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Publisher: John Wiley and Sons   (Total: 1580 journals)

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Showing 1 - 200 of 1580 Journals sorted alphabetically
Abacus     Hybrid Journal   (Followers: 13, SJR: 0.48, h-index: 22)
About Campus     Hybrid Journal   (Followers: 5)
Academic Emergency Medicine     Hybrid Journal   (Followers: 65, SJR: 1.385, h-index: 91)
Accounting & Finance     Hybrid Journal   (Followers: 47, SJR: 0.547, h-index: 30)
ACEP NOW     Free   (Followers: 1)
Acta Anaesthesiologica Scandinavica     Hybrid Journal   (Followers: 52, SJR: 1.02, h-index: 88)
Acta Archaeologica     Hybrid Journal   (Followers: 158, SJR: 0.101, h-index: 9)
Acta Geologica Sinica (English Edition)     Hybrid Journal   (Followers: 3, SJR: 0.552, h-index: 41)
Acta Neurologica Scandinavica     Hybrid Journal   (Followers: 5, SJR: 1.203, h-index: 74)
Acta Obstetricia et Gynecologica Scandinavica     Hybrid Journal   (Followers: 15, SJR: 1.197, h-index: 81)
Acta Ophthalmologica     Hybrid Journal   (Followers: 6, SJR: 0.112, h-index: 1)
Acta Paediatrica     Hybrid Journal   (Followers: 56, SJR: 0.794, h-index: 88)
Acta Physiologica     Hybrid Journal   (Followers: 6, SJR: 1.69, h-index: 88)
Acta Polymerica     Hybrid Journal   (Followers: 9)
Acta Psychiatrica Scandinavica     Hybrid Journal   (Followers: 35, SJR: 2.518, h-index: 113)
Acta Zoologica     Hybrid Journal   (Followers: 6, SJR: 0.459, h-index: 29)
Acute Medicine & Surgery     Hybrid Journal   (Followers: 4)
Addiction     Hybrid Journal   (Followers: 35, SJR: 2.086, h-index: 143)
Addiction Biology     Hybrid Journal   (Followers: 13, SJR: 2.091, h-index: 57)
Adultspan J.     Hybrid Journal   (SJR: 0.127, h-index: 4)
Advanced Energy Materials     Hybrid Journal   (Followers: 27, SJR: 6.411, h-index: 86)
Advanced Engineering Materials     Hybrid Journal   (Followers: 26, SJR: 0.81, h-index: 81)
Advanced Functional Materials     Hybrid Journal   (Followers: 51, SJR: 5.21, h-index: 203)
Advanced Healthcare Materials     Hybrid Journal   (Followers: 14, SJR: 0.232, h-index: 7)
Advanced Materials     Hybrid Journal   (Followers: 268, SJR: 9.021, h-index: 345)
Advanced Materials Interfaces     Hybrid Journal   (Followers: 6, SJR: 1.177, h-index: 10)
Advanced Optical Materials     Hybrid Journal   (Followers: 7, SJR: 2.488, h-index: 21)
Advanced Science     Open Access   (Followers: 5)
Advanced Synthesis & Catalysis     Hybrid Journal   (Followers: 17, SJR: 2.729, h-index: 121)
Advances in Polymer Technology     Hybrid Journal   (Followers: 13, SJR: 0.344, h-index: 31)
Africa Confidential     Hybrid Journal   (Followers: 21)
Africa Research Bulletin: Economic, Financial and Technical Series     Hybrid Journal   (Followers: 13)
Africa Research Bulletin: Political, Social and Cultural Series     Hybrid Journal   (Followers: 10)
African Development Review     Hybrid Journal   (Followers: 33, SJR: 0.275, h-index: 17)
African J. of Ecology     Hybrid Journal   (Followers: 15, SJR: 0.477, h-index: 39)
Aggressive Behavior     Hybrid Journal   (Followers: 15, SJR: 1.391, h-index: 66)
Aging Cell     Open Access   (Followers: 11, SJR: 4.374, h-index: 95)
Agribusiness : an Intl. J.     Hybrid Journal   (Followers: 6, SJR: 0.627, h-index: 14)
Agricultural and Forest Entomology     Hybrid Journal   (Followers: 16, SJR: 0.925, h-index: 43)
Agricultural Economics     Hybrid Journal   (Followers: 45, SJR: 1.099, h-index: 51)
AIChE J.     Hybrid Journal   (Followers: 31, SJR: 1.122, h-index: 120)
Alcoholism and Drug Abuse Weekly     Hybrid Journal   (Followers: 7)
Alcoholism Clinical and Experimental Research     Hybrid Journal   (Followers: 7, SJR: 1.416, h-index: 125)
Alimentary Pharmacology & Therapeutics     Hybrid Journal   (Followers: 33, SJR: 2.833, h-index: 138)
Alimentary Pharmacology & Therapeutics Symposium Series     Hybrid Journal   (Followers: 3)
Allergy     Hybrid Journal   (Followers: 51, SJR: 3.048, h-index: 129)
Alternatives to the High Cost of Litigation     Hybrid Journal   (Followers: 3)
American Anthropologist     Hybrid Journal   (Followers: 145, SJR: 0.951, h-index: 61)
American Business Law J.     Hybrid Journal   (Followers: 24, SJR: 0.205, h-index: 17)
American Ethnologist     Hybrid Journal   (Followers: 90, SJR: 2.325, h-index: 51)
American J. of Economics and Sociology     Hybrid Journal   (Followers: 28, SJR: 0.211, h-index: 26)
American J. of Hematology     Hybrid Journal   (Followers: 33, SJR: 1.761, h-index: 77)
American J. of Human Biology     Hybrid Journal   (Followers: 12, SJR: 1.018, h-index: 58)
American J. of Industrial Medicine     Hybrid Journal   (Followers: 16, SJR: 0.993, h-index: 85)
American J. of Medical Genetics Part A     Hybrid Journal   (Followers: 16, SJR: 1.115, h-index: 61)
American J. of Medical Genetics Part B: Neuropsychiatric Genetics     Hybrid Journal   (Followers: 4, SJR: 1.771, h-index: 107)
American J. of Medical Genetics Part C: Seminars in Medical Genetics     Partially Free   (Followers: 6, SJR: 2.315, h-index: 79)
American J. of Physical Anthropology     Hybrid Journal   (Followers: 37, SJR: 1.41, h-index: 88)
American J. of Political Science     Hybrid Journal   (Followers: 272, SJR: 5.101, h-index: 114)
American J. of Primatology     Hybrid Journal   (Followers: 15, SJR: 1.197, h-index: 63)
American J. of Reproductive Immunology     Hybrid Journal   (Followers: 3, SJR: 1.347, h-index: 75)
American J. of Transplantation     Hybrid Journal   (Followers: 17, SJR: 2.792, h-index: 140)
American J. on Addictions     Hybrid Journal   (Followers: 9, SJR: 0.843, h-index: 57)
Anaesthesia     Hybrid Journal   (Followers: 136, SJR: 1.404, h-index: 88)
Analyses of Social Issues and Public Policy     Hybrid Journal   (Followers: 10, SJR: 0.397, h-index: 18)
Analytic Philosophy     Hybrid Journal   (Followers: 18)
Anatomia, Histologia, Embryologia: J. of Veterinary Medicine Series C     Hybrid Journal   (Followers: 3, SJR: 0.295, h-index: 27)
Anatomical Sciences Education     Hybrid Journal   (Followers: 1, SJR: 0.633, h-index: 24)
Andrologia     Hybrid Journal   (Followers: 2, SJR: 0.528, h-index: 45)
Andrology     Hybrid Journal   (Followers: 2, SJR: 0.979, h-index: 14)
Angewandte Chemie     Hybrid Journal   (Followers: 196)
Angewandte Chemie Intl. Edition     Hybrid Journal   (Followers: 219, SJR: 6.229, h-index: 397)
Animal Conservation     Hybrid Journal   (Followers: 39, SJR: 1.576, h-index: 62)
Animal Genetics     Hybrid Journal   (Followers: 8, SJR: 0.957, h-index: 67)
Animal Science J.     Hybrid Journal   (Followers: 6, SJR: 0.569, h-index: 24)
Annalen der Physik     Hybrid Journal   (Followers: 5, SJR: 1.46, h-index: 40)
Annals of Anthropological Practice     Partially Free   (Followers: 2, SJR: 0.187, h-index: 5)
Annals of Applied Biology     Hybrid Journal   (Followers: 7, SJR: 0.816, h-index: 56)
Annals of Clinical and Translational Neurology     Open Access   (Followers: 1)
Annals of Human Genetics     Hybrid Journal   (Followers: 9, SJR: 1.191, h-index: 67)
Annals of Neurology     Hybrid Journal   (Followers: 47, SJR: 5.584, h-index: 241)
Annals of Noninvasive Electrocardiology     Hybrid Journal   (Followers: 2, SJR: 0.531, h-index: 38)
Annals of Public and Cooperative Economics     Hybrid Journal   (Followers: 9, SJR: 0.336, h-index: 23)
Annals of the New York Academy of Sciences     Hybrid Journal   (Followers: 5, SJR: 2.389, h-index: 189)
Annual Bulletin of Historical Literature     Hybrid Journal   (Followers: 13)
Annual Review of Information Science and Technology     Hybrid Journal   (Followers: 14)
Anthropology & Education Quarterly     Hybrid Journal   (Followers: 25, SJR: 0.72, h-index: 31)
Anthropology & Humanism     Hybrid Journal   (Followers: 17, SJR: 0.137, h-index: 3)
Anthropology News     Hybrid Journal   (Followers: 15)
Anthropology of Consciousness     Hybrid Journal   (Followers: 11, SJR: 0.172, h-index: 5)
Anthropology of Work Review     Hybrid Journal   (Followers: 11, SJR: 0.256, h-index: 5)
Anthropology Today     Hybrid Journal   (Followers: 90, SJR: 0.545, h-index: 15)
Antipode     Hybrid Journal   (Followers: 49, SJR: 2.212, h-index: 69)
Anz J. of Surgery     Hybrid Journal   (Followers: 7, SJR: 0.432, h-index: 59)
Anzeiger für Schädlingskunde     Hybrid Journal   (Followers: 1)
Apmis     Hybrid Journal   (Followers: 1, SJR: 0.855, h-index: 73)
Applied Cognitive Psychology     Hybrid Journal   (Followers: 70, SJR: 0.754, h-index: 69)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 7, SJR: 0.632, h-index: 58)
Applied Psychology     Hybrid Journal   (Followers: 206, SJR: 1.023, h-index: 64)
Applied Psychology: Health and Well-Being     Hybrid Journal   (Followers: 49, SJR: 0.868, h-index: 13)
Applied Stochastic Models in Business and Industry     Hybrid Journal   (Followers: 5, SJR: 0.613, h-index: 24)
Aquaculture Nutrition     Hybrid Journal   (Followers: 14, SJR: 1.025, h-index: 55)
Aquaculture Research     Hybrid Journal   (Followers: 31, SJR: 0.807, h-index: 60)
Aquatic Conservation Marine and Freshwater Ecosystems     Hybrid Journal   (Followers: 36, SJR: 1.047, h-index: 57)
Arabian Archaeology and Epigraphy     Hybrid Journal   (Followers: 11, SJR: 0.453, h-index: 11)
Archaeological Prospection     Hybrid Journal   (Followers: 12, SJR: 0.922, h-index: 21)
Archaeology in Oceania     Hybrid Journal   (Followers: 13, SJR: 0.745, h-index: 18)
Archaeometry     Hybrid Journal   (Followers: 27, SJR: 0.809, h-index: 48)
Archeological Papers of The American Anthropological Association     Hybrid Journal   (Followers: 15, SJR: 0.156, h-index: 2)
Architectural Design     Hybrid Journal   (Followers: 25, SJR: 0.261, h-index: 9)
Archiv der Pharmazie     Hybrid Journal   (Followers: 4, SJR: 0.628, h-index: 43)
Archives of Drug Information     Hybrid Journal   (Followers: 5)
Archives of Insect Biochemistry and Physiology     Hybrid Journal   (SJR: 0.768, h-index: 54)
Area     Hybrid Journal   (Followers: 12, SJR: 0.938, h-index: 57)
Art History     Hybrid Journal   (Followers: 246, SJR: 0.153, h-index: 13)
Arthritis & Rheumatology     Hybrid Journal   (Followers: 50, SJR: 1.984, h-index: 20)
Arthritis Care & Research     Hybrid Journal   (Followers: 26, SJR: 2.256, h-index: 114)
Artificial Organs     Hybrid Journal   (Followers: 1, SJR: 0.872, h-index: 60)
ASHE Higher Education Reports     Hybrid Journal   (Followers: 15)
Asia & the Pacific Policy Studies     Open Access   (Followers: 16)
Asia Pacific J. of Human Resources     Hybrid Journal   (Followers: 323, SJR: 0.494, h-index: 19)
Asia Pacific Viewpoint     Hybrid Journal   (Followers: 1, SJR: 0.616, h-index: 26)
Asia-Pacific J. of Chemical Engineering     Hybrid Journal   (Followers: 8, SJR: 0.345, h-index: 20)
Asia-pacific J. of Clinical Oncology     Hybrid Journal   (Followers: 6, SJR: 0.554, h-index: 14)
Asia-Pacific J. of Financial Studies     Hybrid Journal   (SJR: 0.241, h-index: 7)
Asia-Pacific Psychiatry     Hybrid Journal   (Followers: 4, SJR: 0.377, h-index: 7)
Asian Economic J.     Hybrid Journal   (Followers: 8, SJR: 0.234, h-index: 21)
Asian Economic Policy Review     Hybrid Journal   (Followers: 4, SJR: 0.196, h-index: 12)
Asian J. of Control     Hybrid Journal   (SJR: 0.862, h-index: 34)
Asian J. of Endoscopic Surgery     Hybrid Journal   (SJR: 0.394, h-index: 7)
Asian J. of Organic Chemistry     Hybrid Journal   (Followers: 6, SJR: 1.443, h-index: 19)
Asian J. of Social Psychology     Hybrid Journal   (Followers: 5, SJR: 0.665, h-index: 37)
Asian Politics and Policy     Hybrid Journal   (Followers: 12, SJR: 0.207, h-index: 7)
Asian Social Work and Policy Review     Hybrid Journal   (Followers: 5, SJR: 0.318, h-index: 5)
Asian-pacific Economic Literature     Hybrid Journal   (Followers: 5, SJR: 0.168, h-index: 15)
Assessment Update     Hybrid Journal   (Followers: 4)
Astronomische Nachrichten     Hybrid Journal   (Followers: 2, SJR: 0.701, h-index: 40)
Atmospheric Science Letters     Open Access   (Followers: 29, SJR: 1.332, h-index: 27)
Austral Ecology     Hybrid Journal   (Followers: 15, SJR: 1.095, h-index: 66)
Austral Entomology     Hybrid Journal   (Followers: 9, SJR: 0.524, h-index: 28)
Australasian J. of Dermatology     Hybrid Journal   (Followers: 8, SJR: 0.714, h-index: 40)
Australasian J. On Ageing     Hybrid Journal   (Followers: 6, SJR: 0.39, h-index: 22)
Australian & New Zealand J. of Statistics     Hybrid Journal   (Followers: 14, SJR: 0.275, h-index: 28)
Australian Accounting Review     Hybrid Journal   (Followers: 4, SJR: 0.709, h-index: 14)
Australian and New Zealand J. of Family Therapy (ANZJFT)     Hybrid Journal   (Followers: 3, SJR: 0.382, h-index: 12)
Australian and New Zealand J. of Obstetrics and Gynaecology     Hybrid Journal   (Followers: 47, SJR: 0.814, h-index: 49)
Australian and New Zealand J. of Public Health     Hybrid Journal   (Followers: 11, SJR: 0.82, h-index: 62)
Australian Dental J.     Hybrid Journal   (Followers: 7, SJR: 0.482, h-index: 46)
Australian Economic History Review     Hybrid Journal   (Followers: 4, SJR: 0.171, h-index: 12)
Australian Economic Papers     Hybrid Journal   (Followers: 29, SJR: 0.23, h-index: 9)
Australian Economic Review     Hybrid Journal   (Followers: 6, SJR: 0.357, h-index: 21)
Australian Endodontic J.     Hybrid Journal   (Followers: 3, SJR: 0.513, h-index: 24)
Australian J. of Agricultural and Resource Economics     Hybrid Journal   (Followers: 3, SJR: 0.765, h-index: 36)
Australian J. of Grape and Wine Research     Hybrid Journal   (Followers: 5, SJR: 0.879, h-index: 56)
Australian J. of Politics & History     Hybrid Journal   (Followers: 14, SJR: 0.203, h-index: 14)
Australian J. of Psychology     Hybrid Journal   (Followers: 18, SJR: 0.384, h-index: 30)
Australian J. of Public Administration     Hybrid Journal   (Followers: 408, SJR: 0.418, h-index: 29)
Australian J. of Rural Health     Hybrid Journal   (Followers: 5, SJR: 0.43, h-index: 34)
Australian Occupational Therapy J.     Hybrid Journal   (Followers: 72, SJR: 0.59, h-index: 29)
Australian Psychologist     Hybrid Journal   (Followers: 12, SJR: 0.331, h-index: 31)
Australian Veterinary J.     Hybrid Journal   (Followers: 20, SJR: 0.459, h-index: 45)
Autism Research     Hybrid Journal   (Followers: 36, SJR: 2.126, h-index: 39)
Autonomic & Autacoid Pharmacology     Hybrid Journal   (SJR: 0.371, h-index: 29)
Banks in Insurance Report     Hybrid Journal   (Followers: 1)
Basic & Clinical Pharmacology & Toxicology     Hybrid Journal   (Followers: 11, SJR: 0.539, h-index: 70)
Basic and Applied Pathology     Open Access   (Followers: 2, SJR: 0.113, h-index: 4)
Basin Research     Hybrid Journal   (Followers: 5, SJR: 1.54, h-index: 60)
Bauphysik     Hybrid Journal   (Followers: 2, SJR: 0.194, h-index: 5)
Bauregelliste A, Bauregelliste B Und Liste C     Hybrid Journal  
Bautechnik     Hybrid Journal   (Followers: 1, SJR: 0.321, h-index: 11)
Behavioral Interventions     Hybrid Journal   (Followers: 9, SJR: 0.297, h-index: 23)
Behavioral Sciences & the Law     Hybrid Journal   (Followers: 24, SJR: 0.736, h-index: 57)
Berichte Zur Wissenschaftsgeschichte     Hybrid Journal   (Followers: 9, SJR: 0.11, h-index: 5)
Beton- und Stahlbetonbau     Hybrid Journal   (Followers: 2, SJR: 0.493, h-index: 14)
Biochemistry and Molecular Biology Education     Hybrid Journal   (Followers: 6, SJR: 0.311, h-index: 26)
Bioelectromagnetics     Hybrid Journal   (Followers: 1, SJR: 0.568, h-index: 64)
Bioengineering & Translational Medicine     Open Access  
BioEssays     Hybrid Journal   (Followers: 10, SJR: 3.104, h-index: 155)
Bioethics     Hybrid Journal   (Followers: 14, SJR: 0.686, h-index: 39)
Biofuels, Bioproducts and Biorefining     Hybrid Journal   (Followers: 1, SJR: 1.725, h-index: 56)
Biological J. of the Linnean Society     Hybrid Journal   (Followers: 16, SJR: 1.172, h-index: 90)
Biological Reviews     Hybrid Journal   (Followers: 4, SJR: 6.469, h-index: 114)
Biologie in Unserer Zeit (Biuz)     Hybrid Journal   (Followers: 42, SJR: 0.12, h-index: 1)
Biology of the Cell     Full-text available via subscription   (Followers: 9, SJR: 1.812, h-index: 69)
Biomedical Chromatography     Hybrid Journal   (Followers: 6, SJR: 0.572, h-index: 49)
Biometrical J.     Hybrid Journal   (Followers: 5, SJR: 0.784, h-index: 44)
Biometrics     Hybrid Journal   (Followers: 36, SJR: 1.906, h-index: 96)
Biopharmaceutics and Drug Disposition     Hybrid Journal   (Followers: 10, SJR: 0.715, h-index: 44)
Biopolymers     Hybrid Journal   (Followers: 18, SJR: 1.199, h-index: 104)
Biotechnology and Applied Biochemistry     Hybrid Journal   (Followers: 45, SJR: 0.415, h-index: 55)
Biotechnology and Bioengineering     Hybrid Journal   (Followers: 160, SJR: 1.633, h-index: 146)
Biotechnology J.     Hybrid Journal   (Followers: 14, SJR: 1.185, h-index: 51)
Biotechnology Progress     Hybrid Journal   (Followers: 39, SJR: 0.736, h-index: 101)
Biotropica     Hybrid Journal   (Followers: 20, SJR: 1.374, h-index: 71)
Bipolar Disorders     Hybrid Journal   (Followers: 9, SJR: 2.592, h-index: 100)
Birth     Hybrid Journal   (Followers: 38, SJR: 0.763, h-index: 64)
Birth Defects Research Part A : Clinical and Molecular Teratology     Hybrid Journal   (Followers: 2, SJR: 0.727, h-index: 77)
Birth Defects Research Part B: Developmental and Reproductive Toxicology     Hybrid Journal   (Followers: 6, SJR: 0.468, h-index: 47)
Birth Defects Research Part C : Embryo Today : Reviews     Hybrid Journal   (SJR: 1.513, h-index: 55)
BJOG : An Intl. J. of Obstetrics and Gynaecology     Partially Free   (Followers: 243, SJR: 2.083, h-index: 125)

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Journal Cover Angewandte Chemie
  [196 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  [1580 journals]
  • Spata-13,17-dien-Synthase – ein Enzym mit Sesqui-, Di- und
           Sesterterpen-Synthase-Aktivität aus Streptomyces xinghaiensis
    • Authors: Jan Rinkel; Lukas Lauterbach, Jeroen S. Dickschat
      Abstract: Eine Terpensynthase aus dem marinen Bakterium Streptomyces xinghaiensis wurde charakterisiert, einschließlich einer vollen Strukturaufklärung ihrer Produkte aus verschiedenen Substraten. Weiterhin wurden detaillierte Untersuchungen des Enzymmechanismus durch Isotopenmarkierungsexperimente, Variationen des Metallcofaktors und Mutageneseexperimente durchgeführt. Die Daten zeigten eine Abhängigkeit der Mn2+-katalysierten Reaktion von der Gegenwart von Asp-217, einem Rest, der in anderen bakteriellen Terpensynthasen von einem hochkonservierten Glu eingenommen wird.Eine Terpensynthase aus Streptomyces xinghaiensis mit Sesqui-, Di- und Sesterterpen-Synthase-Aktivität wurde identifiziert. Der Enzymmechanismus wurde durch Isotopenmarkierungen untersucht. Ortsgerichtete Mutagenese deckte zuvor unerkannte, hochkonservierte Reste mit Bedeutung für die Katalyse auf. Einer dieser Reste wurde mit den Erfordernissen an den Metallcofaktor – Mg2+ oder Mn2+ – in Verbindung gebracht.
      PubDate: 2017-11-23T04:57:54.831029-05:
      DOI: 10.1002/ange.201711142
       
  • Organocatalytic Atroposelective Arylation of 2-Naphthylamines as a
           Practical Approach to Axially Chiral Biaryl Amino Alcohols
    • Authors: Ye-Hui Chen; Liang-Wen Qi, Fang Fang, Bin Tan
      Abstract: The first phosphoric acid catalyzed direct arylation of 2-naphthylamines with iminoquinones for the atroposelective synthesis of axially chiral biaryl amino alcohols has been developed. This reaction constitutes a highly functional-group-tolerant route for the rapid construction of enantioenriched axially chiral biaryl amino alcohols, and is a rare example of 2-naphthylamines acting as nucleophiles in an organocatalytic enantioselective transformation. Furthermore, the products, which feature various halogen atoms, provide access to structurally diverse axially chiral amino alcohols through further transformations.Die Phosphorsäure-katalysierte direkte Arylierung von 2-Naphthylaminen mit Iminochinonen ermöglicht die atropselektive Synthese von Biaryl-substituierten Aminoalkoholen mit axialer Chiralität. Viele funktionelle Gruppen werden in dieser Reaktion toleriert, die wiederum eines von wenigen Beispielen für die Verwendung von 2-Naphthylaminen als Nucleophile in einer organokatalysierten enantioselektiven Umsetzung ist.
      PubDate: 2017-11-23T04:57:14.013102-05:
      DOI: 10.1002/ange.201710537
       
  • Controlling the Host–Guest Interaction Mode through a Redox Stimulus
    • Authors: György Szalóki; Vincent Croué, Vincent Carré, Frédéric Aubriet, Olivier Alévêque, Eric Levillain, Magali Allain, Juan Aragó, Enrique Ortí, Sébastien Goeb, Marc Sallé
      Abstract: A proof-of-concept related to the redox-control of the binding/releasing process in a host–guest system is achieved by designing a neutral and robust Pt-based redox-active metallacage involving two extended-tetrathiafulvalene (exTTF) ligands. When neutral, the cage is able to bind a planar polyaromatic guest (coronene). Remarkably, the chemical or electrochemical oxidation of the host–guest complex leads to the reversible expulsion of the guest outside the cavity, which is assigned to a drastic change of the host–guest interaction mode, illustrating the key role of counteranions along the exchange process. The reversible process is supported by various experimental data (1H NMR spectroscopy, ESI-FTICR, and spectroelectrochemistry) as well as by in-depth theoretical calculations performed at the density functional theory (DFT) level.Stimuli-responsive metallierte Käfige: Ein selbstorganisierter redoxaktiver Käfig aus Platin und einem ausgedehnten Tetrathiafulvalen-Liganden kann reversibel in den stabilen tetrakationischen Zustand oxidiert werden. Durch Variation der Ladung von 0 bis +4 können die Bindung eines polyaromatischen Gasts im Hohlraum und seine Freigabe gesteuert werden.
      PubDate: 2017-11-23T04:56:52.542254-05:
      DOI: 10.1002/ange.201709483
       
  • The Effect of Methylammonium Iodide on the Supersaturation and Interfacial
           Energy of the Crystallization of Methylammonium Lead Triiodide Single
           Crystals
    • Authors: Bichen Li; Furkan H. Isikgor, Hikmet Coskun, Jianyong Ouyang
      Abstract: It is very important to study the crystallization of hybrid organic–inorganic perovskites because their thin films are usually prepared from solution. The investigation on the growth of perovskite films is however limited by their polycrystallinity. In this work, methylammonium lead triiodide single crystals grown from solutions with different methylammonium iodide (MAI):lead iodide (PbI2) ratios were investigated. We observed a V-shaped dependence of the crystallization onset temperature on the MAI:PbI2 ratio. This is attributed to the MAI effects on the supersaturation of precursors and the interfacial energy of the crystal growth. At low MAI:PbI2 ratio (
      PubDate: 2017-11-23T04:56:43.805384-05:
      DOI: 10.1002/ange.201710234
       
  • High-Magnesium Calcite Mesocrystals: Formation in Aqueous Solution under
           Ambient Conditions
    • Authors: Pao-Tao Yu; Chieh Tsao, Chun-Chieh Wang, Chun-Yu Chang, Chia-Hsin Wang, Jerry Chun Chung Chan
      Abstract: Mesocrystals of high-magnesian calcites are commonly found in biogenic calcites. Under ambient conditions, it remains challenging to prepare mesocrystals of high-magnesian calcite in aqueous solution. We report that mesocrystals of calcite with magnesium content of about 20 mol % can be obtained from the phase transformation of magnesian amorphous calcium carbonate (Mg-ACC) in lipid solution. The limited water content on the Mg-ACC surface would reduce the extent of the dissolution–reprecipitation process and bias the phase transformation pathway toward solid-state reaction. We infer from the selected area electron diffraction patterns and the dark-field transmission electron microscopic images that the formation of Mg-calcite mesocrystals occurs through solid-state secondary nucleation, for which the phase transformation is initiated near the mineral surface and the crystalline phase propagates gradually toward the interior part of the microspheres of Mg-ACC.Mesokristalle von Calcit mit hohem Mg-Gehalt wurden in wässriger Lösung unter Verwendung von Phospholipid-Additiven hergestellt. Die Dunkelfeldbilder mit dem Ursprung im (104)-Beugungspunkt legen nahe, dass zahlreiche Mg-Calcit-Nanokristallite die gleiche Orientierung haben.
      PubDate: 2017-11-23T04:56:39.576082-05:
      DOI: 10.1002/ange.201708507
       
  • O2-Aktivierung an Cerdioxid-Katalysatoren – Zur Bedeutung der
           kristallographischen Orientierung des Substrats
    • Authors: Chengwu Yang; Xiaojuan Yu, Stefan Heißler, Peter G. Weidler, Alexei Nefedov, Yuemin Wang, Christof Wöll, Thomas Kropp, Joachim Paier, Joachim Sauer
      Abstract: Das Verständnis der Sauerstoffaktivierung auf Metalloxiden auf atomarer Ebene ist eine der größten Herausforderungen der heterogenen Katalyse. Eine oberflächenwissenschaftliche Untersuchung an allen drei niedrigindizierten Einkristalloberflächen von Cerdioxid, dem vermutlich wichtigsten Redoxkatalysator, ermöglichte den direkten spektroskopischen Nachweis reaktiver Sauerstoffspezies an Fehlstellen an den reduzierten Oberflächen von CeO2(110) und CeO2(100). An CeO2(111), der thermodynamisch stabilsten Oberfläche dieses Oxids, wurden jedoch keine Superoxo- und Peroxo-Spezies gefunden. Mithilfe von Dichtefunktionalrechnungen konnten diese scheinbar widersprüchlichen Ergebnisse auf eine Migration von O-Leerstellen in das Innere der Einkristalle zurückgeführt werden, die jedoch nur im Fall von (111)-Substraten auftritt. Diese Beobachtungen beenden eine lang anhaltende Debatte über die Position von O-Leerstellen an Cerdioxidoberflächen und die Aktivierung von O2 auf Cerdioxid-Pulvern.Ein Rätsel ist gelöst: IRRAS-Daten zur Sauerstoffaktivierung an Oxid-Einkristalloberflächen belegen, in Verbindung mit theoretischen Studien, die Bildung zahlreicher Superoxo- und Peroxo-Spezies an reduzierten CeO2(110)- und CeO2(100)-Oberflächen, nicht jedoch an CeO2(111). Dieser Widerspruch erklärt sich aus der Diffusion von O-Leerstellen unter der Oberfläche.
      PubDate: 2017-11-23T04:56:15.95048-05:0
      DOI: 10.1002/ange.201709199
       
  • Bilaterale Preise europäischer chemischer Gesellschaften /
           Catalán-Sabatier-Preis und Grignard-Wittig-Vorlesung: Paolo Samorì /
           Elhuyar-Goldschmidt-Preis für Karsten Meyer / Gamboa-Winkler-Preis
    • PubDate: 2017-11-23T04:50:28.902132-05:
      DOI: 10.1002/ange.201711378
       
  • Arjan W. Kleij
    • PubDate: 2017-11-23T04:50:21.100687-05:
      DOI: 10.1002/ange.201711677
       
  • Quaternary β2,2-Amino Acids: Catalytic Asymmetric Synthesis and
           Incorporation into Peptides by Fmoc-Based Solid Phase Peptide Synthesis
    • Authors: Jin-Sheng Yu; Hidetoshi Noda, Masakatsu Shibasaki
      Abstract: β-Amino acid incorporation has emerged as a promising approach to enhance the stability of parent peptides and to improve their biological activity. Owing to the lack of reliable access to β2,2-amino acids in a setting suitable for peptide synthesis, most contemporary research efforts focus on the use of β3- and certain β2,3-amino acids. Herein, we report a catalytic asymmetric synthesis of β2,2-amino acids and their incorporation into peptides by Fmoc-based solid phase peptide synthesis (Fmoc-SPPS). Construction of a quaternary carbon is accomplished by Pd-catalyzed decarboxylative allylation of 4-substituted isoxazolidin-5-ones. The N-O bond in the products not only acts as a traceless protecting group for β-amino acids but also undergoes amide formation with α-ketoacids derived from Fmoc-protected α-amino acids, providing expeditious access to α-β2,2-dipeptides ready for Fmoc-SPPS.
      PubDate: 2017-11-22T21:55:37.739004-05:
      DOI: 10.1002/ange.201711143
       
