuosine1 (preQ1) derivatives. The caging groups severely reduce mRNA translation efficiency when strategically placed in the 5′ UTR. Using this method, we demonstrate the successful spatiotemporal photoregulation of gene expression with single-cell precision. Our method can be applied to therapeutically relevant chemically modified mRNA (mod-mRNA) transcripts. This strategy provides a modular and efficient approach for developing synthetic gene regulatory circuits, biotechnological applications, and therapeutic discovery.Freie Fahrt für die Translation: Die Gentranslation kann durch Abspaltung hemmender Gruppen (rot) vom untranslatierten 5′-Ende von mRNA unter Bestrahlung mit sichtbarem Licht aktiviert werden. Die hemmenden Gruppen werden durch RNA-Transglykosylierung angebracht und reduzieren die mRNA-Translationseffizienz erheblich. Mit dieser Methode wird die räumliche und zeitliche Steuerung der Genexpression mithilfe von Licht auf der Ebene einzelner Zellen möglich.
      PubDate: 2018-02-14T05:15:32.586042-05:
      DOI: 10.1002/ange.201710917
  • Effect of Cation-π Interaction on the Macroionic Self-Assembly
    • Authors: JIANCHENG LUO; Kun Chen, Panchao Yin, Tao Li, Gang Wan, Jin Zhang, Songtao Ye, Xiaoman Bi, Yi Pang, Yongge Wei, Tianbo Liu
      Abstract: A series of rod-shaped polyoxometalates (POMs) were chosen to study the effects of cation-π interaction on the macroionic self-assembly. Diffusion Ordered Spectroscopy (DOSY) and Isothermal Titration Calorimetry (ITC) techniques show that the binding affinity between the POMs and Zn2+ ions is enhanced significantly after grafting aromatic groups onto the clusters, leading to the effective replacement of TBAs upon the addition of ZnCl₂. The incorporation of aromatic groups results in the significant contribution of cation-π interaction to the self-assembly, as confirmed by the opposite trend of assembly size vs. ionic strength when compared with those without aromatic groups. The small difference between two aromatic groups toward the Zn2+ ions is amplified after combining with the clusters, which consequently triggers the self-recognition behavior between these two highly similar macroanions.
      PubDate: 2018-02-13T22:35:32.136736-05:
      DOI: 10.1002/ange.201800409
  • Towards Sequence-Controlled Antimicrobial Polymers: Effect of Polymer
           Block Order on Antimicrobial Activity
    • Authors: Peter R Judzewitsch; Thuy-Khanh Nguyen, Sivaprakash Shanmugam, Edgar H. H. Wong, Cyrille Andre Jean Marie Boyer
      Abstract: The biological effects of sequence control in synthetic antimicrobial polymers are currently not well understood. As such, we investigate the antimicrobial effects of monomer distribution within linear high-order multiblock copolymers which were made in a one-pot synthesis approach via photoinduced electron transfer-reversible addition-fragmentation chain transfer polymerisation (PET-RAFT). Through different combinations of monomer/polymer block order, the antimicrobial and haemolytic activities are tuneable in a manner comparable to antimicrobial peptides. Specifically, the partitioning of cationic functional groups from amphiphilic domains results in bacterial genus specificity that has yet to be observed in antimicrobial polymers. This study indicates that the design of new antimicrobial polymers should focus on manipulating localised functional group composition for specific biological outcomes, rather than solely on global compositional manipulations.
      PubDate: 2018-02-13T22:06:29.744183-05:
      DOI: 10.1002/ange.201713036
  • Chemoselective Z-Olefin Synthesis via Rh-Catalyzed, Formate Mediated
    • Authors: Raphael Dada; Zhongyu Wei, Ruohua Gui, Rylan J. Lundgren
      Abstract: Z-olefins are important functional units in synthetic chemistry; thus their preparation has received considerable attention. Many prevailing methods for cis-olefination are complicated by the presence of multiple unsaturated units or electrophilic functional groups. In this study, Z-olefin products are delivered via selective reduction of activated dienes using formic acid. The reaction proceeds with high regio- and stereoselectivity (typically>90:10 and>95:5 respectively) and preserves other alkenyl, alkynyl, protic and electrophilic groups.
      PubDate: 2018-02-13T22:06:22.205336-05:
      DOI: 10.1002/ange.201800361
  • Heteroleptic Copper(I)-Based Complexes for Photocatalysis: Combinatorial
           Assembly, Discovery, and Optimization
    • Authors: Shawn Collins; Clémentine Minozzi, Antoine Caron, Jeffrey Santandrea, Jean-Christophe Grenier-Petel
      Abstract: A library of 50 copper-based complexes derived from bisphosphines and diamines was prepared and evaluated in three mechanistically distinct photocatalytic reactions. In all cases, a copper-based catalyst was identified to afford high yields, where new heteroleptic complexes derived from the bisphosphine BINAP displayed high efficiency across all reaction types. Importantly, the evaluation of the library of copper-complexes revealed that even when photophysical data is available, it is not always possible to predict which catalyst structure will be efficient or inefficient in a given process, emphasizing the advantages for catalyst structures with high modularity and structural variability.
      PubDate: 2018-02-13T09:05:56.305402-05:
      DOI: 10.1002/ange.201800144
  • Nucleophilic Activation of Sulfur Hexafluoride: Metal-free, Selective
           Degradation by Phosphines
    • Authors: Fabian Dielmann; Florenz Buß, Christian Mück-Lichtenfeld, Paul Mehlmann
      Abstract: The development of new methods for the chemical activation of the extremely inert greenhouse gas sulfur hexafluoride (SF6) not only is of current environmental interest, but also offers new opportunities for applications of SF6 as a reagent in organic synthesis. We herein report the first nucleophilic activation of SF6 by Lewis bases, namely by phosphines, which results either in its complete degradation to phosphine sulfides and difluorophosphoranes or in the selective conversion of SF6 into a bench-stable, crystalline salt containing the SF5− anion. Quantum chemical calculations reveal a nucleophilic substitution mechanism (SN2) for the initial fluorine abstraction from SF6 by the phosphine. Furthermore, a scalable one-pot procedure for the complete decomposition of SF6 into solid, nonvolatile products is presented based on cheap and commercially available starting materials.
      PubDate: 2018-02-13T09:05:44.14283-05:0
      DOI: 10.1002/ange.201713206
  • Hybrid Indicators for Fast and Sensitive Voltage Imaging
    • Authors: Yongxian Xu; Luxin Peng, Sicong Wang, Anqi Wang, Ruirui Ma, Ying Zhou, Jiahe Yang, De-en Sun, Wei Lin, Xing Chen, Peng Zou
      Abstract: Membrane voltage is an important biophysical signal that underlies intercellular electrical communications. In this study, we present a novel fluorescent voltage indicator that enables the investigation of electrical signaling at high spatial resolution. Our method is built upon the site-specific modification of microbial rhodopsin proteins with organic fluorophores, resulting in a hybrid indicator scaffold that represents one of the most sensitive and fastest orange-colored voltage indicators developed to date. We applied this technique to optically map electrical connectivity in cultured cells, which revealed gap junction-mediated long-range coupling that spanned over hundreds of micrometers.
      PubDate: 2018-02-13T08:36:10.418974-05:
      DOI: 10.1002/ange.201712614
  • Dynamic Kinetic Resolution of Heterobiaryl Ketones via Zn-catalyzed
           Asymmetric Hydrosilylation
    • Authors: José M. Lassaletta; Valentín Hornillos, Jose Alberto Carmona, Abel Ros, Javier Iglesias-Sigüenza, Rosario Fernández, Joaquín López-Serrano
      Abstract: A diastereo and highly enantioselective dynamic kinetic resolution (DKR) of configurationally labile heterobiaryl ketones is described. The DKR proceeds by zinc-catalyzed hydrosilylation of the carbonyl group, leading to secondary alcohols bearing axial and central chirality. The strategy relies on the labilization of the stereogenic axis that takes place thanks to a Lewis acid-base interaction between a nitrogen atom in the heterocycle and the ketone carbonyl. The synthetic utility of the methodology is demonstrated through racemization-free, stereospecific transformations into N,N-ligands or appealing axially chiral, bifunctional thiourea organocatalysts.
      PubDate: 2018-02-13T08:35:52.513562-05:
      DOI: 10.1002/ange.201713200
  • Catalytic Enantioselective Aza-Benzoin Reactions of Aldehydes with
    • Authors: Jian Wang; qiupeng peng, Donghui Guo, Jianbo Bie
      Abstract: The unprecedented enantioselective aza-benzoin reaction of aldehydes with 2H-azirines has been developed. In the presence of a L-phenylalanine-derived N-heterocyclic carbene catalyst, reactions promoted smoothly and yielded corresponding products in good yield with high enantioselectivity. The obtained optically active aziridines as useful synthons could further transfer to other valuable molecules.
      PubDate: 2018-02-13T07:05:45.921621-05:
      DOI: 10.1002/ange.201712785
  • Reversible Hydrogen Activation by a Pyridonate Borane Complex: Combining
           Frustrated Lewis Pair Reactivity with Boron-Ligand Cooperation
    • Authors: Urs Gellrich
      Abstract: A pyridone borane complex that liberates dihydrogen under mild conditions is described. The reverse reaction, dihydrogen activation by the formed pyridonate borane complex, is achieved under moderate H2 pressure (2 bar) at room temperature. DFT and DLPNO CCSD(T) computations reveal that the active form of the pyridonate borane complex is a boroxypyridine that can be described as single component Frustrated Lewis Pair (FLP). Significantly, the boroxypyridine undergoes a chemical transformation to a neutral pyridone donor ligand in the course of the hydrogen activation. This unprecedented mode of action may thus, in analogy to metal-ligand cooperation, be regarded as an example of boron-ligand cooperation.
      PubDate: 2018-02-13T06:35:43.749984-05:
      DOI: 10.1002/ange.201713119
  • A Manganese Nanosheet: New Cluster Topology and Catalysis
    • Authors: Axel Jacobi von Wangelin; Uttam Chakraborty, Efrain Reyes-Rodriguez, Serhiy Demeshko, Franc Meyer
      Abstract: While the coordination chemistry of monometallic complexes and the surface characteristics of larger metal particles are well understood, preparations of molecular metallic nanoclusters remain a great challenge. Discrete planar metal clusters constitute nanoscale snapshots of cluster growth but are especially rare due to the strong preference for three-dimensional structures and rapid aggregation or decomposition. A simple ligand exchange protocol has led to the formation of a novel heteroleptic Mn6 nanocluster that crystallized in an unprecedented flat chair topology and exhibited unique magnetic and catalytic properties. Magnetic susceptibility studies documented strong electronic communication between the Mn ions. Reductive activation of the molecular Mn6 cluster enabled catalytic hydrogenations of alkenes, alkynes, and imines.
      PubDate: 2018-02-13T06:05:47.975941-05:
      DOI: 10.1002/ange.201800079
  • Solid-Solution Alloy Nanoparticles of the Immiscible Ir-Cu System with a
           Wide Composition Range for Enhanced Electrocatalytic Applications
    • Authors: Fenglong Wang; Kohei Kusada, Dongshuang Wu, Tomokazu Yamamoto, Takaaki Toriyama, Syo Matsumura, Yusuke Nanba, Michihisa Koyama, Hiroshi Kitagawa
      Abstract: For the first time, we have synthesized solid-solution alloy nanoparticles between Ir and Cu with a size of ~2 nm, despite Ir and Cu being immiscible in the bulk up to their melting over the whole composition range. We performed a systematic characterization on the nature of the IrxCu1-x solid-solution alloys using powder X-ray diffraction, scanning transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. The results showed that the obtained IrxCu1-x alloys had a face-centered-cubic structure; charge transfer from Cu to Ir occurred in the alloy nanoparticles, as the core-level Ir 4f peaks shifted to lower energy region with the increase in Cu content. The electron transfer from Cu to Ir observed in the alloy nanoparticles matched the theoretical results well. Furthermore, we observed that the alloying of Ir with Cu enhanced both the electrocatalytic oxygen evolution and oxygen reduction reactions. The enhanced activities could be attributed to the electronic interaction between Ir and Cu arising from the alloying effect at atomic-level.
      PubDate: 2018-02-13T03:30:38.340371-05:
      DOI: 10.1002/ange.201800650
  • Glycosyl-Substituted Dicarboxylates as Detergents for the Extraction,
           Overstabilization, and Crystallization of Membrane Proteins
    • Authors: Kim-Anh Nguyen; Marine Peuchmaur, Sandrine Magnard, Romain Haudecoeur, Cédric Boyère, Saravanan Mounien, Ikram Benammar, Veronica Zampieri, Sébastien Igonet, Vincent Chaptal, Anass Jawhari, Ahcène Boumendjel, Pierre Falson
      Abstract: To tackle the problems associated with membrane protein (MP) instability in detergent solutions, we designed a series of glycosyl-substituted dicarboxylate detergents (DCODs) in which we optimized the polar head to clamp the membrane domain by including, on one side, two carboxyl groups that form salt bridges with basic residues abundant at the membrane–cytoplasm interface of MPs and, on the other side, a sugar to form hydrogen bonds. Upon extraction, the DCODs 8 b, 8 c, and 9 b preserved the ATPase function of BmrA, an ATP-binding cassette pump, much more efficiently than reference or recently designed detergents. The DCODs 8 a, 8 b, 8 f, 9 a, and 9 b induced thermal shifts of 20 to 29 °C for BmrA and of 13 to 21 °C for the native version of the G-protein-coupled adenosine receptor A2AR. Compounds 8 f and 8 g improved the diffraction resolution of BmrA crystals from 6 to 4 Å. DCODs are therefore considered to be promising and powerful tools for the structural biology of MPs.Tenside, die für das Extrahieren von Membranproteinen (MPs) in wässrige Lösung verwendet werden, destabilisieren diese oftmals. Neue Derivate auf der Basis von Glykosyl-substituierten Dicarboxylaten umklammern die Membrandomäne und bilden Salzbrücken zu basischen Resten in den MPs. Sie erhalten die ATPase-Funktion von BmrA nach dem Extrahieren und verbessern die Stabilität und Kristallisation.
      PubDate: 2018-02-13T02:35:50.881707-05:
      DOI: 10.1002/ange.201713395
  • Catalyst-Enabled Site-divergent Stereoselective Michael Reactions:
           Overriding Intrinsic Reactivity of Enynyl Carbonyl Acceptors
    • Authors: Daisuke Uraguchi; Ryo Shibazaki, Naoya Tanaka, Kohei Yamada, Ken Yoshioka, Takashi Ooi
      Abstract: A site-divergent stereoselective Michael reaction system is developed based on the identification of two distinct catalysts. Cinchonidine-derived thiourea catalyzes the 1,4-addition of prochiral azlactone enolates to enynyl N-acyl pyrazoles in a highly diastereo- and enantioselective manner to give stereochemically defined alkynes, while P-spiro chiral triaminoiminophosphorane catalytically controls the stereoselective 1,6-addition and the consecutive γ-protonation of the vinylogous enolate intermediate to afford Z,E-configured conjugated dienes. This 1,6-adduct serves as a valuable precursor for the synthesis of a 2-amino-2-deoxy sugar.
