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Publisher: John Wiley and Sons   (Total: 1583 journals)

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Showing 1 - 200 of 1583 Journals sorted alphabetically
Abacus     Hybrid Journal   (Followers: 11, SJR: 0.48, h-index: 22)
About Campus     Hybrid Journal   (Followers: 5)
Academic Emergency Medicine     Hybrid Journal   (Followers: 54, SJR: 1.385, h-index: 91)
Accounting & Finance     Hybrid Journal   (Followers: 43, SJR: 0.547, h-index: 30)
ACEP NOW     Free  
Acta Anaesthesiologica Scandinavica     Hybrid Journal   (Followers: 50, SJR: 1.02, h-index: 88)
Acta Archaeologica     Hybrid Journal   (Followers: 135, 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: 5, SJR: 0.112, h-index: 1)
Acta Paediatrica     Hybrid Journal   (Followers: 54, SJR: 0.794, h-index: 88)
Acta Physiologica     Hybrid Journal   (Followers: 7, 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: 5, SJR: 0.459, h-index: 29)
Acute Medicine & Surgery     Hybrid Journal   (Followers: 2)
Addiction     Hybrid Journal   (Followers: 32, SJR: 2.086, h-index: 143)
Addiction Biology     Hybrid Journal   (Followers: 12, SJR: 2.091, h-index: 57)
Adultspan J.     Hybrid Journal   (SJR: 0.127, h-index: 4)
Advanced Energy Materials     Hybrid Journal   (Followers: 24, SJR: 6.411, h-index: 86)
Advanced Engineering Materials     Hybrid Journal   (Followers: 24, SJR: 0.81, h-index: 81)
Advanced Functional Materials     Hybrid Journal   (Followers: 48, SJR: 5.21, h-index: 203)
Advanced Healthcare Materials     Hybrid Journal   (Followers: 13, SJR: 0.232, h-index: 7)
Advanced Materials     Hybrid Journal   (Followers: 246, 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: 4, SJR: 2.488, h-index: 21)
Advanced Science     Open Access   (Followers: 4)
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: 19)
Africa Research Bulletin: Economic, Financial and Technical Series     Hybrid Journal   (Followers: 12)
Africa Research Bulletin: Political, Social and Cultural Series     Hybrid Journal   (Followers: 9)
African Development Review     Hybrid Journal   (Followers: 32, SJR: 0.275, h-index: 17)
African J. of Ecology     Hybrid Journal   (Followers: 14, SJR: 0.477, h-index: 39)
Aggressive Behavior     Hybrid Journal   (Followers: 15, SJR: 1.391, h-index: 66)
Aging Cell     Open Access   (Followers: 9, 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: 14, SJR: 0.925, h-index: 43)
Agricultural Economics     Hybrid Journal   (Followers: 44, SJR: 1.099, h-index: 51)
AIChE J.     Hybrid Journal   (Followers: 28, 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: 49, SJR: 3.048, h-index: 129)
Alternatives to the High Cost of Litigation     Hybrid Journal   (Followers: 3)
American Anthropologist     Hybrid Journal   (Followers: 127, 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: 30, 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: 15, SJR: 1.115, h-index: 61)
American J. of Medical Genetics Part B: Neuropsychiatric Genetics     Hybrid Journal   (Followers: 3, SJR: 1.771, h-index: 107)
American J. of Medical Genetics Part C: Seminars in Medical Genetics     Partially Free   (Followers: 5, SJR: 2.315, h-index: 79)
American J. of Orthopsychiatry     Hybrid Journal   (Followers: 4, SJR: 0.756, h-index: 69)
American J. of Physical Anthropology     Hybrid Journal   (Followers: 35, SJR: 1.41, h-index: 88)
American J. of Political Science     Hybrid Journal   (Followers: 237, SJR: 5.101, h-index: 114)
American J. of Primatology     Hybrid Journal   (Followers: 14, 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: 15, SJR: 2.792, h-index: 140)
American J. on Addictions     Hybrid Journal   (Followers: 9, SJR: 0.843, h-index: 57)
Anaesthesia     Hybrid Journal   (Followers: 116, SJR: 1.404, h-index: 88)
Analyses of Social Issues and Public Policy     Hybrid Journal   (Followers: 11, SJR: 0.397, h-index: 18)
Analytic Philosophy     Hybrid Journal   (Followers: 15)
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: 153)
Angewandte Chemie Intl. Edition     Hybrid Journal   (Followers: 204, SJR: 6.229, h-index: 397)
Animal Conservation     Hybrid Journal   (Followers: 34, SJR: 1.576, h-index: 62)