  • Photocatalytic Oxygen Evolution from Functional Triazine-based Polymers
           with Tunable Band Structure
    • Authors: Zhi-An Lan; Yuanxing Fang, Yongfan Zhang, Xinchen Wang
      Abstract: Conjugated polymers (CPs) are emerging and appealing light-harvesters for photocatalytic water splitting due to the adjustable bandgap and ease-processing properties. Here, we report an advanced mild synthesis of three conjugated triazine-based polymers (CTPs) with different chain length by increasing the quantity of electron-donated benzyl units in the backbone. Adjusting the chain length of CTPs enables the modulation of their electronic, optical and redox properties, resulting in the enhanced performance for photocatalytic oxygen evolution that is the more challenging half-reaction of water splitting due to the sluggish reaction kinetics. The results could stimulate interests in these functional polymers where a molecular engineering strategy enables the production of suitable semiconductor-redox energetics for oxygenic photosynthesis.
      PubDate: 2017-11-22T21:55:34.346431-05:
      DOI: 10.1002/ange.201711155
       
  • Katalytische Drei-Komponenten-Maschinen: Steuerung der katalytischen
           Aktivität mittels Maschinengeschwindigkeit
    • Authors: Michael Schmittel; Indrajit Paul, Abir Goswami, Nikita Mittal
      Abstract: Drei supramolekulare Gleitsysteme DS1-DS3 wurden als Zwei-Komponenten-Aggregate aus den Gleitern S1-S3 und der Plattform D mit ihren drei Zinkporphyrin-(ZnPor) Bindungsstellen erzeugt. Die Anbindung des zweifüßigen Gleiters an die Plattform variiert mit der Donorqualität und sterischen Hinderung an den Pyridin/Pyrimidin (pyr)-Gleitfüßen. Entsprechend bewegen sich die Gleiter mit unterschiedlichen Geschwindigkeiten über die drei Zinkporphyrine der Plattform: bei Raumtemperatur mit 32.2, 220 und 440 kHz. Die Zugabe von N-Methylpyrrolidin als Katalysator zu DS1-DS3 erzeugt katalytische Drei-Komponenten-Maschinen. Bei der Verwendung einer konjugierten Addition als Testreaktion kann man eine Korrelation zwischen der Maschinengeschwindigkeit und den Ausbeuten der katalytischen Reaktion feststellen. Mit abnehmender thermodynamischer Bindung des Gleiters nimmt sowohl die Frequenz der Gleitbewegung als auch die Ausbeute der katalytischen Reaktion zu.
      PubDate: 2017-11-22T14:20:48.633571-05:
      DOI: 10.1002/ange.201709644
       
  • Maximizing Catalysis of Nanoparticles via Their Monolayer Assembly on
           Nitrogen-doped Graphene
    • Authors: Chao Yu; Xuefeng Guo, Mengqi Shen, Bo Shen, Michelle Muzzio, Zhouyang Yin, Qing Li, Zheng Xi, Junrui Li, Christopher Takakazu Seto, Shouheng Sun
      Abstract: We report a facile interface assembly method to assemble a monolayer array of nitrogen-doped graphene (NG) and nanoparticles (NPs) and then to transfer the dual monolayers onto a solid substrate. Using 3 nm NiPd NPs as an example, we demonstrate that NiPd-NG-Si can function as a catalyst probe and show maximum NiPd catalysis for the hydrolysis of ammonia borane (H3NBH3, AB) with its TOF = 4896.8 h-1 and Ea = 18.8 kJ/mol. The NiPd-NG-Si is also highly active for catalyzing the synthesis of quinazolines in water, only 0.016 mol% is needed to give quantitative yields. Our assembly method can be extended to other graphene and NP catalyst materials, providing a new 2D NP catalyst platform for catalyzing reactions in one-pot with maximum efficiency.
      PubDate: 2017-11-22T13:50:36.618475-05:
      DOI: 10.1002/ange.201709815
       
  • Treten in der N-heterozyklischen Carben-Organokatalyse wirklich Carbene
           auf'
    • Authors: Sascha Gehrke; Oldamur Hollóczki
      Abstract: In der Organokatalyse werden häufig Azolium-Kationen in Anwesenheit einer Base eingesetzt, um wertvolle Syntheseschritte zu realisieren. Aufgrund der Annahme, dass durch Deprotonierung des Kations ein freies Carben entsteht, welches mit dem Substrat reagiert und somit dessen Reaktivität entscheidend beeinflusst, werden Reaktionen dieses Types als N-heterozyklische Carben-Katalyse bezeichnet. Wir können hier jedoch zeigen, dass ein Mechanismus, in dem das Azolium-Kation analog der elektrophilen aromatischen Substitution direkt mit dem Substrat reagiert und somit eine freie Carbenspezies vermieden wird, energetisch deutlich günstiger ist.Alternative identifiziert: Für die Organokatalyse mit N-heterozyklischen Carbenen (NHCs) wird ein neuartiger Reaktionsweg vorgestellt. Der Protonentransfer und die Herstellung der Bindung zwischen Katalysator und Substrat geschehen gleichzeitig in einem einzelnen Elementarschritt, ohne dass eine freie Carbenspezies in der Reaktionsmischung auftritt.
      PubDate: 2017-11-22T11:04:19.940442-05:
      DOI: 10.1002/ange.201708305
       
  • Herstellung von funktionalisierten Diaryl- und
           Diheteroaryl-Lanthanreagenzien mittels eines schnellen
           Halogen-Lanthan-Austausches
    • Authors: Andreas D. Benischke; Lucile Anthore-Dalion, Guillaume Berionni, Paul Knochel
      Abstract: Ausgehend von Aryl- und Heteroarylhalogeniden (X=Br, I) erlaubt nBu2LaMe einen schnellen und praktischen Halogen-Lanthan-Austausch, welcher zu funktionalisierten Diaryl- und Diheteroaryl-Lanthanderivaten führt. Deren anschließende Abfangreaktionen mit ausgewählten Elektrophilen, wie Ketonen, Aldehyden oder Amiden, gelangen reibungslos bei −50 °C in THF, und polyfunktionalisierte Alkohole und Carbonylderivate wurden erhalten. Kinetische Vergleichsexperimente zeigen einen ähnlichen Reaktivitätsverlauf wie bei einem Br-Mg-Austausch, jedoch machen um 106 höhere Austauschgeschwindigkeiten ihn eher vergleichbar mit einem Br-Li-Austausch.Lanthan als Alternative zu Lithium: Aryl- und Heteroarylhalogeniden gehen mit nBu2LaMe einen schnellen und praktischen Halogen-Lanthan-Austausch ein, der zu funktionalisierten Diaryl- und Diheteroaryl-Lanthanderivaten führt. Anschließende Abfangreaktionen mit ausgewählten Elektrophilen, wie Ketonen, Aldehyden oder Amiden, bei −50 °C in THF lieferten polyfunktionalisierte Alkohole und Carbonylderivate.
      PubDate: 2017-11-22T11:04:13.637108-05:
      DOI: 10.1002/ange.201709553
       
  • Cooperative Multifunctional Catalysts for Nitrone Synthesis: Platinum
           Nanoclusters in Amine-Functionalized Metal–Organic Frameworks
    • Authors: Xinle Li; Biying Zhang, Linlin Tang, Tian Wei Goh, Shuyan Qi, Alexander Volkov, Yuchen Pei, Zhiyuan Qi, Chia-Kuang Tsung, Levi Stanley, Wenyu Huang
      Abstract: Nitrones are key intermediates in organic synthesis and the pharmaceutical industry. The heterogeneous synthesis of nitrones with multifunctional catalysts is extremely attractive but rarely explored. Herein, we report ultrasmall platinum nanoclusters (PtNCs) encapsulated in amine-functionalized Zr metal–organic framework (MOF), UiO-66-NH2 (Pt@UiO-66-NH2) as a multifunctional catalyst in the one-pot tandem synthesis of nitrones. By virtue of the cooperative interplay among the selective hydrogenation activity provided by the ultrasmall PtNCs and Lewis acidity/basicity/nanoconfinement endowed by UiO-66-NH2, Pt@UiO-66-NH2 exhibits remarkable activity and selectivity, in comparison to Pt/carbon, Pt@UiO-66, and Pd@UiO-66-NH2. Pt@UiO-66-NH2 also outperforms Pt nanoparticles supported on the external surface of the same MOF (Pt/UiO-66-NH2). To our knowledge, this work demonstrates the first examples of one-pot synthesis of nitrones using recyclable multifunctional heterogeneous catalysts.Katalyse im Wechselspiel: Platin-Nanocluster (PtNCs), die in Amin-funktionalisiertem UiO-66-NH2 verkapselt sind (Pt@UiO-66-NH2), wirken als multifunktionelle Katalysatoren in der Ein-Topf-Tandemsynthese von Nitronen. Das kooperative Wechselspiel zwischen selektiver Hydrierungsaktivität der PtNCs und Lewis-Acidität/Lewis-Basizität/Nanoumgebung des MOF verleiht Pt@UiO-66-NH2 eine bemerkenswerte Aktivität und Selektivität.
      PubDate: 2017-11-22T11:04:02.617394-05:
      DOI: 10.1002/ange.201710164
       
  • Alkene 1,2-difunctionalization via Radical Alkenyl Migration
    • Authors: Xinjun Tang; Armido Studer
      Abstract: Transition metal-free radical α-perfluoroalkylation with accompanying vicinal β-alkenylation of unactivated alkenes is presented. These radical cascades proceed via 1,4 or 1,5-alkenyl migration by electron catalysis on readily accessed allylic alcohols. Reactions comprise a regioselective perfluoroalkyl radical addition with subsequent alkenyl migration and concomitant deprotonation to generate a ketyl radical anion that sustains the chain as a single electron transfer reducing reagent.
      PubDate: 2017-11-22T09:51:09.387442-05:
      DOI: 10.1002/ange.201710397
       
  • Mimicking class Ib Mn2 ribonucleotide reductase: a MnII2 complex and its
           reaction with superoxide
    • Authors: Adriana Magherusan, Ang Zhou, Erik Farquhar, Max Garcia Melchor, Brendan Twamley, Lawrence Que, Jr; Aidan Richard McDonald
      Abstract: Class Ib RNRs require superoxide anion (O2*-), rather than dioxygen (O2), to access a high-valent Mn2 oxidant. Complex 1 ([Mn2(O2CCH3)(N-Et-HPTB)](ClO4)2, N-Et-HPTB = N,N,N',N'-tetrakis(2-(1-ethylbenzimidazolyl))-2-hydroxy-1,3-diaminopropane) was synthesised in high yield (90%). 1 was reacted with O2*- at -40 °C resulting in the formation of a metastable species (2). 2 displayed electronic absorption features (λmax = 460, 610 nm) typical of a Mn-peroxide species, and a 29 line EPR signal typical of a MnIIMnIII entity. Mn K-edge X-ray absorption near-edge spectroscopy (XANES) suggested a formal oxidation state change of MnII2 in 1 to MnIIMnIII for 2. Electrospray ionisation mass spectrometry (ESI-MS) suggested 2 was a MnIIMnIII-peroxide complex. 2 was capable of oxidizing ferrocene and weak O-H bonds upon activation with proton donors. Our findings provide support for the postulated mechanism of O2*- activation at class Ib Mn2 RNRs.
      PubDate: 2017-11-22T08:26:33.615509-05:
      DOI: 10.1002/ange.201709806
       
  • On the Non-Metallicity of 2.2 nm Au246(SR)80 Nanoclusters
    • Authors: Meng Zhou; Chenjie Zeng, Yongbo Song, Jonathan W. Padelford, Gangli Wang, Matthew Y. Sfeir, Tatsuya Higaki, Rongchao Jin
      Abstract: The transition from molecular to plasmonic behaviour in metal nanoparticles with increasing size remains a central question in nanoscience. We report that the giant 246-gold-atom nanocluster (2.2 nm in gold core diameter) protected by 80 thiolate ligands is surprisingly non-metallic based on UV/Vis and femtosecond transient absorption spectroscopy as well as electrochemical measurements. Specifically, the Au246 nanocluster exhibits multiple excitonic peaks in transient absorption spectra and electron dynamics independent of the pump power, which are in contrast to the behaviour of metallic gold nanoparticles. Moreover, a prominent oscillatory feature with frequency of 0.5 THz can be observed in almost all the probe wavelengths. The phase and amplitude analysis of the oscillation suggests that it arises from the wavepacket motion on the ground state potential energy surface, which also indicates the presence of a small band-gap and thus non-metallic or molecular-like behaviour.Nichtmetallisches Metall' Ultraschnelle Studien zur Elektronen- und Phononendynamik von Au246(SR)80-Nanoclustern zeigen, dass Au246 – bei einem Durchmesser von immerhin 2.2 nm – noch nicht metallisch ist. Eine hervorstechende Oszillation mit einer Frequenz von 0.5 THz deutet auf die Existenz einer kleinen Bandlücke hin, und damit auf nichtmetallisches oder molekülartiges Verhalten.
      PubDate: 2017-11-22T06:05:26.007781-05:
      DOI: 10.1002/ange.201709095
       
  • Palladium-Catalyzed Intermolecular Acylation of Aryldiazoesters with
           ortho-Bromobenzaldehydes
    • Authors: Yinghua Yu; Qianqian Lu, Gui Chen, Chunsen Li, Xueliang Huang
      Abstract: In this work, we describe a palladium-catalyzed intermolecular O-acylation of α-diazoesters with ortho-bromo benzaldehydes. The C(sp2)-H bond activation of the aldehyde was enabled by migratory insertion of palladium carbene intermediate. As such, the diazoesters were found to act as modular three-atom units to build up the key seven-membered palladacycles, from which a variety of isocoumarin derivatives were produced after reductive elimination. Mechanistic experiments and DFT calculations have provided deep insights on the reaction pathway.
      PubDate: 2017-11-22T05:20:43.198366-05:
      DOI: 10.1002/ange.201710317
       
  • Frontispiz: Triaminotriborane(3): A Homocatenated Boron Chain Connected by
           B−B Multiple Bonds
    • Authors: Shogo Morisako; Rong Shang, Yohsuke Yamamoto, Hiroshi Matsui, Masayoshi Nakano
      Abstract: Borverbindungen In ihrer Zuschrift auf S. 15436 berichten Y. Yamamoto et al. über die Isolierung einer gebogenen Bor-Kette, in der drei Boratome über Mehrfachbindungen ohne zusätzliche Liganden verknüpft sind. Diese Spezies kann auch als ein Bis(borylen)-stabilisiertes Borylen aufgefasst werden.
      PubDate: 2017-11-22T04:35:44.165667-05:
      DOI: 10.1002/ange.201784861
       
  • Quantum refinement does not support dinuclear copper sites in crystal
           structures of particulate methane monooxygenase
    • Authors: Lili Cao; Octav Caldararu, Amy C Rosenzweig, Ulf Ryde
      Abstract: Particulate methane monooxygenase (pMMO) is one of the few enzymes that can activate methane. The metal content of this enzyme has been highly controversial with suggestions of a dinuclear Fe site or mono-, di- or trinuclear Cu sites. Crystal structures have shown a mono- or dinuclear Cu site, but the resolution is low and the geometry of the dinuclear sites is unusual. We have employed quantum refinement (i.e. crystallographic refinement enhanced with quantum-mechanical calculations) to improve the structure of the active site. We have compared a number of different mono- and dinuclear geometries, in some cases enhanced with more protein ligands or one or two water molecules to determine which structure fits two sets of crystallographic raw data best. In all cases, the best results are obtained with mononuclear Cu sites, occasionally with an extra water molecule. Thus, we conclude that there is no crystallographic support for a dinuclear Cu site in pMMO.
      PubDate: 2017-11-22T04:07:30.331875-05:
      DOI: 10.1002/ange.201708977
       
  • Jan-E. Bäckvall
    • PubDate: 2017-11-22T04:06:32.258584-05:
      DOI: 10.1002/ange.201711014
       
  • Three-Dimensional Anionic Cyclodextrin-Based Covalent Organic Frameworks
    • Authors: Yuanyuan Zhang; Jiyun Duan, Dou Ma, Pengfei Li, Siwu Li, Haiwei Li, Junwen Zhou, Xiaojie Ma, Xiao Feng, Bo Wang
      Abstract: Three-dimensional covalent organic frameworks (3D COFs) are promising crystalline materials with well-defined structures, high porosity, and low density; however, the limited choice of building blocks and synthetic difficulties have hampered their development. Herein, we used a flexible and aliphatic macrocycle, namely γ-cyclodextrin (γ-CD), as the soft struts for the construction of a polymeric and periodic 3D extended network, with the units joined via tetrakis(spiroborate) tetrahedra with various counterions. The inclusion of pliable moieties in the robust open framework endows these CD-COFs with dynamic features, leading to a prominent Li ion conductivity of up to 2.7 mS cm−1 at 30 °C and excellent long-term Li ion stripping/plating stability. Exchanging the counterions within the pores can effectively modulate the interactions between the CD-COF and CO2 molecules.Dreidimensionale anionische kovalente organische Gerüste (COFs) mit unterschiedlichen Gegenionen wurden aus aliphatischen flexiblen makrocyclischen γ-Cyclodextrin(γ-CD)-Einheiten aufgebaut, die über Spiroborat-Linker verknüpft wurden. Das CD-COF mit Li+ ist ein guter Lithiumionenleiter, und verschiedene Gegenionen führen zu unterschiedlichen Wechselwirkungen mit CO2.
      PubDate: 2017-11-22T04:06:25.332667-05:
      DOI: 10.1002/ange.201710633
       
  • Functional Cellular Mimics for the Spatiotemporal Control of Multiple
           Enzymatic Cascade Reactions
    • Authors: Xiaoling Liu; Petr Formanek, Brigitte Voit, Dietmar Appelhans
      Abstract: Next-generation therapeutic approaches are expected to rely on the engineering of biomimetic cellular systems that can mimic specific cellular functions. Herein, we demonstrate a highly effective route for constructing structural and functional eukaryotic cell mimics by loading pH-sensitive polymersomes as membrane-associated and free-floating organelle mimics inside the multifunctional cell membrane. Metabolism mimicry has been validated by performing successive enzymatic cascade reactions spatially separated at specific sites of cell mimics in the presence and absence of extracellular organelle mimics. These enzymatic reactions take place in a highly controllable, reproducible, efficient, and successive manner. Our biomimetic approach to material design for establishing functional principles brings considerable enrichment to the fields of biomedicine, biocatalysis, biotechnology, and systems biology.Stoffwechselmimikry in Zellmimetika: Multikompartiment-Systeme mit pH-responsiven Ada-Polymersomen als Mimetika von Organellen wurden entwickelt. Die Systeme wurden als Zellmimetika zur Nachahmung des zellulären Stoffwechsels eingesetzt, indem verschiedene Stimuli zur Regulierung enzymatischer Reaktionskaskaden und zur Steuerung der simultanen und/oder nachgeschalteten Freisetzung der verkapselten (therapeutischen) Moleküle integriert wurden.
      PubDate: 2017-11-22T04:06:11.73407-05:0
      DOI: 10.1002/ange.201708826
       
  • Room-Temperature-Phosphorescence-Based Dissolved Oxygen Detection by
           Core-Shell Polymer Nanoparticles Containing Metal-Free Organic Phosphors
    • Authors: Youngchang Yu; Min Sang Kwon, Jaehun Jung, Yingying Zeng, Mounggon Kim, Kyeongwoon Chung, Johannes Gierschner, Ji Ho Youk, Sergey M. Borisov, Jinsang Kim
      Abstract: The highly sensitive optical detection of oxygen including dissolved oxygen (DO) is of great interest in various applications. We devised a novel room-temperature-phosphorescence (RTP)-based oxygen detection platform by constructing core–shell nanoparticles with water-soluble polymethyloxazoline shells and oxygen-permeable polystyrene cores crosslinked with metal-free purely organic phosphors. The resulting nanoparticles show a very high sensitivity for DO with a limit of detection (LOD) of 60 nm and can be readily used for oxygen quantification in aqueous environments as well as the gaseous phase.O2 als Leuchtmittel: Ein Nachweissystem für gelösten Sauerstoff beruht auf Nanopartikeln mit wasserlöslicher Polymethyloxazolin-Schale und sauerstoffdurchlässigem Polystyrolkern, vernetzt über metallfreie, rein organische Phosphore. Die Kern-Schale-Nanopartikel eignen sich für die hoch empfindliche Sauerstoffquantifizierung in zahlreichen Umgebungen.
      PubDate: 2017-11-22T03:37:51.634962-05:
      DOI: 10.1002/ange.201708606
       
  • Mario Ruben
    • PubDate: 2017-11-22T03:37:37.641635-05:
      DOI: 10.1002/ange.201711461
       
  • Microwave-Assisted Synthesis of Heterocycles by Rhodium(III)-Catalyzed
           Annulation of N-Methoxyamides with α-Chloroaldehydes
    • Authors: Ji-Rong Huang; Carsten Bolm
      Abstract: α-Chloroaldehydes have been used as alkyne equivalents in rhodium-catalyzed syntheses of isoquinolones and 3,4-dihydroisoquinolins starting from N-methoxyamides. Compared to the existing technology, a complementary regioselectivity is achieved. Mechanistic investigations have been performed, and it was found that steric effects of both substrate and additive determine the product selectivity. Various other heterocycles, such as isoquinolines and lactones, can be prepared by transformation of the obtained products.Salzeffekt: α-Chloraldehyde dienen als Äquivalente für endständige Alkine in einer Synthese von Isochinolonen, 2-Pyridonen und 3,4-Dihydroisochinolinen, welche die Regioselektivität bekannter Prozesse umkehrt. Die Produkte sind nützlich für die Herstellung weiterer Heterocyclen. Das Anion eines zugesetzten Natriumsalzes scheint die Esterenolat-Bildung zu unterstützen oder durch Wasserstoffbrücken gebildete Aggregate zu stabilisieren.
      PubDate: 2017-11-22T03:13:00.924442-05:
      DOI: 10.1002/ange.201710776
       
  • Cyclic (Amino)(Phosphonium Bora-Ylide)Silanone: A Remarkable
           Room-Temperature-Persistent Silanone
    • Authors: Alfredo Rosas-Sánchez; Isabel Alvarado-Beltran, Antoine Baceiredo, Nathalie Saffon-Merceron, Stéphane Massou, Daisuke Hashizume, Vicenç Branchadell, Tsuyoshi Kato
      Abstract: A silanone substituted by bulky amino and phosphonium bora-ylide substituents has been isolated in crystalline form. Thanks to the exceptionally strong electron-donating phosphonium bora-ylide substituent, the lifetime at room temperature of the silanone is dramatically extended (t1/2=4 days) compared to the related (amino)(phosphonium ylide)silanone VI (t1/2=5 h), allowing easier manipulation and its use as precursor of new valuable silicon compounds. The interaction of silanone with a weak Lewis acid such as MgBr2 increases further its stability (no degradation after 3 weeks at room temperature).Ein Silanon mit sperrigen Amino- und Phosphoniumbor-Ylid-Substituenten wurde synthetisiert und in kristalliner Form isoliert. Der stark elektronenschiebende Ylid-Substituent verleiht der Verbindung eine lange Lebensdauer (t1/2=4 Tage). Die Wechselwirkung mit einer schwachen Lewis-Säure wie MgBr2 wirkt weiter stabilisierend, sodass nach 3 Wochen bei Raumtemperatur keine Zersetzung des Silanons beobachtet wurde.
      PubDate: 2017-11-22T03:12:51.305312-05:
      DOI: 10.1002/ange.201710358
       
  • Oxidation von organischen Substraten mit einem redoxaktiven
           Guanidinkatalysator
    • Authors: Ute Wild; Florian Schön, Hans-Jörg Himmel
      Abstract: Hier wird über die ersten Beispiele für die Verwendung von redoxaktiven Guanidinen als Katalysatoren bei der grünen Oxidation von organischen Substraten mit Sauerstoff berichtet. In einer Halbreaktion wird die oxidierte Form des redoxaktiven Guanidins in die reduzierte, protonierte Form umgewandelt, wodurch eine oxidative Dehydrierung des Substrats (3,5-Di-tert-butylcatecholo-Benzochinon, BenzoinBenzil und 2,4-Di-tert-butylphenolBiphenol) stattfindet. In der anderen Halbreaktion wird eine effiziente Reoxidation des Guanidins in den oxidierten Zustand mit molekularem Sauerstoff in Gegenwart eines Kupfercokatalysators erreicht. Die Ergebnisse ebnen den Weg für eine breitere Verwendung von redoxaktiven Guanidinen als Oxidationskatalysatoren.Die Kombination von hoher Brønsted-Basizität und Elektronendonor-Eigenschaften ermöglicht es, redoxaktive Guanidine als hervorragende organische Redoxkatalysatoren einzusetzen, wie die ersten katalytischen Oxidationsreaktionen mit molekularem Sauerstoff zeigen.
      PubDate: 2017-11-22T03:12:07.184514-05:
      DOI: 10.1002/ange.201709809
       
  • Record High-Nuclearity Polyoxoniobates: Discrete Nanoclusters {Nb114},
           {Nb81}, and {Nb52}, and Extended Frameworks Based on {Cu3Nb78} and
           {Cu4Nb78}
    • Authors: Lu Jin; Zeng-Kui Zhu, Yan-Lan Wu, Yan-Jie Qi, Xin-Xiong Li, Shou-Tian Zheng
      Abstract: A series containing the highest nuclearity polyoxoniobate (PONb) nanoclusters, ranging from dimers to tetramers, has been obtained. They include one 114-nuclear {Li8⊂Nb114O316}, one 81-nuclear {Li3K⊂Nb81O225}, and one 52-nuclear {H4Nb52O150}. The Nb nuclearity of these PONbs is remarkably larger than those of all known high-nuclearity PONbs (≤32). Furthermore, the introduction of 3d Cu2+ ions can lead to the generation of extended inorganic–organic hybrid frameworks built from novel, high-nuclearity, nanoscale heterometallic PONb building blocks {H3Cu3Nb78O222} or {H3Cu4(en)Nb78O222}. These building blocks also contain the largest number of Nb centers of any heterometallic PONbs reported to date. The synthesis of new-type PONbs has long been a challenging subject in PONb chemistry.Sehr große PONbs, von einer {Nb52}- über eine {Nb81}- zu einer {Nb114}-Spezies, wurden hergestellt. Durch Einführung von 3d-Ionen (Cu2+) werden ausgedehnte organisch-anorganische PONb-Hybridgerüste aufgebaut, die riesige {Cu3Nb78}- und {Cu4Nb78}-Heterometallnanocluster enthalten.
      PubDate: 2017-11-22T03:12:00.942666-05:
      DOI: 10.1002/ange.201709565
       
  • Rhodium(II)- or Copper(I)-Catalyzed Formal Intramolecular Carbene
           
    • Authors: Qi Zhou; Shichao Li, Yan Zhang, Jianbo Wang
      Abstract: A rhodium(II)- or copper(I)-catalyzed formal intramolecular carbene insertion into vinylic C(sp2)−H bonds is reported herein. This method provides straightforward access to 1H-indenes with high efficiency and excellent functional-group compatibility. Mechanistically, the reaction is proposed to involve the following sequence: metal carbene formation, intramolecular nucleophilic addition of the double bond to the electron-deficient carbene carbon atom, dearomatization, and finally a 1,5-H shift.Kurz und bündig: Eine Rhodium(II)- oder Kupfer(I)-katalysierte formale Carben-Insertion in vinylische C-H-Bindungen wurde entwickelt und für die kurze Synthese von 1H-Indenen genutzt (siehe Schema). Die Reaktion ist gut verträglich mit funktionellen Gruppen und folgt vermutlich einem stufenweisen Mechanismus aus nukleophiler Addition der Doppelbindung an das Metallcarben und Dearomatisierungs/Aromatisierungs-Prozessen.
      PubDate: 2017-11-22T03:11:51.333701-05:
      DOI: 10.1002/ange.201709375
       
  • Bifurcated Nickel-Catalyzed Functionalizations: Heteroarene C−H
           Activation with Allenes
    • Authors: Sachiyo Nakanowatari; Thomas Müller, João C. A. Oliveira, Lutz Ackermann
      Abstract: A unified strategy for nickel(0)-catalyzed C−H allylations, alkenylations, and dienylations has been realized through versatile hydroarylations of allenes with ample scope. Thus, an inexpensive nickel catalyst modified with a N-heterocyclic carbene ligand enabled the direct transformation of C−H bonds of biologically relevant imidazole and purine derivatives with full control of regio- and chemoselectivity.Einfache C-H-Aktivierung: Gegabelte Nickel(0)-katalysierte C-H-Allylierungen, Alkenylierungen und Dienylierungen wurden durch Hydroarylierung von Allenen unter vollständiger Kontrolle der Regio- und Chemoselektivität durchgeführt. Das Substratspektrum umfasst eine Vielzahl von Imidazol- und Purinderivaten.
      PubDate: 2017-11-22T03:11:41.908751-05:
      DOI: 10.1002/ange.201709087
       
  • Site-Specific Pre-Swelling-Directed Morphing Structures of Patterned
           Hydrogels
    • Authors: Zhi Jian Wang; Wei Hong, Zi Liang Wu, Qiang Zheng
      Abstract: Morphing materials have promising applications in various fields, yet how to program the self-shaping process for specific configurations remains a challenge. Herein we show a versatile approach to control the buckling of individual domains and thus the outcome configurations of planar-patterned hydrogels. By photolithography, high-swelling disc gels were positioned in a non-swelling gel sheet; the swelling mismatch resulted in out-of-plain buckling of the disc gels. To locally control the buckling direction, masks with holes were used to guide site-specific swelling of the high-swelling gel under the holes, which built a transient through-thickness gradient and thus directed the buckling during the subsequent unmasked swelling process. Therefore, various configurations of an identical patterned hydrogel can be programmed by the pre-swelling step with different masks to encode the buckling directions of separate domains.Unterschiedliche Strukturänderungen in photolithographisch gemusterten Hydrogelen wurden durch selektives Vorquellen von stark quellfähigen Bereichen vorprogrammiert. Dieser Schritt erzeugt einen vorübergehenden Dickegradienten und gibt die Wölbungsrichtung vor. Verschiedene Kombinationen lokalisierter Wölbungen in identisch gemusterten Hydrogelen ergaben verschiedene Strukturen.
      PubDate: 2017-11-22T03:11:31.527489-05:
      DOI: 10.1002/ange.201708926
       
  • Temperature-Mediated Template Release: Facile Growth of Copper(I) Mixed
           Ethynediide/Isopropylethynide Nanoclusters
    • Authors: Leon Li-Min Zhang; Thomas C. W. Mak
      Abstract: In the comproportionation reaction of CuIIX2 and Cu0 with isopropylacetylene (iPr−C≡C−H), the ethynediide species C22− is generated via concomitant C−H/C−C bond cleavage of the iPr−C≡C−H precursor under moderate temperature to direct the formation of CuI mixed ethynediide/isopropylethynide nanoclusters (potentially explosive). The active ethynediide dianion C22− exhibits chameleon-like templating behavior to form C2@Cum (m=6 (3, 4), 7 (2, 4), 8 (1)) central structural units for successive formation of {C22−⊂Cu24} (1, 2), {6 C22−⊂Cu48} (3), and {18 C22−⊂Cu92} (4) complexes. Bearing the highest C22− content, complex 4 features an unprecedented nanoscale Cu2C2 kernel. Furthermore, 1–3 exhibit structure-controlled photoluminescence in the solid state.Temperaturänderungen lösen die Freisetzung von Ethindiid, C22−, aus Isopropylacetylen unter C-H-/C-C-Bindungsspaltung aus, bei der gemischte Ethindiid/Alkinid-CuI-Nanocluster entstehen. Die Synthese von {C22−⊂Cu24}, {6 C22−⊂Cu48} und {18 C22−⊂Cu92} etabliert eine Klasse von Nanostrukturen, deren Kernzahl mit steigender Zahl an Ethindiid-Einheiten zunimmt.
      PubDate: 2017-11-22T03:11:23.925473-05:
      DOI: 10.1002/ange.201708760
       