      PubDate: 2018-02-13T01:31:11.757338-05:
      DOI: 10.1002/ange.201800057
  • Thermally Rearranged Polymer Membranes Containing Tröger's Base Units
           with Exceptional Performance for Air Separations
    • Authors: Stephen M. Meckler; Jonathan E. Bachman, Benjamin P. Robertson, Chenhui Zhu, Jeffrey R. Long, Brett A. Helms
      Abstract: The influence of backbone rigidity on the gas separation performance of thermally rearranged (TR) polymer membranes is established for TR polybenzoxazoles featuring Tröger's base (TB) monomer subunits as exceptionally rigid sites of contortion along the polymer backbone. These TR polymers are accessed from solution-processable ortho-acetate functionalized polyimides, which are readily synthesized with sufficiently high molecular weight for membrane casting. We find that thermal rearrangement leads to a small increase in d-spacing between polymer chains, and a dramatic pore-network reconfiguration that increases both membrane permeability and selectivity for air separations, putting its performance above the 2015 upper bound.
      PubDate: 2018-02-12T22:06:22.769193-05:
      DOI: 10.1002/ange.201800556
  • Mitigation of Inflammatory Immune Responses with Hydrophilic Nanoparticles
    • Authors: Bowen Li; Shaoyi Jiang, Jingyi Xie, Zhefan Yuan, Priyesh Jain, Xiaojie Lin, Kan Wu
      Abstract: While hydrophobic nanoparticles (NPs) have been long recognized to boost the immune activation, whether hydrophilic NPs modulate an immune system challenged by immune stimulators and how their hydrophilic properties may affect the immune response is still unclear. To answer this question, three polymers, poly(ethylene glycol)(PEG), poly(sulfobetaine)(PSB) and poly(carboxybetaine)(PCB) are studied. For fair comparison, nanogels with uniform size and pure surface functionalities were made from these polymers. Peripheral blood mononuclear cells stimulated by lipopolysaccharide (LPS), and LPS-induced lung inflammation murine model were used to investigate the influence of nanogels on the immune system. Results show that hydrophilic NPs attenuated the immune responses both in vitro and in vivo. Moreover, PCB NPs with the strongest hydration and the lowest non-specific protein binding manifested the best performance in alleviating the immune activation, followed by PSB and PEG NPs.
      PubDate: 2018-02-12T22:06:12.626441-05:
      DOI: 10.1002/ange.201710068
  • Direct Cyclization of Tertiary Arylamines with Iodonium Ylides
    • Authors: Zhiguo Zhao; Yongrui Luo, Shuya Liu, Liang Zhang, Lei Feng, Yao Wang
      Abstract: Described herein is a direct cyclization of simple tertiary arylamines with iodonium ylides leading to a broad range of N-heterocycles. Completely different from known reactivity of iodonium ylides, an exceptional finding reported herein is that iodonium ylide is capable of cleaving a C(sp3)-H bond and accepting two hydrogen atoms of tertiary arylamine, thus inducing a novel cyclization process. This transformation can proceed without assistance of a transition metal catalyst while eliminating the need for premodification of amines or using additional initiator/oxidant.
      PubDate: 2018-02-12T22:05:54.189755-05:
      DOI: 10.1002/ange.201800389
  • Highly Stable Aqueous Zinc-ion Storage Using Layered Calcium Vanadium
           Oxide Bronze Cathode
    • Authors: Chuan Xia; Jing Guo, Peng Li, Xixiang Zhang, Husam N. Alshareef
      Abstract: Cost-effective aqueous rechargeable batteries are attractive alternatives to non-aqueous cells for stationary grid energy storage. Among different aqueous cells, zinc-ion batteries (ZIBs), based on Zn2+ intercalation chemistry, stand out as they can employ high-capacity Zn metal as anode material. Herein, we report a layered calcium vanadium oxide bronze as cathode material for aqueous Zn batteries. For the storage of Zn2+ ions in aqueous electrolyte, we demonstrate that calcium based bronze structure can deliver a high capacity of 340 mAh g-1 at 0.2 C, good rate capability and very long cycling life (96% retention after 3000 cycles at 80 C). Further, we investigate the Zn2+ storage mechanism, and the corresponding electrochemical kinetics in this bronze cathode. Finally, we show that our Zn cell delivers an energy density of 267 Wh kg-1 at a power density of 53.4 W kg-1.
      PubDate: 2018-02-12T14:00:29.362486-05:
      DOI: 10.1002/ange.201713291
  • Barium as honorary transition metal in action: Experimental and
           theoretical study of [Ba(CO)]+ and [Ba(CO)]−
    • Authors: Gernot Frenking; Lili Zhao, Israel Fernandez, Robert Berger, Mingfei Zhou, Dandan Jiang
      Abstract: BaCO+ and BaCO− were and isolated in a low-temperature neon matrix. The observed C-O stretching wavenumber for BaCO+ of 1911.2 cm−1 is the most red-shifted value measured for any metal carbonyl cations, indicating strong π backdonation of electron density from Ba+ to CO. Quantum chemical calculations indicate that BaCO+ has a 2 ground state, which correlates with the 2D(5d1) excited state of Ba+ that comprises significant Ba+(5dπ1)CO(* LUMO) backbonding, letting the BaCO+ complex behave like a conventional transition-metal carbonyl. A bonding analysis shows that the  backdonation in BaCO+ is much stronger than the Ba+(5dσ/6s)CO(HOMO)  donation interaction. The Ba+ cation in the 2D(5d1) excited state is a donor rather than an acceptor. Covalent bonding in the radical anion Ba(CO)− takes place mainly through Ba(5dπ)CO-(π* SOMO) π donation and Ba(5dσ/6s)CO-(HOMO) σ donation. The most important valence functions at barium in BaCO+ cation and BaCO− anion are the 5d orbitals.
      PubDate: 2018-02-12T11:00:24.158132-05:
      DOI: 10.1002/ange.201713002
  • Ion-selective electrodes based on hydrophilic ionophore-modified nanopores
    • Authors: Soma Papp; Gyula Jágerszki, Róbert Ervin Gyurcsanyi
      Abstract: We report the synthesis and analytical application of the first Cu(II)-selective synthetic ion channel based on peptide-modified gold nanopores. A Cu(II) binding peptide motif (Gly-Gly-His) along with two additional functional thiol derivatives inferring cation-permselectivity and hydrophobicity was self-assembled on the surface of gold nanoporous membranes comprising of ca. 5 nm diameter pores. These membranes were used to construct Cu(II) ion-selective electrodes (ISEs) with extraordinary Cu(II) selectivities, approaching 6 orders of magnitude over certain ions. Since all constituents are immobilized to a supporting nanoporous membrane, their leaching, that is a ubiquitous problem of conventional ionophore-based ISEs was effectively suppressed.
      PubDate: 2018-02-12T10:06:02.919-05:00
      DOI: 10.1002/ange.201800954
  • Sample Ripening through Nanophase Separation Impacts the Performance of
           Dynamic Nuclear Polarization
    • Authors: Emmanuelle Weber; Giuseppe Sicoli, Hervé Vezin, Ghislaine Frébourg, Daniel Abergel, Geoffrey Bodenhausen, Dennis Kurzbach
      Abstract: Mixtures of water and glycerol provide popular matrices for low-temperature spectroscopy of vitrified samples. However, they involve counterintuitive physicochemical properties, such as spontaneous nanoscopic phase separations (NPS) in solutions that appear macroscopically homogeneous. We demonstrate that such phenomena can substantially impact the efficiency of dynamic nuclear polarization (DNP) by factors up to 20% by causing fluctuations in local concentrations of polarization agents (radicals). Thus, a spontaneous NPS of water/glycerol mixtures that takes place on time scales on the order of 30-60 min results in a confinement of polarization agents in nanoscopic water-rich vesicles, which in return affects the DNP. Such effects were found for three common polarization agents, TEMPOL, AMUPol and Trityl.
      PubDate: 2018-02-12T10:05:51.299259-05:
      DOI: 10.1002/ange.201800493
  • Counterion-Induced Asymmetric Control on Azetidiniums: A Facile Access to
           Chiral Amines
    • Authors: Deyun Qian; Min Chen, Alex C. Bissember, Jianwei Sun
      Abstract: Counterion-induced stereocontrol is a powerful tool in organic synthesis. However, such enantiocontrol on tetrahedral ammonium cations remains challenging. Herein we demonstrate the first example of using chiral anion phase-transfer catalysis to achieve intermolecular ring-opening of azetidiniums with excellent enantioselectivity (up to 97% ee). Precise control over the formation and reaction of the chiral ion pair as well as inhibition of the background reaction by the biphasic system is key to success.
      PubDate: 2018-02-12T10:05:38.41216-05:0
      DOI: 10.1002/ange.201712395
  • Does Charge Matter' Formation of Highly Reactive Cobalt Nanocluster
           Crystal within Highly Negative Porous Coordination Cage
    • Authors: Yu Fang; Zhifeng Xiao, Jialuo Li, Christina Lollar, Lujia Liu, Xizhen Lian, Shuai Yuan, Sayan Banerjee, Peng Zhang, Hongcai Zhou
      Abstract: Earth abundant first-row transition-metal nanoclusters (NCs) have been extensively investigated as catalysts. However, their catalytic activity is relatively low compared with noble metal NCs. In this work we show that enhanced catalytic activity of cobalt NCs can be achieved by encapsulating Co NCs in soluble porous coordination cages. Two cages, PCC-2a and 2b, possess almost identical cavity in shape and size, while PCC-2a has five times more net charges than PCC-2b. Co2+ cations were accumulated in PCC-2a and reduced to Co NCs in situ, while for PCC-2b, only bulky Co particles were formed. As a result, Co NCs@PCC-2a accomplished the highest catalytic activity in the hydrolysis of ammonium borane among all the first-row transition-metals NPs. Based on these results we envision that confining in the charged porous coordination cage can be a novel route for the synthesis of ultrasmall NCs with extraordinary properties.
      PubDate: 2018-02-12T09:00:43.054411-05:
      DOI: 10.1002/ange.201712372
  • Rhodium(I)-Catalyzed Carboacylation/Aromatization Cascade Initiated by
           Regioselective C−C Activation of Benzocyclobutenones
    • Authors: Tianwen Sun; Yuna Zhang, Bo Qiu, Yafei Wang, Yuting Qin, Guangbin Dong, Tao Xu
      Abstract: Described here is the first example of a rhodium-catalyzed carboacylation/aromatization cascade of a C=O bond by C−C activation. In this transformation, a reactive rhodaindanone complex is regioselectively generated and adds across a C=O bond with subsequent elimination, thus providing a unique strategy to access a multisubstituted benzofuran scaffold. A diverse range of benzofuran analogues were obtained in good yields. Mechanistic studies show a tricyclic lactone was a viable intermediate. Application of this methodology to the total synthesis of C13-deOH-viniferifuran and C13-deOH-diptoindonesin G was achieved.Ein reaktiver Rhodaindanon-Komplex wird bei der Titelreaktion regioselektiv erzeugt. Addition an eine C=O-Bindung mit anschließender Eliminierung führt in guten Ausbeuten zu mehrfach substituierten Benzofuranen. Die Methode wurde in Totalsynthesen von C13-deOH-Viniferifuran und C13-deOH-Diptoindonesin G eingesetzt.
      PubDate: 2018-02-12T07:21:03.083799-05:
      DOI: 10.1002/ange.201713179
  • Preise der Académie des Sciences 2017/Horst-Dietrich-Hardt-Preis für
           Lutz H. Gade/Yamada-Koga-Preis für Jan-E. Bäckvall/
    • PubDate: 2018-02-12T07:15:56.976792-05:
      DOI: 10.1002/ange.201801303
  • Four-fold Channel-Nicked Human Ferritin Nanocages for Active Drug Loading
           and pH-Responsive Drug Release
    • Authors: Byungjun Ahn; Seong-Gyu Lee, Hye Ryeon Yoon, Jeong Min Lee, Hyeok Jin Oh, Ho Min Kim, Yongwon Jung
      Abstract: Human ferritins are emerging platforms for non-toxic protein-based drug delivery, owing to their intrinsic or acquirable targeting abilities to cancer cells and hollow cage structures for drug loading. However, reliable strategies for high-level drug encapsulation within ferritin cavities and prompt cellular drug release are still lacking. Ferritin nanocages were developed with partially opened hydrophobic channels, which provide stable routes for spontaneous and highly accumulated loading of FeII-conjugated drugs as well as pH-responsive rapid drug release at endoplasmic pH. Multiple cancer-related compounds, such as doxorubicin, curcumin, and quercetin, were actively and heavily loaded onto the prepared nicked ferritin. Drugs on these minimally modified ferritins were effectively delivered inside cancer cells with high toxicity.Spontan und hochkonzentriert können diverse Wirkstoffe durch einen Ferritin-Nanokäfig aufgenommen werden, wenn die hydrophoben Kanäle von Ferritin etwas geöffnet werden. Wirkstoff-FeII-Komplexe wurden in diesem modifizierten Ferritin akkumuliert, in Zellen transportiert und dort durch einen pH-responsiven Prozess freigesetzt.
      PubDate: 2018-02-12T07:15:33.75461-05:0
      DOI: 10.1002/ange.201800516
  • Ralf I. Kaiser
    • PubDate: 2018-02-12T07:15:21.120421-05:
      DOI: 10.1002/ange.201800440
  • Single-Molecule Determination of the Isomers of d-Glucose and d-Fructose
           that Bind to Boronic Acids
    • Authors: William J. Ramsay; Hagan Bayley
      Abstract: Monosaccharides, such as d-glucose and d-fructose, exist in aqueous solution as an equilibrium mixture of cyclic isomers and can be detected with boronic acids by the reversible formation of boronate esters. The engineering of accurate, discriminating and continuous monitoring devices relies on knowledge of which cyclic isomer of a sugar binds to a boronic acid receptor. Herein, by monitoring fluctuations in ionic current, we show that an engineered α-hemolysin (αHL) nanopore modified with a boronic acid reacts reversibly with d-glucose as the pyranose isomer (α-d-glucopyranose) and d-fructose as either the furanose (β-d-fructofuranose) or the pyranose (β-d-fructopyranose). Both of these binding modes contradict current binding models. With this knowledge, we distinguished the individual sugars in a mixture of d-maltose, d-glucose, and d-fructose.Süß und sauer: Die reversible kovalente Verknüpfung von Boronsäuren mit Diolen lässt sich im Inneren eines Protein-Nanoreaktors verfolgen. Der Ansatz kann diejenigen cyclischen Isomere von d-Glucose und d-Fructose identifizieren, die in wässriger Lösung an eine Boronsäure binden. Beide Bindungsmodi sind in gängigen Bindungsmodellen nicht vorgesehen.