Animal Genetics     Hybrid Journal   (Followers: 8, SJR: 0.957, h-index: 67)
Animal Science J.     Hybrid Journal   (Followers: 5, 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: 8, 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: 42, 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: 12)
Annual Review of Information Science and Technology     Hybrid Journal   (Followers: 14)
Anthropology & Education Quarterly     Hybrid Journal   (Followers: 24, SJR: 0.72, h-index: 31)
Anthropology & Humanism     Hybrid Journal   (Followers: 16, SJR: 0.137, h-index: 3)
Anthropology News     Hybrid Journal   (Followers: 14)
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: 93, SJR: 0.545, h-index: 15)
Antipode     Hybrid Journal   (Followers: 45, SJR: 2.212, h-index: 69)
Anz J. of Surgery     Hybrid Journal   (Followers: 6, 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: 66, SJR: 0.754, h-index: 69)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 6, SJR: 0.632, h-index: 58)
Applied Psychology     Hybrid Journal   (Followers: 133, SJR: 1.023, h-index: 64)
Applied Psychology: Health and Well-Being     Hybrid Journal   (Followers: 48, 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: 13, 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: 34, 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: 14, SJR: 0.156, h-index: 2)
Architectural Design     Hybrid Journal   (Followers: 24, 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: 4)
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: 205, SJR: 0.153, h-index: 13)
Arthritis & Rheumatology     Hybrid Journal   (Followers: 48, SJR: 1.984, h-index: 20)
Arthritis Care & Research     Hybrid Journal   (Followers: 27, 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: 13)
Asia & the Pacific Policy Studies     Open Access   (Followers: 15)
Asia Pacific J. of Human Resources     Hybrid Journal   (Followers: 319, SJR: 0.494, h-index: 19)
Asia Pacific Viewpoint     Hybrid Journal   (SJR: 0.616, h-index: 26)
Asia-Pacific J. of Chemical Engineering     Hybrid Journal   (Followers: 7, 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: 3, 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: 3, 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: 4, 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: 13, 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: 12, SJR: 1.095, h-index: 66)
Austral Entomology     Hybrid Journal   (Followers: 10, SJR: 0.524, h-index: 28)
Australasian J. of Dermatology     Hybrid Journal   (Followers: 7, SJR: 0.714, h-index: 40)
Australasian J. On Ageing     Hybrid Journal   (Followers: 7, SJR: 0.39, h-index: 22)
Australian & New Zealand J. of Statistics     Hybrid Journal   (Followers: 13, SJR: 0.275, h-index: 28)
Australian Accounting Review     Hybrid Journal   (Followers: 3, 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: 42, 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: 6, 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: 22, 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: 13, SJR: 0.203, h-index: 14)
Australian J. of Psychology     Hybrid Journal   (Followers: 16, SJR: 0.384, h-index: 30)
Australian J. of Public Administration     Hybrid Journal   (Followers: 382, SJR: 0.418, h-index: 29)
Australian J. of Rural Health     Hybrid Journal   (Followers: 4, SJR: 0.43, h-index: 34)
Australian Occupational Therapy J.     Hybrid Journal   (Followers: 64, SJR: 0.59, h-index: 29)
Australian Psychologist     Hybrid Journal   (Followers: 11, SJR: 0.331, h-index: 31)
Australian Veterinary J.     Hybrid Journal   (Followers: 19, SJR: 0.459, h-index: 45)
Autism Research     Hybrid Journal   (Followers: 31, 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: 9, 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: 3, 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: 8, SJR: 0.297, h-index: 23)
Behavioral Sciences & the Law     Hybrid Journal   (Followers: 22, 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: 14, SJR: 1.172, h-index: 90)
Biological Reviews     Hybrid Journal   (Followers: 2, SJR: 6.469, h-index: 114)
Biologie in Unserer Zeit (Biuz)     Hybrid Journal   (Followers: 44, 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: 37, 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: 135, SJR: 1.633, h-index: 146)