  • A Tunable and Enantioselective Hetero-Diels–Alder Reaction Provides
           Access to Distinct Piperidinoyl Spirooxindoles
    • Authors: Samydurai Jayakumar; Kathrin Louven, Carsten Strohmann, Kamal Kumar
      Abstract: The active complexes of chiral N,N′-dioxide ligands with dysprosium and magnesium salts catalyze the hetero-Diels–Alder reaction between 2-aza-3-silyloxy-butadienes and alkylidene oxindoles to selectively form 3,3′- and 3,4′-piperidinoyl spirooxindoles, respectively, in very high yields and with excellent enantioselectivities. The exo-selective asymmetric cycloaddition successfully regaled the construction of sp3-rich and highly substituted natural-product-based spirooxindoles supporting many chiral centers, including contiguous all-carbon quaternary centers.Spirocyclisierung: DyIII- und MgII-Salze katalysieren in Kombination mit einem N,N′-Dioxid-Liganden hoch enantioselektive Hetero-Diels-Alder-Reaktionen von Silyloxy-2-azadienen mit Alkylidenoxindolen zu 3,3′- bzw. 3,4′-Piperidinoyl-Spirooxindolen in ausgezeichneten Ausbeuten. Boc=tert-Butoxycarbonyl, TBS=tert-Butyldimethylsilyl, Tf=Trifluormethansulfonyl.
      PubDate: 2017-11-22T03:11:16.392217-05:
      DOI: 10.1002/ange.201708355
       
  • Die Suche nach einkernigem Gold(II) und seine mögliche Rolle in
           Photokatalyse und Medizinalchemie
    • Authors: Katja Heinze
      Abstract: Die Chemie des Goldes wird von den allgegenwärtigen Oxidationsstufen +I und +III beherrscht. In einkernigen Goldverbindungen wird die Oxidationsstufe +II im Allgemeinen vermieden. In den letzten Jahren wurde Gold(II) wiederholt als Schlüsselintermediat in künstlichen Photosynthese-Systemen mit Gold(III)-Einheiten als Elektronenakzeptoren, in Gold-katalysierten Photoredoxreaktionen und in der Radikalchemie vorgeschlagen. Dieser Kurzaufsatz fasst alle bestätigten und charakterisierten offenschaligen Gold(II)-Komplexe zusammen. Aktuelle Erkenntnisse über Strukturmotive und Reaktivitätsmuster werden diskutiert. Spannende Entwicklungen auf den Gebieten der Photosynthese, der Photokatalyse und der Medizinalchemie werden umrissen.Gold(II) spielt in künstlichen Photosynthesesystemen mit Gold(III)-Einheiten als Elektronenakzeptoren, in der Gold-Photoredoxchemie und in der Gold-Radikalchemie eine Schlüsselrolle. Dieser Kurzaufsatz fasst die zweifelsfrei charakterisierten Gold(II)-Komplexe sowie sich abzeichnende Strukturmotive und Reaktivitätsmuster zusammen. Entwicklungen auf den Gebieten der Photosynthese, der Photokatalyse und der möglichen Wirkungsweise von Krebsmedikamenten werden umrissen.
      PubDate: 2017-11-22T03:11:05.090041-05:
      DOI: 10.1002/ange.201708349
       
  • Transition-Metal-Free Catalytic Hydrodefluorination of Polyfluoroarenes by
           Concerted Nucleophilic Aromatic Substitution with a Hydrosilicate
    • Authors: Kotaro Kikushima; Mary Grellier, Masato Ohashi, Sensuke Ogoshi
      Abstract: A transition-metal-free catalytic hydrodefluorination (HDF) reaction of polyfluoroarenes is described. The reaction involves direct hydride transfer from a hydrosilicate as the key intermediate, which is generated from a hydrosilane and a fluoride salt. The eliminated fluoride regenerates the hydrosilicate to complete the catalytic cycle. Dispersion-corrected DFT calculations indicated that the HDF reaction proceeds through a concerted nucleophilic aromatic substitution (CSNAr) process.Eine clevere Kombination: Die übergangsmetallfreie katalytische Hydrodefluorierung (HDF) von Polyfluorarenen gelingt mit einem Hydrosilicat-Katalysator, der in situ aus einem Hydrosilan und einem Fluoridion gebildet wird. Die Reaktion umfasst einen direkten Hydridtransfer aus dem Hydrosilicat durch konzertierte nukleophile aromatische Substitution (CSNAr; siehe Schema).
      PubDate: 2017-11-22T03:10:58.286595-05:
      DOI: 10.1002/ange.201708003
       
  • Polyproline as a Minimal Antifreeze Protein Mimic That Enhances the
           Cryopreservation of Cell Monolayers
    • Authors: Ben Graham; Trisha L. Bailey, Joseph R. J. Healey, Moreno Marcellini, Sylvain Deville, Matthew I. Gibson
      Abstract: Tissue engineering, gene therapy, drug screening, and emerging regenerative medicine therapies are fundamentally reliant on high-quality adherent cell culture, but current methods to cryopreserve cells in this format can give low cell yields and require large volumes of solvent “antifreezes”. Herein, we report polyproline as a minimum (bio)synthetic mimic of antifreeze proteins that is accessible by solution, solid-phase, and recombinant methods. We demonstrate that polyproline has ice recrystallisation inhibition activity linked to its amphipathic helix and that it enhances the DMSO cryopreservation of adherent cell lines. Polyproline may be a versatile additive in the emerging field of macromolecular cryoprotectants.Kein Kulturschock: Polyprolin imitiert Frostschutzproteine und inhibiert aufgrund seiner amphipathischen Helix die Eisrekristallisation, was zur besseren Kryokonservierung von Zellmonoschichten genutzt werdenkann. Polyprolin kann synthetisch und biosynthetisch hergestellt werden und bietet sich als ein makromolekulares Kryokonservierungsmittel für die Lagerung von Zellen und Geweben an.
      PubDate: 2017-11-22T03:10:50.730814-05:
      DOI: 10.1002/ange.201706703
       
  • Exploiting the strong hydrogen bond donor properties of the borinic acid
           functionality for fluoride anion recognition
    • Authors: Chang-Hong Chen; Francois Pierre Gabbai
      Abstract: Borinic acids have typically not been considered as hydrogen bond donor groups in molecular recognition. Here, we describe a bifunctional borane / borinic acid derivative (2) in which the two functionalities are connected by a 1,8-biphenylenediyl backbone. Anion binding studies reveal that 2 readily binds a fluoride anion via formation of a unique B-F···H-O-B hydrogen bond. This hydrogen bond is characterized by a short H-F distance of 1.79(3) Å and a large coupling constant 1JHF of 57.2 Hz. The magnitude of this interaction, which has also been investigated computationally, augments the fluoride anion binding properties of 2, making it compatible with aqueous environments.
      PubDate: 2017-11-21T11:50:37.876318-05:
      DOI: 10.1002/ange.201709494
       
  • On the Use of Polyelectrolytes and Polymediators in Organic
           Electrosynthesis
    • Authors: Benjamin Schille; Niels Ole Giltzau, Robert Francke
      Abstract: Although organic electrosynthesis is generally considered to be a green method, the necessity for excess amounts of supporting electrolyte constitutes a severe drawback. Furthermore, the employment of redox mediators represents an additional separation problem. In this context, we have explored the applicability of soluble polyelectrolytes and polymediators using the TEMPO-mediated transformation of alcohols to carbonyl compounds as test reaction. Catalyst benchmarking based on CV studies indicates that the redox-active polymer can compete with molecularly defined TEMPO species. While a high efficiency of the alcohol oxidation was achieved in preparative-scale electrolysis, our polymer-based approach allows for the separation of both mediator and supporting electrolyte in a single membrane filtration step. Moreover, we have shown that both components can be reused for multiple cycles.
      PubDate: 2017-11-21T11:20:38.767695-05:
      DOI: 10.1002/ange.201710659
       
  • Silicon-based dielectric metamaterials: Focus on the current synthetic
           challenges
    • Authors: Maria Letizia De Marco; Sanaa Semlali, Brian A. Korgel, Philippe Barois, Glenna L. Drisko, Cyril Aymonier
      Abstract: Metamaterials have optical properties that are unprecedented in nature. They have opened new horizons in light manipulation, with the ability to bend, focus, and completely reflect, transmit or absorb an incident wave front. Optically active metamaterials in particular could be used for applications ranging from 3D information storage, more efficient photovoltaic cells, high security watermarks, and fiber optics. Silicon (Si) particles are some of the most promising building blocks for optically active metamaterials, with high scattering efficiency coupled to low light absorption for visible frequencies. However, to date ideal Si building blocks cannot be produced using bulk synthesis techniques, and thus metamaterial construction is currently confounded. The key to unleashing the potential of Si metamaterials is to find a route to produce Si building blocks between 75-200 nm in diameter that are uniform in size and shape, crystalline, have few impurities and little to no porosity. This review provides theoretical background about Si optical properties for metamaterials, an overview of current synthetic methods and provides direction towards the most promising routes to ideal Si particles for metamaterials.
      PubDate: 2017-11-21T11:20:23.207113-05:
      DOI: 10.1002/ange.201709044
       
  • A Metal-Organic Framework with Exceptional Activity for C-H Bond Amination
    • Authors: Le Wang; Douglas W Agnew, Xiao Yu, Joshua S Figueroa, Seth Mason Cohen
      Abstract: The development of catalysts capable of fast, robust C-H bond amination under mild conditions is an unrealized goal despite substantial progress in the field of C-H activation in recent years. Here we describe a Mn-based metal-organic framework (CPF-5) that promotes the direct amination of C-H bonds with exceptional activity. CPF-5 is capable of functionalizing C-H bonds in an intermolecular fashion with unrivaled catalytic stability producing an unrivaled>105 turnovers.
      PubDate: 2017-11-21T10:51:22.559045-05:
      DOI: 10.1002/ange.201709420
       
  • Cobalt-Catalyzed Electrophilic Amination of Aryl- and Heteroaryl-Zinc
           Pivalates with N-Hydroxylamine Benzoates
    • Authors: Yi-Hung Chen; Simon Graßl, Paul Knochel
      Abstract: Aryl- and heteroaryl-zinc pivalates are aminated with O-benzoylhydroxylamines at 25 °C within 2-4 h in the presence of 2-5% CoCl2*2LiCl furnishing the corresponding tertiary arylated or heteroarylated amines in good yields. This electrophilic amination provides also an access to diarylamines and aryl(heteroaryl)amines. A new tuberculosis drug candidate (Q203) was prepared in 6 steps and 56% overall yield using this cobalt-catalyzed amination as the key step.
      PubDate: 2017-11-21T10:51:06.951227-05:
      DOI: 10.1002/ange.201710931
       
  • Liquid Photonic Crystals for Mesopore Detection
    • Authors: Biting Zhu; Qianqian Fu, Ke Chen, Jianping Ge
      Abstract: Nitrogen adsorption-desorption for mesopore characterization requires the using of expensive instrument, time-consuming process and consumption of liquid nitrogen. Here, a new method was developed to measure the pore parameters through mixing of mesoporous substance with supersaturated SiO2 colloidal solution at different temperatures, followed by quick measurement of reflection changes of the precipitated liquid photonic crystals. Pore volumes and diameters of mesoporous silica were measured according to the positive correlation between unit mass reflection change (Δλ/m) and pore volume (V), and the negative correlation between average absorption temperature (T) and pore diameter (D). This new method may provide an alternative method for fast, convenient and economical characterization of mesoporous materials.
      PubDate: 2017-11-21T09:50:55.252015-05:
      DOI: 10.1002/ange.201710456
       
  • Superconductivity in a Cu(II) based coordination polymer with perfect
           kagomè structure
    • Authors: Xing Huang; Shuai Zhang, Liyao Liu, Lei Yu, Genfu Chen, Wei Xu, Daoben Zhu
      Abstract: Highly crystalline material of Copper (II) benzenehexathiolate coordination polymer (Cu-BHT) has been prepared. Its two dimensional kagomè structure has been confirmed by powder x-ray diffraction (PXRD), high-resolution transmission electron microscope (HRTEM) and high-resolution scanning transmission electron microscope (STEM). The as-prepared sample exhibits bulk superconductivity at ~ 0.25 K which is confirmed by the zero resistivity, AC magnetic susceptibility and specific heat measurements. Another diamagnetic transition at ~ 3K suggests that there is a second superconducting phase which may be associated to the single layer or few-layer of Cu-BHT. It is the first time that superconductivity has been discovered in the coordination polymers.
      PubDate: 2017-11-21T08:52:01.911061-05:
      DOI: 10.1002/ange.201707568
       
  • Wässrige Goldüberwachsung von Silbernanopartikeln: Vereinigung der
           plasmonischen Eigenschaften von Silber mit der Funktionalität von Gold
    • Authors: Martin Mayer; Anja Maria Steiner, Falk Röder, Petr Formanek, Tobias A. F. König, Andreas Fery
      Abstract: Bis heute war es nicht möglich, die optische Güte von Silbernanopartikeln mit Eigenschaften wie chemischer Stabilität, Oberflächenmodifizierbarkeit und kontrollierter Synthese in Verbindung zu bringen. Wir präsentieren eine Synthesemethode, die zukünftige Entwicklungen in Informations-, Energie- und Medizintechnologie ermöglicht, in denen optische oder elektronische Eigenschaften eine zentrale Rolle spielen. Dafür kombinieren wir die goldtypischen Eigenschaften mit der Plasmonik von Silber in einem rein wasserbasierten Au/Ag/Au-Kern-Schale-Schale-System. Die Dispersität der Nanopartikel wird durch maskierte Goldkerne vorgegeben, wobei die Optik von Silber bestimmt wird. Die Überwachsung mit einer sehr dünnen, schützenden Goldschicht verleiht Oxidationsstabilität und Oberflächenfunktionalität, ohne die optischen Eigenschaften des Silbers zu beeinträchtigen. Damit werden die optische Güte von Silber und die chemische Stabilität von Gold vereint – ohne Limitierung auf eine Morphologie.Optische Güte und chemische Stabilität: In einem allgemeinen Syntheseansatz wird die Dispersität durch die maskierten Goldkerne vorgegeben, während die Optik von Silber bestimmt wird. Die erneute Überwachsung mit einer sehr dünnen, schützenden Goldschicht ermöglicht Oxidationsstabilität und Oberflächenfunktionalität ohne die durch Silber gewonnenen optischen Eigenschaften zu beeinträchtigen.
      PubDate: 2017-11-21T03:31:43.187136-05:
      DOI: 10.1002/ange.201708398
       
  • Understanding LiOH Chemistry in a Ruthenium-Catalyzed Li–O2 Battery
    • Authors: Tao Liu; Zigeng Liu, Gunwoo Kim, James T. Frith, Nuria Garcia-Araez, Clare P. Grey
      Abstract: Non-aqueous Li–O2 batteries are promising for next-generation energy storage. New battery chemistries based on LiOH, rather than Li2O2, have been recently reported in systems with added water, one using a soluble additive LiI and the other using solid Ru catalysts. Here, the focus is on the mechanism of Ru-catalyzed LiOH chemistry. Using nuclear magnetic resonance, operando electrochemical pressure measurements, and mass spectrometry, it is shown that on discharging LiOH forms via a 4 e− oxygen reduction reaction, the H in LiOH coming solely from added H2O and the O from both O2 and H2O. On charging, quantitative LiOH oxidation occurs at 3.1 V, with O being trapped in a form of dimethyl sulfone in the electrolyte. Compared to Li2O2, LiOH formation over Ru incurs few side reactions, a critical advantage for developing a long-lived battery. An optimized metal-catalyst–electrolyte couple needs to be sought that aids LiOH oxidation and is stable towards attack by hydroxyl radicals.Energiespeicher der nächsten Generation: Die Ru-katalysierte Bildung von LiOH und dessen Zersetzungsreaktionen werden in einer Li-O2-Batterie mit zugesetztem Wasser demonstriert. Der Batteriemechanismus wurde durch Isotopenmarkierung aufgeklärt.
      PubDate: 2017-11-21T03:31:25.21615-05:0
      DOI: 10.1002/ange.201709886
       
  • In-Situ Microfluidic Study of Biphasic Nanocrystal Ligand-Exchange
           Reactions Using an Oscillatory Flow Reactor
    • Authors: Yi Shen; Milad Abolhasani, Yue Chen, Lisi Xie, Lu Yang, Connor W. Coley, Moungi G. Bawendi, Klavs F. Jensen
      Abstract: Oscillatory flow reactors provide a surface energy-driven approach for automatically screening reaction conditions and studying reaction mechanisms of biphasic nanocrystal ligand-exchange reactions. Sulfide and cysteine ligand-exchange reactions with as-synthesized CdSe quantum dots (QDs) are chosen as two model reactions. Different reaction variables including the new-ligand-to-QD ratio, the size of the particles, and the original ligand type are examined systematically. Based on the in situ-obtained UV/Vis absorption spectra during the reaction, we propose two different exchange pathways for the sulfide exchange reaction.Oszillatorische Flussreaktoren wurden zum automatisierten Screening von Reaktionskinetiken und zur Untersuchung der Reaktionsmechanismen des Ligandenaustauschs an CdSe-Quantenpunkten (QDs) in einem Zweiphasensystem eingesetzt. In situ während des Prozesses aufgenommene UV/Vis-Absorptionsspektren weisen auf zwei unterscheidbare Reaktionswege hin.
      PubDate: 2017-11-21T03:31:16.271106-05:
      DOI: 10.1002/ange.201710899
       
  • Nickel(0)-Catalyzed Hydroarylation of Styrenes and 1,3-Dienes with
           Organoborons
    • Authors: Qi-Lin Zhou; Li-Jun Xiao, Lei Cheng, Wei-Min Feng, Mao-Lin Li, Jian-Hua Xie
      Abstract: The Ni-catalyzed hydroarylation of styrenes and 1,3-dienes with organoborons has been developed. The reaction offers a highly selective approach to the diarylalkanes and allylarenes under redox-neutral condition. In this hydroarylation reaction, a new strategy that uses easily available proton of methanol to generate active catalyst species Ni-H was developed. The Ni-catalyzed hydroarylation, combining with a Ir-catalyzed C-H borylation, affords a very efficient and straightforward access to retinoic acid receptor agonist.
      PubDate: 2017-11-20T23:20:36.27312-05:0
      DOI: 10.1002/ange.201710735
       
  • Dose Dependencies and Biocompatibility of Renal Clearable Gold
           Nanoparticles
    • Authors: Jie Zheng; Jing Xu, Mengxiao Yu, Chuanqi Peng, Phoebe Carter, Jia Tian, Xuhui Ning, Qinhan Zhou, Qiu Tu, Greg Zhang, Anthony Dao, Xingya Jiang, Payal Kapur, Jer-Tsong Hsieh, Xudong Zhao, Pengyu Liu
      Abstract: While dose dependencies in pharmacokinetics and clearance are often observed in clinically used small molecules, very few studies have been dedicated to the understandings of potential dose-dependent in vivo transport of nanomedicines. Here we report that the pharmacokinetics and clearance of renal clearable gold nanoparticles (GS-AuNPs) are strongly dose-dependent once injection doses are above 15 mg/kg: high dose expedited the renal excretion and shortened the blood retention. As a result, the no-observed-adverse-effect-level (NOAEL) of GS-AuNPs was>1000 mg/kg in CD-1 mice. The efficient renal clearance and high compatibility can be translated to the non-human primates: no adverse effects were observed within 90 days after intravenous injection of 250 mg/kg GS-AuNPs. These fundamental understanding of dose effect on the in vivo transport of ultrasmall AuNPs open up a pathway to maximize their biomedical potentials and minimize their toxicity in the future clinical translation.
      PubDate: 2017-11-20T22:51:07.974045-05:
      DOI: 10.1002/ange.201710584
       
  • Integrated Transmission Electron and Single-Molecule Fluorescence
           Microscopy Correlates Reactivity with Ultrastructure in a Single Catalyst
           Particle
    • Authors: Frank C. Hendriks; Sajjad Mohammadian, Zoran Ristanović, Sam Kalirai, Florian Meirer, Eelco T. C. Vogt, Pieter C. A. Bruijnincx, Hans C. Gerritsen, Bert M. Weckhuysen
      Abstract: Establishing structure–activity relationships in complex, hierarchically structured nanomaterials, such as fluid catalytic cracking (FCC) catalysts, requires characterization with complementary, correlated analysis techniques. An integrated setup has been developed to perform transmission electron microscopy (TEM) and single-molecule fluorescence (SMF) microscopy on such nanostructured samples. Correlated structure–reactivity information was obtained for 100 nm thin, microtomed sections of a single FCC catalyst particle using this novel SMF-TEM high-resolution combination. High reactivity in a thiophene oligomerization probe reaction correlated well with TEM-derived zeolite locations, while matrix components, such as clay and amorphous binder material, were found not to display activity. Differences in fluorescence intensity were also observed within and between distinct zeolite aggregate domains, indicating that not all zeolite domains are equally active.Struktur-Reaktivitäts-Beziehungen von Partikeln für katalytisches Cracken wurden durch integrierte Einzelmolekülfluoreszenzmikroskopie und Rasterelektronenmikroskopie untersucht, um korrelierte, hochaufgelöste Informationen zu erhalten. Ähnlich scheinende Zeolithdomänen zeigen Unterschiede in der Reaktivität.
      PubDate: 2017-11-20T14:00:55.65148-05:0
      DOI: 10.1002/ange.201709723
       
  • Catalytic dibenzocyclooctene synthesis via cobalt(III)-carbene radical and
           ortho-quinodimethane intermediates
    • Authors: Colet te Grotenhuis; Naudin van den Heuvel, Jarl Ivar van der Vlugt, Bas de Bruin
      Abstract: Metalloradical activation of N-tosyl hydrazones 1 (o-benzallyl-aryl-tosylhydrazones), using [Co(TPP)] as a catalyst (TPP = tetraphenylporphyrin), allows controlled exploitation of single-electron reactivity of the redox non-innocent carbene intermediate. This method offers a novel route to prepare 8-membered rings, using base metal catalysis to construct a series of unique dibenzocyclooctenes via selective CcarbeneCaryl cyclization, producing the desired 8 membered ring products in good to excellent yields. A large variety of aromatic substituents is tolerated. The proposed reaction mechanism involves intramolecular HAT to Co(III)-carbene radical intermediates, followed by dissociation of o quinodimethides undergoing 8π-cyclisation. The mechanism is supported by DFT calculations and the presence of radical-type intermediates was confirmed by trapping experiments.
      PubDate: 2017-11-20T10:21:50.488478-05:
      DOI: 10.1002/ange.201711028
       
  • Iron(II)-Catalyzed Direct Synthesis of NH Sulfoximines from Sulfoxides
    • Authors: Hao Yu; Zhen Li, Carsten Bolm
      Abstract: Free NH-sulfoximines have directly been prepared from sulfoxides by iron catalysis applying a readily available, shelf-stable hydroxylamine triflic acid salt. No additional oxidant is needed, and the substrate scope is wide including a range of heterocyclic compounds.
      PubDate: 2017-11-20T10:21:16.755248-05:
      DOI: 10.1002/ange.201710498
       
  • Gram-Scale Synthesis of the (-)-Sparteine Surrogate and (-)-Sparteine
    • Authors: James D Firth; Steven J Canipa, Peter O'Brien, Leigh Ferris
      Abstract: An 8-step, gram-scale synthesis of the (-)-sparteine surrogate (22% yield, with just 3 chromatographic purifications) and a 10-step, gram-scale synthesis of (-)-sparteine (31% yield) are reported. Both syntheses proceed with complete diastereocontrol and allow access to either antipode. Since the syntheses do not rely on natural product extraction, our work addresses long-term supply issues relating to these widely used chiral ligands.
      PubDate: 2017-11-20T09:21:07.280588-05:
      DOI: 10.1002/ange.201710261
       
  • Nanoscale Trimetallic Metal-Organic Frameworks Enable Efficient Oxygen
           Evolution Electrocatalysis
    • Authors: Xiaoqing Huang
      Abstract: Metal-organic frameworks (MOFs) are a class of promising materials for diverse catalysis, but they are usually not directly employed for oxygen evolution electrocatalysis. Most reports focus on using MOFs as templates to in-situ create efficient electrocatalysts via annealing. Herein, we prepared a series of Fe/Ni/-based trimetallic MOFs (Fe/Ni/Co(Mn)-Material of Institute Lavoisier (MIL-53)) by solvothermal synthesis, which can be directly adopted as electrocatalysts. It was revealed that the Fe/Ni/Co(Mn)-MIL-53 exhibited volcano-type oxygen evolution reaction (OER) activity as a function of compositions. The optimized Fe/Ni2.4/Co0.4-MIL-53 can reach the current density of 20 mA*cm-2 at low overpotential of 236 mV with small Tafel slope of 52.2 mV*dec-1. The OER performance of these MOFs can be further enhanced by directly being grown on nickel foam (NF), in which the optimized Fe/Ni/Mn0.4-MIL-53/NF exhibits low overpotential of 290 mV at 500 mA*cm-2 as well as high durability.
      PubDate: 2017-11-20T09:20:57.967827-05:
      DOI: 10.1002/ange.201711376
       
  • Von Lithium- zu Natriumionenbatterien: Vorteile, Herausforderungen und
           Überraschendes
    • Authors: Prasant Kumar Nayak; Liangtao Yang, Wolfgang Brehm, Philipp Adelhelm
      Abstract: Die mobile und stationäre Energiespeicherung durch wiederaufladbare Batterien ist ein Thema von breiter gesellschaftlicher und ökonomischer Bedeutung. Die wichtigste Technologie in diesem Bereich ist die Lithiumionenbatterie (LIB), jedoch muss man davon ausgehen, dass ein massiv wachsender LIB-Markt ernsten Druck auf Ressourcen und Lieferketten ausüben wird. Seit kurzem richtet sich die Aufmerksamkeit daher auch wieder auf die Natriumionenbatterie (SIB), die eine preisgünstige Alternative darstellen könnte, die weniger anfällig für Ressourcen- und Versorgungsrisiken ist. Auf dem Papier scheint der Austausch von Lithium durch Natrium in einer Batterie unkompliziert, jedoch erlebt man in der Praxis oft unvorhersehbare Überraschungen. Was geschieht, wenn in Elektrodenreaktionen Lithium durch Natrium ersetzt wird' Dieser Aufsatz bietet einen aktuellen Überblick über das Redoxverhalten von Materialien bei ihrer Verwendung als Elektroden in LIBs bzw. SIBs. Die Vorteile und Herausforderungen im Zusammenhang mit der Verwendung von Natrium anstelle von Lithium werden diskutiert.Natriumionenbatterien: Die Nachfrage nach Batterien wird in Anbetracht der zu erwartenden Märkte für Elektrofahrzeuge und stationäre Energiespeicherung stark ansteigen. Seit kurzem richtet sich die Aufmerksamkeit auch wieder auf die Natriumionenbatterie, die eine preisgünstige Alternative zur Lithiumionenbatterie darstellen könnte. Dieser Aufsatz diskutiert die oftmals überraschenden Folgen des Austauschs von Li+ durch Na+ in einer Batterie.
      PubDate: 2017-11-20T07:57:38.491707-05:
      DOI: 10.1002/ange.201703772
       
  • Paleo-inspired systems: Durability, Sustainability and Remarkable
           Properties
    • Authors: Loïc Bertrand; Claire Gervais, Admir Masic, Luc Robbiola
      Abstract: We designate as paleo-inspiration, the process of mimicking properties of specific interest (mechanical, optical, structural, etc.) observed in ancient and historical systems. For instance, recovery in archaeology or paleontology identifies materials that are a posteriori extremely resilient to alteration. This is all the more enthusing that many ancient materials were synthesized in soft chemical ways, often using low energy resources, and sometimes rudimentary manufacturing equipment. In this review, we highlight ancient systems as a source of inspiration for innovative conception in the Anthropocene.
      PubDate: 2017-11-20T07:52:10.634623-05:
      DOI: 10.1002/ange.201709303
       
  • Ru(II)-Catalyzed Synthesis of Spiro Benzofuranones via Decarbonylative
           Annulation Reaction
    • Authors: Partha P. P Kaishap; Gauri Duarah, Bipul Sarma, Dipak Chetia, Sanjib Gogoi
      Abstract: The first decarbonylative insertion of alkyne through C-H/C-C activation of six membered compounds is reported. This Ru-catalyzed reaction of 3-hydroxy-2-phenyl-chromones with alkynes works most efficiently in the presence of ligand PPh3 to provide spiro-indenebenzofuranones. Unlike the previously reported metal-catalyzed decarbonylative annulation reactions, in the present decarbonylative annulation reaction, the annulation occurs before extrusion of carbon monoxide.
      PubDate: 2017-11-20T07:26:09.799883-05:
      DOI: 10.1002/ange.201710049
       
  • A Supramolecular Capsule for Reversible Polysulfide Storage/Delivery in
           Lithium-Sulfur Batteries
    • Authors: Jin Xie; Hong-Jie Peng, Jia-Qi Huang, Wen-Tao Xu, Xiang Chen, Qiang Zhang
      Abstract: Supramolecular materials, in which small organic molecules are assembled into regular structures by non-covalent interactions, attract tremendous interests because of their highly tunable functional groups and porous structure. Supramolecular adsorbents are expected to fully expose their abundant adsorptive sites in a dynamic framework. In this contribution, we introduced cucurbit[6]uril as a supramolecular capsule for reversible storage/delivery of mobile polysulfides in lithium-sulfur (Li-S) batteries to control undesirable polysulfide shuttle. The Li-S battery equipped with the supramolecular capsules retains a high Coulombic efficiency and shows a large increase in capacity from 300 to 900 mAh g−1 at a sulfur loading of 4.2 mg cm−2. The implementation of supramolecular capsules offers insights into intricate multi-electron-conversion reactions and manifests as an effective and efficient strategy to enhance Li-S batteries and analogous applications that involve complex transport phenomena and intermediate manipulation.Smarter Energiespeicher: Lösungen für die effektive Transportkontrolle von Polysulfiden in Li-S-Batterien befassen sich mit dem Shuttle. Eine supramolekulare Kapsel mit der Fähigkeit der reversiblen Polysulfid-Speicherung/Lieferung wurde in Li-S-Batterien verwendet.
      PubDate: 2017-11-20T05:52:32.466391-05:
      DOI: 10.1002/ange.201710025
       
  • 7%+Efficiency&rft.title=Angewandte+Chemie&rft.issn=0044-8249&rft.date=2017&rft.volume=&rft.aulast=Liu&rft.aufirst=Shengjian&rft.au=Shengjian+Liu&rft.au=Yuliar+Firdaus,++Simil+Thomas,++Zhipeng+Kan,++Federico+Cruciani,++Sergei+Lopatin,++Jean-Luc++M.+Bredas,++Pierre++M.+Beaujuge&rft_id=info:doi/10.1002/ange.201709509">Isoindigo-3,4-Difluorothiophene Polymer Acceptors Yield "All-Polymer" BHJ
           Solar Cells with>7% Efficiency
    • Authors: Shengjian Liu; Yuliar Firdaus, Simil Thomas, Zhipeng Kan, Federico Cruciani, Sergei Lopatin, Jean-Luc M. Bredas, Pierre M. Beaujuge
      Abstract: Poly(isoindigo-alt-3,4-difluorothiophene) (PIID[2F]T) analogues used as "polymer acceptors" in bulk-heterojunction (BHJ) solar cells achieve>7% efficiency when used in conjunction with the polymer donor PBFTAZ (model system). Considering that most efficient polymer acceptor alternatives to fullerenes (e.g. PC61BM or its C71 derivative) are based on perylenediimide (PDI) or naphthalenediimide (NDI) motifs thus far, branched alkyl-substituted PIID[2F]T polymers are remarkably promising nonfullerene candidates for "all-polymer" BHJ solar cells.
      PubDate: 2017-11-20T05:52:13.859266-05:
      DOI: 10.1002/ange.201709509
       