      PubDate: 2018-02-12T07:10:51.249819-05:
      DOI: 10.1002/ange.201712740
  • Stimuli-Responsive Dual-Color Photon Upconversion: A Singlet-to-Triplet
           Absorption Sensitizer in a Soft Luminescent Cyclophane
    • Authors: Kazuma Mase; Yoichi Sasaki, Yoshimitsu Sagara, Nobuyuki Tamaoki, Christoph Weder, Nobuhiro Yanai, Nobuo Kimizuka
      Abstract: Reversible emission color switching of triplet–triplet annihilation-based photon upconversion (TTA-UC) is achieved by employing an Os complex sensitizer with singlet-to-triplet (S-T) absorption and an asymmetric luminescent cyclophane with switchable emission characteristics. The cyclophane contains the 9,10-bis(phenylethynyl)anthracene unit as an emitter and can assemble into two different structures, a stable crystalline phase and a metastable supercooled nematic phase. The two structures exhibit green and yellow fluorescence, respectively, and can be accessed by distinct heating/cooling sequences. The hybridization of the cyclophane with the Os complex allows near-infrared-to-visible TTA-UC. The large anti-Stokes shift is possible by the direct S-T excitation, which dispenses with the use of a conventional sequence of singlet–singlet absorption and intersystem crossing. The TTA-UC emission color is successfully switched between green and yellow by thermal stimulation.Gelb oder Grün' Bei einer Photonenaufwärtskonversion auf Basis von Triplett-Triplett-Annihilierung (TTA-UC) kann die Farbe reversibel geschaltet werden. Dazu wird ein unsymmetrisches Cyclophan, das infolge einer Strukturpolymorphie verschiedenfarbig fluoreszieren kann, mit einem Singulett-Triplett(S-T)-Absorptionssensibilisator für den Nah-IR-Bereich kombiniert, der Energieverluste bei der Besetzung des Triplettzustands minimiert.
      PubDate: 2018-02-12T07:10:44.33382-05:0
      DOI: 10.1002/ange.201712644
  • (Radio)fluoroclick Reaction Enabled by a Hydrogen-Bonding Cluster
    • Authors: Xiaojun Zeng; Junling Li, Chin K. Ng, Gerald B. Hammond, Bo Xu
      Abstract: We have developed a widely applicable nucleophilic (radio)fluoroclick reaction of ynamides with readily available and easy-to-handle KF(18F). The reactions exhibited high functional-group tolerance and needed only an ambient atmosphere. This 18F addition to C−C unsaturated bonds proceeded with extraordinarily high radiochemical yields.Bereit und in der Lage: α-Fluorenamide werden in einer nukleophilen Fluorierung von Inamiden mit leicht verfügbarem KF(18F) in Hexafluor-2-propanol (HFIP), das als Protonenquelle fungiert, gebildet (siehe Schema). Die Reaktionen sind gut verträglich mit funktionellen Gruppen und lassen sich an der Luft ausführen. Die Methode ermöglicht die Addition von 18F an ungesättigte C-C-Bindungen mit hoher radiochemischer Ausbeute (RCY).
      PubDate: 2018-02-12T07:10:31.263423-05:
      DOI: 10.1002/ange.201711341
  • DNA Origami Directed Assembly of Gold Bowtie Nanoantennas for
           Single-Molecule Surface-Enhanced Raman Scattering
    • Authors: Pengfei Zhan; Te Wen, Zhen-gang Wang, Yingbo He, Jia Shi, Ting Wang, Xinfeng Liu, Guowei Lu, Baoquan Ding
      Abstract: Metallic bowtie nanoarchitectures can produce dramatic electric field enhancement, which is advantageous in single-molecule analysis and optical information processing. Plasmonic bowtie nanostructures were successfully constructed using a DNA origami-based bottom-up assembly strategy, which enables precise control over the geometrical configuration of the bowtie with an approximate 5 nm gap. A single Raman probe was accurately positioned at the gap of the bowtie. Single-molecule surface-enhanced Raman scattering (SM-SERS) of individual nanostructures, including ones containing an alkyne group, was observed. The design achieved repeatable local field enhancement of several orders of magnitude. This method opens the door on a novel strategy for the fabrication of metal bowtie structures and SM-SERS, which can be utilized in the design of highly-sensitive photonic devices.Plasmonische Nanostrukturen in Doppeldreieck-Form wurden selbstorganisiert nach einem DNA-Origami-Ansatz aufgebaut. Eine einzelne Raman-Sonde wurde genau an dem Berührungspunkt der beiden Dreiecke positioniert, und Einzelmolekül-SERS der Nanostrukturen wurde beobachtet.
      PubDate: 2018-02-12T07:05:40.472338-05:
      DOI: 10.1002/ange.201712749
  • From Aniline to Aryl Ether: A Facile, Efficient and Versatile Synthetic
           Protocol Employing Mild Conditions
    • Authors: Dong-Yu Wang; Ze-Kun Yang, Chao Wang, Ao Zhang, Masanobu Uchiyama
      Abstract: We have developed a simple and direct protocol for synthesis of aryl ethers by reaction of alcohols/phenols (ROH) with aryl ammonium salts (ArNMe3+), which are readily prepared from anilines (ArNR´2, R' = H or Me). This reaction proceeds smoothly and rapidly (within a few hours) at room temperature in the presence of a commercially available base, such as KOtBu or KHMDS, and has a broad substrate scope for both ROH and ArNR´2. It is scalable, and compatible with a wide range of functional groups. We show that various functional molecules, including natural products, pharmaceuticals, dyes, etc., can be directly transformed to ethereal derivatives in high yield with excellent chemo-selectivity.
      PubDate: 2018-02-12T07:00:44.879814-05:
      DOI: 10.1002/ange.201712618
  • Amipurimycin: Total Synthesis of the Proposed Structures and
    • Authors: Shengyang Wang; Jiansong Sun, Qingju Zhang, Xin Cao, Yachen Zhao, Gongli Tang, Biao Yu
      Abstract: The proposed diastereoisomers (1 a–d) together with their C8′-epimers (1 e–h) of amipurimycin, a unique antifungal peptidyl nucleoside antibiotic, have been synthesized for the first time. The synthetic approach is efficient and stereodivergent, and features a stereoselective aldol condensation to build the branched C9 sugar amino acid skeleton and a regio- and stereocontrolled gold(I)-catalyzed N-glycosylation to furnish the purine nucleoside. Analysis of the NMR data suggests that the previously assigned configuration of the tertiary C3′ in amipurimycin should be of opposite configuration.Umkonfiguriert: Die vorgeschlagenen Diastereomere und die entsprechenden C8′-Epimere des Peptidylnukleosid-Antibiotikums Amipurimycin wurden synthetisiert. Eine Analyse der NMR-Daten deutet darauf hin, dass das tertiäre C3′ in Amipurimycin die entgegengesetzte Konfiguration haben sollte als früher postuliert.
      PubDate: 2018-02-12T03:12:00.780082-05:
      DOI: 10.1002/ange.201800169
  • Die enantioselektive Totalsynthese von Bischinolizidin-Alkaloiden: Ein
           modularer “Inside-Out”-Zugang
    • Authors: Dagmar Scharnagel; Jessica Goller, Nicklas Deibl, Wolfgang Milius, Matthias Breuning
      Abstract: Charakteristisch für Bischinolizidin-Alkaloide ist ein chirales Bispidin-Kerngerüst (3,7-Diazabicylo[3.3.1]nonan), an das Kombinationen aus einem α,N-anellierten 2-Pyridon, endo- oder exo-α,N-anellierten Piperidin(on)en und einem exo-Allylsubstituenten angebracht sind. Wir entwickelten eine modulare “Inside-Out”-Strategie, die einen Zugang zu den meisten Vertretern dieser Naturstoffklasse erlaubt. Ihr Anwendungspotential wurde anhand der asymmetrischen Synthese von 21 Bischinolizidin-Naturstoffen demonstriert, darunter mehr als zehn enantioselektive Erstsynthesen. Schlüsselschritte sind die erste erfolgreiche Herstellung beider Enantiomere von C2-symmetrischem 2,6-Dioxobispidin durch Desymmetrisierung einer 2,4,6,8-Tetraoxo-Vorstufe, der Aufbau des α,N-anellierten 2-Pyridons über eine Enamin-Bromacrylsäure-Strategie und die Einführung von endo- oder, wahlweise, exo-anellierten Piperidin(on)en.Alle auf einen Streich: Ein diversitätsorientierter, modularer „Inside-Out”-Zugang zu Bischinolizidin-Naturstoffen wurde entwickelt und seine Flexibilität anhand der enantioselektiven Totalsynthese von 21 Alkaloiden demonstriert. Schlüsselschritte sind eine Desymmetrisierung, die Zugang zu beiden Enantiomeren eines C2-symmetrischen 2,6-Dioxobispidins erlaubt, und die Anellierung eines 2-Pyridons und von endo- oder exo-Piperidin(on)en an diesen chiralen Kernbaustein.
      PubDate: 2018-02-12T03:11:32.743185-05:
      DOI: 10.1002/ange.201712852
  • Konfigurationsisomerie in Polyoxovanadaten
    • Authors: Lisa K. Mahnke; Aleksandar Kondinski, Ulrike Warzok, Christian Näther, Jan van Leusen, Christoph A. Schalley, Kirill Yu. Monakhov, Paul Kögerler, Wolfgang Bensch
      Abstract: Ein wasserlöslicher Abkömmling des Polyoxovanadat-Archetyps {V15E6O42} (E=Halbmetall) ermöglicht die Untersuchung supramolekular induzierter Clusterschalen-Umwandlungen. Eine für E=Sb spezifische Reaktion, die durch einen Ligandenaustausch in [Ni(ethylendiamin)3]2+-Gegenionen eingeleitet wird, resultiert in der Bildung des metastabilen α1*-Konfigurationsisomers des {V14Sb8O42}-Clustertyps. Im Unterschied zu allen bisher bekannten Polyoxovanadat-Schalenarchitekturen weist dieses Isomer eine nach innen ausgerichtete Vanadylgruppe auf und ist ca. 50 bzw. 12 kJ mol−1 energiereicher als die zuvor isolierten α- und β-Isomere. Diese unerwartete Reaktion wird im Hinblick auf supramolekulare Sb-O⋅⋅⋅V- und Sb-O⋅⋅⋅Sb-Bindungen diskutiert, die sich in {V14Sb8O42}2-Dimeren im Festkörper manifestieren. ESI-MS-Experimente untermauern die Stabilität dieser Dimere auch in Lösung und in der Gasphase. DFT-Rechnungen zufolge sollten so auch weitere, bislang noch nicht gefundene {V14Sb8}-Isomere zugänglich sein.Supramolekulare Wechselwirkungen innerhalb von und zwischen Clustern begünstigen die energetisch aufwändige Bildung eines Konfigurationsisomers (α1*) aus der {V14Sb8}-Familie der Antimonatopolyoxovanadate.
      PubDate: 2018-02-12T03:11:09.983083-05:
      DOI: 10.1002/ange.201712417
  • Tuning the High-Temperature Wetting Behavior of Metals toward Ultrafine
    • Authors: Yubing Zhou; Bharath Natarajan, Yanchen Fan, Hua Xie, Chunpeng Yang, Shaomao Xu, Yonggang Yao, Feng Jiang, Qianfan Zhang, Jeffrey W. Gilman, Liangbing Hu
      Abstract: The interaction between metal nanoparticles (NPs) and their substrate plays a critical role in determining the particle morphology, distribution, and properties. The pronounced impact of a thin oxide coating on the dispersion of metal NPs on a carbon substrate is presented. Al2O3-supported Pt NPs are compared to the direct synthesis of Pt NPs on bare carbon surfaces. Pt NPs with an average size of about 2 nm and a size distribution ranging between 0.5 nm and 4.0 nm are synthesized on the Al2O3 coated carbon nanofiber, a significant improvement compared to those directly synthesized on a bare carbon surface. First-principles modeling verifies the stronger adsorption of Pt clusters on Al2O3 than on carbon, which attributes the formation of ultrafine Pt NPs. This strategy paves the way towards the rational design of NPs with enhanced dispersion and controlled particle size, which are promising in energy storage and electrocatalysis.Eine dünne Oxidschicht hat starke Auswirkungen auf die Dispersion metallischer Nanopartikel (NPs) auf einem Kohlenstoffsubstrat. Direkt auf Kohlenstoffoberflächen synthetisierte Pt-NPs wurden mit Pt-NPs auf einer Al2O3-beschichteten Kohlenstoffnanofaser verglichen. Letztere wiesen eine durchschnittliche Größe von 2 nm und eine Größenverteilung von 0.5 bis 4.0 nm auf – ein deutlicher Vorteil gegenüber den direkt auf Kohlenstoff synthetisierten Pt-NPs.
      PubDate: 2018-02-09T05:35:36.566474-05:
      DOI: 10.1002/ange.201712202
  • Katalytische, positions- und enantioselektive C-H-Oxygenierung durch einen
           chiralen Mangan-Porphyrin-Komplex mit einer entfernten Bindungsstelle
    • Authors: Finn Burg; Maxime Gicquel, Stefan Breitenlechner, Alexander Pöthig, Thorsten Bach
      Abstract: Ein chiraler Mangan-Porphyrin-Komplex mit einem Wasserstoffbrückenmotiv wurde synthetisiert und anschließend in der katalytischen C-H-Oxygenierung von 3,4-Dihydrochinolonen erprobt. Die gewünschte Oxygenierung fand mit perfekter Positionsselektivität an der C4-Methylengruppe und mit hoher Enantioselektivität zugunsten des entsprechenden (4S)-konfigurierten sekundären Alkohols statt (12 Beispiele, 29–97 % Umsatz, 19–68 % Ausbeute, 87–99 % ee). Mechanistische Studien unterstützen einen geschwindigkeits- und selektivitätsbestimmenden Angriff des reaktiven Mangan-Oxo-Komplexes am Wasserstoffbrücken-gebundenen Substrat sowie eine Sauerstoffübertragung durch einen Rebound-Mechanismus.Schau mir ins aktive Zentrum, Kleines: Ein chiraler Mangan-Porphyrin-Komplex katalysiert die Oxygenierung von 3,4-Dihydrochinolonen zur entsprechenden (4S)-Hydroxyverbindung (12 Beispiele, 87–99 % ee). Die Enantio- und Positionsselektivität wird durch Wasserstoffbrücken zum Katalysator bewirkt: Methylengruppen am C3 oder C7 Kohlenstoff werden nicht angegriffen.