Biotechnology J.     Hybrid Journal   (Followers: 13, SJR: 1.185, h-index: 51)
Biotechnology Progress     Hybrid Journal   (Followers: 39, SJR: 0.736, h-index: 101)
Biotropica     Hybrid Journal   (Followers: 17, SJR: 1.374, h-index: 71)
Bipolar Disorders     Hybrid Journal   (Followers: 10, SJR: 2.592, h-index: 100)
Birth     Hybrid Journal   (Followers: 33, 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: 5, SJR: 0.468, h-index: 47)
Birth Defects Research Part C : Embryo Today : Reviews     Hybrid Journal   (SJR: 1.513, h-index: 55)

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Journal Cover Angewandte Chemie
  [153 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  [1583 journals]
  • Terminal Parent Phosphanide and Phosphinidene Complexes of Zirconium(IV)
    • Authors: Hannah Stafford; Thomas M. Rookes, Elizabeth P. Wildman, Gábor Balázs, Ashley J. Wooles, Manfred Scheer, Stephen T. Liddle
      Abstract: The reaction of [Zr(TrenDMBS)(Cl)] [Zr1; TrenDMBS=N(CH2CH2NSiMe2But)3] with NaPH2 gave the terminal parent phosphanide complex [Zr(TrenDMBS)(PH2)] [Zr2; Zr−P=2.690(2) Å]. Treatment of Zr2 with one equivalent of KCH2C6H5 and two equivalents of benzo-15-crown-5 ether (B15C5) afforded an unprecedented example (outside of matrix isolation) of a structurally authenticated transition-metal terminal parent phosphinidene complex [Zr(TrenDMBS)(PH)][K(B15C5)2] [Zr3; Zr=P=2.472(2) Å]. DFT calculations reveal a polarized-covalent Zr=P double bond, with a Mayer bond order of 1.48, and together with IR spectroscopic data also suggest an agostic-type Zr⋅⋅⋅HP interaction [∡ZrPH=66.7°] which is unexpectedly similar to that found in cryogenic, spectroscopically observed phosphinidene species. Surprisingly, computational data suggest that the Zr=P linkage is similarly polarized, and thus as covalent, as essentially isostructural U=P and Th=P analogues.Phosphanid- und Phosphiniden-Zirconiumkomplexe der Stammverbindungen wurden synthetisiert. Von Matrixisolationsexperimenten abgesehen ist das Zirconiumphosphiniden der erste strukturell charakterisierte Übergangsmetallkomplex mit unsubstituiertem terminalem Phosphiniden-Liganden. Rechnungen zufolge sind die Bindungsverhältnisse in Zr=P sehr ähnlich zu denen in U=P und Th=P.
      PubDate: 2017-05-26T12:00:48.658832-05:
      DOI: 10.1002/ange.201703870
  • Sol-Gel Derived Biohybrid Materials Incorporating Long-Chain DNA Aptamers
    • Authors: Carmen Carrasquilla; Emily Kapteyn, Yingfu Li, John David Brennan
      Abstract: Sol-gel derived bio/inorganic hybrid materials have been examined for diverse applications, including biosensing, affinity chromatography and drug discovery. However, such materials have mostly been restricted to the interaction between entrapped biorecognition elements and small molecules, owing to the requirement for nanometer-scale mesopores in the matrix to retain entrapped biorecognition elements. Herein, we report on a new class of macroporous bio/inorganic hybrids, engineered through a high-throughput materials screening approach, that entrap micron-sized concatemeric DNA aptamers. We demonstrate that the entrapment of these long-chain DNA aptamers allows their retention within the macropores of the silica material, so that aptamers can interact with high molecular weight targets such as proteins. Our approach overcomes the major limitation of previous sol-gel derived biohybrid materials by enabling molecular recognition for targets beyond small molecules.
      PubDate: 2017-05-26T11:28:06.446765-05:
      DOI: 10.1002/ange.201702859
  • Reductive Trapping of [(OC)5W-W(CO)5]2- in a Mixed Valent SmII/III
           Calix[4]pyrrolide Sandwich
    • Authors: Glen Deacon; Zhifang Guo, Peter Courtney Junk, Jun Wang
      Abstract: Reduction of tungsten hexacarbonyl by the divalent samarium(II) complex [Sm2(N4Et8)(thf)4] ((N4Et8)4- = meso-octaethylcalix[4]pyrrolide) in toluene at ambient temperature gave the remarkable heteronuclear mixed-valent samarium(II/III)/tungsten complex [{(thf)2SmII(N4Et8)SmIII(thf)}2{(µ-OC)2W2(CO)8}] 1 which features the trapping of a rare [W2(CO)10]2- anion with an unsupported W-W bond.