  • GOx@ZIF-8(NiPd) Nanoflower: An Artificial Enzyme System for Tandem
           Catalysis
    • Authors: Qingqing Wang; Xueping Zhang, Liang Huang, Zhiquan Zhang, Shaojun Dong
      Abstract: We report a facile approach to prepare an artificial enzyme system for tandem catalysis. NiPd hollow nanoparticles and glucose oxidase (GOx) were simultaneously immobilized on the zeolitic imidazolate framework 8 (ZIF-8) via a co-precipitation method. The as-prepared GOx@ZIF-8(NiPd) nanoflower not only exhibited the peroxidase-like activity of NiPd hollow nanoparticles but also maintained the enzymatic activity of GOx. A colorimetric sensor for rapid detection of glucose was realized through the GOx@ZIF-8(NiPd) based multi-enzyme system. Moreover, the GOx@ZIF-8(NiPd) modified electrode showed good bioactivity of GOx and high electrocatalytic activity for the oxygen reduction reaction (ORR), which could also be used for electrochemical detection of glucose.Flower Power: Hohle NiPd-Nanopartikel und Glucose-Oxidase (GOx) wurden durch gemeinsame Fällung in einem Metall-organischen Gerüst (ZIF-8) immobilisiert. Das resultierende System verbindet GOx-Aktivität mit Sauerstoffreduktionsfähigkeit und schlägt somit eine Brücke zwischen natürlichen Enzymen und Nanozymen.
      PubDate: 2017-11-20T05:45:24.387412-05:
      DOI: 10.1002/ange.201710418
       
  • Adsorption-Induced Structural Phase Transformation in Nanopores
    • Authors: Bogdan Kuchta; Ege Dundar, Filip Formalik, Philip L. Llewellyn, Lucyna Firlej
      Abstract: We report a new type of structural transformation occurring in methane adsorbed in micropores. The observed methane structures are defined by probability distributions of molecular positions. The mechanism of the transformation has been modeled using Monte Carlo method. The transformation is totally determined by a reconstruction of the probability distribution functions of adsorbed molecules. The methane molecules have some freedom to move in the pore but most of the time they are confined to the positions around the high probability adsorption sites. The observed high-probability structures evolve as a function of temperature and pressure. The transformation is strongly discontinuous at low temperature and becomes continuous at high temperature. The mechanism of the transformation is influenced by a competition between different components of the interaction and the thermal energy. The methane structure represents a new state of matter, intermediate between solid and liquid.Zwischen fest und flüssig: Ein neuartiger Strukturübergang, dessen Mechanismus auf einer Wahrscheinlichkeitsverteilung beruht, wurde in einem Modell für adsorbierte Methanmoleküle in Mikroporen des Metall-organischen Gerüsts IRMOF-1 entdeckt. Die Methanstruktur in den Poren wird durch die eingeschränkte Beweglichkeit bestimmt und stellt eine Mischung aus festem und flüssigem Zustand dar.
      PubDate: 2017-11-20T05:41:56.482405-05:
      DOI: 10.1002/ange.201708993
       
  • Gold-Catalyzed Asymmetric Intramolecular Cyclization of N-Allenamides for
           the Synthesis of Chiral Tetrahydrocarbolines
    • Authors: Yidong Wang; Peichao Zhang, Xiaoyu Di, Qiang Dai, Zhan-Ming Zhang, Junliang Zhang
      Abstract: Highly enantioselective gold-catalyzed intramolecular cyclization of N-allenamides was implemented by utilizing a designed chiral sulfinamide phosphine ligand (PC-Phos). This represents the first example of highly enantioselective intramolecular cyclization of N-allenamides. The practicality of this reaction was validated in the total synthesis of (R)-desbromoarborescidine A and formal synthesis of (R)-desbromoarborescidine C and (R)-deplancheine. Moreover, the catalyst system PC-Phos/AuNTf2 proved to be specifically efficient to promote the desymmetrization of N-allenamides in excellent yields with satisfactory ee values.Dritter Ring: Eine hoch enantioselektive goldkatalysierte intramolekulare Cyclisierung von N-Allenamiden unter Verwendung von PC-Phos-Liganden wurde entwickelt und in der Totalsynthese von (R)-Debromarborescidin A verwendet.
      PubDate: 2017-11-20T05:36:01.319272-05:
      DOI: 10.1002/ange.201709595
       
  • The MOF+ Technique: A Significant Synergic Effect Enables High Performance
           Chromate Removal
    • Authors: Ming Biao Luo; Yang Yang Xiong, Hui Qiong Wu, Xue Feng Feng, Jian Qiang Li, Feng Luo
      Abstract: A significant synergic effect between a metal–organic framework (MOF) and Fe2SO4, the so-called MOF+ technique, is exploited for the first time to remove toxic chromate from aqueous solutions. The results show that relative to the pristine MOF samples (no detectable chromate removal), the MOF+ method enables super performance, giving a 796 Cr mg g−1 adsorption capacity. The value is almost eight-fold higher than the best value of established MOF adsorbents, and the highest value of all reported porous adsorbents for such use. The adsorption mechanism, unlike the anion-exchange process that dominates chromate removal in all other MOF adsorbents, as unveiled by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), is due to the surface formation of Fe0.75Cr0.25(OH)3 nanospheres on the MOF samples.Poren machen Pause: Die MOF+-Methode nutzt statt des Porensystems eines Metall-organischen Gerüsts dessen Oberfläche und ermöglicht die hoch effiziente Entfernung von Chromat aus wässrigen Lösungen von bis zu 796 mg(Cr) g−1. Chromat wird durch FeSO4 reduziert, wobei FeIII- und CrIII-Ionen entstehen; anschließend induziert die MOF-Oberfläche die Bildung von Fe0.75Cr0.25(OH)3-Nanopartikeln.
      PubDate: 2017-11-20T02:56:01.33252-05:0
      DOI: 10.1002/ange.201709197
       
  • Die direkte katalytische Oxidation von Methan zu Methanol – eine
           kritische Beurteilung
    • Authors: Manoj Ravi; Marco Ranocchiari, Jeroen A. van Bokhoven
      Abstract: Es gibt vielzählige direkte, selektive Ansätze, um Methan partiell zu oxidieren, jedoch ist noch keiner von ihnen zur industriellen Reife gelangt. In diesem Zusammenhang ist die Oxidation von Methan zu Methanol eine schwierige, aber lohnende Aufgabe, da sie eine wirkungsvolle Methode ist, um das Abfackeln von Erdgas, das als Nebenprodukt in der Erdölindustrie anfällt, zu unterbinden, und zugleich die Möglichkeit bietet, Methan zu valorisieren. Dieser Aufsatz berücksichtigt die Synthese von Methanol und seinen Derivaten ausgehend von Methan durch homogen- und heterogenkatalytische Methoden. Er zeigt die starken Einschränkungen der direkten katalytischen Synthese von Methanol aus Methan auf und unterstreicht dabei die enorme Überlegenheit von Systemen, die Methanolderivate produzieren oder sich durch Besonderheiten wie die Verwendung von Mehrkomponenten-Katalysatoren zur Methanolstabilisierung auszeichnen. Für die zukünftige Forschung erweist sich die Stabilisierung von Methanol in der homogenen und heterogenen Katalyse als unentbehrlich.Die selektive Oxidation von Methan zu Methanol in hoher Ausbeute ist derzeit schwer umsetzbar, hat aber ein immenses Potential. Dieser Aufsatz veranschaulicht die homogenen und heterogenen katalytischen Wege für diesen Prozess und erläutert die vielversprechendsten Ansätze, welche die Petroindustrie revolutionieren könnten.
      PubDate: 2017-11-20T02:55:42.478614-05:
      DOI: 10.1002/ange.201702550
       
  • Synthesis and reactivity of nickel-stabilised µ2:η2,η2-P2,
           As2 and PAs units.
    • Authors: Gabriele Hierlmeier; Alexander Hinz, Robert Wolf, Jose Manuel Goicoechea
      Abstract: The reactivity of two paramagnetic nickel(I) compounds, CpNi(NHC) (where Cp = cyclopentadienyl; NHC = 1,3-bis(2,4,6-trimethylphenyl)-imidazol-2-ylidene (IMes) or 1,3-bis(2,6-diisopropylphenyl)-imidazol-2-ylidene (IPr)), towards [Na(dioxane)x][PnCO] (Pn = P, As) is described. These reactions afford symmetric bimetallic compounds (µ2:η2,η2-Pn2){Ni(NHC)(CO)}2. Several novel intermediates en route to such species are identified and characterised, including a compound containing the PCO- anion in an unprecedented µ2:η2,η2-binding mode. Ultimately, on treatment of the (µ2:η2,η2-Pn2){Ni(NHC)(CO)}2 compounds with carbon monoxide the Pn2 units can be released, affording P4 in the case of the phosphorus-containing species, and elemental arsenic in the case of (µ2:η2,η2-As2){Ni(IMes)(CO)}2.
      PubDate: 2017-11-20T01:50:36.395393-05:
      DOI: 10.1002/ange.201710582
       
  • Mono- and Bis-Imidazolidinium Ethynyl Cations and the Reduction of the
           Latter to give an Extended Bis-1,4-([3]Cumulene)-p-Carbo-Quinoid System
    • Authors: Brain Barry; Graeme Soper, Juha Hurmalainen, Akseli Mansikkamäki, , Katherine N Robertson, William L McClennan, Alex J. Veinot, Tracey L. Roemmele, Ulrike Werner-Zwanziger, René T Boeré, Heikki M. Tuononen, Jason Clyburne, Jason Masuda
      Abstract: An extended π-system containing two [3]cumulene fragments separated by a p-carbo-quinoid and stabilized by two capping N-heterocyclic carbenes (NHCs) has been prepared. Mono- and bis-imidazolidinium ethynyl cations have also been synthesized from the reaction of an NHC with phenylethynyl bromide or 1,4-bis(bromoethynyl)benzene. Cyclic voltammetry coupled with synthetic and structural studies showed that the dication is readily reduced to a neutral, singlet bis-1,4-([3]cumulene)-p-carbo-quinoid due to the π-accepting properties of the capping NHCs.
      PubDate: 2017-11-19T21:51:09.908256-05:
      DOI: 10.1002/ange.201711031
       
  • Dynamic Cross-Exchange in Halophosphonium Species: First Direct
           Observation of Stereochemical Inversion in the Course of an SN2 Process
    • Authors: Kirill Nikitin; Elizabeth V. Jennings, Sulaiman Al Sulaimi, Yannick Ortin, Declan G Gilheany
      Abstract: The complex fluxional interconversions between, otherwise very similar, phosphonium bromides and chlorides R3PX+X- (R = Alk, Ar, X = Cl or Br) was studied by NMR techniques. Their energy barriers are typically ca. 11 kcal/mol but rise rapidly as bulky groups are attached to phosphorus, revealing the importance of steric factors. In contrast, electronic effects, as measured by Hammett analysis, are modest (rho 1.46) but still clearly indicate negative charge flow towards phosphorus in the transition state. Most significantly, detailed analysis of the exchange pathways unequivocally, and for the first time in any such process, shows that nucleophilic attack of the nucleophilic anion on the tetrahedral centre results in inversion of configuration.
      PubDate: 2017-11-17T14:55:24.543288-05:
      DOI: 10.1002/ange.201708649
       
  • A redox-activated G-quadruplex DNA binder based on a platinum(IV)-salphen
           complex
    • Authors: Ramon Vilar; Stephane Bandeira, Jorge Gonzalez Garcia, Evangelina Pensa, Tim Albrecht
      Abstract: There has been increasing interest in the development of small molecules that can selectively bind to G-quadruplex DNA structures. The latter have been associated to a number of key biological processes and therefore are proposed to be potential targets for drug development. In this paper we report the first example of a reduction-activated G-quadruplex DNA binder. We show that a new octahedral platinum(IV)-salphen complex does not interact with DNA in aqueous media at pH 7.4; however, upon addition of bio-reductants such as ascorbic acid or glutathione, the compound readily reduces to the corresponding square planar platinum(II) complex. In contrast to the parent platinum(IV) complex, the in situ generated platinum(II) complex binds to HTelo and c-Myc G-quadruplex DNA with affinity constants up to 106 M-1.
      PubDate: 2017-11-17T13:00:25.046695-05:
      DOI: 10.1002/ange.201709968
       
  • The Weakly Coordinating Tris(trichlorosilyl)silyl Anion
    • Authors: Marian Olaru; Maxie F. Hesse, Elena Rychagova, Sergey Ketkov, Stefan Mebs, Jens Beckmann
      Abstract: Closely following the procedure for the preparation of the base-stabilized dichlorosilylene complex NHCDipp∙SiCl2 by Roesky and Stalke et al. (Angew. Chem. Int. Ed. 2009, 48, 5683-5686), besides the reported by-product [NHCDipp-H+∙∙∙Cl−], few crystals of the salt [NHCDipp-H∙∙∙Cl∙∙∙H-NHCDipp]Si(SiCl3)3 were isolated and characterized by X-ray crystallography (NHCDipp = N,N-di(2,6-isopropylphenyl)-imidazo-2-ylidene). They feature the weakly-coordinating anion Si(SiCl3)3−, which was more rationally obtained in high yields upon deprotonation of conjugate Brønsted acid HSi(SiCl3)3 with NHCDipp or PMP (PMP = 1,2,2,6,6-pentamethylpiperidine). The acidity of HSi(SiCl3)3 estimated by DFT calculations is substantially higher than those of other H-silanes. The electronic structure of Si(SiCl3)3− studied by DFT calculations including the electrostatic potential and the electron localizability confirms the low basicity and nucleophilicity in comparison to other silyl anions.
      PubDate: 2017-11-17T10:55:22.087893-05:
      DOI: 10.1002/ange.201710416
       
  • Controlled Sol-Gel Transitions of a Thermoresponsive Polymer in a
           Photoswitchable Azobenzene Ionic Liquid as a Molecular Machine
    • Authors: Masayoshi Watanabe; Caihong, Wang, Kei Hashimoto, Ryota Tamate, Hisashi Kokubo
      Abstract: Producing ionic liquids (ILs) that function as molecular machines for macroscopic change is a challenging issue. We report that photoisomerization of an azobenzene IL at the molecular level could evoke a macroscopic response (light-controlled mechanical sol-gel transitions) for ABA triblock copolymer solutions. The A endblocks, poly(2-phenylethyl methacrylate), show a low critical solution temperature in the IL mixture containing azobenzene while the B midblock, poly(methyl methacrylate), is compatible with the mixture. In a concentrated polymer solution, we observed different gelation temperatures in it under dark and UV conditions. In this temperature range, light-controlled sol-gel transitions were achieved by a photoresponsive solubility change of the A endblocks upon photoisomerization of the azobenzene IL. Therefore, an azobenzene IL as a molecular switch can tune the self-assembly of a thermoresponsive polymer, leading to macroscopic light-controlled sol-gel transitions.
      PubDate: 2017-11-17T10:25:46.775562-05:
      DOI: 10.1002/ange.201710288
       
  • Control of N-Heterocyclic Carbene Catalyzed Switchable Linear and
           Cycloaddition Reactions of Enals: Asymmetric Synthesis of
           Oxindole-γ-Amino Acid Derivatives
    • Authors: Dieter Enders; Xiang-Yu Chen, Jia-Wen Xiong, Qiang Liu, Sun Li, He Sheng, Carolina von Essen, Kari Rissanen
      Abstract: A strategy to control the switchable linear and cycloaddition reactions of enals through NHC catalyisis has been developed. The new scalable protocol leads to γ-amino acid esters bearing a tetrasubstituted stereocenter in good yields and high stereoselectivities via homo-Mannich reactions of enals and isatin-derived ketimines. By simply changing the N-ketimine substituent to an ortho-hydroxy phenyl group, the corresponding spirocyclic oxindolo-γ-lactams are obtained.
      PubDate: 2017-11-17T09:25:54.76112-05:0
      DOI: 10.1002/ange.201708994
       
  • Can coordination-driven supramolecular self-assembly reactions be
           conducted from fully aliphatic linkers '
    • Authors: Christophe Lescop; Mehdi Elsayed Moussa, Sloane Evariste, Barbara Kräemer, Régis Réau, Manfred Scheer
      Abstract: A series of fully aliphatic cyano-capped ditopic linkers with increasing lengths were reacted with a pre-assembled Cu(I) bimetallic molecular clip bearing short intermetallic distances. It is shown that, depending on the length of the ditopic linkers, a rational design of unprecedented supramolecular compact metallacycles bearing fully aliphatic walls is possible. The specific pre-organized molecular arrangement of the molecular clip used favors stabilizing interlinker London dispersion interactions allowing, as the linkers' lengths increase, the selective formation of discrete compact metallacycles at the expense of 1D coordination polymers. The generalizability of this approach is demonstrated by reacting fully aliphatic cyano-capped linkers with two other types of pre-assembled Cu(I) bimetallic molecular clips also having short intermetallic distances.
      PubDate: 2017-11-17T08:26:25.235598-05:
      DOI: 10.1002/ange.201709119
       
  • Dual Functionalization of White Phosphorus: Formation, Characterization,
           and Reactivity of Rare-Earth-Metal Cyclo-P3 Complexes
    • Authors: Shanshan Du; Jianhao Yin, Yue Chi, Ling Xu, Wen-Xiong Zhang
      Abstract: The [3+1] fragmentation reaction of rare-earth metallacyclopentadienes 1 a–c with 0.5 equivalents of P4 affords a series of rare-earth metal cyclo-P3 complexes 2 a–c and a phospholyl anion 3. 2 a–c demonstrate an unusual η3 coordination mode with one P−P bond featuring partial π-bonding character. 2 a–c are the first cyclo-P3 complexes of rare-earth metals, and also the first organo-substituted polyphosphides in the category of Group 3 and f-block elements. Rare-earth metallacyclopentadienes play a dual role in the combination of aromatization and Diels–Alder reaction. Compounds 2 a–c can coordinate to one or two [W(CO)5] units, yielding 4 a–c or 5 c, respectively. Furthermore, oxidation of 2 a with p-benzoquinone produces its corresponding phospholyllithium and regenerated P4.Die Fragmentierung von P4 liefert cyclo-P3-Seltenerdmetallkomplexen mit ungewöhnlicher η3-Koordination, wobei eine P-P-Bindung π-Anteile aufweist. Durch Oxidation des cyclo-P3-Komplexes mit p-Benzochinon sind Phospholylanionen zugänglich; bei diesem Prozess wird zusätzlich P4 regeneriert.
      PubDate: 2017-11-17T05:36:32.397334-05:
      DOI: 10.1002/ange.201708897
       
  • Double Regioselective Asymmetric C-Allylation of Isoxazolinones: Iridium
           Catalyzed N-Allylation Followed by an Aza-Cope-Rearrangement
    • Authors: Stefan Rieckhoff; Jan Meisner, Johannes Kästner, Wolfgang Frey, René Peters
      Abstract: Isoxazolinones are biologically and synthetically interesting densely functionalized heterocycles, which for a long time were not accessible in enantioenriched form by asymmetric catalysis. Next to the deficit of enantioselective methods, the functionalization of isoxazolinones is often plagued by regioselectivity issues due to the competition of various nucleophilic centers within the heterocycles. Here we report the first regio- and enantioselective C-allylations of isoxazolinones. They also allowed for high regioselectivity in favor of the linear allylation products, although Ir phosphoramidite catalysts were used, which commonly result in branched isomers. Our studies suggest that this outcome is the result of a reaction cascade via an initial regio- and enantioselective N-allylation providing a branched allyl intermediate, followed by a spontaneous [3,3]-rearrangement permitting a chirality transfer.
      PubDate: 2017-11-17T05:25:54.583372-05:
      DOI: 10.1002/ange.201710940
       
  • Shunai Che
    • PubDate: 2017-11-17T05:16:07.771887-05:
      DOI: 10.1002/ange.201711485
       
  • Access to α-Amino Acid Esters through Palladium-Catalyzed Oxidative
           Amination of Vinyl Ethers with Hydrogen Peroxide as the Oxidant and Oxygen
           Source
    • Authors: Lu Ouyang; Jianxiao Li, Jia Zheng, Jiuzhong Huang, Chaorong Qi, Wanqing Wu, Huanfeng Jiang
      Abstract: A novel and convenient palladium catalytic system for the synthesis of α-amino acid esters from simple starting materials is reported. Hydrogen peroxide not only acts as the green oxidant, but also as the oxygen source. This strategy for the conversion of amines and vinyl ethers into highly functionalized and structurally diverse α-amino acid esters is characterized by the simplicity of the experimental procedure, mild reaction conditions, high atom economy, scalability, and practicability.Beginnen wir mit etwas Einfachem: Ein praktisches Palladiumkatalysesystem, in dem Wasserstoffperoxid zugleich als Oxidationsmittel und Sauerstoffatomquelle fungiert, überführt leicht verfügbare Amine und Vinylether in hoch funktionalisierte α-Aminosäureester (siehe Schema). Die vielseitige Strategie zeichnet sich durch ein einfaches Syntheseprotokoll, milde Reaktionsbedingungen und hohe Atomökonomie aus.
      PubDate: 2017-11-17T05:15:41.492383-05:
      DOI: 10.1002/ange.201709285
       
  • Efficient Water Reduction with sp3-sp3 Diboron(4) Compounds: Application
           to Hydrogenations, H–D Exchange Reactions, and Carbonyl Reductions
    • Authors: Mathias Flinker; Hongfei Yin, René W. Juhl, Espen Z. Eikeland, Jacob Overgaard, Dennis U. Nielsen, Troels Skrydstrup
      Abstract: A series of crystalline sp3-sp3 diboron(4) compounds were synthesized and shown to promote the facile reduction of water with dihydrogen formation. The application of these diborons as simple and effective dihydrogen and dideuterium sources was demonstrated by conducting a series of selective reductions of alkynes and alkenes, and hydrogen–deuterium exchange reactions using two-chamber reactors. Finally, as the water reduction reaction generates an intermediate borohydride species, a range of aldehydes and ketones were reduced by using water as the hydride source.BH-Chemie: sp3-sp3-Diborane(4) können Wasser reduzieren und dadurch Wasserstoff für eine Reihe von Umsetzungen zur Verfügung stellen. Ausgewählte Aldehyde und Ketone wurden in Gegenwart dieser Diborane in Wasser durch intermediäre Borhydridspezies reduziert.
      PubDate: 2017-11-17T05:10:43.29944-05:0
      DOI: 10.1002/ange.201709685
       
  • Ring-Size-Modulated Reactivity of Putative Dicobalt-Bridging Nitrides:
           C−H Activation versus Phosphinimide Formation
    • Authors: Peng Cui; Qiuran Wang, Samuel P. McCollom, Brian C. Manor, Patrick J. Carroll, Neil C. Tomson
      Abstract: Dicobalt complexes supported by flexible macrocyclic ligands were used to target the generation of the bridging nitrido species [(nPDI2)Co2(μ-N)(PMe3)2]3+ (PDI=2,6-pyridyldiimine; n=2, 3, corresponding to the number of catenated methylene units between imino nitrogen atoms). Depending on the size of the macrocycle and the reaction conditions (solution versus solid-state), the thermolysis of azide precursors yielded bridging phosphinimido [(2PDI2)Co2(μ-NPMe3)(PMe3)2]3+, amido [(nPDI2)Co2(μ-NH2)(PMe3)2]3+ (n=2, 3), and C−H amination [(3PDI2*-μ-NH)Co2(PMe3)2]3+ products. All results are consistent with the initial formation of [(nPDI2)Co2(μ-N)(PMe3)2]3+, followed by 1) PMe3 attack on the nitride, 2) net hydrogen-atom transfer to form N−H bonds, or 3) C−H amination of the alkyl linker of the nPDI2 ligand.Produkte von C-H-Aminierung, Wasserstoffatomtransfer und Phosphinimid-Bildung wurden nach thermischer Aktivierung von azidverbrückten Dicobaltkomplexen mit flexiblen makrocyclischen Liganden erhalten. Die Größe des Makrocyclus beeinflusst dabei die Produktverteilung.
      PubDate: 2017-11-17T05:05:40.427537-05:
      DOI: 10.1002/ange.201708966
       
  • Polycyclische, polyprenylierte Acylphloroglucinole – eine Klasse
           nicht-peptidbasierter MRSA- und VRE-aktiver Antibiotika
    • Authors: Claudia Guttroff; Aslihan Baykal, Huanhuan Wang, Peter Popella, Frank Kraus, Nicole Biber, Sophia Krauss, Friedrich Götz, Bernd Plietker
      Abstract: In den vergangenen 20 Jahren wurden peptidbasierte Antibiotika wie Vancomycin, Teicoplanin oder Daptomycin als Reserveantibiotika betrachtet. In den letzten Jahren erschienen jedoch vermehrt Berichte über Vancomycin-resistente Krankheitserreger, was die Entwicklung neuartiger Leitstrukturen für neue wirksame Antibiotika motivierte. Hier wird über die Totalsynthese einer definierten endo-Typ-B-PPAP-Bibliothek und deren antibiotische Aktivität gegen multiresistente Staphylococcus-aureus- und diverse Vancomycin-resistente Enterococcus-Stämme berichtet. Es wurden vier neue Strukturen identifiziert, die zeigen, dass das PPAP-Grundgerüst eine neue nicht-peptidbasierte Leitstruktur in der Antibiotika-Forschung werden könnte, die sich durch die Kombination von hoher Aktivität und geringer Zytotoxizität auszeichnet.Eine definierte endo-Typ-B-PPAP-Bibliothek wurde synthetisiert und auf ihre antibiotische Aktivität gegen multiresistente Staphylococcus-aureus- und Vancomycin-resistente Enterococci-Stämme untersucht. Vier neue Strukturen wurden identifiziert (Beispiel siehe Bild), die zeigen, dass PPAPs in der Antibiotikaforschung eine neue Leitstruktur mit hoher Aktivität und geringer Zytotoxizität werden könnten. PPAP=polycyclisches, polyprenyliertes Acylphloroglucinol.
      PubDate: 2017-11-17T04:31:14.945732-05:
      DOI: 10.1002/ange.201707069
       
  • Visible-Light-Mediated Metal-Free Hydrosilylation of Alkenes through
           Selective Hydrogen Atom Transfer for Si-H Activation
    • Authors: Rong Zhou; Yi Yiing Goh, Haiwang Liu, Hairong Tao, Lihua Li, Jie Wu
      Abstract: Although developments on the transition-metal-catalyzed hydrosilylation of alkenes have achieved great progress over the past several decades, metal-free hydrosilylation is still rare and highly desirable. Herein, we report a convenient visible-light-driven metal-free hydrosilylation of both electron-deficient and electron-rich alkenes via selective hydrogen atom transfer for Si-H activation. By the synergistic combination of an organo-photocatalyst 4CzIPN and quinuclidin-3-yl acetate catalyst, the hydrosilylation of electron-deficient alkenes exclusively occurred with Si-H activation. Additionally, the hydrosilylation of electron-rich alkenes was achieved by merging photoredox and polarity-reversal catalysis.
      PubDate: 2017-11-16T21:55:48.823482-05:
      DOI: 10.1002/ange.201711250
       
  • Controlled radical polymerization of ethylene using organotellurium
           compounds
    • Authors: Franck D'Agosto; Arne Wolpers, Bastian Ebeling, Yasuyuki Nakamura, Shigeru Yamago, Vincent Monteil
      Abstract: The first successfully controlled radical polymerization (CRP) of ethylene is reported using several organotellurium chain-transfer agents (CTAs) under mild conditions (70 °C, 200 bar of ethylene) within the concept of organotellurium-mediated radical polymerization (TERP). In contrast to preceding works on CRPs of ethylene applying reversible addition-fragmentation chain-transfer (RAFT), the organotellurium-mediated system provided a high livingness and chain-end functionalization of polyethylene chains. Molar-mass distributions with dispersities between 1.3 and 2.1 were obtained up to average molar masses of 5000 g mol−1. As in the RAFT system, the high reactivity of the growing polyethylenyl radical led to an inherent side reaction. However, for the presented TERP systems, this side reaction did not result in dead chains, while it could even be effectively suppressed by a good choice of the CTA.
      PubDate: 2017-11-16T11:56:20.458125-05:
      DOI: 10.1002/ange.201709946
       
  • A Gold-Catalyzed Domino Cyclization Enabling Rapid Construction of Diverse
           Polyheterocyclic Frameworks
    • Authors: Erik Van der Eycken; Yi He, Zhenghua Li, Koen Robeyns, Luc Van Meervelt
      Abstract: We report herein an efficient gold(I)-catalyzed post-Ugi domino dearomatization/ipso-cyclization/Michael sequence that enables access to libraries of diverse (hetero)arene-annulated tricyclic heterocycles. This process affords novel complex polycyclic scaffolds in moderate to good yields from readily available acyclic precursors with excellent chemo-, regio-, and diastereo-selectivity. The power of this strategy has been demonstrated by the rapid synthesis of 40 highly functionalized polyheterocycles bearing indole, pyrrole, (benzo)furan, (benzo)thiophene, pyrazole and electron-rich arenes in two-operational steps.
      PubDate: 2017-11-16T07:58:40.035033-05:
      DOI: 10.1002/ange.201710592
       
  • A Copper(II)-Phenanthroline Metallopeptide that Targets and Disrupts
           Mitochondrial Function in Breast Cancer Stem Cells
    • Authors: Kristine Laws Laws; Ganka Bineva-Todd, Arvin Eskandari, Chunxin Lu, Nicola O'Reilly, Kogularamanan Suntharalingam
      Abstract: The breast cancer stem cell (CSC) and bulk breast cancer cell potency of a series of metallopeptides, 1-4 containing dichloro(1,10-phenanthroline) copper(II) and various organelle-targeting peptide sequences, is reported. The mitochondrial-targeting metallopeptide, 1 exploits the higher mitochondrial load in breast CSCs over corresponding non-CSCs, and the vulnerability of breast CSCs to mitochondrial damage, to potently and selectivity kill breast CSCs. Strikingly, 1 reduces the formation and size of mammospheres to a better extent than salinomycin, an established CSC-potent agent. Mechanistic studies show that 1 enters CSC mitochondria, induces mitochondrial dysfunction, generates reactive oxygen species (ROS), activates JNK and p38 pathways, and prompts apoptosis. To the best of our knowledge, 1 is the first metallopeptide to selectivity kill breast CSC in vitro.
      PubDate: 2017-11-16T07:25:29.981922-05:
      DOI: 10.1002/ange.201710910
       
  • A Strontium- and Chlorine-Free Pyrotechnic Illuminant of High Color Purity
    • Authors: Thomas M. Klapötke; Magdalena Rusan, Joerg Stierstorfer, Jesse Sabatini, Johann Glueck
      Abstract: The need to develop a red-light-emitting pyrotechnic illuminant has garnered interest from the pyrotechnics community due to potential Environmental Protection Agency (EPA) regulations of strontium and chlorinated organic materials. To address these environmental regulatory concerns, the development of lithium-based red-light-emitting pyrotechnic compositions of high purity and color is described. These formulations do not contain strontium or chlorinated organic materials. Rather, the disclosed formulations are based on a non-hygroscopic dilithium high-nitrogen salt which serves as both the oxidizer and red colorant. These formulations are likely to draw interest from the civilian fireworks and military pyrotechnics communities for further development; both of whom have a vested interest in the development of environmentally conscious formulations.
      PubDate: 2017-11-16T06:25:22.467004-05:
      DOI: 10.1002/ange.201710746
       
  • Systemic Delivery of Bc12-Targeting siRNA by DNA Nanoparticles Suppresses
           Cancer Cell Growth
    • Authors: Mohammad Aminur Rahman; Pengfei Wang, Zhixiang Zhao, Dongsheng Wang, Sreenivas Nannapaneni, Chao Zhang, Zhengjia Chen, Christopher C. Griffith, Selwyn J. Hurwitz, Zhuo G. Chen, Yonggang Ke, Dong M. Shin
      Abstract: Short interfering RNA (siRNA) is a promising molecular tool for cancer therapy, but its clinical success is limited by the lack of robust in vivo delivery systems. Rationally designed DNA nanoparticles (DNPs) have emerged as facile delivery vehicles because their physicochemical properties can be precisely controlled. Nonetheless, few studies have used DNPs to deliver siRNAs in vivo, and none has demonstrated therapeutic efficacy. Herein, we constructed a number of DNPs of rectangular and tubular shapes with varied dimensions using the modular DNA brick method for the systemic delivery of siRNA that targets anti-apoptotic protein Bcl2. The siRNA delivered by the DNPs inhibited cell growth both in vitro and in vivo, which suppressed tumor growth in a xenograft model that specifically correlated with Bcl2 depletion. This study suggests that DNPs are effective tools for the systemic delivery of therapeutic siRNA and have great potential for further clinical translation.DNA-Nanopartikel unterdrücken durch systemische Transporter von siRNA das Tumorwachstum, indem sie ein antiapoptotisches Protein Bcl2 spezifisch inaktivieren.
      PubDate: 2017-11-16T04:50:59.566117-05:
      DOI: 10.1002/ange.201709485
       