      PubDate: 2018-02-09T04:01:21.799308-05:
      DOI: 10.1002/ange.201712340
  • A Three-Component Organometallic Tyrosine Bioconjugation
    • Authors: Jun Ohata; Mary K. Miller, Courtney M. Mountain, Farrukh Vohidov, Zachary T. Ball
      Abstract: Metal-based bioconjugation linkages represent a little-studied approach to protein functionalization that provides novel reactivity, stability, and function. Described is an organometallic bioconjugation, employing rhodium(III) salts, to link boronic acids with tyrosine residues by an arene complex. Both peptides and proteins are amenable to the mild bioconjugation in aqueous media, allowing incorporation of useful functionalities, such as affinity handles or fluorophores. Because of the metastability of the inorganic linkage, the conjugates are susceptible to cleavage by nucleophilic redox mediators but are stable toward typical biological conditions.In Gegenwart von Boronsäuren bilden Rhodium(III)-Salze metallorganische Arenkomplexe an Tyrosinresten. Die Verknüpfung mit Rhodium stellt eine unter biologischen Bedingungen stabile Proteinfunktionalisierung dar. DTT=Dithiothreitol.
      PubDate: 2018-02-09T04:01:01.58088-05:0
      DOI: 10.1002/ange.201711868
  • Accelerating Membrane-based CO2 Separation by Soluble Nanoporous Polymer
           Networks Produced by Mechanochemical Oxidative Coupling
    • Authors: Xiang Zhu; Yinying Hua, Chengcheng Tian, Carter W. Abney, Peng Zhang, Tian Jin, Gongping Liu, Katie L. Browning, Robert L. Sacci, Gabriel M. Veith, Hong-Cai Zhou, Wanqin Jin, Sheng Dai
      Abstract: Achieving homogeneous dispersion of nanoporous fillers within membrane architectures remains a great challenge for mixed-matrix membrane (MMMs) technology. Imparting solution processability of nanoporous materials would help advance the development of MMMs for membrane-based gas separations. A mechanochemically assisted oxidative coupling polymerization strategy was used to create a new family of soluble nanoporous polymer networks. The solid-state ball-milling method affords inherent molecular weight control over polymer growth and therefore provides unexpected solubility for the resulting nanoporous frameworks. MMM-based CO2/CH4 separation performance was significantly accelerated by these new soluble fillers. We anticipate this facile method will facilitate new possibilities for the rational design and synthesis of soluble nanoporous polymer networks and promote their applications in membrane-based gas separations.Mechanochemie hilft bei der Bildung nanoporöser Polymergerüste durch oxidative Kupplung. In der Kugelmühle lässt sich das Molekulargewicht des wachsenden Polymers kontrollieren, und es werden nanoporöse Gerüste mit ungewöhnlicher Löslichkeit erhalten. Der Einsatz dieser löslichen Füllstoffe in Mischmembranen beschleunigt die Trennung von CO2 und CH4 deutlich.
      PubDate: 2018-02-09T04:00:55.102404-05:
      DOI: 10.1002/ange.201710420
  • Herkunftsbezogene Nomenklatur für einstrangige Homo- und Copolymere
           (IUPAC-Empfehlungen 2016)
    • Authors: Karl-Heinz Hellwich; Kathrin-M. Roy
      Abstract: IUPAC-Empfehlungen zur herkunftsbezogenen Nomenklatur für einstrangige Polymere wurden bisher hauptsächlich im Hinblick auf Copolymere, nichtlineare Polymere und Polymerassoziate sowie im Zusammenhang mit der generischen herkunftsbezogenen Polymernomenklatur formuliert. Im Folgenden werden möglichst klare und präzise Regeln zur Entwicklung eines geeigneten herkunftsbezogenen Namens für ein Polymer, ob Homopolymer oder Copolymer, formuliert. Somit wird das herkunftsbezogene System zur Benennung von Polymeren in einer Gesamtheit vorgelegt, die als nutzerfreundliche Alternative zum strukturbezogenen System der Polymernomenklatur dient. Zudem wurden Empfehlungen für die Verwendung traditioneller Polymernamen ausgearbeitet, da deren Gebrauch weit verbreitet und etabliert ist.Möglichst klare und präzise Regeln zur Entwicklung eines geeigneten herkunftsbezogenen Namens für ein Polymer, ob Homopolymer oder Copolymer, zu entwickeln, war das Ziel der Verfasser der hier in deutscher Übersetzung vorliegenden IUPAC-Empfehlung.
      PubDate: 2018-02-09T04:00:34.323303-05:
      DOI: 10.1002/ange.201706791
  • Decoupling Hydrogen and Oxygen Production in Acidic Water Electrolysis
           Using a Polytriphenylamine-Based Battery Electrode
    • Authors: Yuanyuan Ma; Xiaoli Dong, Yonggang Wang, Yongyao Xia
      Abstract: Hydrogen production through water splitting is considered a promising approach for solar energy harvesting. However, the variable and intermittent nature of solar energy and the co-production of H2 and O2 significantly reduce the flexibility of this approach, increasing the costs of its use in practical applications. Herein, using the reversible n-type doping/de-doping reaction of the solid-state polytriphenylamine-based battery electrode, we decouple the H2 and O2 production in acid water electrolysis. In this architecture, the H2 and O2 production occur at different times, which eliminates the issue of gas mixing and adapts to the variable and intermittent nature of solar energy, facilitating the conversion of solar energy to hydrogen (STH). Furthermore, for the first time, we demonstrate a membrane-free solar water splitting through commercial photovoltaics and the decoupled acid water electrolysis, which potentially paves the way for a new approach for solar water splitting.Entkoppelte Wasserelektrolyse: Eine organische Polytriphenylamin-basierte Batterieelektrode wird vorgestellt, mit der die Wasser- und Sauerstoffproduktion in der sauren Wasserelektrolyse entkoppelt werden kann, wodurch die membranlose Umwandlung von Sonnenenergie in Wasserstoff möglich wird. Die Trennung von Wasser- und Sauerstoffproduktion könnte zur flexiblen Nutzung von Sonnenenergie führen.
      PubDate: 2018-02-09T03:57:24.551146-05:
      DOI: 10.1002/ange.201800436
  • Reversible Redox Chemistry of Azo Compounds for Sodium-Ion Batteries
    • Authors: Chao Luo; Gui-Liang Xu, Xiao Ji, Singyuk Hou, Long Chen, Fei Wang, Jianjun Jiang, Zonghai Chen, Yang Ren, Khalil Amine, Chunsheng Wang
      Abstract: Sustainable sodium-ion batteries (SSIBs) using renewable organic electrodes are promising alternatives to lithium-ion batteries for the large-scale renewable energy storage. However, the lack of high-performance anode material impedes the development of SSIBs. Herein, we report a new type of organic anode material based on azo group for SSIBs. Azobenzene-4,4′-dicarboxylic acid sodium salt is used as a model to investigate the electrochemical behaviors and reaction mechanism of azo compound. It exhibits a reversible capacity of 170 mAh g−1 at 0.2C. When current density is increased to 20C, the reversible capacities of 98 mAh g−1 can be retained for 2000 cycles, demonstrating excellent cycling stability and high rate capability. The detailed characterizations reveal that azo group acts as an electrochemical active site to reversibly bond with Na+. The reversible redox chemistry between azo compound and Na ions offer opportunities for developing long-cycle-life and high-rate SSIBs.Azoverbindungen wurden als leistungsfähiges organisches Elektrodenmaterial für Natriumionenbatterien (SIBs) vorgestellt. Das ausgedehnte konjugierte π-System aromatischer Azoverbindungen und die starke Anlagerung der Na+-Ionen an den Stickstoffatomen der Azogruppe bilden die Grundlage für eine lange Lebensdauer und gutes Ratenverhalten.
      PubDate: 2018-02-09T03:56:17.906766-05:
      DOI: 10.1002/ange.201713417
  • Kohlenhydratresponsive Oberflächenhaftung basierend auf dynamisch
    • Authors: Sebastian Lamping; Tobias Otremba, Bart Jan Ravoo
      Abstract: Ein Kleber, dessen starke Haftfähigkeit (2.38 kg) auf dynamisch kovalenter Chemie beruht, welche zudem wasserbeständig und durch Kohlenhydrateinfluss schaltbar ist, wird vorgestellt. Zu diesem Zweck wurden Glas- und Siliciumoberflächen mithilfe der oberflächeninitiierten radikalischen Atomtransferpolymerisation (surface-induced atom transfer radical polymerization, SI-ATRP) mit Copolymeren, die zum einen Phenylboronsäuren und zum anderen Catechole enthielten, funktionalisiert. Nach Strukturierung mit Mikrokontaktdruck (microcontact printing, μCP) wird aus den Polymerbürsten ein kohlenhydratresponsiver supramolekularer “Klettverschluss” erhalten.Verklebt und gelöst: Die Kombination von oberflächeninitiierter radikalischer Atomtransferpolymerisation und dynamischer kovalenter Chemie von Phenylboronsäuren und Catecholen führt zu einer supramolekularen Oberflächenhaftung. Die Oberflächenhaftung ist robust (2.38 kg cm−2), wasserbeständig und wiederverwendbar, aber löst sich nach Zugabe eines Kohlenhydrates.
      PubDate: 2018-02-09T02:28:07.975157-05:
      DOI: 10.1002/ange.201711529
  • Titelbild: Die enantioselektive Totalsynthese von
           Bischinolizidin-Alkaloiden: Ein modularer “Inside-Out”-Zugang (Angew.
           Chem. 9/2018)
    • Authors: Dagmar Scharnagel; Jessica Goller, Nicklas Deibl, Wolfgang Milius, Matthias Breuning
      Pages: 2283 - 2283
      Abstract: 21 natürliche Bischinolizidin-Alkaloide wurden nach einem modularen “Inside-out”-Ansatz hergestellt, den M. Breuning et al. in ihrer Zuschrift auf S. 2456 vorstellen. Unter den Beispielen sind mehr als zehn erste enantioselektive Totalsynthesen. Entscheidend waren die erfolgreiche Herstellung beider Enantiomere von C2-symmetrischem 2,6-Dioxobispidin durch Desymmetrisierung und die sukzessive α,N-Anellierung eines 2-Pyridons und endo- oder exo-kondensierter Piperidine an den chiralen Kernbaustein.
      PubDate: 2018-02-05T10:12:34.364326-05:
      DOI: 10.1002/ange.201800930
  • Innentitelbild: Durch zwei Liganden ermöglichte nicht-dirigierte
           C-H-Olefinierung von Arenen (Angew. Chem. 9/2018)
    • Authors: Hao Chen; Philipp Wedi, Tim Meyer, Ghazal Tavakoli, Manuel van Gemmeren
      Pages: 2284 - 2284
      Abstract: Wie viele Liganden braucht man, um eine Bindung zu wechseln' Die oxidative C-H-Arylierung von Olefinen (die Fujiwara-Moritani-Reaktion) litt bisher unter einer geringen Effizienz und der Notwendigkeit, die wertvollen Arene im Überschuss einsetzen zu müssen. M. van Gemmeren und Mitarbeiter berichten in ihrer Zuschrift auf S. 2523 über die Verwendung von zwei Liganden als Strategie zur Optimierung des in dieser Reaktion eingesetzten Palladiumkatalysators.
      PubDate: 2018-02-02T02:53:05.508958-05:
      DOI: 10.1002/ange.201800928
  • Graphisches Inhaltsverzeichnis: Angew. Chem. 9/2018
    • Pages: 2289 - 2300
      PubDate: 2018-02-19T05:11:36.46636-05:0
      DOI: 10.1002/ange.201880911
  • Top-Beiträge aus unseren Schwesterzeitschriften: Angew. Chem. 9/2018
    • Pages: 2302 - 2305
      PubDate: 2018-02-19T05:11:34.911741-05:
      DOI: 10.1002/ange.201880913
  • Keiji Morokuma (1934–2017)
    • Authors: Qiang Cui; Stephan Irle, Jamal Musaev
      Pages: 2310 - 2311
      Abstract: Keiji Morokuma, emeritierter William Henry Emerson Professor der Emory University und Forschungsgruppenleiter am Fukui Institute for Fundamental Chemistry, Kyoto University, ist am 27. November 2017 im Alter von 83 Jahren verstorben. Morokumas Beiträge bereicherten die theoretischen Methoden zur Bestimmung von Reaktionsmechanismen und den zugehörigen intermolekularen Wechselwirkungen.
      PubDate: 2018-02-02T02:52:52.014649-05:
      DOI: 10.1002/ange.201800390
  • Heißes Wasser ermöglicht Kristallinität in organischen
    • Authors: Miriam M. Unterlass
      Pages: 2314 - 2316
      Abstract: Hydrothermale Kristallisation wurde kürzlich angewendet, um amorphe Polymernetzwerke in Amid-verknüpfte, kovalent gebundene organische Gerüststrukturen zu überführen. Diese Arbeit wird im Kontext der Synthese und Kristallisation organischer Materialien mithilfe von Wasser bei hohen Temperaturen diskutiert.
      PubDate: 2018-01-30T08:21:18.824748-05:
      DOI: 10.1002/ange.201713359
  • Steigerung der Katalysatoreffizienz in der C-H-Aktivierungskatalyse
    • Authors: Tobias Gensch; Michael J. James, Toryn Dalton, Frank Glorius
      Pages: 2318 - 2328
      Abstract: Nur wenige Katalysatoren erreichen hohe Umsatzzahlen in Reaktionen zur Aktivierung von C-H-Bindungen. Stattdessen werden üblicherweise 10 Mol-% eines Katalysators in solchen Reaktionen eingesetzt. Wir geben eine repräsentative Übersicht über effiziente Katalysatornutzung in der C-H-Aktivierung, um diesem vernachlässigten Aspekt der Katalyseforschung mehr Aufmerksamkeit zukommen zu lassen und zukünftige Entwicklungen noch effizienterer C-H-Aktivierungen zu inspirieren. Wir zeigen Beispiele aus der Palladiumkatalyse, Cp*RhIII- und Cp*CoIII-katalysierter Reaktionen, der Borylierung und Silylierung von C-H-Bindungen sowie der C-H-Aktivierung von Methan. In diesen Reaktionen wurden bis zu zehntausende Katalysatorumsätze beobachtet.Los, Katalysator! C-H-Aktivierungsreaktionen mit hohen Katalysatorumsätzen sind immer noch sehr selten in der Literatur, und 10 Mol-% ist eine gängige Katalysatorbeladung in diesem Gebiet. Ein repräsentativer Überblick über effiziente katalytische C-H-Aktivierungen wird gegeben, um diesen vernachlässigten Aspekt der Katalysatorentwicklung hervorzuheben und zukünftige Arbeiten an noch effizienteren C-H-Aktivierungen zu inspirieren.