      PubDate: 2017-05-26T05:21:48.325262-05:
      DOI: 10.1002/ange.201702636
  • Continuous Synthesis and Purification by Coupling a Multistep Flow
           Reaction with Centrifugal Partition Chromatography
    • Authors: Róbert Örkényi; János Éles, Ferenc Faigl, Péter Vincze, Anita Prechl, Zoltán Szakács, János Kóti, István Greiner
      Abstract: Continuous-flow multistep synthesis meets quasi-continuous final-product purification to produce pure products from crude reaction mixtures. In the nucleophilic aromatic substitution of 2,4-difluoronitrobenzene with morpholine followed by a heterogeneous catalytic hydrogenation, the desired monosubstituted product can be continuously separated from the by-products in a purity of over 99 % by coupling a flow reactor sequence to a multiple dual-mode (MDM) centrifugal partition chromatography (CPC) device. It has many advantages as compared to HPLC, such as higher resolution, no need for column replacement or silica to recycle, and it is absolutely free of irreversible adsorption.
      PubDate: 2017-05-26T04:25:48.750505-05:
      DOI: 10.1002/ange.201703852
  • Naoto Chatani
    • PubDate: 2017-05-26T04:25:23.728819-05:
      DOI: 10.1002/ange.201704772
  • Insulin - a persistent synthetic challenge
    • Authors: Luis Moroder; Hans-Jürgen Musiol
      Abstract: After a short historical overview from the discovery to production of insulin from animal sources, later via semi-synthesis and finally rDNA-based expression, the review focuses on the most recent advances of chemical synthesis that progressively sur-mounted all technical obstacles of assembling heterodimeric structures crosslinked by intra- and intermolecular disulfides via biomimetic insulin precursors in the search for analogues of improved therapeutic properties.
      PubDate: 2017-05-26T04:20:33.715032-05:
      DOI: 10.1002/ange.201702493
  • CsPbBr3 QD/AlOx inorganic nanocomposites with exceptional stability in
           water, light and heat
    • Authors: Anna Loiudice; Seryio Saris, Emad Oveisi, Duncan T. L. Alexander, Raffaella Buonsanti
      Abstract: Herein, the assembly of CsPbBr3 QD/AlOx inorganic nanocomposite, using atomic layer deposition (ALD) for the growth of the amorphous alumina matrix (AlOx), is proven as a novel protection scheme for this new class of QDs. The nucleation and growth process of AlOx on the QD surface was thoroughly investigated by a miscellanea of techniques which highlighed the importance of the interaction between the ALD precursor and the QD surface to uniformely coat the QDs while preserving the optoelectronic properties. These nanocomposites show an exceptional stability against exposure to air (for at least 45 days), irradiation under simulated solar spectrum (for at least 8h), to thermal treatment (at least up to 200ºC in air), and finally against immersion in water. The method was extended to assembly CsPbBrxI3-x QD/AlOx and CsPbI3 QD/AlOx nanocomposites which were more stable compared to the pristine QD films.
      PubDate: 2017-05-26T02:25:36.623751-05:
      DOI: 10.1002/ange.201703703
  • NHC-NiH Catalyzed Intermolecular Regio and Diastereoselective
           Cross-Hydroalkenylations of Endocyclic Dienes with a-Olefins.
    • Authors: Xiaoyan Lian; weihao Chen, Liang Dang, Yuchen Li, Chun Yu Ho
      Abstract: Highly selective cross-hydroalkenylation of endocyclic-1,3-dienes at the least substituted site with a-olefins was achieved by set of neutral NHC-Ni(II)H(OTf), and by cationic Ni(II) catalysts with novel NHC structure. Under the heteroatom assistance, skipped dienes were obtained in good yield by using as low as equal molar amount of substrate pairs and 2-5 mol% catalyst. A rare 4,3- product selectivity (i.e., H at C4 and alkenyl group at C3 of diene) was observed, which is different from known dimerizations of a-olefins with both acyclic Co and Fe systems. The substituent effects of NHC, 1,3-diene and a-olefins on chemo-, regio- and diastereo-selectivity were studied. High level of chirality transfer was observed by using chiral cyclohexadiene derivatives.