  • Atropoenantioselective Redox-Neutral Amination of Biaryls Via Borrowing
           Hydrogen and Dynamic Kinetic Resolution
    • Authors: Jian Wang; Jianwei Zhang
      Abstract: We report here a novel atropoenantioselective redox-neutral amination of biaryls triggered by a cascade of borrowing hydrogen and DKR strategy under the co-catalysis of chiral Ir-complex and achiral Brønsted acid. This protocol features broad substrate scope and good functional group tolerance, and allows the rapid assembly of axially chiral biaryls in good to high yields and with high to excellent enantioselectivities.
      PubDate: 2017-11-16T04:26:36.016372-05:
      DOI: 10.1002/ange.201711126
       
  • Reaction of thiocarbonyl fluoride formed from difluorocarbene with amines
    • Authors: Ji-Chang Xiao; Jiao Yu, Jinhong Lin
      Abstract: The reaction of thiocarbonyl fluoride generated from difluorocarbene with various amines under mild conditions is described. Secondary amines, primary amines, and o-phenylenediamines are converted to thiocarbamoyl fluorides, isothiocyanates, and difluoromethylthiolated heterocycles, respectively. Thiocarbamoyl fluorides were further transformed into trifluoromethylated amines using a one-pot process. As thiocarbonyl fluoride is generated in situ and is rapidly fully converted in one pot under mild conditions, no special safety precautions are needed.
      PubDate: 2017-11-16T03:55:46.911446-05:
      DOI: 10.1002/ange.201710186
       
  • Restoration of ribozyme tertiary contact and function using a molecular
           glue for RNA
    • Authors: Chikara Dohno; Maki Kimura, Kazuhiko Nakatani
      Abstract: Some RNA classes require folding into the proper higher-order structures to exert their functions. Hammerhead ribozyme (HHR) requires a folding conformation stabilized by tertiary interaction for full activity. Here, we developed a rationally engineered HHR that was inactive, but could be activated by a synthetic RNA-binding ligand, naphthyridine carbamate tetramer with Z-stilbene linker (Z-NCTS). Binding of Z-NCTS could induce the formation of an active folding structure and thereby restore ribozyme activity, where Z-NCTS acts as a molecular glue to bring two isolated RNA loops into contact with each other. Next, we designed a Z-NCTS-responsive genetic switch using the HHR sequence inserted into the 3 untranslated region as a cis-acting element. We demonstrated that the rationally designed ribozyme switch enabled regulation of gene expression by Z-NCTS and was functional in mammalian cells.
      PubDate: 2017-11-16T00:26:29.275096-05:
      DOI: 10.1002/ange.201709041
       
  • Bioinspired Chemical Communication between Synthetic Nanomotors
    • Authors: Chuanrui Chen; Xiaocong Chang, Hazhir Teymourian, Doris E Ramírez Herrera, Berta Esteban Fernández de Ávila, Xiaolong Lu, Jinxing Li, Sha He, Chengcheng Fang, Yuyan Liang, Fangzhi Mou, Jianguo Guan, Joseph Wang
      Abstract: While chemical communication plays a key role in diverse natural processes, the intelligent chemical communication between synthetic nanomotors remains unexplored. Here we demonstrate the design and operation of bio-inspired synthetic nanomotors capable of chemical communication among themselves that influences their propulsion behavior. The chemical message is sent from a moving 'activator' motor to a nearby 'activated' (receiver) one, and involves release of silver ions from a Janus PS/Ni/Au/Ag 'activator' motor to the 'activated' Janus SiO2/Pt nanomotor. The transmitted silver signal is translated rapidly into a dramatic speed change associated with the enhanced catalytic activity of 'activated' motors. The concept of establishing chemical communication between different synthetic nanomotors paves the way to intelligent nanoscale robotic systems that are capable of cooperating with each other.
      PubDate: 2017-11-15T21:55:41.124841-05:
      DOI: 10.1002/ange.201710376
       
  • Distal Weak Coordination of Acetamides in Ruthenium(II)-Catalyzed C-H
           Activation Processes
    • Authors: Qingqing Bu; Torben Rogge, Vladislav Kotek, Lutz Ackermann
      Abstract: C-H activations with challenging arylacetamides were accomplished by versatile ruthenium(II) biscarboxylate catalysis. The distal C-H functionalization was characterized by ample scope, including twofold oxidative C-H functionalizations and alkyne hydroarylations, through facile base-assisted internal electrophilic-type substitution (BIES) C-H ruthenation by weak O coordination.
      PubDate: 2017-11-15T15:25:43.378394-05:
      DOI: 10.1002/ange.201711108
       
  • Highly Selective Manganese(I)/Lewis Acid Cocatalyzed Direct C−H
           Propargylation using Bromoallenes
    • Authors: Can Zhu; Luca Jonas Schwarz, Sara Cembellin, Steffen Greßies, Frank Glorius
      Abstract: A manganese(I)/Lewis acid cocatalyzed direct C−H propargylation with high selectivity has been developed. BPh3 was discovered to not only promote the reactivity, but also enhance the selectivity to afford the propargylation products rather than allene derivatives. Secondary, tertiary or even quaternary carbon centers at the propargylic position could be directly constructed. Both internal and terminal alkynes are easily accessible. The chirality was successfully transferred from an axially chiral allene to the central chirality. The reactivity of the manganese catalyst in this chemistry was found to be unique comparing other transition metal catalysts.
      PubDate: 2017-11-15T15:25:38.786766-05:
      DOI: 10.1002/ange.201710835
       
  • Fluorine in a C-F Bond as the Key to Cage Formation
    • Authors: Maxwell Gargiulo Holl; Cody Ross Pitts, Thomas Lectka
      Abstract: Cage molecules have long been employed to trap reactive or fleeting species, as their rigid nature allows them to enforce situations that otherwise would not persist. In this minireview, we discuss our use of rigid cage structures to investigate the close noncovalent interactions of fluorine with other functional groups and determine how mutual proximity affects both physical properties and reactivity. Unusual covalent interactions of fluorine are also explored: the cage can close to form the first solution-phase C-F-C fluoronium ion.
      PubDate: 2017-11-15T15:25:22.698228-05:
      DOI: 10.1002/ange.201710423
       
  • PbS/CdS core/shell QDs suppress charge transfer and enhance triplet
           transfer
    • Authors: Zhiyuan Huang; Zihao Xu, Melika Mahboub, Xin Li, Jordan Taylor, Hill Harman, Tianquan Lian, MingLee Tang
      Abstract: Here, we observe that a sub-monolayer CdS shell on PbS quantum dots (QDs) enhances triplet energy transfer (TET) by suppressing competitive charge transfer from QDs to molecules. The CdS shell increases the linear photon upconversion quantum yield (QY) from 3.5% for PbS QDs to 5.0% for PbS/CdS QDs when functionalized with a tetracene acceptor, 5-CT. While transient absorption spectroscopy reveals that both PbS and PbS/CdS QDs show the formation of the 5-CT triplet (with rate constants of 5.91 ±0.60 ns-1 and 1.03 ±0.09 ns-1 respectively), ultrafast hole transfer occurs only from PbS QDs to 5-CT. Although the CdS shell decreases the TET rate, it enhances TET efficiency from 60.3± 6.1% to 71.8 ±6.2% by suppressing the hole transfer process. In addition, the CdS shell prolongs the lifetime of the 5-CT triplet and thus enhances TET from 5-CT to the rubrene emitter, further bolstering the upconverison QY.
      PubDate: 2017-11-15T12:55:39.708654-05:
      DOI: 10.1002/ange.201710224
       
  • Multi-Step Crystallization of Barium Carbonate: Rapid Interconversion of
           Amorphous and Crystalline Precursors
    • Authors: Michael L. Whittaker; Paul J. M. Smeets, Hasti Asayesh-Ardakani, Reza Shahbazian-Yassar, Derk Joester
      Abstract: The direct observation of amorphous barium carbonate (ABC), which transforms into a previously unknown barium carbonate hydrate (herewith named gortatowskite) within a few hundred milliseconds of formation, is described. In situ X-ray scattering, cryo-, and low-dose electron microscopy were used to capture the transformation of nanoparticulate ABC into gortatowskite crystals, highly anisotropic sheets that are up to 1 μm in width, yet only about 10 nm in thickness. Recrystallization of gortatowskite to witherite starts within 30 seconds. We describe a bulk synthesis and report a first assessment of the composition, vibrational spectra, and structure of gortatowskite. Our findings indicate that transient amorphous and crystalline precursors can play a role in aqueous precipitation pathways that may often be overlooked owing to their extremely short lifetimes and small dimensions. However, such transient precursors may be integral to the formation of more stable phases.Die Präzipitation von Witherit (BaCO3) aus wässriger Lösung erfolgt unter Beteiligung von nicht nur einer, sondern zwei Vorstufen: amorphem Bariumcarbonat (ABC) und kristallinem Bariumcarbonat-Monohydrat (Gortatowskit), das mit quasi-zweidimensionalem Habitus kristallisiert. Beide Intermediate sind sehr kurzlebig, und ihre Charakterisierung erfordert In-situ-Techniken mit hoher Zeitauflösung, niedriger Strahlendosis und/oder Kryo-Elektronenmikroskopie.
      PubDate: 2017-11-15T12:27:21.256841-05:
      DOI: 10.1002/ange.201709526
       
  • The Metal–Support Interaction Concerning the Particle Size Effect of
           Pd/Al2O3 on Methane Combustion
    • Authors: Kazumasa Murata; Yuji Mahara, Junya Ohyama, Yuta Yamamoto, Shigeo Arai, Atsushi Satsuma
      Abstract: The particle size effect of Pd nanoparticles supported on alumina with various crystalline phases on methane combustion was investigated. Pd/θ, α-Al2O3 with weak metal-support interaction showed a volcano-shaped dependence of the catalytic activity on the size of Pd particles, and the catalytic activity of the strongly interacted Pd/γ-Al2O3 increased with the particle size. Based on a structural analysis of Pd nanoparticles using CO adsorption IR spectroscopy and spherical aberration-corrected scanning/transmission electron microscopy, the dependence of catalytic activity on Pd particle size and the alumina crystalline phase was due to the fraction of step sites on Pd particle surface. The difference in fraction of the step site is derived from the particle shape, which varies not only with Pd particle size but also with the strength of metal–support interaction. Therefore, this interaction perturbs the particle size effect of Pd/Al2O3 for methane combustion.Größe und Phase: Pd/θ-Al2O3 und Pd/ α-Al2O3 zeigen einen anderen Größeneffekt als Pd/γ-Al2O3. Einer spektroskopischen und mikroskopischen Strukturanalyse zufolge beruht die Größen- und Phasenabhängigkeit der katalytischen Aktivität auf dem Anteil an Stufenpositionen im Pd-Partikel. Unterschiedliche Anteile ergeben sich aus der Partikelform, die von der Größe der Pd-Partikel und der Stärke der Metall-Träger-Wechselwirkungen bestimmt wird.
      PubDate: 2017-11-15T12:26:33.419572-05:
      DOI: 10.1002/ange.201709124
       
  • Activation and Deactivation of Gold/Ceria–Zirconia in the
           Low-Temperature Water–Gas Shift Reaction
    • Authors: James H. Carter; Xi Liu, Qian He, Sultan Althahban, Ewa Nowicka, Simon J. Freakley, Liwei Niu, David J. Morgan, Yongwang Li, J. W. (Hans) Niemantsverdriet, Stanislaw Golunski, Christopher J. Kiely, Graham J. Hutchings
      Abstract: Gold (Au) on ceria–zirconia is one of the most active catalysts for the low-temperature water–gas shift reaction (LTS), a key stage of upgrading H2 reformate streams for fuel cells. However, this catalyst rapidly deactivates on-stream and the deactivation mechanism remains unclear. Using stop–start scanning transmission electron microscopy to follow the exact same area of the sample at different stages of the LTS reaction, as well as complementary X-ray photoelectron spectroscopy, we observed the activation and deactivation of the catalyst at various stages. During the heating of the catalyst to reaction temperature, we observed the formation of small Au nanoparticles (NPs; 1–2 nm) from subnanometer Au species. These NPs were then seen to agglomerate further over 48 h on-stream, and most rapidly in the first 5 h when the highest rate of deactivation was observed. These findings suggest that the primary deactivation process consists of the loss of active sites through the agglomeration and possible dewetting of Au NPs.Nach dem Goldrausch: Stopp-Start-Raster-TEM wurde genutzt, um während der Niedertemperatur-Wassergasreaktion über Au/CeZrO4 gebildete Au-Spezies zu detektieren. Au-Nanopartikel, die beim Aufheizen des Katalysators auf Reaktionstemperatur gebildet werden, agglomerieren unter den Reaktionsbedingungen. Röntgen-PES offenbart, dass die Katalysatordeaktivierung aus der Partikelagglomeration resultiert.
      PubDate: 2017-11-15T12:09:41.483644-05:
      DOI: 10.1002/ange.201709708
       
  • Intermolecular Pummerer Coupling with Carbon Nucleophiles in
           Non-Electrophilic Media
    • Authors: Kilian Colas; Raúl Martín-Montero, Abraham Mendoza
      Abstract: A new Pummerer-type C−C coupling protocol is introduced based on turbo-organomagnesium amides, which unlike traditional Pummerer reactions, does not require strong electrophilic activators, engages a broad range of C(sp3)-, C(sp2)-, and C(sp)-nucleophiles, and seamlessly integrates with C−H and C−X magnesiation. Given the central character of sulfur compounds in organic chemistry, this protocol allows access to unrelated carbonyls, olefins, organometallics, halides, and boronic esters through a single strategy.C-C-Verknüpfungen durch Pummerer-Kupplung gelingen in einem einzigen Arbeitsschritt, zur Aktivierung werden jedoch Elektrophile benötigt. Eine effiziente orthogonale Vorgehensweise für elektrophilfreie Pummerer-C-C-Kupplungen unter Verwendung von DIPAMgCl⋅ LiCl wird vorgestellt, die Einschränkungen des etablierten Protokolls überwindet.
      PubDate: 2017-11-15T12:09:27.708147-05:
      DOI: 10.1002/ange.201709715
       
  • Lead- and Iodide-Deficient (CH3NH3)PbI3 (d-MAPI): The Bridge between 2D
           and 3D Hybrid Perovskites
    • Authors: Antonin Leblanc; Nicolas Mercier, Magali Allain, Jens Dittmer, Vincent Fernandez, Thierry Pauporté
      Abstract: 3D and 2D hybrid perovskites, which have been known for more than 20 years, have emerged recently as promising materials for optoelectronic applications, particularly the 3D compound (CH3NH3)PbI3 (MAPI). The discovery of a new family of hybrid perovskites called d-MAPI is reported: the association of PbI2 with both methyl ammonium (MA+) and hydroxyethyl ammonium (HEA+) cations leads to a series of five compounds with general formulation (MA)1−2.48x(HEA)3.48x[Pb1−xI3−x]. These materials, which are lead- and iodide-deficient compared to MAPI while retaining 3D architecture, can be considered as a bridge between the 2D and 3D materials. Moreover, they can be prepared as crystallized thin films by spin-coating. These new 3D materials appear very promising for optoelectronic applications, not only because of their reduced lead content, but also in account of the large flexibility of their chemical composition through potential substitutions of MA+, HEA+, Pb2+ and I− ions.Die Assoziation von PbI2 mit Methylammonium (MA+) und Hydroxyethylammonium (HEA+) führt zu fünf Verbindungen der allgemeinen Summenformel (MA)1−2.48x(HEA)3.48x[Pb1−xI3−x]. Diese d-MAPI-Materialien, die gegenüber der Stammverbindung (CH3NH3)PbI3 (MAPI) einen Blei- und Iodidunterschuss aufweisen, können in Form dünner Filme hergestellt werden. Durch Beibehaltung ihrer 3D-Architektur bilden sie eine Brücke zwischen 2D-Hybridperowskiten und MAPI.
      PubDate: 2017-11-15T12:09:08.625175-05:
      DOI: 10.1002/ange.201710021
       
  • Olefin-Bildung durch eliminierende Dimerisierung und eliminierende
           Kreuzkupplung von Carbenoiden: eine stereochemische Herausforderung
    • Authors: Paul R. Blakemore; Reinhard W. Hoffmann
      Abstract: Bei der Dimerisierung von Carbenoiden entstehen Olefine, und zwar über die Bildung eines At-Komplexes, eine nachfolgende 1,2-Metallat-Umlagerung und eine abschließende β-Eliminierung. Da jeder dieser Schritte stereospezifisch ist, kann man das stereochemische Endergebnis nachvollziehen und – im Prinzip – auch steuern, vorausgesetzt, die absolute Konfiguration der reagierenden Carbenoide ist festgelegt. Eine eliminierende Kreuzkupplung zweier unterschiedlicher Carbenoide ermöglicht eine Aufbaureaktion, bei der im Unterschied zu bekannten Olefin-Synthesen die Geometrie der Doppelbindung unabhängig von der Art der Reste an der Doppelbindung festgelegt werden kann. Die Bildung von Olefinen durch eliminierende Dimerisierung/Kreuzkupplung von Carbenoiden wird an einer Reihe von typischen Beispielen illustriert, etwa an Reaktionen von α-lithiierten Halogenalkanen, Epoxiden und Carbamaten. Dabei gilt das Augenmerk auch der Erzeugung von sp3-hybridisierten Carbenoiden mit definierter Konfiguration und deren stereochemischer Zuordnung.Die wechselseitige Eliminierung einer elektrofugen (M) und einer nukleofugen (X) Abgangsgruppe aus einem Paar miteinander reagierender Carbenoide führt zur Bildung einer C-C-Doppelbindung. Diese elementare Aufbaureaktion ist inhärent regio- und stereospezifisch. In diesem Aufsatz werden Homo- und Kreuzkupplungen von Carbenoiden beschrieben und weitere Entwicklungsmöglichkeiten skizziert.
      PubDate: 2017-11-15T12:09:01.024201-05:
      DOI: 10.1002/ange.201707026
       
  • Creation of “Rose Petal” and “Lotus Leaf” Effects on Alumina by
           Surface Functionalization and Metal-Ion Coordination
    • Authors: Rahul Dev Mukhopadhyay; Balaraman Vedhanarayanan, Ayyappanpillai Ajayaghosh
      Abstract: Functional differences between superhydrophobic surfaces, such as lotus leaf and rose petals, are due to the subtle architectural features created by nature. Mimicry of these surfaces with synthetic molecules continues to be fascinating as well as challenging. Herein, we demonstrate how inherently hydrophilic alumina surface can be modified to give two distinct superhydrophobic behaviors. Functionalization of alumina with an organic ligand resulted in a rose-petal-like surface (water pinning) with a contact angle of 145° and a high contact angle hysteresis (±69°). Subsequent interaction of the ligand with Zn2+ resulted in a lotus-leaf-like surface with water rolling behavior owing to high contact angle (165°) and low-contact-angle-hysteresis (±2°). In both cases, coating of an aromatic bis-aldehyde with alkoxy chain substituents was necessary to emulate the nanowaxy cuticular feature of natural superhydrophobic materials.Ein neues Blatt: Oberflächenfunktionalisierung und Koordinationspolymerchemie werden genutzt, um MOF-basierte Nanoarchitekturen auf einer Aluminiumoxidoberfläche zu erzeugen. Die inhärente Superhydrophilie der Oberfläche wird derart modifiziert, dass sie das superhydrophobe Verhalten von Rosenblüten und Lotusblättern annimmt.
      PubDate: 2017-11-15T12:08:53.0811-05:00
      DOI: 10.1002/ange.201709463
       
  • Atomically Dispersed Copper–Platinum Dual Sites Alloyed with Palladium
           Nanorings Catalyze the Hydrogen Evolution Reaction
    • Authors: Tingting Chao; Xuan Luo, Wenxing Chen, Bin Jiang, Jingjie Ge, Yue Lin, Geng Wu, Xiaoqian Wang, Yanmin Hu, Zhongbin Zhuang, Yuen Wu, Xun Hong, Yadong Li
      Abstract: Designing highly active catalysts at an atomic scale is required to drive the hydrogen evolution reaction (HER). Copper–platinum (Cu-Pt) dual sites were alloyed with palladium nanorings (Pd NRs) containing 1.5 atom % Pt, using atomically dispersed Cu on ultrathin Pd NRs as seeds. The ultrafine structure of atomically dispersed Cu-Pt dual sites was confirmed with X-ray absorption fine structure (XAFS) measurements. The Pd/Cu-Pt NRs exhibit excellent HER properties in acidic solution with an overpotential of only 22.8 mV at a current density of 10 mA cm−2 and a high mass current density of 3002 A g−1(Pd+Pt) at a −0.05 V potential.Atomar dispergierte duale Kupfer-Platin(Cu-Pt)-Zentren legiert mit Palladium(Pd)-Nanoringen zeigen exzellente Eigenschaften in der Wasserstoffentwicklung. Die elektrokatalytische Aktivität übertrifft diejenige kommerzieller Platin-Kohlenstoff(Pt/C)-Katalysatoren.
      PubDate: 2017-11-15T12:08:28.623015-05:
      DOI: 10.1002/ange.201709803
       
  • Atom-Specific Mutagenesis Reveals Structural and Catalytic Roles for an
           Active-Site Adenosine and Hydrated Mg2+ in Pistol Ribozymes
    • Authors: Sandro Neuner; Christoph Falschlunger, Elisabeth Fuchs, Maximilian Himmelstoss, Aiming Ren, Dinshaw J. Patel, Ronald Micura
      Abstract: The pistol RNA motif represents a new class of self-cleaving ribozymes of yet unknown biological function. Our recent crystal structure of a pre-catalytic state of this RNA shows guanosine G40 and adenosine A32 close to the G53–U54 cleavage site. While the N1 of G40 is within 3.4 Å of the modeled G53 2′-OH group that attacks the scissile phosphate, thus suggesting a direct role in general acid–base catalysis, the function of A32 is less clear. We present evidence from atom-specific mutagenesis that neither the N1 nor N3 base positions of A32 are involved in catalysis. By contrast, the ribose 2′-OH of A32 seems crucial for the proper positioning of G40 through a H-bond network that involves G42 as a bridging unit between A32 and G40. We also found that disruption of the inner-sphere coordination of the active-site Mg2+ cation to N7 of G33 makes the ribozyme drastically slower. A mechanistic proposal is suggested, with A32 playing a structural role and hydrated Mg2+ playing a catalytic role in cleavage.Feuer frei: Atomspezifische Mutagenese zeigt, dass die Ribose-Einheit des konservierten Adenosins A32 und ein hydratisiertes Mg2+-Ion im aktiven Zentrum des Pistolen-Ribozyms zur Spaltungsaktivität beitragen. Im vorgeschlagenen Mechanismus nimmt A32 einen strukturellen Einfluss, und das hydratisierte Mg2+ katalysiert den Spaltungsprozess.
      PubDate: 2017-11-15T12:08:21.27875-05:0
      DOI: 10.1002/ange.201708679
       
  • Access to Chiral Hydropyrimidines through Palladium-Catalyzed Asymmetric
           Allylic C−H Amination
    • Authors: Pu-Sheng Wang; Meng-Lan Shen, Tian-Ci Wang, Hua-Chen Lin, Liu-Zhu Gong
      Abstract: A palladium-catalyzed asymmetric intramolecular allylic C−H amination controlled by a chiral phosphoramidite ligand was established for the preparation of various substituted chiral hydropyrimidinones, the precursors of hydropyrimidines, in high yields with high enantioselectivities. In particular, dienyl sodium N-sulfonyl amides bearing an arylethene-1-sulfonyl group underwent a sequential allylic C−H amination and intramolecular Diels–Alder (IMDA) reaction to produce chiral fused tricyclic tetrahydropyrimidinone frameworks in high yields and with high levels of stereoselectivity. Significantly, this method was used as the key step in an asymmetric synthesis of letermovir.Der Kern der Sache: Eine asymmetrische Palladium-katalysierte intramolekulare allylische C-H-Aminierung, die von einem chiralen Phosphoramiditliganden dirigiert wird, wurde zur effizienten Synthese unterschiedlich substituierter chiraler Hydropyrimidine genutzt. Diese Methode wurde zur asymmetrischen Synthese von Letermovir verwendet (siehe Schema; IMDA=intramolekulare Diels-Alder-Reaktion).
      PubDate: 2017-11-15T12:08:12.832036-05:
      DOI: 10.1002/ange.201709681
       
  • Living Supramolecular Polymerization of a Perylene Bisimide Dye into
           Fluorescent J-Aggregates
    • Authors: Wolfgang Wagner; Marius Wehner, Vladimir Stepanenko, Soichiro Ogi, Frank Würthner
      Abstract: The self-assembly of a new perylene bisimide (PBI) organogelator with 1,7-dimethoxy substituents in the bay position affords non-fluorescent H-aggregates at high cooling rates and fluorescent J-aggregates at low cooling rates. Under properly adjusted conditions, the kinetically trapped “off-pathway” H-aggregates are transformed into the thermodynamically favored J-aggregates, a process that can be accelerated by the addition of J-aggregate seeds. Spectroscopic studies revealed a subtle interplay of π–π interactions and intra- and intermolecular hydrogen bonding for monomeric, H-, and J-aggregated PBIs. Multiple polymerization cycles initiated from the seed termini demonstrate the living character of this chain-growth supramolecular polymerization process.Lebende supramolekulare Polymerisation: Erstmals konnte ein Perylenbisimid (PBI) durch lebende Keimpolymerisation in mehreren Wachstumszyklen verlängert werden. Der PBI-Organogelator bildet „off-pathway”-H-Aggregate, die in die thermodynamisch begünstigten fluoreszierenden J-Aggregate überführt werden.
      PubDate: 2017-11-15T12:08:02.314245-05:
      DOI: 10.1002/ange.201709307
       
  • Modulation of Quorum Sensing in a Gram Positive Pathogen by Linear
           Imprinted Copolymers with anti-Infective Properties
    • Authors: Anfal Motib; Antonio Guerreiro, Firas Al-Bayati, Elena Piletska, Irfan Manzoor, Sulman Shafeeq, Anagha Kadam, Oscar Kuipers, Luisa Hiller, Todd Cowen, Sergey Piletsky, Peter Andrew, Hasan Yesilkaya
      Abstract: Here we describe the development, characterization and biological testing of a new type of linear molecularly imprinted polymer (LMIP) designed to act as anti-infective by blocking the quorum sensing (QS) mechanism and so preventing virulence of the pathogen Streptococcus pneumoniae. The LMIP is prepared (polymerized) in presence of a template molecule, but unlike in traditional molecular imprinting approaches no cross-linker is used. This results in soluble low molecular weight polymer that can act as drug agent in vitro and in vivo. The LMIP was characterized by mass spectrometry to determine its monomer composition. Fragments identified were then aligned along the peptide template by computer modeling, predicting the possible monomer sequence of the LMIP. These findings provide proof of principle that LMIP can be used to block QS, setting the stage for studies on a novel drug-discovery platform and class of materials to target Gram positive pathogens.
      PubDate: 2017-11-15T10:39:15.645608-05:
      DOI: 10.1002/ange.201709313
       
  • Simple Access to the Heaviest Alkaline-Earth Metal Hydride: A Strongly
           Reducing Hydrocarbon-Soluble Barium Hydride Cluster
    • Authors: Sjoerd Harder; Brant Maitland, Michael Wiesinger, Christian Färber, Gerd Ballmann, Holger Elsen, Christian Fischer
      Abstract: Reaction of Ba[N(SiMe3)2]2 with PhSiH3 in toluene gave simple access to the unique Ba hydride cluster Ba7H7[N(SiMe3)2]7 that can be described as a square pyramide spanned by five Ba2+ ions with two flanking BaH[N(SiMe3)2] units. This heptanuclear cluster is well soluble in aromatic solvents and the hydride 1H NMR signals and coupling pattern suggests that the structure is stable in solution. At 95 °C, no coalescence of hydride signals is observed but the cluster slowly decomposes to undefined Ba hydride species. Complex Ba7H7[N(SiMe3)2]7 is a very strong reducing agent that already at room temperature reacts with Me3SiCH=CH2, norbornadiene and ethylene. The highly reactive alkylbarium intermediates cannot be observed and deprotonate the (Me3Si)2Nˉ ion, as confirmed by the crystal structure of Ba14H12[N(SiMe3)2]12[(Me3Si)(Me2SiCH2)N]4.
      PubDate: 2017-11-15T09:25:40.142057-05:
      DOI: 10.1002/ange.201709771
       
  • Biomimic Peptide-Gated Nanoporous Membrane for On-Demand Molecule
           Transport
    • Authors: Kai Xiao; Kai Wu, Lu Chen, Xiang-Yu Kong, Yuqi Zhang, Liping Wen, Lei Jiang
      Abstract: The controllable molecule transport is crucial to realize many highly valuable applications both in vivo and in vitro. Nanoporous membrane, with nanoscopic pores, high porosity, uniform pore dimension, and controllable surface chemical properties, hold tremendous potential to achieve this function. Here, we report a nano-gating system for on-demand molecule transport based on peptide-gated nanoporous membrane. Acting as gatekeeper, the peptides introduced to the nanoporous membrane provide an opportunity to realize on-demand on-off-states transport profiles via reversible conformational switch of peptides. This nano-gating system with sustained release performance provides a more sophisticated molecule transport platform, which anticipates applications in localized drug delivery with feedback function.
      PubDate: 2017-11-15T04:59:27.773024-05:
      DOI: 10.1002/ange.201708695
       
  • Photo-induced Pedalo-type Motion in an Azodicarboxamide-based Molecular
           Switch
    • Authors: Saeed Amirjalayer; Alberto Martinez-Cuezva, Jose Berná, Sander Woutersen, Wybren Jan Buma
      Abstract: Well-defined structural changes of molecular units that can be triggered by light are crucial for the development of photoactive functional materials. Here we report on a novel switch that has azodicarboxamide as its photo triggerable element. Time-resolved UV-pump/IR probe spectroscopy in combination with quantum chemical calculations shows that the azodicarboxamide functionality -in contrast to other azo-based chromophores- does not undergo trans-cis photoisomerization. Instead, a photo-induced pedalo-type motion occurs, which due to its volume-conserving properties enables to design functional molecular systems with controllable motion in a confined space.
      PubDate: 2017-11-15T04:59:24.786154-05:
      DOI: 10.1002/ange.201709666
       
  • Deep Level Defect-Enhanced Photothermal Performance of Bismuth
           Sulfide-Gold Heterojunction Nanorods for CT Imaging-Guided Photothermal
           Therapy of Cancer
    • Authors: Yan Cheng; Yun Chang, Yanlin Feng, Hui Jian, Zhaohui Tang, Haiyuan Zhang
      Abstract: Bismuth sulfide (Bi2S3) nanomaterials are emerging as a promising theranostic platform for CT imaging and photothermal therapy of cancer. Herein, the photothermal property of Bi2S3 nanorods (NRs) was unveiled to intensely correlate to their intrinsic deep level defects (DLDs) that potentially could work as electron-hole nonradiative recombination centers to promote phonon production, ultimately leading to photothermal performance. Bi2S3-Au heterojunction NRs were designed to hold more significant DLD property, exhibiting more potent photothermal performance than Bi2S3 NRs. Under 808 nm laser irradiation, Bi2S3-Au NRs could trigger higher cellular heat shock protein 70 expression and more apoptotic cells than Bi2S3 NRs, and caused severe cell death and tumor growth inhibition, showing great potential for CT imaging-guided photothermal therapy of cancer.
      PubDate: 2017-11-15T02:50:31.183409-05:
      DOI: 10.1002/ange.201710399
       
  • Subporpholactone, Subporpholactam, Imidazolosubporphyrin, and Iridium
           Complexes of Imidazolosubporphyrin: Formation of Iridium Carbene Complexes
           