      PubDate: 2018-01-29T08:35:37.354996-05:
      DOI: 10.1002/ange.201710377
  • Lektion gelernt' Die molekularen Grundlagen von Kinase-gerichteten
           Therapien und Wirkstoffresistenz im nicht-kleinzelligen Lungenkrebs
    • Authors: Jonas Lategahn; Marina Keul, Daniel Rauh
      Pages: 2329 - 2335
      Abstract: Die Behandlung des nicht-kleinzelligen Lungenkrebs (NSCLC) erfährt derzeit eine Revolution. Innerhalb der letzten Dekade führten die gewonnenen Erkenntnisse über die biologische Bedeutung von Biomarkern und deren prädiktiver Charakter zur Entwicklung von Tyrosinkinase-Inhibitoren, die eine Alternative zur Chemotherapie darstellen. Die Verwendung dieser innovativen Therapeutika verbessert die Lebensqualität und erhöht das Überleben betroffener Patienten. Das detaillierte Verständnis der Biologie der Zielproteine gepaart mit innovativen chemischen Ansätzen zu deren Modulation, ermutigten weitere Forschungen auf diesem Gebiet. Vor diesem Hintergrund präsentieren wir einen Rückblick auf ausgewählte molekulare Aspekte der Zielproteine und geben einen Überblick über aktuelle Fragestellungen und Herausforderungen bei der rationalen Wirkstoffentwicklung zur Behandlung von NSCLC.Alternative zur Chemotherapie: Das über die letzte Dekade gewonnene Verständnis von Biomarkern und deren prädiktiven Eigenschaften führte zur Entwicklung einer Präzisionsmedizin, die die Lebensqualität und das Überleben von Patienten deutlich verbesserte. Dieser Kurzaufsatz beleuchtet ausgewählte Aspekte der Zielstrukturen und gibt einen Überblick über aktuelle Themen und Herausforderungen bei der Behandlung von Lungenkrebs (NSCLC).
      PubDate: 2018-01-12T03:06:23.527708-05:
      DOI: 10.1002/ange.201710398
  • Nanobodys: Strategien zur chemischen Funktionalisierung und
           intrazelluläre Anwendungen
    • Authors: Dominik Schumacher; Jonas Helma, Anselm F. L. Schneider, Heinrich Leonhardt, Christian P. R. Hackenberger
      Pages: 2336 - 2357
      Abstract: Nanobodys sind ein modernes Mittel zur Erkennung und Modulation von Antigenen, die für herkömmliche Antikörper unzugänglich sind. Aufgrund ihrer kompakten Form und ihrer hohen Stabilität werden sie häufig in der Grundlagenforschung verwendet. In diesem Aufsatz werden zentrale Aspekte der Funktionalisierung von Nanobodys nebst ausgewählten Anwendungen in der Molekularbiologie dargestellt. Während ältere Konjugationsstrategien auf der zufälligen Modifikation natürlicher Aminosäuren beruhen, basieren neuere Methoden auf ortsspezifischer Modifikation mit funktionellen Einheiten. Solche Techniken umfassen chemoenzymatische Ansätze, Ligation exprimierter Proteine und die Unterdrückung des Amber-Codons in Kombination mit bioorthogonalen Modifikationsstrategien. Mit einer ständig wachsenden Auswahl an Methoden aus der Proteinsynthese und -konjugation sind auch die Anwendungen auf dem Vormarsch. Diese reichen von hochentwickelter Bildgebung und Massenspektrometrie bis hin zum Einschleusen von Nanobodys in lebende Zellen, um intrazelluläre Antigene zu visualisieren und zu manipulieren.Nano-Bodybuilding: Kleine antigenbindende Proteine (Nanobodys) sind leistungsfähige Hilfsmittel in den Lebenswissenschaften. Durch Anwendung chemischer Markierungsstrategien lassen sich intrazelluläre Zielstrukturen bildlich darstellen und manipulieren.
      PubDate: 2018-01-26T03:35:55.626838-05:
      DOI: 10.1002/ange.201708459
  • Enantio- and Diastereoselective Cyclopropanation of 1-Alkenylboronates:
           Synthesis of 1-Boryl-2,3-Disubstituted Cyclopropanes
    • Authors: Javier Carreras; Ana Caballero, Pedro J. Pérez
      Pages: 2358 - 2362
      Abstract: A novel, highly enantio- and diastereoselective synthesis of 1-boryl-2,3-disubstituted cyclopropanes has been developed by means of the cyclopropanation of alkenylboronates with ethyl diazoacetate in the presence of catalytic amounts of a chiral copper(I) complex. The products can also be directly accessed from alkynes through an operationally simple, sequential hydroboration–cyclopropanation protocol. The resulting enantioenriched 1-boryl-2,3-disubstituted cyclopropanes are versatile synthetic intermediates that undergo further transformations at the carbon–boron bond.Mehrfach funktionalisierte, 1-Boryl-2,3-disubstituierte Cyclopropane werden in hohen Ausbeuten, Diastereo- und Enantioselektivitäten aus Alkenylboronsäureestern durch Umsetzung mit Diazoessigsäureethylester in Gegenwart eines Kupfer(I)-Bisoxazolin-Katalysators erhalten. Die Produkte sind vielseitige Synthesebausteine und durch das Vorhandensein einer Kohlenstoff-Bor-Bindung leicht modifizierbar.
      PubDate: 2018-01-02T08:36:00.45144-05:0
      DOI: 10.1002/ange.201710415
  • Seeded Polymerization through the Interplay of Folding and Aggregation of
           an Amino-Acid-based Diamide
    • Authors: Soichiro Ogi; Kentaro Matsumoto, Shigehiro Yamaguchi
      Pages: 2363 - 2367
      Abstract: Amino acid based diamides are widely used as a substructure in supramolecular polymers and are also key components of polypeptides that help to understand protein folding. The interplay of folding and aggregation of a diamide was used to achieve seed-initiated supramolecular polymerization. For that purpose, a pyrene-substituted diamide was synthesized in which pyrene is used as a tracer to monitor the supramolecular polymerization. Thermodynamics and time-dependent studies revealed that the folding of the diamide moiety, via the formation of intramolecular hydrogen bonds, effectively prevents a spontaneous nucleation that leads to supramolecular polymerization. Under such out-of-equilibrium conditions, the addition of seeds successfully initiates the supramolecular polymerization. These results demonstrate the utility of such amino acid based diamides in programmable supramolecular polymerizations.Wasserstoffbrücken steuern die Faltung einer Diamidgruppe und vermeiden dadurch effektiv die spontane Keimbildung für eine supramolekulare Polymerisation. Die Polymerisation des Pyrenderivats, als Beispiel für ein lumineszierendes konjugiertes π-System, lief dagegen unter Ungleichgewichtsbedingungen ab.
      PubDate: 2018-02-02T02:51:40.392212-05:
      DOI: 10.1002/ange.201712119
  • The Ideal Ionic Liquid Salt Bridge for the Direct Determination of Gibbs
           Energies of Transfer of Single Ions, Part I: The Concept
    • Authors: Valentin Radtke; Andreas Ermantraut, Daniel Himmel, Thorsten Koslowski, Ivo Leito, Ingo Krossing
      Pages: 2368 - 2371
      Abstract: Described is a procedure for the thermodynamically rigorous, experimental determination of the Gibbs energy of transfer of single ions between solvents. The method is based on potential difference measurements between two electrochemical half cells with different solvents connected by an ideal ionic liquid salt bridge (ILSB). Discussed are the specific requirements for the IL with regard to the procedure, thus ensuring that the liquid junction potentials (LJP) at both ends of the ILSB are mostly canceled. The remaining parts of the LJPs can be determined by separate electromotive force measurements. No extra-thermodynamic assumptions are necessary for this procedure. The accuracy of the measurements depends, amongst others, on the ideality of the IL used, as shown in our companion paper Part II.Extralos! Können Gibbs-Transferenergien einzelner Ionen ohne außerthermodynamische Annahmen bestimmt werden' Bisher lautete die Antwort „Nein”. Um ein „Ja” daraus zu machen, wird eine Methode vorgeschlagen, die auf einfachen potentiometrischen Messungen beruht. Eine zweite Zuschrift liefert erste experimentelle Belege hierfür.
      PubDate: 2018-02-05T10:18:44.764101-05:
      DOI: 10.1002/ange.201707333
  • The Ideal Ionic Liquid Salt Bridge for Direct Determination of Gibbs
           Energies of Transfer of Single Ions, Part II: Evaluation of the Role of
           Ion Solvation and Ion Mobilities
    • Authors: Andreas Ermantraut; Valentin Radtke, Niklas Gebel, Daniel Himmel, Thorsten Koslowski, Ivo Leito, Ingo Krossing
      Pages: 2372 - 2376
      Abstract: An important intermediate goal to evaluate our concept for the assumption-free determination of single-ion Gibbs transfer energies ΔtrG°(i, S1S2) is presented. We executed the crucial steps a) and b) of the methodology, described in Part I of this treatise, exemplarily for Ag+ and Cl- with S1 being water and S2 being acetonitrile. The experiments showed that virtually all parts of the liquid junction potentials (LJPs) at both ends of a salt bridge cancel, if the bridge electrolyte is an “ideal” ionic liquid, that is, one with nearly identical diffusion of anion and cation. This ideality holds for [N2225]+[NTf2]- in the pure IL, but also in water and acetonitrile solution. Electromotive force measurements of solvation cells between S1 and S2 demonstrated Nernstian behavior for Ag+ concentration cells and constant like cell potentials for solutions with five tested Ag+ counterions.Ideal: Ein Schritt hin zur Messung von Gibbs-Transferenergien einzelner Ionen ohne außerthermodynamische Annahmen wurde aufgezeigt. Die Messung von Zellspannungen mithilfe einer ionischen Flüssigkeit als ideale Salzbrücke konnte zeigen, dass praktisch alle Teile des Flüssigkeitsgrenzpotentials zwischen verschiedenen Lösungsmitteln für Ag+-Systeme umgangen werden, da [N2225]+ und [NTf2]− sowohl in der Salzbrücke als auch im Medium fast identische Diffusionseigenschaften aufweisen.
      PubDate: 2018-02-07T02:20:27.927079-05:
      DOI: 10.1002/ange.201707334
  • All-in-One Cellulose Nanocrystals for 3D Printing of Nanocomposite
    • Authors: Jieping Wang; Annalisa Chiappone, Ignazio Roppolo, Feng Shao, Erika Fantino, Massimo Lorusso, Daniel Rentsch, Kurt Dietliker, Candido Fabrizio Pirri, Hansjörg Grützmacher
      Pages: 2377 - 2380
      Abstract: Cellulose nanocrystals (CNCs) with>2000 photoactive groups on each can act as highly efficient initiators for radical polymerizations, cross-linkers, as well as covalently embedded nanofillers for nanocomposite hydrogels. This is achieved by a simple and reliable method for surface modification of CNCs with a photoactive bis(acyl)phosphane oxide derivative. Shape-persistent and free-standing 3D structured objects were printed with a mono-functional methacrylate, showing a superior swelling capacity and improved mechanical properties.Alleskönner: Multifunktionelle Cellulose-Nanokristalle (CNCs) wurden durch einfache Oberflächenimmobilisierung photoaktiver Gruppen erhalten. Die modifizierten CNCs dienen als hoch effiziente Photoinitiatoren unter sichtbarem Licht, Vernetzungsagentien und kovalent eingelassene Nanofüllstoffe für den 3D-Druck von Nanokomposithydrogelen, wobei als Monomer ein monofunktionelles Methacrylat ohne jedes konventionelle Vernetzungsagens zum Einsatz kommt.
      PubDate: 2018-01-16T09:51:08.744647-05:
      DOI: 10.1002/ange.201710951
  • Rapid Capture and Release of Nucleic Acids through a Reversible
           Photo-Cycloaddition Reaction in a Psoralen-Functionalized Hydrogel
    • Authors: Yizhe Zhang; Peggy P. Y. Chan, Amy E. Herr
      Pages: 2381 - 2385
      Abstract: Reversible immobilization of DNA and RNA is of great interest to researchers who seek to manipulate DNA or RNA in applications such as microarrays, DNA hydrogels, and gene therapeutics. However, there is no existing system that can rapidly capture and release intact nucleic acids. To meet this unmet need, we developed a functional hydrogel for rapid DNA/RNA capture and release based on the reversible photo-cycloaddition of psoralen and pyrimidines. The functional hydrogel can be easily fabricated through copolymerization of acrylamide with the synthesized allylated psoralen. The psoralen-functionalized hydrogel exhibits effective capture and release of nucleic acids spanning a wide range of lengths in a rapid fashion; over 90 % of the capture process is completed within 1 min, and circa 100 % of the release process is completed within 2 min. We observe no deleterious effects on the hybridization to the captured targets.Reversibler DNA- und RNA-Einfang: Ein Polyacrylamid-Gel wurde durch Copolymerisation von Acrylamid mit allyliertem Psoralen dahingehend modifiziert, dass es DNA/RNA effizient einfangen kann. Die reversible Photocycloaddition zwischen Psoralen und Pyrimidin führt zu DNA/RNA-Einfang und -Freisetzung binnen Minuten unter UV-Bestrahlung. Vielfältige DNA- und RNA-Sequenzen unterschiedlicher Länge reagieren in dieser Weise, und der Prozess ist kompatibel mit Hybridisierung.
      PubDate: 2018-01-24T04:10:25.594217-05:
      DOI: 10.1002/ange.201711441
  • Optical Control of a Biological Reaction–Diffusion System
    • Authors: Philipp Glock; Johannes Broichhagen, Simon Kretschmer, Philipp Blumhardt, Jonas Mücksch, Dirk Trauner, Petra Schwille
      Pages: 2386 - 2390
      Abstract: Patterns formed by reaction and diffusion are the foundation for many phenomena in biology. However, the experimental study of reaction–diffusion (R–D) systems has so far been dominated by chemical oscillators, for which many tools are available. In this work, we developed a photoswitch for the Min system of Escherichia coli, a versatile biological in vitro R–D system consisting of the antagonistic proteins MinD and MinE. A MinE-derived peptide of 19 amino acids was covalently modified with a photoisomerizable crosslinker based on azobenzene to externally control peptide-mediated depletion of MinD from the membrane. In addition to providing an on–off switch for pattern formation, we achieve frequency-locked resonance with a precise 2D spatial memory, thus allowing new insights into Min protein action on the membrane. Taken together, we provide a tool to study phenomena in pattern formation using biological agents.Von Licht geleitet: Das Min-System, ein biologisches Reaktions-Diffusions-System vieler Bakterien, kann in vitro mithilfe eines Azobenzol-vernetzten, von MinE abgeleiteten Peptids optisch gesteuert werden. Dieses System öffnet neue Wege für die Untersuchung biologischer Musterbildungsprozesse.
      PubDate: 2018-01-26T03:36:37.877843-05:
      DOI: 10.1002/ange.201712002
  • Discovery and Enumeration of Organic-Chemical and Biomimetic Reaction
           Cycles within the Network of Chemistry
    • Authors: Michał D. Bajczyk; Piotr Dittwald, Agnieszka Wołos, Sara Szymkuć, Bartosz A. Grzybowski
      Pages: 2391 - 2395
      Abstract: Analysis of the chemical-organic knowledge represented as a giant network reveals that it contains millions of reaction sequences closing into cycles. Without realizing it, independent chemists working at different times have jointly created examples of cyclic sequences that allow for the recovery of useful reagents and for the autoamplification of synthetically important molecules, those that mimic biological cycles, and those that can be operated one-pot.Eine Big-Data-Analyse des Netzwerks der organischen Chemie (NOC) offenbart, dass Chemiker unwissentlich Millionen zyklischer Reaktionssequenzen erschaffen haben, z. B. solche, die wertvolle Substrate zurückbringen, nützliche Chemikalien vervielfältigen und biologische Zyklen nachahmen. Das Bild zeigt einen Zyklustyp (die „Clique”; Farben: Jahre der erstmaligen Beschreibung einer Reaktion), in dem jedes Mitglied aus einem anderen in einem Schritt hergestellt werden kann.