    • Authors: Atsuhiro Osuka; Kota Yoshida
      Abstract: Pyrrole-modified subporphyrins bearing a non-pyrrolic cyclic unit, subporpholactone, subporpholactam, and imidazolosubporphyrin were newly synthesized. They show subporphyrin-like absorption and fluorescence spectra that are red-shifted in the order of subporpholactam < subporpholactone < imidazolosubporphyrin. Metalation of the imidazolosubporphyrin with (pentamethylcyclopentadienyl)iridium(III) dichloride dimer gave a complex, in which the Ir(III) atom was attached at the peripheral nitrogen atom of the imidazole moiety and the ortho-position of the meso-phenyl group. Reaction of this complex with diphenylacetylene gave different products depending on an additive; a phenyl-rearranged product in the presence of NaBArF4 (ArF = 3,5-bis(trifluoromethyl)phenyl) and two isomeric carbene complexes in the presence of KPF6.
      PubDate: 2017-11-15T00:50:45.490897-05:
      DOI: 10.1002/ange.201711166
       
  • Achieving Strong Positive Cooperativity through Activating Weak
           Non-Covalent Interactions
    • Authors: Yan-Long Ma; Hua Ke, Arto Valkonen, Kari Rissanen, Wei Jiang
      Abstract: Positive cooperativity achieved through activating weak non-covalent interactions is common in biological assemblies but is rarely observed in synthetic complexes. Two new naphthotubes have been synthesized and the syn isomer binds DABCO-based organic cations with high orientational selectivity. Surprisingly, the ternary complex with two hosts and one guest shows a high cooperativity factor (α=580), which is the highest reported for synthetic systems without involving ion-pairing interactions. The X-ray single-crystal structure revealed that the strong positive cooperativity likely originates from eight C-H⋅⋅⋅O hydrogen bonds between the two head-to-head-arranged syn tube molecules. These relatively weak hydrogen bonds were not observed in the free hosts and only emerged in the complex. Furthermore, this complex was used as a basic motif to construct a robust [2+2] cyclic assembly, thus demonstrating its potential in molecular self-assembly.
      PubDate: 2017-11-14T21:55:42.050967-05:
      DOI: 10.1002/ange.201711077
       
  • N-Heterocyclic Carbene Catalysis via Azolium Dienolates: An Efficient
           Strategy for Enantioselective Remote Functionalizations
    • Authors: Dieter Enders; Xiang-Yu Chen, Qiang Liu, Pankaj Chauhan
      Abstract: N-heterocyclic carbene (NHC) catalysis has emerged as a powerful strategy in organic synthesis. In recent years a number of reviews have been published on NHC-catalyzed transformations involving Breslow intermediates, acyl azoliums, α,β-unsaturated acyl azoliums, homoenolate equivalents and azolium enolates. However, the azolium dienolate intermediates generated by NHCs have been employed in asymmetric synthesis only very recently, especially in cycloadditions dealing with remote functionalization. This Minireview highlights all the developments and the new advances in the NHC-catalyzed asymmetric cycloaddition resections involving azolium dienolate intermediates.
      PubDate: 2017-11-14T10:21:46.574416-05:
      DOI: 10.1002/ange.201709684
       
  • In Situ Scatheless Cell Detachment Reveals Connections Between Adhesion
           Strength and Viability at Single-Cell Resolution
    • Authors: Sifeng Mao; Wanling Zhang, Qiushi Huang, Masqooh Khan, Haifang Li, Katsumi Uchiyama, Jin-Ming Lin
      Abstract: Single-cell biology provides insights to some of the most fundamental processes in biology and promotes the understanding of life's mysteries. And as the technologies to study single-cells expand, they will require sophisticated analytical tools to make sense of various behaviors and components of single-cells as well as their relations in adherent tissue culture. In this paper, we revealed cell heterogeneity and uncovered the connections between cell adhesion strength and cell viability at single-cell resolution by extracting single adherent cells of interest from standard tissue culture via a microfluidic chip based Live Single-Cell Extractor (LSCE). We not only uncovered cell heterogeneity and the connections between cell adhesion strength and cell viability, but also provided a new methodology for single-cell biology.
      PubDate: 2017-11-14T10:20:43.385235-05:
      DOI: 10.1002/ange.201710273
       
  • Oxime Ether Radical Cations Stabilized by N-Heterocyclic Carbene
    • Authors: Youngsuk Kim; Kimoon Kim, Eunsung Lee
      Abstract: N-heterocyclic carbene nitric oxide (NHCNO) radicals, which can be regarded as iminoxyl radicals stabilized by NHCs, were found to react with a series of silyl and alkyl triflates to generate the corresponding oxime ether radical cations. The structures of the resulting oxime ether radical cations were determined by X-ray crystallography, along with EPR and computational analysis. In contrast, lutidinium triflate produced a 1:1 mixture of [NHCNO+][OTf-] and [NHCNHOH+][OTf-] upon the reaction with NHCNO. This study adds an important example of stable singlet carbenes stabilizing main group radicals due to their π-conjugating effect, the synthesis and structures of which have never been elucidated previously.
      PubDate: 2017-11-14T08:27:18.810563-05:
      DOI: 10.1002/ange.201710530
       
  • A Simple Pre-lithiation Strategy to Build High-Rate and Long-life
           Lithium-ion Battery with Improved Low-temperature Performance
    • Authors: Yonggang Wang; Yao Liu, Bingchang Yang, Xiaoli Dong, Yongyao Xia
      Abstract: Lithium-ion batteries (LIBs) are being used to power the commercial electric vehicles (EVs). However, the charge/discharge rate and life of current LIBs still cannot satisfy the further development of EVs. Furthermore, the poor low temperature performance of LIBs limits their application in cold climates and high altitude areas. Herein, a simple pre-lithiation method is developed to fabricate a new LIB. In this strategy, a Li3V2(PO4)3 cathode and a pristine hard carbon anode are used to form a primary cell, and the initial Li+ extraction from Li3V2(PO4)3 is used to pre-lithiate the hard carbon. Then, the self-formed Li2V2(PO4)3 cathode and pre-lithiated hard carbon anode are used to form a 4 V LIB. It is demonstrated that the LIB exhibits a maximum energy density of 208.3 Wh kg-1, a maximum power density of 8291 W kg-1 and a long-life of 2000 cycles. When operated at -40 oC, the LIB can keep 67 % capacity of room temperature, which is much better than conventional LIBs.
      PubDate: 2017-11-14T08:27:08.723545-05:
      DOI: 10.1002/ange.201710555
       
  • Internal Peptide Late-Stage Diversification: Peptide Isosteric Triazoles
           for Primary and Secondary C(sp3)‒H Activation
    • Authors: Michaela Bauer; Wei Wang, Mélanie L. Lorion, Chuan Dong, Lutz Ackermann
      Abstract: Secondary C(sp3)-H arylations were accomplished by peptide bond isosteric triazoles in palladium catalysis. The unique power of this approach was reflected by enabling secondary C(sp3)-H functionalizations on terminal peptides as well as the unprecedented positional-selective C(sp3)-H functionalization of internal peptides, setting the stage for modular peptide late-stage diversification.
      PubDate: 2017-11-14T08:26:38.861505-05:
      DOI: 10.1002/ange.201710136
       
  • Organocatalyzed photo-controlled radical polymerization of
           semi-fluorinated (meth)acrylates driven by visible light
    • Authors: Mao Chen; Honghong Gong, Yucheng Zhao, Xianwang Shen, Jun Lin
      Abstract: Fluorinated polymers are important materials that are widely used in many areas. Herein, we report the development of a metal-free photo-controlled radical polymerization of semi-fluorinated (meth)acrylates with a new visible light absorbing organocatalyst. This method allows the production of a variety of semi-fluorinated polymers with narrow molar weight distributions from semi-fluorinated trithiocarbonates or perfluoroalkyl iodide. The high performance of "ON/OFF" control and chain extension experiments further demonstrate the utility and reliability of this method. Furthermore, to streamline the preparation of semi-fluorinated polymers, a scalable continuous-flow approach has been developed. Given the broad interest in fluorinated materials and photopolymerization, we expect this method will facilitate the development of advanced materials with unique property.
      PubDate: 2017-11-14T07:50:27.6974-05:00
      DOI: 10.1002/ange.201711053
       
  • Conductive Microporous Covalent Triazine-Based Framework for
           High-Performance Electrochemical Capacitive Energy Storage
    • Authors: Weiqiao Deng; Yajuan Li, Shuanghao Zheng, Xue Liu, Pan Li, Lei Sun, Ruixia Yang, Sen Wang, Zhongshuai Wu, Xinhe Bao
      Abstract: Nitrogen enriched porous nanocarbon, graphene and conductive polymers attracted increasing attention in the application of supercapacitors. However, the electrode material possessing large specific surface area (SSA) and high nitrogen doping concentration simultaneously, which is needed for excellent supercapacitors, has not been achieved thus far. Herein, we developed a class of tetracyanoquinodimethane-derived conductive microporous covalent triazine-based frameworks (marked as TCNQ-CTFs) with high nitrogen content (> 8%) and large SSA (> 3600 m²/g) at the same time. These CTFs exhibited excellent specific capacitances with the highest value exceeding 380 F/g, considerable energy density of 42.8 Wh/kg and remarkable cycling stability without any capacitance degradation after 10000 cycles. This class of CTFs should hold a great potential as high-performance electrode material for electrochemical energy storage system.
      PubDate: 2017-11-14T07:20:50.82118-05:0
      DOI: 10.1002/ange.201711169
       
  • Cobalt-catalyzed Suzuki biaryl coupling of aryl halides
    • Authors: Robin Bedford; Soneela Asghar, Sanita Tailor, Elorriaga David
      Abstract: Readily accessed cobalt pre-catalysts with N-heterocyclic carbene ligands catalyze the Suzuki cross-coupling of aryl chlorides and bromides with alkyllithium-activated arylboronic pinacolate esters. Preliminary mechanistic studies indicate that the cobalt is reduced to Co(0) during catalysis.
      PubDate: 2017-11-14T05:51:52.277173-05:
      DOI: 10.1002/ange.201710053
       
  • EU-40 Materials Prize für Bettina V. Lotsch / Ehrenmitgliedschaft in
           der polnischen chemischen Gesellschaft für Hans-Ulrich Reißig / Welch
           Award für John B. Goodenough
    • PubDate: 2017-11-13T06:15:31.919291-05:
      DOI: 10.1002/ange.201710408
       
  • An in-situ Dynamic Continuum of Supramolecular Phosphoglycopeptides
           Enables Formation of 3D Cell Spheroids
    • Authors: Huaimin Wang; Junfeng Shi, Zhaoqianqi Feng, Rong Zhou, Shiyu Wang, Avital A. Rodal, Bing Xu
      Abstract: Higher-order assemblies of proteins, with a structural and dynamic continuum, is a new paradigm in biology, but these insights have yet to be applied in designing biomaterials. Dynamic assemblies of supramolecular phosphoglycopeptides (sPGPs) transform a 2D cell sheet to 3D cell spheroids. A ligand-receptor interaction between a glycopeptide and a phosphopeptide produces sPGPs that form nanoparticles, which transform to nanofibrils upon partially enzymatic dephosphorylation. The assemblies form dynamically and hierarchically in situ on the cell surface, and interact with extracellular matrix molecules and effectively abolish contact inhibition of locomotion (CIL) of the cells. Integrating molecular recognition, catalysis, and assembly, these active assemblies act as a dynamic continuum to disrupt CIL, thus illustrating a new kind of biomaterials for regulating cell behavior.
      PubDate: 2017-11-10T15:04:53.897633-05:
      DOI: 10.1002/ange.201710269
       
  • Titelbild: Hydrogen Peroxide Insular Dodecameric and Pentameric Clusters
           in Peroxosolvate Structures (Angew. Chem. 48/2017)
    • Authors: Dmitry A. Grishanov; Mger A. Navasardyan, Alexander G. Medvedev, Ovadia Lev, Petr V. Prikhodchenko, Andrei V. Churakov
      Pages: 15365 - 15365
      Abstract: Dodecamere und pentamere Cluster … …, (H2O2)12 und (H2O2)5, wurden in Kristallstrukturen der Peroxosolvate von 2-Aminonicotinsäure und Lidocain-N-oxid entdeckt. In ihrer Zuschrift auf S. 15443 zeigen P. V. Prikhodchenko, A. V. Churakov et al., dass die Selbstorganisation der Wasserstoffperoxid-Moleküle keine speziellen Bedingungen erfordert. Große H2O2-Cluster können entstehen, wenn sich Freiraum in einer Kristallpackung bietet.
      PubDate: 2017-11-02T08:21:55.844621-05:
      DOI: 10.1002/ange.201710881
       
  • Innentitelbild: Das C3-symmetrische Tricyclo[2.2.1.02,6]heptan-3,5,7-triol
           (Angew. Chem. 48/2017)
    • Authors: Volodymyr Kozel; Constantin-Gabriel Daniliuc, Peer Kirsch, Günter Haufe
      Pages: 15366 - 15366
      Abstract: Das kleinste tricyclische C3-symmetrische Triol wurde in racemischer Form in einer einfachen Eintopf-Reaktion aus kommerziell leicht zugänglichen Ausgangsmaterialien und Reagenzien synthetisiert. Eine klassische Racematspaltung führte zu “Propeller-ähnlichen” Enantiomeren, die großes Anwendungspotential in der asymmetrischen Synthese, der molekularen Erkennung und den Materialwissenschaften haben. In ihrer Zuschrift auf S. 15659 liefern G. Haufe et al. mehr Details, unter anderem zur Synthese eines chiralen Dotierstoffs für Flüssigkristalle.
      PubDate: 2017-11-09T12:20:23.778953-05:
      DOI: 10.1002/ange.201710815
       
  • Editorial: Drug Delivery: zu kompliziert und nicht reproduzierbar
           genug'
    • Authors: Jean-Christophe Leroux
      Pages: 15368 - 15369
      Abstract: Die Forschung zum Wirkstofftransport boomt, doch die Zunahme an Veröffentlichungen korreliert nicht mit Fortschritten in der Therapie. Das Beschreiben komplexer Systeme scheint attraktiver zu sein, als eine Krankheit mit einer robusten und sicheren Formulierung effektiv behandeln zu können. Ein weiteres wichtiges Thema ist die mangelnde Reproduzierbarkeit veröffentlichter Befunde …” Lesen Sie mehr im Editorial von Jean-Christophe Leroux.
      PubDate: 2017-10-04T02:30:04.092739-05:
      DOI: 10.1002/ange.201709002
       
  • Graphisches Inhaltsverzeichnis: Angew. Chem. 48/2017
    • Pages: 15371 - 15385
      PubDate: 2017-11-22T04:35:37.613989-05:
      DOI: 10.1002/ange.201784811
       
  • Top-Beiträge aus unseren Schwesterzeitschriften: Angew. Chem. 48/2017
    • Pages: 15386 - 15389
      PubDate: 2017-11-22T04:35:38.335383-05:
      DOI: 10.1002/ange.201784813
       
  • Takahiro Nishimura
    • Pages: 15390 - 15390
      Abstract: „Mein Lieblingsgericht ist Brot mit Kaffee. Wenn ich kein Wissenschaftler wäre, wäre ich Zimmermann ...“ Dies und mehr von und über Takahiro Nishimura finden Sie auf Seite 15390.
      PubDate: 2017-08-17T07:51:02.997336-05:
      DOI: 10.1002/ange.201707583
       
  • Überführung von Ladderenen in plastische Halbleiter mithilfe der
           Mechanochemie
    • Authors: Samuel W. Thomas
      Pages: 15394 - 15396
      Abstract: Von Leitern zu Halbleitern: Xia, Burns, Martinez et al. ist es gelungen, die Ringspannung von Ladderenen mit leiterähnlicher Struktur zu nutzen, um sowohl die Polymerisation der Ladderene als auch deren mechanochemisches Auftrennen zu erzielen, woraus halbleitende Polyacetylen-basierte Blockcopolymere resultieren. Diese Materialien sind vielversprechend als funktionale Polymere für Anwendungen wie die Detektion physikalischer Spannung.
      PubDate: 2017-10-11T06:16:31.654216-05:
      DOI: 10.1002/ange.201709598
       
  • Auf Lysin zielende, kovalente Inhibitoren
    • Authors: Jonathan Pettinger; Keith Jones, Matthew D. Cheeseman
      Pages: 15398 - 15408
      Abstract: Zielgerichtete kovalente Inhibitoren haben in der Wirkstoffentwicklung breite Beachtung gefunden, da sie in der Onkologie eine validierte Methode zur Verhinderung erworbener Resistenzen bieten. Dabei werden die Kristallstrukturen der Komplexe von Proteinen mit niedermolekularen Verbindungen verwendet, um fest bindende Liganden mit passend positionierten elektrophilen Gefechtsköpfen (“warheads”) zu entwickeln. Der Schwerpunkt liegt zwar auf Cysteinresten als Bindungsstellen, aber auch nukleophile Lysinreste können einen Zugang zu irreversibler Inhibierung bieten. Allerdings sind mit dieser Methode wegen der Basizität der ϵ-Aminogruppe in Lysin eine Reihe spezifischer Herausforderungen verbunden. Wir besprechen hier die wichtigen Grundlagen für die Inhibitorplanung, geben historische Beispiele und stellen neue Entwicklungen vor, die das Potenzial von Lysin als Konjugationsstelle in der Wirkstoff-Forschung belegen.Ziel erreicht: Zielgerichtete kovalente Inhibitoren haben in der Wirkstoff-Forschung breite Beachtung gefunden. Dabei kommen vor allem Cysteinreste als Bindungsstellen in Betracht, aber auch ein Zugang über nukleophile Lysinreste kann realisierbar sein. Dieser Kurzaufsatz fasst die Grundlagen dieser Strategie zusammen, weist auf besondere Herausforderungen hin, nennt historische Beispiele und stellt neue Entwicklungen vor.
      PubDate: 2017-10-27T02:55:56.887177-05:
      DOI: 10.1002/ange.201707630
       
  • Triplex-DNA-Nanostrukturen: von grundlegenden Eigenschaften zu Anwendungen
    • Authors: Yuwei Hu; Alessandro Cecconello, Andrea Idili, Francesco Ricci, Itamar Willner
      Pages: 15410 - 15434
      Abstract: Triplex-Nukleinsäuren sind ein Teil des umfangreichen “Struktur-Werkzeugkastens”, der für die Entwicklung von Nanostrukturen und Materialien auf DNA-Basis eingesetzt wird. Dieser Aufsatz behandelt die Verwendung von DNA-Triplexen für die Konstruktion von Sensorplattformen und molekularen Schaltern. Daneben behandeln wir die pH-induzierte, schaltbare Assoziation und Dissoziation von Triplex-DNA-verbrückten Nanostrukturen. Dazu gehören die Aggregation/Deaggregation von Nanopartikeln, die reversible Oligomerisierung von Origamikacheln oder DNA-Zyklen und die Verwendung von Triplex-DNA-Strukturen als Funktionseinheiten zum Aufbau von pH-responsiven Systemen und Materialien. Beispiele hierfür sind Halbleiter-beladene DNA-stabilisierte Mikrokapseln und DNA-funktionalisierte Farbstoff-beladene Metall-organische Gerüste (MOFs) sowie die pH-induzierte Freisetzung der Beladungen. Auch stimuliresponsive Hydrogele auf DNA-Basis, die unter Verwendung von Triplex-Nukleinsäuren reversible pH-induzierte Hydrogel-zu-Lösung-Übergänge durchlaufen und die Verwendung von Triplex-DNA zum Herstellen von Formgedächtnis-Hydrogelen werden behandelt. Schließlich wird ein Ausblick auf zukünftige Anwendungen und Perspektiven für Triplex-Nukleinsäuren gegeben.DNA-Triplexstrukturen werden von Watson-Crick- und Hoogsteen/Reverse-Hoogsteen-Wechselwirkungen zwischen den Strängen stabilisiert. Dieser Aufsatz fasst aktuelle DNA-Triplexsysteme und ihre Anwendung als Schalter, Sensoren und Systeme für die kontrollierte Wirkstofffreisetzung zusammen. Ferner wird die Anwendung von DNA-Triplexstrukturen für die Entwicklung von stimuliresponsiven Materialien beschrieben.
      PubDate: 2017-11-08T09:10:03.451685-05:
      DOI: 10.1002/ange.201701868
       
  • Triaminotriborane(3): A Homocatenated Boron Chain Connected by B−B
           Multiple Bonds
    • Authors: Shogo Morisako; Rong Shang, Yohsuke Yamamoto, Hiroshi Matsui, Masayoshi Nakano
      Pages: 15436 - 15442
      Abstract: A triaminotriborane(3) was isolated as purple crystals through the reduction of (TMP)BCl2 (TMP=2,2,6,6-tetramethylpiperidino) by sodium naphthalenide. Single-crystal X-ray diffraction and computational studies of the obtained triaminotriborane(3) revealed a bent structure of the [B(NR2)]3 chain. The bond lengths between the central and terminal boron atoms were similar to those observed in neutral diborene species. The multiple-bonding character may be best described by a three-center two-electron π-bond along the B3 chain. The distance between the two terminal boron atoms (2.177 Å) in the solid-state structure implies a weak interaction between them. When an excess amount of Li was used as the reducing agent, the reaction yielded an unusual dianionic species. The isolation and characterization of these two reduction products are reported herein.Kein schwächstes Glied: Ein Triaminotriboran(3) wurde durch Reduktion von Dichlor(2,2,6,6-tetramethylpiperidino)boran synthetisiert und vollständig charakterisiert (siehe Schema). Die B-B-B-Kette besteht aus Bor-Bor-Mehrfachbindungen; Experimente und Rechnungen zeigen außerdem eine Drei-Zentren-zwei-Elektronen-π-Bindung außerhalb der Ebene der B3-Kette.
      PubDate: 2017-11-02T08:10:31.898444-05:
      DOI: 10.1002/ange.201708215
       
  • Hydrogen Peroxide Insular Dodecameric and Pentameric Clusters in
           Peroxosolvate Structures
    • Authors: Dmitry A. Grishanov; Mger A. Navasardyan, Alexander G. Medvedev, Ovadia Lev, Petr V. Prikhodchenko, Andrei V. Churakov
      Pages: 15443 - 15447
      Abstract: Peroxosolvates of 2-aminonicotinic acid (I) and lidocaine N-oxide (II) including the largest insular hydrogen peroxide clusters were isolated and their crystal structures were determined by single-crystal X-ray diffraction. An unprecedented dodecameric hydrogen peroxide insular cluster was found in I. An unusual cross-like pentameric cluster was observed in the structure of II. The topology of the (H2O2)12 assembly was never observed for small-molecule clusters. In I and II new double and triple cross-orientational disorders of H2O2 were found. Cluster II is the first example of a peroxosolvate crystal structure containing H2O2 molecules with a homoleptic hydrogen peroxide environment. In II, a hydrogen bond between an H2O2 molecule and a peptide group -CONH⋅⋅⋅O2H2 was observed for the first time.Peroxid-Bindung: Peroxosolvate von 2-Aminonicotinsäure (I) und Lidocain-N-oxid (II), die beispiellose dodekamere und pentamere Wasserstoffperoxid-Cluster enthalten, wurden isoliert und röntgenkristallographisch untersucht. Dabei wurden in I und II doppelte und dreifache kreuzförmige Fehlordnungen für H2O2 gefunden. II zeigt zudem die erste Wasserstoffbrücke zwischen einem H2O2-Molekül und einem Peptid.
      PubDate: 2017-10-19T01:57:40.308823-05:
      DOI: 10.1002/ange.201709699
       
  • A Polymer/Peptide Complex-Based Sensor Array That Discriminates Bacteria
           in Urine
    • Authors: Jinsong Han; Haoran Cheng, Benhua Wang, Markus Santhosh Braun, Xiaobo Fan, Markus Bender, Wei Huang, Cornelius Domhan, Walter Mier, Thomas Lindner, Kai Seehafer, Michael Wink, Uwe H. F. Bunz
      Pages: 15448 - 15453
      Abstract: A negatively charged poly(para-phenyleneethynylene) (PPE) forms electrostatic complexes with four positively charged antimicrobial peptides (AMP). The AMPs partially quench the fluorescence of the PPE and discriminate fourteen different bacteria in water and in human urine by pattern-based fluorescence recognition; the AMP-PPE complexes bind differentially to the components of bacterial surfaces. The bacterial species and strains form clusters according to staining properties (Gram-positive and Gram-negative) or genetic similarity (genus, species, and strain). The identification and data treatment is performed by pattern evaluation with linear discriminant analysis (LDA) of the collected fluorescence intensity data.Diskriminierung! Aus vier kationischen antimikrobiellen Peptiden (AMPs) und einem anionischen Poly(para-phenylenethinylen) (PPE) aufgebaute elektrostatische Komplexe wurden als neuartige Array-Sensoren getestet. In menschlichem Urin können mithilfe der Sensoren 14 Bakterienarten anhand von Gram-Status und genetischer Verwandtschaft identifiziert und unterschieden werden, indem Fluoreszenzmuster gemessen und einer linearen Diskriminanzanalyse unterzogen werden.
      PubDate: 2017-10-26T08:26:36.695307-05:
      DOI: 10.1002/ange.201706101
       
  • Feedback Kinetics in Mechanochemistry: The Importance of Cohesive States
    • Authors: Benjamin P. Hutchings; Deborah E. Crawford, Lei Gao, Peijun Hu, Stuart L. James
      Pages: 15454 - 15458
      Abstract: Although mechanochemical synthesis is becoming more widely applied and even commercialised, greater basic understanding is needed if the field is to progress on less of a trial-and-error basis. We report that a mechanochemical reaction in a ball mill exhibits unusual sigmoidal feedback kinetics that differ dramatically from the simple first-order kinetics for the same reaction in solution. An induction period is followed by a rapid increase in reaction rate before the rate decreases again as the reaction goes to completion. The origin of these unusual kinetics is found to be a feedback cycle involving both chemical and mechanical factors. During the reaction the physical form of the reaction mixture changes from a powder to a cohesive rubber-like state, and this results in the observed reaction rate increase. The study reveals that non-obvious and dynamic rheological changes in the reaction mixture must be appreciated to understand how mechanochemical reactions progress.Festkörperreaktionen: Die ungewöhnliche sigmoidale Kinetik mechanochemischer Reaktionen kann mit einer Rückkopplungsschleife, die chemische und mechanische Faktoren einbezieht, erklärt werden. Während der Reaktion verändert sich die Konsistenz der Reaktionsmischung von einem Pulver zu einem gummiartigen Zustand.
      PubDate: 2017-10-30T06:26:57.730768-05:
      DOI: 10.1002/ange.201706723
       
  • Direct Access to MIDA Acylboronates through Mild Oxidation of MIDA
           Vinylboronates
    • Authors: Mathieu L. Lepage; Samson Lai, Nicolas Peressin, Romain Hadjerci, Brian O. Patrick, David M. Perrin
      Pages: 15459 - 15463
      Abstract: Acylboronate esters/trifluoroborates represent an elusive class of boronates that are of increasing interest for both fundamental study as well as applications at the interface of chemistry and biology. Their preparation has been limited by the use of strongly basic anions, often introduced in multistep reactions. Herein, we demonstrate the facile preparation of acylboronate N-methyliminodiacetyl (MIDA) esters from alkenyl-2-boronate esters through mild dihydroxylation and meta-periodate cleavage. Given the well-known functional-group tolerance of this mild reaction sequence and the availability of alkenyl-2-boronates, this method should greatly increase access to acylboronate MIDA esters.O statt CH2: Acylbor-N-methyliminodiacetyl(MIDA)-Ester sind ausgehend von Alkenyl-2-boronsäureestern über milde Dihydroxylierung und meta-Periodat-Spaltung in zwei Stufen erhältlich. Die bekannte Verträglichkeit dieser Reaktionssequenz mit funktionellen Gruppen und die gute Verfügbarkeit der Alkenyl-2-boronate erleichtern den Zugang zu Acylbor-MIDA-Estern.
      PubDate: 2017-10-24T06:28:47.739368-05:
      DOI: 10.1002/ange.201707125
       
  • Structural Characterization of a Covalent Monolayer Sheet Obtained by
           Two-Dimensional Polymerization at an Air/Water Interface
    • Authors: Vivian Müller; Feng Shao, Milos Baljozovic, Mina Moradi, Yao Zhang, Thomas Jung, William B. Thompson, Benjamin T. King, Renato Zenobi, A. Dieter Schlüter
      Pages: 15464 - 15468
      Abstract: This work describes a two-dimensional polymerization at an air/water interface and provides, for the first time, direct spectroscopic evidence for the kind of crosslinks formed and for the conversion reached in a covalently bonded monolayer sheet. This evidence was obtained through a combination of a variety of monolayer characterization techniques before and after transfer onto solid substrates, in particular by tip-enhanced Raman spectroscopy (TERS) and TERS mapping after transfer of both the monomer and polymer monolayer onto Au(111). This work is a major advance for the field of 2D polymers synthesized at the air/water interface as it, in principle, allows estimation of the crystallinity by percolation theory and the location of regions with defects.Spitze-Leistung: Die photochemisch induzierte zweidimensionale Polymerisation eines trifunktionellen Monomers an einer Luft-Wasser-Grenzfläche verläuft über Anthracendimerisierung benachbarter Monomere. Dichtefunktionalrechnungen und konfokale Raman-Spektroskopie an Referenzverbindungen bestätigen, dass Monomer wie Polymer bestimmte Signale in spitzenverstärkten Raman-Spektren (TERS) liefern, anhand derer der Umsatz abgeschätzt werden kann.
      PubDate: 2017-11-02T08:15:49.178004-05:
      DOI: 10.1002/ange.201707140
       
  • Exploring the Formation of Black Phosphorus Intercalation Compounds with
           Alkali Metals
    • Authors: Gonzalo Abellán; Christian Neiss, Vicent Lloret, Stefan Wild, Julio C. Chacón-Torres, Katharina Werbach, Filippo Fedi, Hidetsugu Shiozawa, Andreas Görling, Herwig Peterlik, Thomas Pichler, Frank Hauke, Andreas Hirsch
      Pages: 15469 - 15475
      Abstract: Black phosphorus intercalation compounds (BPICs) with alkali metals (namely: K and Na) have been synthesized in bulk by solid-state as well as vapor-phase reactions. By means of a combination of in situ X-ray diffraction, Raman spectroscopy, and DFT calculations the structural behavior of the BPICs at different intercalation stages has been demonstrated for the first time. Our results provide a glimpse into the very first steps of a new family of intercalation compounds, with a distinct behavior as compared to its graphite analogues (GICs), showing a remarkable structural complexity and a dynamic behavior.Nuancen von Schwarz: Interkalationsverbindungen von schwarzem Phosphor (BPICs) mit den Alkalimetallen K und Na (im Bild als dunkle Kugeln dargestellt) zeigen eine komplexe strukturelle Dynamik. In-situ-Raman-Spektroskopie und Dichtefunktionalrechnungen liefern Vergleichsdaten zur Identifizierung dieser Interkalationsverbindungen.
      PubDate: 2017-10-26T03:56:13.363441-05:
      DOI: 10.1002/ange.201707462
       
  • Oxyfunctionalization of the Remote C−H Bonds of Aliphatic Amines by
           Decatungstate Photocatalysis
    • Authors: Danielle M. Schultz; François Lévesque, Daniel A. DiRocco, Mikhail Reibarkh, Yining Ji, Leo A. Joyce, James F. Dropinski, Huaming Sheng, Benjamin D. Sherry, Ian W. Davies
      Pages: 15476 - 15480
      Abstract: Aliphatic amines, oxygenated at remote positions within the molecule, represent an important class of synthetic building blocks to which there are currently no direct means of access. Reported herein is an efficient and scalable solution that relies upon decatungstate photocatalysis under acidic conditions using either H2O2 or O2 as the terminal oxidant. By using these reaction conditions a series of simple and unbiased aliphatic amine starting materials can be oxidized to value-added ketone products. Lastly, NMR spectroscopy using in situ LED-irradiated samples was utilized to monitor the kinetics of the reaction, thus enabling direct translation of the reaction into flow.Das Decawolframat-Anion, ein UV-absorbierender Photokatalysator, wurde zur Umsetzung von ungeschützten aliphatischen Aminen in Produkte mit einer entfernt positionierten Ketonfunktionalität eingesetzt, wobei H2O2 oder O2 als Oxidationsmittel diente. NMR-Studien an LED-bestrahlten Proben führten zur Identifizierung eines Schlüsselintermediats und ermöglichten letztlich die Übertragung der Reaktion in einen Durchflussreaktor.
      PubDate: 2017-10-26T08:27:31.295018-05:
      DOI: 10.1002/ange.201707537
       