      PubDate: 2018-02-06T08:20:44.289786-05:
      DOI: 10.1002/ange.201712052
  • Palladium-Catalyzed Asymmetric Aminohydroxylation of 1,3-Dienes
    • Authors: Hong-Cheng Shen; Yu-Feng Wu, Ying Zhang, Lian-Feng Fan, Zhi-Yong Han, Liu-Zhu Gong
      Pages: 2396 - 2400
      Abstract: A PdII-catalyzed asymmetric aminohydroxylation of 1,3-dienes with N-tosyl-2-aminophenols was developed by making use of a chiral pyridinebis(oxazoline) ligand. The highly regioselective reaction provides direct and efficient access to chiral 3,4-dihydro-2H-1,4-benzoxazines in high yield and enantioselectivity (up to 96:4 e.r.). The reaction employs readily available N-tosyl-2-aminophenols as a unique aminohydroxylation reagent and is complementary to known asymmetric aminohydroxylation methods.Ein neuer Ring: Die Titelreaktion von 1,3-Dienen mit N-Tosyl-2-aminophenolen in Gegenwart eines chiralen Pyridinbis(oxazolin)-Liganden ergibt optisch aktive 3,4-Dihydro-2H-1,4-benzoxazine in hohen Ausbeuten und mit hoher Regio- und Stereoselektivität.
      PubDate: 2018-02-06T02:31:00.11353-05:0
      DOI: 10.1002/ange.201712350
  • Highly Fluorescent Chiral N-S-Doped Carbon Dots from Cysteine: Affecting
           Cellular Energy Metabolism
    • Authors: Feng Li; Yiye Li, Xiao Yang, Xuexiang Han, Yang Jiao, Taotao Wei, Dayong Yang, Huaping Xu, Guangjun Nie
      Pages: 2401 - 2406
      Abstract: Cysteine-based chiral optically active carbon dots (CDs) and their effects on cellular energy metabolism, which is vital for essential cellular functions, have been barely reported. A green and effective synthesis strategy for chiral N-S-doped CDs (fluorescence quantum yield ca. 41.26 %) based on hydrothermal treatment of l- or d-cysteine at as low as 60 °C has been developed. This suggested that cysteine was instable in aqueous solutions and acts as a warning for high-temperature synthesis of nanomaterials using cysteine as stabilizer. Human bladder cancer T24 cells treated with l-CDs showed up-regulated glycolysis, while d-CDs had no similar effects. In contrast, no disturbance to the basal mitochondrial aerobic respiration of T24 cells was caused by either chiral CD.Der grüne Punkt: Eine grüne und effiziente Synthese chiraler Kohlenstoffpunkte (CDs; Fluoreszenzquantenausbeute ca. 41 %) beruht auf der hydrothermalen Behandlung von l- oder d-Cystein bei nur 60 °C. Die l-CDs ergeben eine chiralitätsabhängige Erhöhung der zellulären Glykolyse, beeinflussen aber nicht die ATP-Spiegel von T24-Zellen.
      PubDate: 2018-02-08T02:56:55.265328-05:
      DOI: 10.1002/ange.201712453
  • Electrochemical C−H/N−H Activation by Water-Tolerant Cobalt Catalysis
           at Room Temperature
    • Authors: Cong Tian; Leonardo Massignan, Tjark H. Meyer, Lutz Ackermann
      Pages: 2407 - 2411
      Abstract: Electrochemistry enabled C−H/N−H functionalizations at room temperature by external oxidant-free cobalt catalysis. Thus, the sustainable cobalt electrocatalysis manifold proceeds with excellent levels of chemoselectivity and positional selectivity, and with ample scope, thus allowing electrochemical C−H activation under exceedingly mild reaction conditions at room temperature in water.Strom und Wasser: Cobaltkatalysierte C-H/N-H-Funktionalisierungen, die elektrochemisch in H2O bei 23 °C ablaufen, machen den Einsatz giftiger oxidierender Metallreagentien überflüssig. Die nachhaltigen Cobalt-Elektrokatalysen sind hoch chemo- und positionsselektiv für ein breites Substratspektrum.
      PubDate: 2018-01-17T09:21:14.42323-05:0
      DOI: 10.1002/ange.201712647
  • Cationic Metallo-Polyelectrolytes for Robust Alkaline Anion-Exchange
    • Authors: Tianyu Zhu; Shichao Xu, Anisur Rahman, Emir Dogdibegovic, Peng Yang, Parasmani Pageni, Mohammad Pabel Kabir, Xiao-dong Zhou, Chuanbing Tang
      Pages: 2412 - 2416
      Abstract: Chemically inert, mechanically tough, cationic metallo-polyelectrolytes were conceptualized and designed as durable anion-exchange membranes (AEMs). Ring-opening metathesis polymerization (ROMP) of cobaltocenium-containing cyclooctene with triazole as the only linker group, followed by backbone hydrogenation, led to a new class of AEMs with a polyethylene-like framework and alkaline-stable cobaltocenium cation for ion transport. These AEMs exhibited excellent thermal, chemical and mechanical stability, as well as high ion conductivity.ROMP (Ringöffnungsmetathesepolymerisation) von Cobaltocenium-haltigem Cycloocten mit Triazol als einzigem Linker mit nachfolgender Rückgrat-Hydrierung liefert eine neue Klasse von Anionenaustauschmembranen (AEMs) mit Polyethylen-Gerüst und alkalistabilen Cobaltocenium-Kationen für den Ionentransport. Die AEMs zeigen eine exzellente thermische, chemische und mechanische Stabilität sowie eine hohe Ionenleitfähigkeit.
      PubDate: 2018-01-16T03:35:30.291707-05:
      DOI: 10.1002/ange.201712387
  • Design of Metal-Free Polymer Carbon Dots: A New Class of Room-Temperature
           Phosphorescent Materials
    • Authors: Songyuan Tao; Siyu Lu, Yijia Geng, Shoujun Zhu, Simon A. T. Redfern, Yubin Song, Tanglue Feng, Weiqing Xu, Bai Yang
      Pages: 2417 - 2422
      Abstract: Polymer carbon dots (PCDs) are proposed as a new class of room-temperature phosphorescence (RTP) materials. The abundant energy levels in PCDs increase the probability of intersystem crossing (ISC) and their covalently crosslinked framework structures greatly suppress the nonradiative transitions. The efficient methods allow the manufacture of PCDs with unique RTP properties in air without additional metal complexation or complicated matrix composition. They thus provide a route towards the rational design of metal-free RTP materials that may be synthesized easily. Furthermore, we find that RTP is associated with a crosslink-enhanced emission (CEE) effect, which provides further routes to design improved PCDs with diverse RTP performance. Our results show the potential of PCDs as a universal route to achieve effective metal-free RTP.Raumtemperatur-Phosphoreszenz: Polymere Kohlenstoffpunkte (PCDs) mit Metall-freier Raumtemperatur-Phosphoreszenz (RTP) wurden mithilfe einer einfachen Synthesemethode hergestellt. Der Beitrag eines durch Quervernetzung verstärkten Emissionseffekts auf die RTP-Erzeugung wurde verifiziert und als Richtlinie zur Vorhersage und Synthese einer Reihe von PCDs mit unterschiedlichen RTP-Leistungen vorgeschlagen (ISC=Intersystem Crossing).
      PubDate: 2018-02-06T09:27:07.29292-05:0
      DOI: 10.1002/ange.201712662
  • Orientation Control of Molecularly Functionalized Surfaces Applied to the
           Simultaneous Alignment and Sorting of Carbon Nanotubes
    • Authors: Serxho Selmani; Derek J. Schipper
      Pages: 2423 - 2427
      Abstract: Self-assembly has been relied upon for molecular alignment in many advanced technological applications. However, although effective, it is inherently limited in its capability for optimization. Despite the potential benefits, the seemingly fundamental strategy of external orientation control has yet to be realized. Herein we demonstrate an approach that allows control of the orientation of small molecules covalently bound to a surface. The method exploits an alignment relay technique, passing alignment information through a liquid-crystal medium to small molecules to control surface functionalization events. The method is technically simple and can be carried out on a bench top without the need for specialized equipment. Moreover, we demonstrate the utility of the resulting surfaces to address two long-standing problems in nanoscience: the sorting and alignment of single-walled carbon nanotubes. This new method enabled significant alignment of the nanotubes as well as length and diameter sorting.Molekülartistik: Eine als ART („alignment relay technique”) bezeichnete Methode zur Anordnung von kovalent gebundenen organischen Molekülen auf einer Oberfläche wurde entwickelt. Die resultierende funktionalisierte Oberfläche wurde für die simultane Ausrichtung, Längen- und Durchmessersortierung von einwandigen Kohlenstoffnanoröhren genutzt (siehe Bild).
      PubDate: 2018-02-05T10:14:55.700007-05:
      DOI: 10.1002/ange.201712779
  • Enzymatic Electrosynthesis of Alkanes by Bioelectrocatalytic
           Decarbonylation of Fatty Aldehydes
    • Authors: Sofiene Abdellaoui; Florika C. Macazo, Rong Cai, Antonio L. De Lacey, Marcos Pita, Shelley D. Minteer
      Pages: 2428 - 2432
      Abstract: An enzymatic electrosynthesis system was created by combining an aldehyde deformylating oxygenase (ADO) from cyanobacteria that catalyzes the decarbonylation of fatty aldehydes to alkanes and formic acid with an electrochemical interface. This system is able to produce a range of alkanes (octane to propane) from aldehydes and alcohols. The combination of this bioelectrochemical system with a hydrogenase bioanode yields a H2/heptanal enzymatic fuel cell (EFC) able to simultaneously generate electrical energy with a maximum current density of 25 μA cm−2 at 0.6 V and produce hexane with a faradaic efficiency of 24 %.Eine Aldehyd-deformylierende Oxygenase für die Decarbonylierung von Lipidaldehyden zu Alkanen und Ameisensäure ergibt zusammen mit einer elektrochemischen Grenzfläche ein System, das Alkane aus Aldehyden und Alkoholen generiert. In Kombination mit einer Hydrogenase-Bioanode bildet dieses bioelektrochemische System eine enzymatische H2/Heptanal-Brennstoffzelle, die gleichzeitig elektrische Energie und Hexan erzeugt.
      PubDate: 2018-01-16T10:01:40.980354-05:
      DOI: 10.1002/ange.201712890
  • Fe2Si5N8: Access to Open-Shell Transition-Metal Nitridosilicates
    • Authors: Philipp Bielec; Oliver Janka, Theresa Block, Rainer Pöttgen, Wolfgang Schnick
      Pages: 2433 - 2436
      Abstract: Highly condensed nitridosilicates doped with Eu2+ or Ce3+ play an important role in saving energy by converting the blue light of (In,Ga)N-LEDs. Although nitridosilicates are known for great structural variety based on covalent anionic Si-N networks, elemental variety is restricted. Presenting a significant extension of the latter, this work describes a general access to open-shell transition-metal nitridosilicates. As a proof-of-principle, the first iron nitridosilicate, namely Fe2Si5N8, was prepared by exchanging Ca2+ in α-Ca2Si5N8 applying a FeCl2 melt (salt metathesis). The title compound was analyzed by powder X-ray diffraction, EDX, ICP-OES, combustion analysis, TG/DSC, Mössbauer spectroscopy and magnetic susceptibility measurements. Furthermore, the structure of α-Ca2Si5N8 was determined at 1073 and 1173 K confirming the anionic network of α-Ca2Si5N8 providing possible migration pathways for the ion-exchange reaction.Kationenaustausch ist machbar in Nitridosilicaten: Durch den Einsatz von Salzschmelzen wurde das erste Eisennitridosilicat, Fe2Si5N8, hergestellt und somit die Elementvielfalt der Nitridosilicate deutlich erweitert. Auf der Grundlage der experimentellen Resultate wurde der Mechanismus des Ionenaustauschs untersucht, und mögliche Kanäle für die Wanderung zweiwertiger Kationen in α-Ca2Si5N8 wurden ausfindig gemacht.
      PubDate: 2018-02-06T06:10:50.97414-05:0
      DOI: 10.1002/ange.201713006
  • Manipulating Band Structure through Reconstruction of Binary Metal Sulfide
           for High-Performance Thermoelectrics in Solution-Synthesized
           Nanostructured Bi13S18I2
    • Authors: Biao Xu; Tianli Feng, Matthias T. Agne, Qing Tan, Zhe Li, Kazuki Imasato, Lin Zhou, Je-Hyeong Bahk, Xiulin Ruan, G. Jeffery Snyder, Yue Wu
      Pages: 2437 - 2442
      Abstract: Reconstructing canonical binary compounds by inserting a third agent can significantly modify their electronic and phonon structures. Therefore, it has inspired the semiconductor communities in various fields. Introducing this paradigm will potentially revolutionize thermoelectrics as well. Using a solution synthesis, Bi2S3 was rebuilt by adding disordered Bi and weakly bonded I. These new structural motifs and the altered crystal symmetry induce prominent changes in electrical and thermal transport, resulting in a great enhancement of the figure of merit. The as-obtained nanostructured Bi13S18I2 is the first non-toxic, cost-efficient, and solution-processable n-type material with z T=1.0.Bi2S3 wurde rekonstruiert, indem fehlgeordnetes Bi und schwach gebundenes I durch eine Synthese in Lösung addiert wurden. Die neuen Strukturmotive und die veränderte Kristallsymmetrie induzieren ausgeprägte Veränderungen in Elektronen- und Wärmeleitung. Das nanostrukturierte Bi13S18I2 ist ein ungiftiges, kostengünstiges und in Lösung prozessierbares thermoelektrisches Material vom n-Typ mit z T=1.0.
      PubDate: 2018-02-05T10:13:03.436099-05:
      DOI: 10.1002/ange.201713223
  • Synthesis and Structure Revision of Dichrocephones A and B
    • Authors: Volker M. Schmiedel; Young J. Hong, Dieter Lentz, Dean J. Tantillo, Mathias Christmann
      Pages: 2443 - 2446
      Abstract: Herein, we report the first enantioselective synthesis of dichrocephones A and B, which are cytotoxic triquinane sesquiterpenes with a dense array of stereogenic centers within a strained polycyclic environment. Key features include the application of a catalytic asymmetric Wittig reaction, followed by stereoselective functionalization of the propellane core into a pentacyclic intermediate. Double reductive ring cleavage yielded the proposed structure of dichrocephone A. Mismatched spectroscopic data for our synthetic material compared to the natural isolate led us to revise the previously proposed configuration based on biosynthetic considerations and NMR calculations. Implementation of these findings culminated in the synthesis of dichrocephones A and B.Cyclisieren und revidieren: Die Schlüsselschritte einer Totalsynthese der Dichrocephone A und B sind eine katalytische asymmetrische Wittig-Reaktion mit anschließender stereoselektiver Funktionalisierung des Propellan-Strukturkerns zu einer pentacyclischen Zwischenstufe. Abweichende spektroskopische Daten für das ursprüngliche Syntheseprodukt und den isolierten Naturstoff führten zu einer Revision der zuvor vorgeschlagenen Konfiguration.