  • Structures of the Heme Acquisition Protein HasA with
           Iron(III)-5,15-Diphenylporphyrin and Derivatives Thereof as an Artificial
           Prosthetic Group
    • Authors: Hiromu Uehara; Yuma Shisaka, Tsubasa Nishimura, Hiroshi Sugimoto, Yoshitsugu Shiro, Yoshihiro Miyake, Hiroshi Shinokubo, Yoshihito Watanabe, Osami Shoji
      Pages: 15481 - 15485
      Abstract: Iron(III)-5,15-diphenylporphyrin and several derivatives were accommodated by HasA, a heme acquisition protein secreted by Pseudomonas aeruginosa, despite possessing bulky substituents at the meso position of the porphyrin. Crystal structure analysis revealed that the two phenyl groups at the meso positions of porphyrin extend outside HasA. It was shown that the growth of P. aeruginosa was inhibited in the presence of HasA coordinating the synthetic porphyrins under iron-limiting conditions, and that the structure of the synthetic porphyrins greatly affects the inhibition efficiency.Eisensammler: Eisen(III)-5,15-diphenylporphyrin und seine Derivate werden von HasA, einem von Pseudomonas aeruginosa ausgeschiedenen Hämbindeprotein, trotz der sperrigen meso-Substituenten angenommen. Kristallstrukturanalysen zufolge ragen die beiden meso-Phenylgruppen aus der HasA-Bindetasche heraus.
      PubDate: 2017-10-06T05:57:11.673668-05:
      DOI: 10.1002/ange.201707212
       
  • Encapsulation of a Quinhydrone Cofactor in the Inner Pocket of Cobalt
           Triangular Prisms: Combined Light-Driven Reduction of Protons and
           Hydrogenation of Nitrobenzene
    • Authors: Liang Zhao; Jianwei Wei, Jing Zhang, Cheng He, Chunying Duan
      Pages: 15486 - 15490
      Abstract: The design of artificial systems that mimic highly evolved and finely tuned natural photosynthetic systems has attracted intensive research interest. A new system was formulated that encapsulates a quinhydrone (QHQ) cofactor in metal–organic hosts based on inspiration from the redox relays of photosystem II. The M6L3 triangular prism hosts provided a special redox-modulated environment for the cofactor localized within the pocket, and the proximity effects of the host–guest interactions facilitated the formation of charge-transfer complexes that are typically very difficult to form in normal homogeneous systems. Extensive electron delocalization and well-controlled redox potential were induced to decrease the overpotential of the metal sites for proton reduction. The excellent activity and stability of the supramolecular systems allow the tandem reductions being combined to efficiently reduce nitrobenzene using active H-sources from the light activation of water.Die Verkapselung von Chinhydron in redoxaktiven molekularen Containern ist eine neue Strategie für den Aufbau von Wirt-Gast-Ladungstransferkomplexen. Die Methode kombiniert die redoxmodulierbare Umgebung des Metall-organischen Wirtes mit den sterischen Effekten der Wirt-Gast-Wechselwirkungen. Das System wandelt Nitrobenzol unter Lichteinstrahlung um und imitiert dabei die Funktion von Enzymen.
      PubDate: 2017-11-02T04:45:44.090883-05:
      DOI: 10.1002/ange.201707676
       
  • Differential Epitope Mapping by STD NMR Spectroscopy To Reveal the Nature
           of Protein–Ligand Contacts
    • Authors: Serena Monaco; Louise E. Tailford, Nathalie Juge, Jesus Angulo
      Pages: 15491 - 15495
      Abstract: Saturation transfer difference (STD) NMR spectroscopy is extensively used to obtain epitope maps of ligands binding to protein receptors, thereby revealing structural details of the interaction, which is key to direct lead optimization efforts in drug discovery. However, it does not give information about the nature of the amino acids surrounding the ligand in the binding pocket. Herein, we report the development of the novel method differential epitope mapping by STD NMR (DEEP-STD NMR) for identifying the type of protein residues contacting the ligand. The method produces differential epitope maps through 1) differential frequency STD NMR and/or 2) differential solvent (D2O/H2O) STD NMR experiments. The two approaches provide different complementary information on the binding pocket. We demonstrate that DEEP-STD NMR can be used to readily obtain pharmacophore information on the protein. Furthermore, if the 3D structure of the protein is known, this information also helps in orienting the ligand in the binding pocket.Proteinkartierung: Informationen über die Art der Aminosäurereste, die einen Ligand in der Bindetasche eines Proteins umgeben, sind durch differenzielle Epitopkartierung mit STD-NMR-Spektroskopie (DEEP-STD-NMR) rasch zugänglich. Die Methode liefert Epitopkarten über Experimente bei verschiedenen Frequenzen und/oder mit verschiedenen Lösungsmitteln (D2O/H2O). Die Ergebnisse beider Ansätze ergänzen sich beim Erstellen eines Bilds der Bindetasche.
      PubDate: 2017-10-23T06:51:00.413581-05:
      DOI: 10.1002/ange.201707682
       
  • A Hydrogen-Bonded Hexagonal Buckybowl Framework
    • Authors: Ichiro Hisaki; Hideaki Toda, Hiroyasu Sato, Norimitsu Tohnai, Hidehiro Sakurai
      Pages: 15496 - 15500
      Abstract: A hydrogen-bonded two-dimensionally networked buckybowl architecture is presented. Two types of hexagonal network (HexNet) structures (CPSM-1 and CPSM-2) have been achieved based on a sumanene derivative (CPSM) possessing 4,4′-dicarboxy-o-terphenyl groups in the periphery. CPSM-1 has a waved HexNet structure with an alternate alignment of upward and downward bowls. CPSM-2 has a bilayered HexNet structure composed of hamburger-shaped dimers of the bowls. This demonstrates that non-planar π-systems can be networked two-dimensionally by an appropriate supramolecular synthon to achieve structurally well-defined unique bumpy π-sheets. Furthermore, we revealed that CPSM-2 undergoes anisotropic shrinking along the c axis by 11 % under high pressure conditions (970 MPa). The shrinkage is brought about by offset sliding between bumpy π-surfaces of the bilayered HexNet sheets.Ein Sumanenderivat mit 4,4′-Dicarboxy-o-terphenyl-Einheiten bildet zweierlei wasserstoffverbrückte hexagonale Schichtarchitekturen mit gekrümmten und welligen Oberflächen. Eine davon reagierte mit anisotropem Schrumpfen auf die Anwendung von hohem Druck.
      PubDate: 2017-10-26T08:28:02.399343-05:
      DOI: 10.1002/ange.201708115
       
  • Elucidating the Excited State of Mechanoluminescence in Organic Luminogens
           with Room-Temperature Phosphorescence
    • Authors: Jie Yang; Xuming Gao, Zongliang Xie, Yanbin Gong, Manman Fang, Qian Peng, Zhenguo Chi, Zhen Li
      Pages: 15501 - 15505
      Abstract: Two stable, purely organic luminogens exhibit both mechano- (ML) and photoluminescence (PL) with dual fluorescence–phosphorescence emissions at room temperature. Careful analysis of the crystal structures, coupled with theoretical calculations, demonstrate that room-temperature phosphorescence and ML properties are strongly related to molecular packing. In particular, the formation and fracture of molecular dimers with intermolecular charge-transfer properties has a significant effect on intersystem crossing, as well as excited triplet state emissions, in both PL and ML processes.Licht und Reibung: Zwei stabile organische Luminogene, CzS-CH3 und CzS-C2H5, zeigen Mechano- (ML) und Photolumineszenz (PL) mit dualer Fluoreszenz- und Phosphoreszenz-Emission bei Raumtemperatur. Ein gut verstandener PL-Prozess bildet die Grundlage für die Visualisierung eines unbekannten angeregten ML-Zustands.
      PubDate: 2017-10-24T11:32:44.72053-05:0
      DOI: 10.1002/ange.201708119
       
  • Effects of Bithiophene Imide Fusion on the Device Performance of Organic
           Thin-Film Transistors and All-Polymer Solar Cells
    • Authors: Yingfeng Wang; Zhenglong Yan, Han Guo, Mohammad Afsar Uddin, Shaohua Ling, Xin Zhou, Huimin Su, Junfeng Dai, Han Young Woo, Xugang Guo
      Pages: 15506 - 15510
      Abstract: Two new bithiophene imide (BTI)-based n-type polymers were synthesized. f-BTI2-FT based on a fused BTI dimer showed a smaller band gap, a lower LUMO, and higher crystallinity than s-BTI2-FT containing a BTI dimer connected through a single bond. s-BTI2-FT exhibited a remarkable electron mobility of 0.82 cm2 V−1 s−1, and f-BTI2-FT showed a further improved mobility of 1.13 cm2 V−1 s−1 in transistors. When blended with the polymer donor PTB7-Th, f-BTI2-FT-based all-polymer solar cells (all-PSCs) attained a PCE of 6.85 %, the highest value for an all-PSC not based on naphthalene (or perylene) diimide polymer acceptors. However, s-BTI2-FT all-PSCs showed nearly no photovoltaic effect. The results demonstrate that f-BTI2-FT is one of most promising n-type polymers and that ring fusion offers an effective approach for designing polymers with improved electrical properties.Zwei Bithiophenimid(BTI)-basierte n-Halbleiterpolymere wurden synthetisiert und charakterisiert. Beide zeigen beträchtliche Elektronenbeweglichkeiten in organischen Dünnfilmtransistoren, die Anellierung im BTI-Dimer erhöhte die Leistungsfähigkeit in Polymersolarzellen jedoch deutlich. So konnten bemerkenswerte Wirkungsgrade bis 6.85 % und eine Leerlaufspannung von 1.04 V erreicht werden.
      PubDate: 2017-11-03T07:00:38.037183-05:
      DOI: 10.1002/ange.201708421
       
  • Visible-Light-Initiated Manganese Catalysis for C−H Alkylation of
           Heteroarenes: Applications and Mechanistic Studies
    • Authors: Philippe Nuhant; Martins S. Oderinde, Julien Genovino, Antoine Juneau, Yohann Gagné, Christophe Allais, Gary M. Chinigo, Chulho Choi, Neal W. Sach, Louise Bernier, Yvette M. Fobian, Mark W. Bundesmann, Bhagyashree Khunte, Mathieu Frenette, Olugbeminiyi O. Fadeyi
      Pages: 15511 - 15515
      Abstract: A visible-light-driven Minisci protocol that employs an inexpensive earth-abundant metal catalyst, decacarbonyldimanganese Mn2(CO)10, to generate alkyl radicals from alkyl iodides has been developed. This Minisci protocol is compatible with a wide array of sensitive functional groups, including oxetanes, sugar moieties, azetidines, tert-butyl carbamates (Boc-group), cyclobutanes, and spirocycles. The robustness of this protocol is demonstrated on the late-stage functionalization of complex nitrogen-containing drugs. Photophysical and DFT studies indicate a light-initiated chain reaction mechanism propagated by .Mn(CO)5. The rate-limiting step is the iodine abstraction from an alkyl iodide by .Mn(CO)5.Ein Photoredoxverfahren für die C-H-Alkylierung von Heteroarenen nutzt die Bildung von Alkylradikalen aus Alkyliodiden durch Bestrahlung mit sichtbarem Licht in Gegenwart von Mn2(CO)10. Zahlreiche empfindliche funktionelle Gruppen sind mit diesem Ansatz vereinbar.
      PubDate: 2017-10-26T08:27:39.197794-05:
      DOI: 10.1002/ange.201707958
       
  • Quantifying Guest Exchange in Supramolecular Systems
    • Authors: Liat Avram; Anthony D. Wishard, Bruce C. Gibb, Amnon Bar-Shir
      Pages: 15516 - 15520
      Abstract: The ability to accurately determine and quantitatively evaluate kinetic phenomena associated with supramolecular assemblies, in real time, is key to a better understanding of their defined architectures and diverse functionalities. Therefore, analytical tools that can precisely assess a wide range of exchange rates within such systems are of considerable importance. This study demonstrates the ability to use an NMR approach based on saturation transfer for the determination of rates of guest exchange from molecular capsules. By using cavitands that assemble into distinct dimeric assemblies, we show that this approach, which we term guest exchange saturation transfer (GEST), allows the use of a conventional NMR setup to study and quantitatively assess a wide range of exchange rates, from 35 to more than 5000 s−1.Heimliche Gäste: Gastaustauschsättigungstransfer (GEST), ein NMR-basierter Ansatz zur Untersuchung von dynamischen supramolekularen Aggegaten, ermöglichte die quantitative Bestimmung von Austauschprozessen in dimeren Kapseln – auch dann, wenn 1H- oder 19F-NMR keine Hinweise auf eine Komplexbildung erbracht hatten. Durch Verwendung verschiedener Gäste konnte eine Bandbreite an Austauschraten von 35 bis über 5000 s−1 ermittelt werden.
      PubDate: 2017-10-20T01:20:34.52074-05:0
      DOI: 10.1002/ange.201708726
       
  • A Strategy for Specific Fluorescence Imaging of Monoamine Oxidase A
           in Living Cells
    • Authors: Xiaofeng Wu; Wen Shi, Xiaohua Li, Huimin Ma
      Pages: 15521 - 15525
      Abstract: Monoamine oxidase (MAO) has two isoforms, MAO-A and MAO-B, which show different functions, and thus selective fluorescence imaging is important for biological studies. Currently, however, specific detection of MAO-A remains a great challenge. Herein, we report a new strategy for specific imaging of MAO-A through the design of fluorogenic probes combining the characteristic structure of an inhibitor of the target enzyme along with propylamine as a recognition moiety. The high specificity of our representative probe is demonstrated by imaging MAO-A in different live cells such as SH-SY5Y (high levels of MAO-A) and HepG2 (high levels of MAO-B), and further validated by western blot analyses. The superior specificity of the probe may enable the accurate detection of MAO-A in complex biosystems. Importantly, the use of the characteristic structure of an inhibitor, as demonstrated in this work, may serve as a general strategy to design specific recognition moieties for fluorogenic probes for enzymes.MAO-A, nicht B: Bei der Entwicklung fluorogener Sonden wurde ein Strukturteil eines Inhibitors des Zielenzyms als zielsuchende Gruppe genutzt. Auf diese Weise wurde eine spezifische Sonde für Monoaminoxidase A (MAO-A) hergestellt und zur Bildgebung von SH-SY5Y- und HepG2-Zellen, mit unterschiedlichen Expressionsniveaus für MAO-A, eingesetzt.
      PubDate: 2017-10-25T10:10:03.39498-05:0
      DOI: 10.1002/ange.201708428
       
  • Single-Molecule Observation of the Photoregulated Conformational Dynamics
           of DNA Origami Nanoscissors
    • Authors: Elena M. Willner; Yuu Kamada, Yuki Suzuki, Tomoko Emura, Kumi Hidaka, Hendrik Dietz, Hiroshi Sugiyama, Masayuki Endo
      Pages: 15526 - 15530
      Abstract: We demonstrate direct observation of the dynamic opening and closing behavior of photocontrollable DNA origami nanoscissors using high-speed atomic force microscopy (HS-AFM). First the conformational change between the open and closed state controlled by adjustment of surrounding salt concentration could be directly observed during AFM scanning. Then light-responsive moieties were incorporated into the nanoscissors to control these structural changes by photoirradiation. Using photoswitchable DNA strands, we created a photoresponsive nanoscissors variant and were able to distinguish between the open and closed conformations after respective irradiation with ultraviolet (UV) and visible (Vis) light by gel electrophoresis and AFM imaging. Additionally, these reversible changes in shape during photoirradiation were directly visualized using HS-AFM. Moreover, four photoswitchable nanoscissors were assembled into a scissor–actuator-like higher-order object, the configuration of which could be controlled by the open and closed switching induced by irradiation with UV and Vis light.Lichtgesteuerte Strukturänderungen: Die dynamische Konformationsänderung einer photoschaltbaren DNA-Struktur konnte direkt mittels Hochgeschwindigkeits-Rasterkraftmikroskopie (HS-AFM) beobachtet werden. Das reversible Öffnen und Schließen der Nanostruktur wurde während der Einstrahlung von ultraviolettem bzw. sichtbarem Licht beobachtet. Strukturelles Schalten der photoresponsiven quadratförmigen Anordnung wurde ebenfalls erzielt.
      PubDate: 2017-10-30T06:16:07.33841-05:0
      DOI: 10.1002/ange.201708722
       
  • Single-Molecule Monitoring of the Structural Switching Dynamics of Nucleic
           Acids through Controlling Fluorescence Blinking
    • Authors: Kiyohiko Kawai; Takafumi Miyata, Naohiko Shimada, Syoji Ito, Hiroshi Miyasaka, Atsushi Maruyama
      Pages: 15531 - 15535
      Abstract: Single-molecule fluorescence resonance energy transfer (smFRET) is a powerful tool to investigate the dynamics of biomolecular events in real time. However, it requires two fluorophores and can be applied only to dynamics that accompany large changes in distance between the molecules. Herein, we introduce a method for kinetic analysis based on control of fluorescence blinking (KACB), a general approach to investigate the dynamics of biomolecules by using a single fluorophore. By controlling the kinetics of the redox reaction the blinking kinetics or pattern can be controlled to be affected by microenvironmental changes around a fluorophore (rKACB), thereby enabling real-time single-molecule measurement of the structure-changing dynamics of nucleic acids.Blinker einschalten: Dynamische Wechsel von Nukleinsäuren zwischen Schleife und Stamm von Haarnadelstrukturen wurden durch kinetische Studien auf der Ebene einzelner Moleküle analysiert. Fluorophore in der Schleife ergeben eine schnell blinkende Fluoreszenz, solche im Stamm eine langsam blinkende Fluoreszenz.
      PubDate: 2017-10-24T06:22:02.670755-05:
      DOI: 10.1002/ange.201708705
       
  • Organic Thiocarboxylate Electrodes for a Room-Temperature Sodium-Ion
           Battery Delivering an Ultrahigh Capacity
    • Authors: Hongyang Zhao; Jianwei Wang, Yuheng Zheng, Ju Li, Xiaogang Han, Gang He, Yaping Du
      Pages: 15536 - 15540
      Abstract: Organic room-temperature sodium-ion battery electrodes with carboxylate and carbonyl groups have been widely studied. Herein, for the first time, we report a family of sodium-ion battery electrodes obtained by replacing stepwise the oxygen atoms with sulfur atoms in the carboxylate groups of sodium terephthalate which improves electron delocalization, electrical conductivity and sodium uptake capacity. The versatile strategy based on molecular engineering greatly enhances the specific capacity of organic electrodes with the same carbon scaffold. By introducing two sulfur atoms to a single carboxylate scaffold, the molecular solid reaches a reversible capacity of 466 mAh g−1 at a current density of 50 mA g−1. When four sulfur atoms are introduced, the capacity increases to 567 mAh g−1 at a current density of 50 mA g−1, which is the highest capacity value reported for organic sodium-ion battery anodes until now.Eine Reihe organischer Elektroden für Natriumionenbatterien wurde entwickelt, indem stufenweise Sauerstoff durch Schwefel in den Carboxylatgruppen von Natriumterephthalat ersetzt wurde. Die Elektroden zeigen eine verbesserte Elektronendelokalisierung, elektrische Leitfähigkeit und Natriumaufnahmekapazität. Diese Strategie erhöht die spezifische Kapazität der organischen Elektroden.
      PubDate: 2017-11-02T08:11:48.519522-05:
      DOI: 10.1002/ange.201708960
       
  • Silicon Wafers with Facet-Dependent Electrical Conductivity Properties
    • Authors: Chih-Shan Tan; Pei-Lun Hsieh, Lih-Juann Chen, Michael H. Huang
      Pages: 15541 - 15545
      Abstract: By breaking intrinsic Si (100) and (111) wafers to expose sharp {111} and {112} facets, electrical conductivity measurements on single and different silicon crystal faces were performed through contacts with two tungsten probes. While Si {100} and {110} faces are barely conductive at low applied voltages, as expected, the Si {112} surface is highly conductive and Si {111} surface also shows good conductivity. Asymmetrical I–V curves have been recorded for the {111}/{112}, {111}/{110}, and {112}/{110} facet combinations because of different degrees of conduction band bending at these crystal surfaces presenting different barrier heights to current flow. In particular, the {111}/{110} and {112}/{110} facet combinations give I–V curves resembling those of p–n junctions, suggesting a novel field effect transistor design is possible capitalizing on the pronounced facet-dependent electrical conductivity properties of silicon.Facettenreich: Wolframsonden wurden an einen Si-Wafer kontaktiert und zur Messung der flächenabhängigen elektrischen Leitfähigkeit von Si-Kristallen genutzt. Für die Flächenkombinationen {111}/{112}, {111}/{110} und {112}/{110} wurden unsymmetrische I-V-Kurven erhalten. Diese intrinsischen flächenabhängigen Effekte beim Silicium könnten für ein neuartiges Feldeffekttransistordesign genutzt werden.
      PubDate: 2017-11-02T07:05:39.302482-05:
      DOI: 10.1002/ange.201709020
       
  • Time-Resolved In Situ MAS NMR Monitoring of the Nucleation and Growth of
           Zeolite BEA Catalysts under Hydrothermal Conditions
    • Authors: Irina I. Ivanova; Yury G. Kolyagin, Ivan A. Kasyanov, Alexander V. Yakimov, Tatiana O. Bok, Dmitry N. Zarubin
      Pages: 15546 - 15549
      Abstract: Time-resolved 13C, 23Na, 27Al, and 29Si MAS NMR has been applied in situ for monitoring the hydrothermal synthesis of zeolite BEA. Isotopic labelling with 29Si and 13C isotopes has been used to follow the fate of siliceous species and structure directing agent ((13CH3−CH2)4NOH). Two mechanistic pathways, namely solution-mediated and solid–solid hydrogel rearrangement have been distinguished for two synthesis procedures studied. The mechanisms of structure-directing behavior of TEA+ cations in two reaction pathways have been elucidated. The results show that multinuclear MAS NMR can serve as a superior tool for monitoring hydrothermal synthesis of various solids including zeolites, zeotypes, mesoporous materials, metal–organic frameworks and so on and for the design of novel outstanding materials for different applications.Zeitauflösende 13C-, 23Na-, 27Al- und 29Si-MAS-NMR-Spektroskopie wurde mit der Markierung durch 29Si- und 13C-Isotope gekoppelt, um die Hydrothermalsynthese von Zeolith BEA in situ nachzuverfolgen. Homogene und heterogene mechanistische Pfade wurden identifiziert.
      PubDate: 2017-11-02T04:46:13.735398-05:
      DOI: 10.1002/ange.201709039
       
  • Precise Assembly of Particles for Zigzag or Linear Patterns
    • Authors: Dan Guo; Chang Li, Yang Wang, Yanan Li, Yanlin Song
      Pages: 15550 - 15554
      Abstract: Precise control of particles assembly has tremendous potential for fabricating intricate structures and functional materials. However, it is still a challenge to achieve one-dimensional assembly with precisely controlled morphology. An effective strategy is reported to precisely assemble particles into well-defined patterns by liquid confinement through controlling the viscosity of the assembly system. It is found that high viscosity of the system impedes particles rearrangement and facilitates the generation of zigzag or twined zigzag assembly structures, while low viscosity of the system allows particles to rearrange into linear or zipper structures driven by lowering the surface deformation of the liquid. As a result, precise control of different assembly patterns can be achieved through tuning the viscosity of solvent and size confinement ratios. This facile approach shows generality for particles assembly of different sizes and materials.Die Aggregation von Partikeln lässt sich über die Viskosität steuern. Hohe Viskosität behindert die Partikelanordnung und erleichtert die Bildung von Zickzackstrukturen. Bei niedriger Viskosität arrangieren sich die Partikel in linearen oder Reißverschluss-förmigen Strukturen, deren Orientierung zur Erzeugung verschiedener Muster gesteuert werden kann.
      PubDate: 2017-11-02T04:41:28.219661-05:
      DOI: 10.1002/ange.201709115
       
  • Catalytic Enantioselective Synthesis of Mariline A and Related
           Isoindolinones through a Biomimetic Approach
    • Authors: Chang Min; Yingfu Lin, Daniel Seidel
      Pages: 15555 - 15559
      Abstract: The catalytic enantioselective synthesis of isoindolinones was achieved through the condensation of 2-acyl-benzaldehydes and anilines. In the presence of 1 mol % of a chiral phosphoric acid catalyst, reactions reach completion within 10 min and provide products with up to 98 % ee. Anilines with an ortho t-butyl group form atropisomeric products, thereby enabling the simultaneous generation of axial and point chirality from two achiral substrates. This method was applied to the first synthesis of mariline A.Katalytisch kondensiert: Die enantioselektive Synthese von Isoindolinonen gelingt durch die Kondensation von 2-Acylbenzaldehyden mit Anilinen. In Gegenwart von 1 Mol-% eines chiralen Phosphorsäure-Katalysators sind die Umsetzungen nach 10 Minuten abgeschlossen. Die Produkte werden mit bis zu 98 % ee erhalten. Aniline mit ortho-tert-Butyl-Gruppe bilden atropisomere Produkte. Die Methode wurde in der ersten Synthese von Marilin A angewendet.
      PubDate: 2017-11-02T04:40:46.572088-05:
      DOI: 10.1002/ange.201709182
       
  • Squaramide-Catalyzed Asymmetric aza-Friedel–Crafts/N,O-Acetalization
           Domino Reactions Between 2-Naphthols and Pyrazolinone Ketimines
    • Authors: Uğur Kaya; Pankaj Chauhan, Suruchi Mahajan, Kristina Deckers, Arto Valkonen, Kari Rissanen, Dieter Enders
      Pages: 15560 - 15564
      Abstract: N-Boc ketimines derived from pyrazolin-5-ones were explored to develop an unprecedented domino aza-Friedel–Crafts/N,O-acetalization reaction with 2-naphthols. The novel method requires a catalyst loading of only 0.5 mol % of a bifunctional squaramide catalyst, is scalable to gram amounts, and provides a new series of furanonaphthopyrazolidinone derivatives bearing two vicinal tetra-substituted stereogenic centers in excellent yields (95–98 %) and stereoselectivity (>99:1 d.r. and 97–98 % ee). A different reactivity was observed in the case of 1-naphthols and other electron-rich phenols, which led to the aza-Friedel–Crafts adducts in 70–98 % yield and 47–98 % ee.Quadratisch, praktisch, gut: Quadratsäureamid katalysiert effizient eine Aza-Friedel-Crafts/N,O-Acetalisierungs-Dominoreaktion zwischen 2-Naphtholen und von Pyrazolin-5-on abgeleiteten N-Boc-Ketiminen. Die Methode ist skalierbar und führt zu Furanonaphthopyrazolidinonen mit zwei vicinalen tetrasubstituierten Stereozentren in exzellenten Ausbeuten und Stereoselektivitäten. Mit 1-Naphtholen und elektronenreichen Phenolen entstehen die entsprechenden Aminopyrazolonderivate.
      PubDate: 2017-11-02T08:21:19.591562-05:
      DOI: 10.1002/ange.201709224
       
  • Synthesis of the Unknown Indeno[1,2-a]fluorene Regioisomer:
           Crystallographic Characterization of Its Dianion
    • Authors: Justin J. Dressler; Zheng Zhou, Jonathan L. Marshall, Ryohei Kishi, Shota Takamuku, Zheng Wei, Sarah N. Spisak, Masayoshi Nakano, Marina A. Petrukhina, Michael M. Haley
      Pages: 15565 - 15569
      Abstract: Of the five possible indenofluorene regioisomers, examples of a fully conjugated indeno[1,2-a]fluorene scaffold have so far remained elusive. This work reports the preparation and characterization of 7,12-dimesitylindeno[1,2-a]fluorene as a highly reactive species. Experimental and computational data support the notion of a molecule with pronounced diradical character that exists in a triplet ground state. As such, both NICS and ACID calculations suggest that the indeno[1,2-a]fluorene scaffold is weakly Baird aromatic. Reduction of the unstable red solid with Cs metal produces the dianion of the title compound, from which single crystals could be obtained and X-ray data acquired, thus fully corroborating the proposed indeno[1,2-a]fluorene hydrocarbon core.Das letzte noch fehlende Indenofluoren-Regioisomer wurde synthetisiert. Verschiedene spektroskopische Daten sprechen für die Bildung eines hoch reaktiven Triplett-Diradikaloids, den eindeutigen Strukturbeweis liefert aber eine Röntgenbeugungsanalyse für das Dianion, das durch Reduktion des Indeno[1,2-a]fluorens mit Cs-Metall entsteht.
      PubDate: 2017-10-24T06:21:14.4411-05:00
      DOI: 10.1002/ange.201709282
       
  • Lithium Azide as an Electrolyte Additive for All-Solid-State
           Lithium–Sulfur Batteries
    • Authors: Gebrekidan Gebresilassie Eshetu; Xabier Judez, Chunmei Li, Oleksandr Bondarchuk, Lide M. Rodriguez-Martinez, Heng Zhang, Michel Armand
      Pages: 15570 - 15574
      Abstract: Of the various beyond-lithium-ion battery technologies, lithium–sulfur (Li–S) batteries have an appealing theoretical energy density and are being intensely investigated as next-generation rechargeable lithium-metal batteries. However, the stability of the lithium-metal (Li°) anode is among the most urgent challenges that need to be addressed to ensure the long-term stability of Li–S batteries. Herein, we report lithium azide (LiN3) as a novel electrolyte additive for all-solid-state Li–S batteries (ASSLSBs). It results in the formation of a thin, compact and highly conductive passivation layer on the Li° anode, thereby avoiding dendrite formation, and polysulfide shuttling. It greatly enhances the cycling performance, Coulombic and energy efficiencies of ASSLSBs, outperforming the state-of-the-art additive lithium nitrate (LiNO3).Lithiumazid begünstigt die Bildung einer dendritfreien und hoch ionenleitfähigen Grenzflächenschicht auf Li-Elektroden. Die Folge sind verbesserte Lade-Entlade-Charakteristika und eine höhere Schwefelnutzung von Lithium-Schwefel-Zellen.
      PubDate: 2017-10-25T10:02:20.51309-05:0
      DOI: 10.1002/ange.201709305
       
  • A Decatwistacene with an Overall 170° Torsion
    • Authors: Wei Fan; Thorsten Winands, Nikos L. Doltsinis, Yan Li, Zhaohui Wang
      Pages: 15575 - 15579
      Abstract: Two different lengths of twistacenes, namely hexatwistacene and decatwistacene, induced by steric hindrance between imide groups and neighboring annulated benzene rings, were synthesized by bottom-up synthesis of palladium-catalyzed Suzuki cross-coupling and C−H activation. Single-crystal X-ray analyses revealed that decatwistacene, which is the longest twistacene reported, exhibits an astonishing overall end-to-end torsion angle of about 170°, the largest torsion angle reported. Both twistacenes have an enhanced solubility and stability with respect to light and oxygen owing to their large twisting deformations together with much lower LUMO levels caused by the introduction of imide groups, opening a window to the narrowest chiral graphene nanoribbons with good stability and processability.Aren-Pirouette: Ein Hexatwistacen und ein Decatwistacen wurden durch Dominocyclisierungen mit palladiumkatalysierter Suzuki-Kreuzkupplung und C-H-Aktivierung synthetisiert. Einkristall-Röntgenstrukturanalysen ergeben einen Torsionswinkel von 170° zwischen den Enden des Decatwistacens. Somit ist das schmalste chirale Graphennanoband in stabiler und leicht handzuhabender Form verfügbar.
      PubDate: 2017-11-02T04:35:30.535328-05:
      DOI: 10.1002/ange.201709342
       