      PubDate: 2018-01-16T09:56:39.170077-05:
      DOI: 10.1002/ange.201711766
  • Mechanochemical Activation of Iron Cyano Complexes: A Prebiotic Impact
           Scenario for the Synthesis of α-Amino Acid Derivatives
    • Authors: Carsten Bolm; Rita Mocci, Christian Schumacher, Mathias Turberg, Francesco Puccetti, José G. Hernández
      Pages: 2447 - 2450
      Abstract: Mechanochemical activation of iron cyano complexes by ball milling results in the formation of HCN, which can be trapped and incorporated into α-aminonitriles. This prebiotic impact scenario can be extended by mechanochemically transforming the resulting α-aminonitriles into α-amino amides using a chemical route related to early Earth conditions.Präbiotischer (An)Stoß: Mithilfe von Mechanochemie wird ein präbiotisches Einschlagszenario zur Bildung von α-Aminosäure-Derivaten nachgestellt. Eisencyanokomplexe setzen bei der Behandlung in einer Kugelmühle HCN frei, das abgefangen und in α-Aminonitrile eingebaut werden kann.
      PubDate: 2018-02-05T09:59:52.962948-05:
      DOI: 10.1002/ange.201713109
  • MoP Nanoparticles Supported on Indium-Doped Porous Carbon: Outstanding
           Catalysts for Highly Efficient CO2 Electroreduction
    • Authors: Xiaofu Sun; Lu Lu, Qinggong Zhu, Congyi Wu, Dexin Yang, Chunjun Chen, Buxing Han
      Pages: 2451 - 2455
      Abstract: Electrochemical reduction of CO2 into value-added product is an interesting area. MoP nanoparticles supported on porous carbon were synthesized using metal–organic frameworks as the carbon precursor, and initial work on CO2 electroreduction using the MoP-based catalyst were carried out. It was discovered that MoP nanoparticles supported on In-doped porous carbon had outstanding performance for CO2 reduction to formic acid. The Faradaic efficiency and current density could reach 96.5 % and 43.8 mA cm−2, respectively, when using ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate as the supporting electrolyte. The current density is higher than those reported up to date with very high Faradaic efficiency. The MoP nanoparticles and the doped In2O3 cooperated very well in catalyzing the CO2 electroreduction.MoP-Nanopartikel auf In-dotiertem porösem Kohlenstoff sind hervorragend für die Reduktion von CO2 zu Formiat geeignet. Faraday-Wirkungsgrad und Stromdichte können 96.5 % bzw. 43.8 mA cm−2 erreichen, wenn eine ionische Flüssigkeit als Elektrolyt eingesetzt wird. MoP und der In-dotierte Kohlenstoffträger wirken bei dieser Reaktion ausgezeichnet zusammen.
      PubDate: 2018-02-02T02:51:45.893736-05:
      DOI: 10.1002/ange.201712221
  • Direkte Umwandlung von Estern in heterocyclische Fluorophore
    • Authors: Christian Fischer; Christof Sparr
      Pages: 2461 - 2465
      Abstract: Obwohl heterocyclische Fluorophore vielseitig eingesetzt werden, kann mit den derzeitigen Synthesemethoden nur ein Bruchteil der erwünschten Farbstoffdiversität zugänglich gemacht werden. Hier beschreiben wir eine modulare Methode, welche verschiedenste Carbonsäureester direkt in ein breites Spektrum an Heteroanthrylium-Fluorophore umwandelt. Die doppelte Addition von Heteroatom-verknüpften 1,5-difunktionellen Organomagnesium-Reagenzien an Ester führt nach dehydratisierender saurer Aufarbeitung zur Bildung von Acridinium-, Xanthylium- und SiR-Fluorophoren. Diese einstufige Synthesemethode liefert organische Photoredoxkatalysatoren für die duale Katalyse mit Nickel und Fluorophore, welche Fluoreszenzverstärkungsreaktionen zulassen.Ein Spektrum an Estern: Mit Heteroatom-verbrückten 1,5-difunktionellen Organomagnesium-Reagenzien wurden Carbonsäureester direkt in Acridinium-, Xanthylium- und SiR-Fluorophore umgesetzt. Durch die Vielfalt von Estern lassen sich die chemischen, photophysikalischen und elektrochemischen Eigenschaften der Fluorophore ideal modulieren und für die Photoredoxkatalyse oder Reaktionen zur Fluoreszenzverstärkung einsetzen.
      PubDate: 2018-01-29T05:00:34.542484-05:
      DOI: 10.1002/ange.201711296
  • Synthese α-chiraler Ketone und chiraler Alkane durch eine
           radikalisch/ionische Kreuzungsreaktion von Vinyl-Bor-At-Komplexen
    • Authors: Carolin Gerleve; Marvin Kischkewitz, Armido Studer
      Pages: 2466 - 2469
      Abstract: Vinyl-Bor-At-Komplexe, hergestellt aus Enantiomeren-angereicherten Alkylpinakolboronsäureestern, durchlaufen stereospezifische, radikalisch induzierte 1,2-Wanderungen in radikalisch/ionischen Kreuzungsreaktionen. In dieser Dreikomponentenreaktion können verschiedene kommerziell erhältliche Alkyliodide als Radikalvorstufen verwendet werden, und Licht fungiert als Ketteninitiator. Eine nachfolgende Oxidation oder Protodeborylierung führt zu wertvollen α-chiralen Ketonen und chiralen Alkanen mit exzellenten Enantiomerenreinheiten.Radikalisch und ionisch: Verschiedene Vinyl-Bor-At-Komplexe, einfach zugänglich aus dem entsprechenden Pinakolboronsäureester und Vinyllithium, reagieren in einer radikalisch/ionischen Kreuzungsreaktion zu sekundären Alkylboronsäureestern, die entweder zu wertvollen α-chiralen Ketonen oxidiert oder zu Alkanen protodeboryliert werden können. Die Produkte werden in guten Gesamtausbeuten mit exzellenter Stereospezifität isoliert. Pin=Pinakolat.
      PubDate: 2018-01-16T09:51:28.9508-05:00
      DOI: 10.1002/ange.201711390
  • Disilenylsilylen-Reaktivität eines Cyclotrisilens
    • Authors: Hui Zhao; Kinga Leszczyńska, Lukas Klemmer, Volker Huch, Michael Zimmer, David Scheschkewitz
      Pages: 2470 - 2474
      Abstract: Die hoch reaktiven Silicium-Kongenere des Cyclopropens, die Cyclotrisilene (c-Si3R4), reagieren typischerweise unter π-Addition an ihre Si=Si-Doppelbindung oder unter σ-Insertion in eine ihrer Si-Si-Einfachbindungen. Im Gegensatz dazu führt die Behandlung von c-Si3Tip4 (Tip=2,4,6-iPr3C6H2) mit Styrol und Benzil zur Ringöffnung des Dreirings zum formalen [1+2]- bzw. [1+4]-Cycloadditionsprodukt des isomeren Disilenysilylens mit der C=C-Bindung bzw. dem Diketon. Bei erhöhten Temperaturen setzt das [1+2]-Additionsprodukt Styrol frei, das in einer [2+2]-Cycloaddition mit c-Si3Tip4 zu der thermodynamisch stabileren Hausan-Spezies reagiert.Geschwindigkeit ist entscheidend, um den Ring des Peraryl-substituierten Cyclotrisilens (R=2,4,6-iPr3C6H2) zu öffnen und ihm die Disilenylsilylen-Reaktivität gegenüber Benzil und Styrol zu entlocken. Im Falle von Styrol wandelt sich das kinetische Produkt mit einem intakten R2Si=SiR-Substituenten bei erhöhten Temperaturen unter Loslösung von Styrol in das gesättigte thermodynamische Produkt um, was durch ein Kontrollexperiment im Vakuum bewiesen wird.
      PubDate: 2018-02-08T05:11:11.098145-05:
      DOI: 10.1002/ange.201711833
  • Aktive Anode auf Molybdänbasis für dehydrierende Kupplungen
    • Authors: Sebastian B. Beil; Timo Müller, Sydney B. Sillart, Peter Franzmann, Alexander Bomm, Michael Holtkamp, Uwe Karst, Wolfgang Schade, Siegfried R. Waldvogel
      Pages: 2475 - 2479
      Abstract: Es wurde ein leistungsfähiges aktives Anodensystem entwickelt, das in 1,1,1,3,3,3-Hexafluor-2-propanol (HFIP) eingesetzt werden kann. Die Molybdänanode bildet in HFIP eine kompakte, leitfähige und elektroaktive Schicht aus höhervalenten Molybdänspezies. Dieses System kann als Ersatz für leistungsfähige, aber stöchiometrisch notwendige MoV-Reagenzien in dehydrierenden Kupplungen von Arenen eingesetzt werden. Diese Elektrolyse ist nachhaltiger und ermöglicht die Umsetzung eines breiten Spektrums von aktivierten Arenen.Elektrochemisch betrieben und mit einer vergleichbaren Reaktivität wie in MoV-Reagenzien vermittelt ein neuartiges aktive System auf Basis einer Molybdänanode und 1,1,1,3,3,3-Hexafluor-2-propanol dehydrierenden Arenkupplungen.
      PubDate: 2018-02-05T10:16:12.918869-05:
      DOI: 10.1002/ange.201712718
  • RuBisCO-inspirierte CO2-Aktivierung und Umwandlung durch einen
    • Authors: Jens Langer; Andrea Hamza, Imre Pápai
      Pages: 2480 - 2483
      Abstract: Die Synthese eines neuen Iridium(I)-Komplexes mit dem Enamidophosphan-Anion dbuP− und seine einzigartige Reaktivität gegenüber CO2 werden vorgestellt. Der Komplex bindet zwei Äquivalente CO2 und initiiert dabei eine hoch selektive Reaktionskaskade, die reversibel zur Spaltung sowohl von CO2 als auch des Enamido-Liganden führt. Die computergestützte Analyse des Systems lässt auf die Bildung eines relativ stabilen CO2-Komplexes als Schlüsselintermediat der CO2-Spaltung schließen, was experimentell bestätigt werden konnte. Die untersuchte Umwandlung weist einige Parallelen zur enzymatischen CO2-Fixierung durch RuBisCO auf.CO2 peration: Die hochselektive Bindung und Transformation von CO2 durch einen Iridiumkomplex zeigt eindeutig kooperative Effekte zwischen den beiden involvierten CO2-Molekülen. Die reversible Transformation ähnelt in einigen Aspekten der CO2-Fixierung durch das Enzym RuBisCO.
      PubDate: 2018-01-29T08:51:00.563068-05:
      DOI: 10.1002/ange.201712893
  • Photokatalytische aerobe Phosphatierung von Alkenen
    • Authors: Christian Depken; Felix Krätzschmar, Rene Rieger, Katharina Rode, Alexander Breder
      Pages: 2484 - 2488
      Abstract: Es wurde ein katalytisches Verfahren für die direkte Phosphatierung einfacher unpolarisierter Alkene entwickelt, das erstmals die Nutzung von gewöhnlichen unaktivierten Phosphorsäurediestern als Phosphatquelle und O2 als terminales Oxidationmittel ermöglicht. Die Methode erlaubt einen direkten und höchst ökonomischen Aufbau von verschiedenen Allylphosphatestern. Im Vergleich zu herkömmlichen Verfahren zur Gewinnung von Phosphorsäureestern ist die aerobe Phosphatierung vollständig komplementär, da erstere zum Großteil auf der Verwendung von vorfunktionalisierten oder voraktivierten Reagenzien wie Alkoholen oder Phosphorylhalogeniden beruhen. Ermöglicht wird die Reaktion durch das katalytische Zusammenwirken eines Photokatalysators und einer Selen-π-Säure über eine Abfolge von Ein-Elektronen-Transferprozessen.Die aerobe dehydrierende Kupplung einfacher Hydrogenphosphate mit unaktivierten Alkenen gelang erstmals durch das katalytische Zusammenspiel eines Photokatalysators (PK) und einer Chalkogen-Lewis-Säure (Se) und bietet Zugang zu einem breiten Spektrum von Allylphosphaten. Neben der hohen Praxistauglichkeit und Chemoselektivität ermöglicht die Methode auch die einfache konsekutive Redoxalkylierung von Olefinen mit Organocupraten.
      PubDate: 2018-01-17T08:45:37.010288-05:
      DOI: 10.1002/ange.201711599
  • Die katalytische, asymmetrische Mukaiyama-Michael-Reaktion von
           Silylketenacetalen mit α,β-ungesättigten Methylestern
    • Authors: Tim Gatzenmeier; Philip S. J. Kaib, Julia B. Lingnau, Richard Goddard, Benjamin List
      Pages: 2489 - 2493
      Abstract: α,β-Ungesättigte Ester sind einfach zugängliche, aber schwierig zu aktivierende Substrate in der asymmetrischen Katalyse. Wir stellen hier eine effiziente, allgemeine und hochenantioselektive Mukaiyama-Michael-Reaktion von Silylketenacetalen mit α,β-ungesättigten Methylestern vor, die durch silylierte Imidodiphosphorimidat(IDPi)-Lewis-Säuren katalysiert wird.Über 35 Millionen Jahre Reaktionshalbwertzeit ohne Katalyse: Zimtsäureester gehören zu den am wenigsten elektrophilen Michael-Akzeptoren und reagieren selbst mit starken Nukleophilen wie Silylketenacetalen extrem langsam ohne Katalyse. Hochaktive silylierte Imidodiphosphorimidat(IDPi)-Lewis-Säuren ermöglichen nun effiziente Mukaiyama-Michael-Reaktionen mit niedrigen Katalysatorbeladungen und exzellenter Kontrolle der Diastereo- und Enantioselektivität.