  • Side-Group-Mediated Mechanical Conductance Switching in Molecular
           Junctions
    • Authors: Ali Khalid Ismael; Kun Wang, Andrea Vezzoli, Mohsin K. Al-Khaykanee, Harry E. Gallagher, Iain M. Grace, Colin J. Lambert, Bingqian Xu, Richard J. Nichols, Simon J. Higgins
      Pages: 15580 - 15584
      Abstract: A key target in molecular electronics has been molecules having switchable electrical properties. Switching between two electrical states has been demonstrated using such stimuli as light, electrochemical voltage, complexation and mechanical modulation. A classic example of the latter is the switching of 4,4′-bipyridine, leading to conductance modulation of around 1 order of magnitude. Here, we describe the use of side-group chemistry to control the properties of a single-molecule electromechanical switch, which can be cycled between two conductance states by repeated compression and elongation. While bulky alkyl substituents inhibit the switching behavior, π-conjugated side-groups reinstate it. DFT calculations show that weak interactions between aryl moieties and the metallic electrodes are responsible for the observed phenomenon. This represents a significant expansion of the single-molecule electronics “tool-box” for the design of junctions with electromechanical properties.Die Kriterien für die Entwicklung elektromechanischer Einzelmolekülschalter wurden analysiert. Konjugierte Einheiten, die zusätzliche Beiträge zur Kopplung an die Metallelektrode eines Einzelmolekülkontakts bereitstellen, erhöhen den Elektronentransmissionskoeffizienten und den Ladungstransport. Der Kontakt kann daraufhin zwischen zwei Leitungszuständen hin- und hergeschaltet werden, indem man den Abstand der beiden Elektroden moduliert.
      PubDate: 2017-11-02T04:41:38.76941-05:0
      DOI: 10.1002/ange.201709419
       
  • A Three-Dimensionally π-Conjugated Diradical Molecular Cage
    • Authors: Xiao Gu; Tullimilli Y. Gopalakrishna, Hoa Phan, Yong Ni, Tun Seng Herng, Jun Ding, Jishan Wu
      Pages: 15585 - 15589
      Abstract: π-Conjugated molecular cages are very challenging targets in structural organic chemistry, supramolecular chemistry, and materials science. The synthesis and physical characterizations are reported of the first three-dimensionally π-conjugated diradical molecular cage PTM-C, in which two polychlorotriphenylmethyl (PTM) radicals are linked by three bis(3,6-carbazolyl) bridges. This cage compound was synthesized mainly by intermolecular Yamamoto coupling followed by deprotonation and oxidation. It is stable and its structure was confirmed by X-ray crystallographic analysis. The two carbon-centered PTM radicals are weakly coupled through electronic interactions with the carbazole spacers, as revealed by optical, electronic, and magnetic measurements as well as theoretical calculations.Ein Diradikalkäfig in 3D: Ein diradikalischer molekularer Käfig, der in drei Raumrichtungen π-konjugiert ist, wurde synthetisiert und durch Röntgenstrukturanalyse bestätigt. Dreidimensionale π-Konjugation und schwache intramolekulare Spinaustauschwechselwirkungen wurden durch optische, elektronische und magnetische Messungen sowie DFT-Rechnungen verifiziert.
      PubDate: 2017-10-24T06:20:51.16453-05:0
      DOI: 10.1002/ange.201709537
       
  • Blockable Zn10L15 Ion Channels through Subcomponent Self-Assembly
    • Authors: Cally J. E. Haynes; Jinbo Zhu, Catalin Chimerel, Silvia Hernández-Ainsa, Imogen A. Riddell, Tanya K. Ronson, Ulrich F. Keyser, Jonathan R. Nitschke
      Pages: 15590 - 15594
      Abstract: Metal–organic anion channels based on Zn10L15 pentagonal prisms have been prepared by subcomponent self-assembly. The insertion of these prisms into lipid membranes was investigated by ion-current and fluorescence measurements. The channels were found to mediate the transport of Cl− anions through planar lipid bilayers and into vesicles. Tosylate anions were observed to bind and plug the central channels of the prisms in the solid state and in solution. In membranes, dodecyl sulfate blocked chloride transport through the central channel. Our Zn10L15 prism thus inserts into lipid bilayers to turn on anion transport, which can then be turned off through addition of the blocker dodecyl sulfate.Clever eingefädelt: Selbstorganisierte pentagonale Prismen der Zusammensetzung Zn10L15 fungieren als Anionenkanäle in Phospholipid-Doppelschichten. Die Kanäle werden durch amphiphile Dodecylsulfat-Anionen blockiert, die in der Kanalmitte gebunden werden und den Durchgang verstopfen (siehe Bild).
      PubDate: 2017-11-03T07:01:44.860269-05:
      DOI: 10.1002/ange.201709544
       
  • Decoupled Thermo- and pH-Responsive Hydrogel Microspheres Cross-Linked by
           Rotaxane Networks
    • Authors: Takuma Kureha; Daichi Aoki, Seina Hiroshige, Keisuke Iijima, Daisuke Aoki, Toshikazu Takata, Daisuke Suzuki
      Pages: 15595 - 15598
      Abstract: Rotaxane cross-linked (RC) microgels that exhibit a decoupled thermo- and pH-responsive volume transition were developed. The pH-induced changes of the aggregation/disaggregation states of cyclodextrin in the RC networks were used to control the swelling capacity of the entire microgels. Different from conventional thermo- and pH-responsive microgels, which are usually obtained from copolymerizations involving charged monomers, the RC microgels respond to temperature as intended, even in the presence of charged functional molecules such as dyes in the microgel dispersion. The results of this study should lead to new applications, including drug delivery systems that require a retention of their smart functions even in environments that may contain foreign ions, for example, in in vivo experiments.Intelligente Mikrogele bestehend aus thermoresponsiven, rotaxanvernetzten Polymeren wurden entwickelt. Obwohl keine geladenen Monomere eingesetzt wurden, die solchen Materialien normalerweise pH-Responsivität verleihen, reagieren die Mikrogele sowohl auf pH- als auch auf Temperaturänderungen. Die duale Responsivität beruht auf der Entstehung von Aggregations-Disaggregations-Zuständen von Cyclodextrin.
      PubDate: 2017-10-26T08:28:14.653667-05:
      DOI: 10.1002/ange.201709633
       
  • Self-Assembly of Chiral Gold Clusters into Crystalline Nanocubes of
           Exceptional Optical Activity
    • Authors: Lin Shi; Lingyun Zhu, Jun Guo, Lijuan Zhang, Yanan Shi, Yin Zhang, Ke Hou, Yonglong Zheng, Yanfei Zhu, Jiawei Lv, Shaoqin Liu, Zhiyong Tang
      Pages: 15599 - 15603
      Abstract: Self-assembly of inorganic nanoparticles into ordered structures is of interest in both science and technology because it is expected to generate new properties through collective behavior; however, such nanoparticle assemblies with characteristics distinct from those of individual building blocks are rare. Herein we use atomically precise Au clusters to make ordered assemblies with emerging optical activity. Chiral Au clusters with strong circular dichroism (CD) but free of circularly polarized luminescence (CPL) are synthesized and organized into uniform body-centered cubic (BCC) packing nanocubes. Once the ordered structure is formed, the CD intensity is significantly enhanced and a remarkable CPL response appears. Both experiment and theory calculation disclose that the CPL originates from restricted intramolecular rotation and the ordered stacking of the chiral stabilizers, which are fastened in the crystalline lattices.Leuchtwürfel: Chirale Au3-Cluster mit bemerkenswertem Anisotropiefaktor des Zirkulardichroismus (CD), der durch selbstorganisierte Aggregation noch verstärkt wird, wurden synthetisiert. Während die einzelnen Cluster nicht lumineszieren, strahlen die Aggregate stark, wobei die stärkste zirkular polarisierte Lumineszenz (CPL) für eine innenzentriert-kubische Anordnung beobachtet wird.
      PubDate: 2017-11-02T08:21:37.469424-05:
      DOI: 10.1002/ange.201709827
       
  • Non-Enzymatic Oxidation of a Pentagalloylglucose Analogue into Members of
           the Ellagitannin Family
    • Authors: Seiya Ashibe; Kazutada Ikeuchi, Yuji Kume, Shinnosuke Wakamori, Yuri Ueno, Takashi Iwashita, Hidetoshi Yamada
      Pages: 15604 - 15608
      Abstract: The occurrence of more than 1000 structurally diverse ellagitannins has been hypothesized to begin with the oxidation of penta-O-galloyl-β-d-glucose (β-PGG) for the coupling of the galloyl groups. However, the non-enzymatic behavior of β-PGG in the oxidation is unknown. Disclosed herein is which galloyl groups tended to couple and which axial chirality was predominant in the derived hexahydroxydiphenoyl groups when an analogue of β-PGG was subjected to oxidation. The galloyl groups coupled in the following order: at the 4,6-, 1,6-, 1,2-, 2,3-, and 3,6-positions with respective S-, S-, R-, S-, and R-axial chirality. Among them, the most preferred 4,6-coupling reflected the what was observed for natural ellagitannins. A new finding was that the second best coupling occured at the 1,6-positions. With the detection of a 3,6-coupled product, this work demonstrated that even ellagitannin skeletons with an axial-rich glucose core may be generated non-enzymatically.Der erste Schritt der strukturellen Diversifizierung innerhalb der Ellagitannin-Familie ist die Oxidation von β-Pentagalloylglucose (β-PGG). Die Oxidation eines β-PGG-Analogons führte zur hoch diastereoselektiven Kupplung der Galloylgruppen in 4,6-, 1,6-, 1,2-, 2,3- und 3,6-Stellung. Die 1,6- und 3,6-Kupplungsprodukte belegen, dass auch Gerüste mit einem Kern aus axial-reicher Glucose nichtenzymatisch zugänglich sind.
      PubDate: 2017-11-02T04:45:57.229497-05:
      DOI: 10.1002/ange.201708703
       
  • General and Efficient Intermolecular [2+2] Photodimerization of Chalcones
           
    • Authors: Tao Lei; Chao Zhou, Mao-Yong Huang, Lei-Min Zhao, Bing Yang, Chen Ye, Hongyan Xiao, Qing-Yuan Meng, Vaidhyanathan Ramamurthy, Chen-Ho Tung, Li-Zhu Wu
      Pages: 15609 - 15612
      Abstract: [2+2] Photocycloaddition, for example, the dimerization of chalcones and cinnamic acid derivatives, is a unique strategy to construct cyclobutanes, which are building blocks for a variety of biologically active molecules and natural products. However, most attempts at the above [2+2] addition have focused on solid-state, molten-state, or host–guest systems under ultraviolet-light irradiation in order to overcome the competition of facile geometric isomerization of nonrigid olefins. We report a general and simple method to realize the intermolecular [2+2] dimerization reaction of these acyclic olefins to construct cyclobutanes in a highly regio- and diastereoselective manner in solution under visible light, which provides an efficient solution to a long-standing problem.Licht-Kreise: Durch sichtbares Licht induzierter Energietransfer kann genutzt werden, um durch [2+2]-Photocycloaddition Cyclobutane aus strukturflexiblen Olefinen in regio- und diastereoselektiver Weise aufzubauen. Chalcon- und Zinnsäure-Derivate wurden bei Raumtemperatur in hohen Ausbeuten zu Cyclobutanen umgesetzt.
      PubDate: 2017-11-03T02:45:51.7896-05:00
      DOI: 10.1002/ange.201708559
       
  • Selective Radical Fluorination of Tertiary Alkyl Halides at Room
           Temperature
    • Authors: He Chen; Zhonglin Liu, Ying Lv, Xinqiang Tan, Haigen Shen, Hai-Zhu Yu, Chaozhong Li
      Pages: 15613 - 15617
      Abstract: Direct fluorination of tertiary alkyl bromides and iodides with Selectfluor is described. The halogen-exchange fluorination proceeds efficiently in acetonitrile at room temperature under metal-free conditions and exhibits a wide range of functional group compatibility. Furthermore, the reactions are highly selective in that alkyl chlorides and primary and secondary alkyl bromides remain intact. A radical mechanism is proposed for this selective fluorination.Radikalische Reaktionen von tertiären Alkylbromiden und -iodiden mit Selectfluor bei Raumtemperatur liefern die entsprechenden Alkylfluoride in guten Ausbeuten. Diese metallfreie Methode ist hoch selektiv: Alkylchloride sowie primäre und sekundäre Alkylbromide werden nicht angegriffen.
      PubDate: 2017-11-02T07:05:43.347303-05:
      DOI: 10.1002/ange.201708197
       
  • Visible-Light-Driven Iron-Promoted Thiocarboxylation of Styrenes and
           Acrylates with CO2
    • Authors: Jian-Heng Ye; Meng Miao, He Huang, Si-Shun Yan, Zhu-Bao Yin, Wen-Jun Zhou, Da-Gang Yu
      Pages: 15618 - 15622
      Abstract: The first thiocarboxylation of styrenes and acrylates with CO2 was realized by using visible light as a driving force and catalytic iron salts as promoters. A variety of important β-thioacids were obtained in high yields. This multicomponent reaction proceeds in an atom- and redox-economical manner with broad substrate scope under mild reaction conditions. Notably, high regio-, chemo-, and diasteroselectivity are observed. Mechanistic studies indicate that a radical pathway can account for the unusual regioselectivity.CO2 -COOH: Die Thiocarboxylierung von Styrolen und Acrylaten mit CO2 zu β-Thiosäuren gelingt mit sichtbarem Licht als Triebkraft in Gegenwart katalytischer Eisensalze. Die Menrkomponentenreaktion überzeugt durch große Substratbreite, milde Bedingungen und hohe Regio-, Chemo- und Diasteroselektivitäten. Die ungewöhnliche Regioselektivität ist durch einen radikalischen Reaktionspfad erklärbar.
      PubDate: 2017-10-26T08:26:52.98411-05:0
      DOI: 10.1002/ange.201707862
       
  • Gate-Voltage Control of Borophene Structure Formation
    • Authors: Zhuhua Zhang; Sharmila N. Shirodkar, Yang Yang, Boris I. Yakobson
      Pages: 15623 - 15628
      Abstract: Boron nanostructures are easily charged but how charge carriers affect their structural stability is unknown. We combined cluster expansion methods with first-principles calculations to analyze the dependence of the preferred structure of two-dimensional (2D) boron, or “borophene”, on charge doping controlled by a gate voltage. At a reasonable doping level of 3.12×1014 cm−2, the hollow hexagon concentration in the ground state of 2D boron increases to 1/7 from 1/8 in its charge-neutral state. The numerical result for the dependence of hollow hexagon concentration on the doping level is well described by an analytical method based on an electron-counting rule. Aside from in-plane electronic bonding, the hybridization among out-of-plane boron orbitals is crucial for determining the relative stability of different sheets at a given doping level. Our results offer new insight into the stability mechanism of 2D boron and open new ways for the control of the lattice structure during formation.Borophen, das Bor-Analogon von Graphen, kann wegen des Elektronenmangels von Bor leicht dotiert werden. Die bevorzugte Gitterstruktur hängt von der Ladungsträgerdichte ab, die von einer Gatterspannung kontrolliert wird. Die so kontrollierte Bildung der Borophenstruktur wird mit einem universellen Mechanismus basierend auf Elektronenbindung außerhalb der Ebene erklärt.
      PubDate: 2017-10-25T10:12:17.346115-05:
      DOI: 10.1002/ange.201705459
       
  • Reversible Cleavage/Formation of the Chromium–Chromium Quintuple Bond in
           the Highly Regioselective Alkyne Cyclotrimerization
    • Authors: Yu-Siang Huang; Gou-Tao Huang, Yao-Lun Liu, Jen-Shiang K. Yu, Yi-Chou Tsai
      Pages: 15629 - 15633
      Abstract: Herein we report the employment of the quintuply bonded dichromium amidinates [Cr{κ2-HC(N-2,6-iPr2C6H3)(N-2,6-R2C6H3)}]2 (R=iPr (1), Me (7)) as catalysts to mediate the [2+2+2] cyclotrimerization of terminal alkynes giving 1,3,5-trisubstituted benzenes. During the catalysis, the ultrashort Cr−Cr quintuple bond underwent reversible cleavage/formation, corroborated by the characterization of two inverted arene sandwich dichromium complexes (μ-η6:η6-1,3,5-(Me3Si)3C6H3)[Cr{κ2-HC(N-2,6-iPr2C6H3)(N-2,6-R2C6H3)}]2 (R=iPr (5), Me (8)). In the presence of σ donors, such as THF and 2,4,6-Me3C6H2CN, the bridging arene 1,3,5-(Me3Si)3C6H3 in 5 and 8 was extruded and 1 and 7 were regenerated. Theoretical calculations were employed to disclose the reaction pathways of these highly regioselective [2+2+2] cylcotrimerization reactions of terminal alkynes.Fünffachbindungsbruch: Ein Dichrombisamidinat katalysiert die hoch regioselektive Cyclotrimerisierung terminaler Alkine unter reversibler Spaltung seiner Cr-Cr-Fünffachbindung. In diesen Katalysen wurden zwei Aren-Dichromamidinate mit invertierter Sandwich-Struktur isoliert, die 1,3,5-(Me3Si)3C6H3 als verbrückende Areneinheit enthalten.
      PubDate: 2017-11-02T04:42:02.219727-05:
      DOI: 10.1002/ange.201709583
       
  • Trifluoromethylfluorosulfonylation of Unactivated Alkenes Using Readily
           Available Ag(O2CCF2SO2F) and N-Fluorobenzenesulfonimide
    • Authors: Yongan Liu; Hao Wu, Yong Guo, Ji-Chang Xiao, Qing-Yun Chen, Chao Liu
      Pages: 15634 - 15637
      Abstract: Presented is a novel intermolecular radical trifluoromethylfluorosulfonylation of unactivated alkenes under mild reaction conditions with good functional-group tolerance in the most atom-economic manner by using readily available Ag(O2CCF2SO2F) and N-fluorobenzenesulfonimide (NFSI). Both the trifluoromethyl and sulfonyl groups in the products originate from Ag(O2CCF2SO2F).Unter milden Bedingungen werden in der Titelreaktion funktionelle Gruppen gut toleriert. Die CF3-Gruppe der Produkte entstammt einer AgCF3-Spezies, die aus Ag(O2CCF2SO2F) entsteht. Das dabei erzeugte SO2 wird in situ abgefangen und in eine Sulfonylgruppe eingebaut. Daraus resultiert ein atomökonomischer Prozess.
      PubDate: 2017-11-02T04:48:50.994426-05:
      DOI: 10.1002/ange.201709663
       
  • A Copper-Catalyzed Aerobic [1,3]-Nitrogen Shift through Nitrogen-Radical
           4-exo-trig Cyclization
    • Authors: Yan Li; Rui Wang, Tao Wang, Xiu-Fen Cheng, Xin Zhou, Fan Fei, Xi-Sheng Wang
      Pages: 15638 - 15642
      Abstract: A novel radical [1,3]-nitrogen shift catalyzed by copper diacetate under an oxygen atmosphere (1 atm) has been developed for the construction of a diverse range of indole derivatives from α,α-disubstituted benzylamine. In this reaction, oxygen was used as a clean terminal oxidant, and water was produced as the only by-product. Five inert bonds were cleaved, and two C−N bonds and one C−C double bond were constructed in one pot during this transformation. This unique method demonstrated broad application protential for the late-stage modification of biologically active natural products and drugs. Mechanistic investigations indicate that a unique 4-exo-trig cyclization of an aminyl radical onto a phenyl ring is involved in the catalytic cycle.Alle auf ihren Platz, bitte! Sauerstoff als Oxidationsmittel und die Bildung von Wasser als einziges Koppelprodukt zeichnen eine radikalische [1,3]-Stickstoff-Verschiebung aus, die mit Kupferdiacetat als Katalysator α,α-disubstituierte Benzylamine in Indole überführt. Bei dieser Transformation, die sich für die späte Modifizierung von biologisch aktiven Molekülen eignet, werden fünf inerte Bindungen gespalten und zwei C-N-Bindungen und eine C-C-Doppelbindung gebildet.
      PubDate: 2017-10-26T08:28:32.49316-05:0
      DOI: 10.1002/ange.201709894
       
  • A Nickel-Catalyzed Carbonyl-Heck Reaction
    • Authors: Jaya Kishore Vandavasi; XiYe Hua, Hamdi Ben Halima, Stephen G. Newman
      Pages: 15643 - 15647
      Abstract: The use of transition-metal catalysis to enable the coupling of readily available organic molecules has greatly enhanced the ability of chemists to access complex chemical structures. In this work, an intermolecular coupling reaction that unites organotriflates and aldehydes is presented. A unique catalyst system is identified to enable this reaction, featuring a Ni0 precatalyst, a tridentate Triphos ligand, and a bulky amine base. This transformation provides access to a variety of ketone-containing products without the selectivity- and reactivity-related challenges associated with more traditional Friedel–Crafts reactions. A Heck-type mechanism is postulated, wherein the π bond of the aldehyde takes the role of the olefin in the insertion/elimination steps.Aldehyde statt Alkene: Die nickelkatalysierte Kupplung von Organotriflaten mit Aldehyden resultiert in der Bildung von Ketonen. Hochdurchsatz-Experimente unter der Annahme eines Heck-Mechanismus führten zu der besonderen Kombination von Metall, Ligand und Base, welche die Reaktion erst möglich macht.
      PubDate: 2017-11-02T08:21:52.470495-05:
      DOI: 10.1002/ange.201710241
       
  • Ein einfach herzustellender elektrochemischer Flussmikroreaktor:
           effiziente Isoindolinon-Synthese und Funktionalisierung im Fluss
    • Authors: Ana A. Folgueiras-Amador; Kai Philipps, Sébastien Guilbaud, Jarno Poelakker, Thomas Wirth
      Pages: 15648 - 15653
      Abstract: Elektrochemie im Fluss ist eine effiziente Methode zur Erzeugung radikalischer Zwischenstufen. Ein elektrochemischer Flussmikroreaktor wurde entwickelt, um die Effizienz von elektrochemischen Flussreaktionen zu verbessern. Mit diesem Gerät werden nur wenig oder keine Leitelektrolyte benötigt, wodurch die Prozesse kostengünstiger werden und saubereres Produkt entsteht. Dies wird anhand einer einfachen Synthese von Amidylradikalen gezeigt, die in intramolekularen Hydroaminierungen zu Isoindolinonen umgesetzt werden. Die Kombination mit Inline-Massenspektrometrie ermöglicht eine einfachere Kombination verschiedener chemischer Schritte in einem einzigen Flussprozess.Kein oder nur wenig Leitelektrolyt wird in der Flusselektrochemie benötigt: Recycling- und Abfallprobleme werden eliminiert, da Cyclisierungsprodukte in einem schnellen und sauberen Prozess erhalten werden.
      PubDate: 2017-11-02T04:36:39.736569-05:
      DOI: 10.1002/ange.201709717
       
  • Selektive C-H-Bindungsaktivierung durch eine Kaskade aus Photochemie und
           Biokatalyse
    • Authors: Wuyuan Zhang; Bastien O. Burek, Elena Fernández-Fueyo, Miguel Alcalde, Jonathan Z. Bloh, Frank Hollmann
      Pages: 15654 - 15658
      Abstract: Selektive Oxyfunktionalisierungen von inerten C-H-Bindungen können unter milden Bedingungen durch den Einsatz von Peroxygenasen erreicht werden. Dieser Ansatz wird jedoch durch die schlechte Stabilität der Enzyme in Anwesenheit stöchiometrischer Mengen des Oxidationsmittels Wasserstoffperoxid erschwert. Hier zeigen wir, dass sich anorganische Photokatalysatoren wie goldbeladenes Titandioxid zur effizienten Bereitstellung geeigneter Mengen an H2O2 durch reduktive Aktivierung von Umgebungssauerstoff und simultaner Oxidation von Methanol eignen und gleichzeitig eine hohe Reaktivität und Stabilität des Enzyms gewährleisten. Mithilfe dieses Ansatzes konnte die stereoselektive Hydroxylierung von Ethylbenzol zu (R)-1-Phenylethanol in hoher Enantioselektivität (>98 % ee) und sehr hoher katalytischer Produktivität (TON>71.000) erreicht werden.Anorganische Photokatalyse durch Au-TiO2 und selektive Enzymkatalyse durch Peroxidasen werden kombiniert, um die selektive Oxyfunktionalisierung von inerten C-H-Bindungen zu erreichen. Mit diesem Ansatz gelang die stereoselektive Hydroxylierung von Ethylbenzol zu (R)-1-Phenylethanol in hoher Enantioselektivität und sehr hoher katalytischer Produktivität (siehe Schema; R=Ph, R′=CH3).
      PubDate: 2017-11-03T06:01:10.10617-05:0
      DOI: 10.1002/ange.201708668
       
  • Das C3-symmetrische Tricyclo[2.2.1.02,6]heptan-3,5,7-triol
    • Authors: Volodymyr Kozel; Constantin-Gabriel Daniliuc, Peer Kirsch, Günter Haufe
      Pages: 15659 - 15663
      Abstract: Ein direkter Zugang zum bisher unbekannten C3-symmetrischen Tricyclo[2.2.1.02,6]heptan-3,5,7-triol sowohl in racemischer als auch in enantiomerenreiner Form wurde ausgearbeitet. Die Umsetzung von 7-tert-Butoxynorbornadien mit Peroxycarbonsäuren führte durch transannulare π-Cyclisierung und Substitution der tert-Butoxy-Gruppe zu Gemischen der entsprechenden C1- und C3-symmetrischen 3,5,7-Triacyloxynortricyclene. Durch Sieden in Ameisensäure wurden die C1-symmetrischen Ester größtenteils in das C3-symmetrische Formiat überführt. Nachfolgende Verseifung lieferte die diastereomeren Triole, die durch fraktionierende Kristallisation getrennt wurden. Die Enantiomerentrennung des C3-symmetrischen Triols erfolgte über die diastereomeren Tri(O-methyl)mandelsäureester. Die so im Gramm-Maßstab zugänglichen enantiomerenreinen Triole wurden als Kerneinheit von Dotierstoffen für flüssigkristalline Phasen eingesetzt.Die C3-Symmetrie schreitet voran: Das bisher unbekannte kleinste C3-symmetrische tricyclische Triol wurde in beiden enantiomeren Formen hergestellt. Die Reaktionen von 7-tert-Butoxynorbornadien mit Peroxycarbonsäuren führen zu C1-symmetrischen Triestern, die säurekatalysiert zu C3-symmetrischen Produkten isomerisieren. Eine klassische Racematspaltung liefert die reinen Enantiomere, aus denen chirale Dotierstoffe für Flüssigkristalle zugänglich sind.
      PubDate: 2017-11-03T05:55:28.778308-05:
      DOI: 10.1002/ange.201709279
       
  • Programmierbare transiente Thermogele vermittelt durch eine pH- und
           Redox-regulierte supramolekulare Polymerisation
    • Authors: Daniel Spitzer; Leona Lucas Rodrigues, David Straßburger, Markus Mezger, Pol Besenius
      Pages: 15664 - 15669
      Abstract: Wir stellen eine durch mehrfache Stimuli ansprechbare transiente supramolekulare Polymerisation von β-Faltblatt-kodierten dendritischen Peptidmonomeren in Wasser vor. Die Glutaminsäure- und Methionin-tragenden Amphiphile gehen eine durch Glucose-Oxidase katalysierte und Glucose-getriebene transiente Hydrogelierung ein. Diese basiert auf einem Zusammenspiel eines pH- und oxidativen Stimulus, der durch die Produktion reaktiver Sauerstoffspezies (ROS) gefördert wird. Mit Veränderung der Enzym- und Glucosekonzentration wird eine Feineinstellung der Assemblierungs- sowie Disassemblierungsgeschwindigkeit vorgenommen, wodurch die Steifigkeit und Stabilität des transienten Hydrogels bestimmt wird. Die Verwendung von Triethylenglycolketten führt zu thermoresponsiven Eigenschaften der Materialien. Weiterhin zeigen wir, dass Reparaturenzyme den oxidativen Schaden in den Methionin-basierten Thioetherseitenketten beheben können. Da reaktive Sauerstoffspezies eine wichtige Rolle in Signaltransduktionskaskaden spielen, bietet unsere Strategie großes Potential zur Anwendung dieser dynamischen Biomaterialien in redoxaktiven Mikroumgebungen.Dendritische Peptidmonomere unterliegen einer transienten supramolekularen Polymerisation als Reaktion auf ein Zusammenspiel von pH- und einem oxidativen Stimulus, der durch die Produktion reaktiver Sauerstoffspezies gefördert wird. Über die Enzym- und Glucosekonzentration wird eine Feineinstellung der Assemblierungs- und Disassemblierungsgeschwindigkeit vorgenommen, wodurch die Festigkeit und Stabilität des transienten Hydrogels bestimmt wird.
      PubDate: 2017-11-03T06:02:06.446113-05:
      DOI: 10.1002/ange.201708857
       
  • CODH-IV: eine hocheffiziente CO-Dehydrogenase mit Resistenz gegen O2
    • Authors: Lilith Domnik; Meriem Merrouch, Sebastian Goetzl, Jae-Hun Jeoung, Christophe Léger, Sébastien Dementin, Vincent Fourmond, Holger Dobbek
      Pages: 15670 - 15674
      Abstract: CO-Dehydrogenasen (CODHs) katalysieren die reversible Umsetzung zwischen CO und CO2. Genomische Analysen deuten darauf hin, dass CODHs unterschiedliche metabolische Funktionen haben. Das Genom von Carboxydothermus hydrogenoformans kodiert fünf CODHs (CODH-I–V), von denen CODH-IV in einem Gencluster gemeinsam mit einem Peroxid-reduzierenden Enzym vorliegt. Unsere kinetischen und kristallographischen Analysen zeigen, dass sich CODH-IV von anderen CODHs durch charakteristische Merkmale unterscheidet: CODH-IV hat eine hohe Affinität für CO, oxidiert CO mit diffusionslimitierter Geschwindigkeit über einen weiten Temperaturbereich und ist toleranter gegen O2 als CODH-II. Daher stützen unsere Beobachtungen die Idee, dass CODH-IV als CO-Fänger bei der Abwehr von oxidativem Stress agiert und unterstreichen, dass CODHs in Bezug auf ihre Reaktivität diverser als erwartet sind.CO-Dehydrogenasen (CODHs) katalysieren die reversible Umwandlung zwischen CO und CO2. CODH-IV unterscheidet sich dabei von anderen CODHs, indem es als CO-Scavenger zur Abwehr von oxidativem Stress fungiert. Dies unterstreicht, dass CODHs in Bezug auf ihre Reaktivität diverser sind als erwartet.
      PubDate: 2017-11-02T04:37:09.054725-05:
      DOI: 10.1002/ange.201709261
       
  • Innenrücktitelbild: Structures of the Heme Acquisition Protein HasA with
           Iron(III)-5,15-Diphenylporphyrin and Derivatives Thereof as an Artificial
           Prosthetic Group (Angew. Chem. 48/2017)
    • Authors: Hiromu Uehara; Yuma Shisaka, Tsubasa Nishimura, Hiroshi Sugimoto, Yoshitsugu Shiro, Yoshihiro Miyake, Hiroshi Shinokubo, Yoshihito Watanabe, Osami Shoji
      Pages: 15675 - 15675
      Abstract: Das Hämbindeprotein HasA aus P. aeruginosa kann Eisen(III)-5,15-diphenylporphyrin und mehrere Derivate aufnehmen, auch wenn sie sperrige Substituenten in der meso-Position des Porphyrins tragen. O. Shoji et al. präsentieren in ihrer Zuschrift auf S. 15481 Kristallstrukturen dieser künstlichen HasAs und weisen nach, dass die wachstumsinhibierende Wirkung gegen P. aeruginosa je nach Struktur des eingefangenen Metallkomplexes variiert.
      PubDate: 2017-11-06T08:05:49.126434-05:
      DOI: 10.1002/ange.201710879
       
  • Rücktitelbild: Quantifying Guest Exchange in Supramolecular Systems
           (Angew. Chem. 48/2017)
    • Authors: Liat Avram; Anthony D. Wishard, Bruce C. Gibb, Amnon Bar-Shir
      Pages: 15676 - 15676
      Abstract: Supramolekulare Container …… haben die Fähigkeit, molekulare Gäste in ihrem Hohlraum einzusperren. Die dynamischen Eigenschaften solcher Assemblate und der Austauschprozess der verkapselten und freien Gäste sind der Schlüssel für verschiedene Anwendungen. B. C. Gibb, A. Bar-Shir und Mitarbeiter demonstrieren in ihrer Zuschrift auf S. 15516 eine als Gastaustauschsättigungstransfer (GEST) bezeichnete NMR-Methode zur Bestimmung der Gastaustauschgeschwindigkeiten dimerer Assemblate des tief bindenden Cavitanden Octasäure.
      PubDate: 2017-11-07T06:05:56.493039-05:
      DOI: 10.1002/ange.201710970
       
 
 
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