      PubDate: 2018-01-26T07:35:57.825327-05:
      DOI: 10.1002/ange.201712088
  • Reduktive Aminierung durch Photoredoxkatalyse über polaritätsangepassten
    • Authors: Xingwei Guo; Oliver S. Wenger
      Pages: 2494 - 2498
      Abstract: Die Anregung eines RuII-Photosensibilisators in Gegenwart von Ascorbinsäure führt zur Reduktion von Iminium-Ionen zu elektronenreichen α-Aminoalkylradikalen, die durch einen thiolvermittelten Wasserstoffatomtransfer (HAT) in Produkte der reduktiven Aminierung umgewandelt werden. Mit diesem Konzept erfolgt die photoredoxkatalytische reduktive Aminierung von Carbonylverbindungen mit Aminen in guten bis hervorragenden Ausbeuten, wobei viele funktionelle Gruppen toleriert werden. Die drei entscheidenden Besonderheiten dieser Arbeit sind: (i) Das schnelle Abfangen elektronenreicher α-Aminoalkylradikale durch polaritätsangepassten HAT, (ii) die eigentliche Methode der reduktiven Aminierung durch Photoredoxkatalyse und (iii) die Anwendung dieser neuen Methode für zeitlich und räumlich kontrollierte Reaktionen auf festen Trägermaterialen, wie durch das Anbringen eines Fluoreszenzfarbstoffs auf einem aktivierten Celluloseträger durch photoredoxkatalytische reduktive Aminierung veranschaulicht wird.Licht ersetzt Hydrid: Eine Methode für die photoredoxkatalytische reduktive Aminierung wird vorgestellt, wobei neben Untersuchungen zum Anwendungsbereich auch detaillierte mechanistische Studien präsentiert werden. Die neue Methode ermöglicht zeitliche und räumliche Reaktionskontrolle (z. B. auf festen Trägern).
      PubDate: 2018-01-18T07:55:30.489756-05:
      DOI: 10.1002/ange.201711467
  • Lichtgesteuerte Freisetzung von Chemikalien aus polymeren Nano- und
    • Authors: Christoph Englert; Ivo Nischang, Cornelia Bader, Philipp Borchers, Julien Alex, Michael Pröhl, Martin Hentschel, Matthias Hartlieb, Anja Traeger, Georg Pohnert, Stephanie Schubert, Michael Gottschaldt, Ulrich S. Schubert
      Pages: 2504 - 2508
      Abstract: Ein Diol-Linker mit Benzoin-Grundkörper wurde synthetisiert und zur Herstellung biokompatibler Polyester verwendet, die bei Bedarf durch UV-Licht vollständig abgebaut werden können. Um eine definierte Einkapselung von strukturell unterschiedlichen organischen Verbindungen in den hergestellten polymeren Materialien und einen gut kontrollierbaren Polymerabbauprozess zu ermöglichen, wurde eine umfassende strukturelle Optimierung der Monomerlinkereinheit durchgeführt. Die Verfolgung der Freisetzungskinetik verkapselter Modellverbindungen aus den polymeren Nano- und Mikropartikelbehältern wurde durch konfokale Laser-Scanning-Mikroskopie als grundsätzlicher Nachweis für gewünschte Anwendungen ermöglicht. Die physikochemischen Eigenschaften der Modellverbindungen reichen dabei von vollständig hydrophil bis vollständig hydrophob. Die nachgewiesene Biokompatibilität der verwendeten Polyester und ihrer Abbauprodukte ermöglichen weitere Anwendungen, z. B. als intelligente Verpackung von UV-empfindlichen pharmazeutisch oder ernährungsrelevanten Substanzen oder auch für räumlich selektive Selbstheilungsprozesse.Chemikalien auf Wunsch: Biokompatible Polyester wurden synthetisiert, die durch UV-Licht vollständig abgebaut werden können. Die Herstellung von Nano- und Mikropartikeln ermöglicht die definierte Verkapselung von organischen Verbindungen und einen kontrollierten Abbauprozess. Entsprechende Partikel können für anspruchsvolle Anwendungen, z. B. für die smarte Verpackung von UV-sensitiven pharmazeutischen Komponenten oder für räumlich selektive Selbstheilungsprozesse eingesetzt werden.
      PubDate: 2018-01-16T09:55:53.530709-05:
      DOI: 10.1002/ange.201710756
  • Kontrollierte Polymermikrostruktur in anionischer Polymerisation durch
    • Authors: Elisabeth Rieger; Jan Blankenburg, Eduard Grune, Manfred Wagner, Katharina Landfester, Frederik R. Wurm
      Pages: 2509 - 2513
      Abstract: Eine ideale, statistische anionische Copolymerisation wird durch physikalische Trennung der beiden Monomere in Kompartimente einer Emulsion gezwungen, um so Gradientencopolymere zu bilden. Das eine Monomer (M) ist vorzugsweise in den Tröpfchen löslich, während das andere (D) die kontinuierliche Phase einer DMSO-in-Cyclohexan-Emulsion bevorzugt. Die lebende anionische Copolymerisation von zwei aktivierten Aziridinen ist auf die DMSO-Kompartimente beschränkt, da die Polymerisation selektiv in diesen Tröpfchen stattfindet. Über die Verdünnung der kontinuierlichen Phase wird die lokale Konzentration von Monomer D in den Tröpfchen bestimmt und folglich der Gradient des resultierenden Copolymers. Die Copolymerisationen in der Emulsion werden durch Echtzeit-1H-NMR-Kinetiken überwacht, was die Änderung der Copolymerisationsparameter beider Monomere bei Verdünnung der kontinuierlichen Phase von ideal statistischen Copolymeren zu Gradientencopolymeren zeigt.Die selektive Löslichkeit von zwei Monomeren in einer DMSO:Cyclohexan-Emulsion erzwingt die Bildung einstellbarer Gradientencopolymere.
      PubDate: 2018-01-18T07:50:36.417754-05:
      DOI: 10.1002/ange.201710417
  • Die gemeinsamen Zwischenprodukte von Sauerstoffentwicklung und Auflösung
           während der Wasserelektrolyse an Iridium
    • Authors: Olga Kasian; Jan-Philipp Grote, Simon Geiger, Serhiy Cherevko, Karl J. J. Mayrhofer
      Pages: 2514 - 2517
      Abstract: Dem Wissen über Reaktionsmechanismen beim Katalysatorabbau während der Sauerstoffentwicklung kommt eine Schlüsselrolle bei der Weiterentwicklung von effizienteren und stabileren Elektrolyseuren zu, da die korrosiven Bedingungen an der Anode selbst für vielversprechende Materialien auf Iridium-Basis problematisch sind. Der Auflösungsmechanismus ist von komplexer Natur, und Zusammenhänge mit der Sauerstoffentwicklung sind wenig erforscht. Die Kopplung einer Rasterflusszelle mit Massenspektrometrie ermöglicht es, Sauerstoffentwicklungs- und Abbauprodukte in situ zu detektieren. Demnach sind bei hohen anodischen Potentialen mehrere Auflösungswege möglich, welche auch die Bildung von gasförmigem IrO3 beinhalten. Auf der Basis der experimentellen Daten werden mögliche Reaktionswege der, durch Sauerstoffentwicklung bedingten, Auflösung von Iridium aufgezeigt und die Rolle von gemeinsamen Intermediaten dieser Reaktionen diskutiert.Mögliche Reaktionswege der Iridium-Auflösung werden auf Basis von gemeinsamen Zwischenprodukten mit der Sauerstoffentwicklung vorgeschlagen. Abhängig von der Art der Elektrode und des Potentials sind mindestens drei Auflösungswege möglich. Bei hohen Stromdichten durchlaufen beide Reaktionen die Bildung von flüchtigem IrO3. Die Hemmung seiner Hydrolyse kann eine Strategie zur Verbesserung der Elektrodenstabilität während der Sauerstoffentwicklung werden.
      PubDate: 2018-02-05T10:18:51.020247-05:
      DOI: 10.1002/ange.201709652
  • Lanthanoidkomplexe mit Trizink-Kronenether als Katalysatoren für die
           alternierende Copolymerisation von Epoxid und CO2: eine durch
           Carboxylat-Anionen kontrollierte Telomerisierung
    • Authors: Haruki Nagae; Ryota Aoki, Shin-nosuke Akutagawa, Julian Kleemann, Risa Tagawa, Tobias Schindler, Gyeongshin Choi, Thomas P. Spaniol, Hayato Tsurugi, Jun Okuda, Kazushi Mashima
      Pages: 2518 - 2522
      Abstract: Eine neue Familie von Heterometallkatalysatoren auf Basis von dreifach metallierten makrocyclischen Tris(salen)-Liganden und Seltenerdmetallen wurde hergestellt und strukturell charakterisiert. Das LaZn3-System mit seinen anionischen Liganden wie Acetat spielt eine zentrale Rolle bei der katalysierten alternierenden Copolymerisation von Cyclohexenoxid (CHO) und CO2 und liefert ein Produkt mit einem hohen Gehalt an Carbonatverknüpfungen. Bei den Lanthanoiden zeigt das CeZn3-System eine hohe katalytische Aktivität mit einer Wechselzahl (TOF) von über 370 h−1. Die NMR-spektroskopische Analyse des Komplexes und die Bestimmung der Endgruppen im Polymer weisen auf einen schnellen Austausch der Acetatliganden hin. Die koordinierten Acetate werden nicht nur untereinander, sondern auch gegen zugesetzte Carboxylat-Anionen ausgetauscht. Mit solch einzigartigen Eigenschaften ist dieses System das erste Beispiel für eine als Telomerisierung ablaufende Copolymerisation von CHO und CO2.Homogene Heterometallkomplexe auf Basis des Makrocyclus Trisaloph mit drei Zinkzentren und einem Seltenerdmetall zeigte eine hohe katalytische Aktivität in der alternierenden Copolymerisation von Cyclohexenoxid und CO2 mit einem hohen Anteil an Carbonat-Wiederholungseinheiten. Das Carboxylat-Anion in Ammoniumsalzen initiierte die fortschreitende Telomerisierung zu Polycarbonat mit entsprechenden Carboxylaten.
      PubDate: 2018-01-17T08:51:15.478885-05:
      DOI: 10.1002/ange.201709218
  • Durch zwei Liganden ermöglichte nicht-dirigierte C-H-Olefinierung von
    • Authors: Hao Chen; Philipp Wedi, Tim Meyer, Ghazal Tavakoli, Manuel van Gemmeren
      Pages: 2523 - 2527
      Abstract: Die klassische Pd-katalysierte oxidative C-H-Olefinierung von Arenen, auch bekannt als die Fujiwara-Moritani-Reaktion, ist durch die Notwendigkeit von dirigierenden Gruppen am Substrat oder des Einsatzes des Arens im großen Überschuss, typischerweise als (Ko-)Lösungsmittel, eingeschränkt. Hier beschreiben wir die Entwicklung eines Katalysatorsystems, das durch das Zusammenwirken von zwei komplementären Liganden erstmals die Nutzung von Arenen ohne dirigierende Gruppen als limitierendes Reagenz ermöglicht. Die Reaktionen verlaufen unter einer Kombination aus sterischer und elektronischer Kontrolle und ermöglichen die Anwendung auf wertvolle Arene, die nicht in Überschuss eingesetzt werden müssen.Wie viele Liganden braucht man, um eine Bindung zu wechseln' Die Pd-katalysierte C-H-Olefinierung von Arenen als limitierende Reagenzien wird beschrieben. Die kombinierte Wirkung zweier Liganden, N-Acetylglycin und ein Pyridin, ermöglicht es, dass diese Fujiwara-Moritani-Reaktion, die klassisch das Aren als (Ko-)Lösungsmittel oder dirigierende Gruppen am Substrat benötigte, ohne diese Anforderungen unter sterischer/elektronischer Kontrolle abläuft.
      PubDate: 2018-01-26T07:36:04.701218-05:
      DOI: 10.1002/ange.201712235
  • Innenrücktitelbild: Cationic Metallo-Polyelectrolytes for Robust Alkaline
           Anion-Exchange Membranes (Angew. Chem. 9/2018)
    • Authors: Tianyu Zhu; Shichao Xu, Anisur Rahman, Emir Dogdibegovic, Peng Yang, Parasmani Pageni, Mohammad Pabel Kabir, Xiao-dong Zhou, Chuanbing Tang
      Pages: 2529 - 2529
      Abstract: Kationische Polyelektrolyte werden in alkalischen Brennstoffzellen als Anionenaustauschmembranen (AEMs) verwendet, um Kraftstoff in Elektrizität umzuwandeln. C. Tang et al. berichten in ihrer Zuschrift auf S. 2412 über eine Klasse von Metallopolyelektrolyten, die für chemisch inerte AEMs unter stark basischen Bedingungen konzipiert wurden. Die AEMs zeigen exzellente thermische, chemische und mechanische Stabilität sowie eine hohe Ionenleitfähigkeit.
      PubDate: 2018-01-31T03:09:40.526209-05:
      DOI: 10.1002/ange.201800722
  • Rücktitelbild: Seeded Polymerization through the Interplay of Folding and
           Aggregation of an Amino-Acid-based Diamide (Angew. Chem. 9/2018)
    • Authors: Soichiro Ogi; Kentaro Matsumoto, Shigehiro Yamaguchi
      Pages: 2530 - 2530
      Abstract: Ein Aminosäure-Diamid …… ist der Schlüssel zu einem supramolekularen Polymerisationsprozess. S. Ogi, K. Matsumoto und S. Yamaguchi zeigen in ihrer Zuschrift auf S. 2363, dass die spontane Aggregation (rechter Weg) von Diamiden in der gestreckten Form durch die Faltung der Diamideinheit über intramolekulare Wasserstoffbrückenbildung effektiv erschwert wird. Unter derartigen Ungleichgewichtsbedingungen kann der zeitliche Verlauf der Selbstorganisation über einen Impfansatz (linker Weg) gesteuert werden.
      PubDate: 2018-02-02T02:53:12.384005-05:
      DOI: 10.1002/ange.201800993
  • Europa und die Chemie voranbringen
    • Authors: Gilberte Chambaud
      Pages: 2286 - 2287
      Abstract: Für die Wissenschaftlerwelt sind die Reisemöglichkeiten, die den persönlichen Austausch zwischen Forschern begünstigen, von großer Bedeutung. Wesentliche Erfolge waren die Verschmelzung nationaler Zeitschriften zu erfolgreichen europäischen Journalen und die Schaffung der EuCheMS-Kongresse …” Lesen Sie mehr im Gast-Editorial von Gilberte Chambaud.
      PubDate: 2017-12-14T04:40:25.016843-05:
      DOI: 10.1002/ange.201709947
  • Shunai Che
    • Pages: 2306 - 2306
      Abstract: „Das Geheimnis, ein erfolgreicher Wissenschaftler zu sein, ist, bekannte Ergebnisse und Folgerungen zu hinterfragen. Mein liebstes Molekül ist die DNA mit ihren wunderschönen Strukturen und erstaunlichen Funktionalitäten ...“ Dies und mehr von und über Shunai Che finden Sie auf Seite 2306.
      PubDate: 2017-11-17T05:16:07.771887-05:
      DOI: 10.1002/ange.201711485
  • Cristina Nevado
    • Pages: 2307 - 2307
      Abstract: „Meine liebste Art, Urlaub zu machen, ist, in warmen Gewässern zu tauchen. Auf meine Karriere zurückblickend würde ich sagen, ich stehe eigentlich noch am Anfang, und die letzten zehn Jahre sind viel zu schnell vergangen! ...“ Dies und mehr von und über Cristina Nevado finden Sie auf Seite 2307.
      PubDate: 2017-12-20T04:56:52.301844-05:
      DOI: 10.1002/ange.201712494
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