      PubDate: 2017-05-26T02:25:26.690365-05:
      DOI: 10.1002/ange.201703706
  • Ein Organoruthenium-Tumortherapeutikum mit unerwartet hoher
           Selektivität für Plectin
    • Authors: Samuel M. Meier; Dominique Kreutz, Lilli Winter, Matthias H. M. Klose, Klaudia Cseh, Tamara Weiss, Andrea Bileck, Beatrix Alte, Johanna C. Mader, Samir Jana, Annesha Chatterjee, Arindam Bhattacharyya, Michaela Hejl, Michael A. Jakupec, Petra Heffeter, Walter Berger, Christian G. Hartinger, Bernhard K. Keppler, Gerhard Wiche, Christopher Gerner
      Abstract: Metallorganische Tumortherapeutika werden durch Ligandenaustausch aktiviert, und es wird gemeinhin angenommen, dass die resultierenden aktivierten Spezies geringe Selektivität für potenzielle zelluläre Ziele zeigen. Durch ein Proteomik-basiertes Ziel-Antwort-Profiling konnte jedoch nachgewiesen werden, dass ein Ruthenium-Aren-Pyridincarbothioamid (Plecstatin) eine unerwartet hohe Selektivität für Plectin, ein Strukturprotein und Vernetzer des Zytoskeletts, zeigt, was in einem Plectin-Knock-out-Modell in vitro validiert wurde. In Sphäroidkulturen konnte gezeigt werden, dass die gezielten Wechselwirkungen mit Plectin das Potenzial haben, den invasiven Charakter von Tumoren zu inhibieren. Nach oraler Gabe wirkte Plecstatin-1 im invasiven B16-Melanom stärker tumorinhibierend als im CT-26-Kolonkarzinom-Tumormodell.Plectin ist das Ziel: Eine unerwartet hohe Selektivität eines Ruthenium-Aren-Tumortherapeutikums für das Strukturprotein Plectin wurde bei einem Proteomik-basierten Ziel-Antwort-Profiling festgestellt. Gezielte Wechselwirkungen mit Plectin wurden validiert, und der metallhaltige Wirkstoff ist tumorinhibierend in vivo nach oraler Gabe.
      PubDate: 2017-05-26T02:11:04.008487-05:
      DOI: 10.1002/ange.201702242
  • Light-Induced Bidirectional Metal-to-Metal Charge Transfer in a Linear
           Fe2Co Complex
    • Authors: Ji-Xiang Hu; Lun Luo, Xiao-Jin Lv, Lei Liu, Qiang Liu, Yi-Kai Yang, Chun-Ying Duan, Yi Luo, Tao Liu
      Abstract: It is a challenge to reversibly switch both magnetism and polarity using light irradiation. Herein we report a linear Fe2Co complex, whereby interconversion between FeIIILS(μ-CN)CoIIHS(μ-NC)FeIIILS (LS=low-spin, HS=high-spin) and FeIIILS(μ-CN)CoIIILS(μ-NC)FeIILS linkages could be achieved upon heating and cooling, or alternating laser irradiation at 808 and 532 nm. The electron spin arrangement and charge distribution were simultaneously tuned accompanying bidirectional metal-to-metal charge transfer, providing switchable polarity and magnetism in the complex.Laser-Show: Thermische und durch Licht induzierte Wechsel von sowohl Magnetisierung als auch Polarisation treten in einem Fe2Co-Dreikernkomplex auf. Die Umwandlung zwischen FeIIILS(μ-CN)CoIIHS(μ-NC)FeIIILS- und FeIIILS(μ-CN)CoIIILS(μ-NC)FeIILS-Brücken gelang durch Erwärmen und Abkühlen oder durch Laserstrahlung. LS=Low-spin, HS=High-spin.
      PubDate: 2017-05-26T02:11:02.38757-05:0
      DOI: 10.1002/ange.201703768
  • Transition Metal Nitride Core-Noble Metal Shell Nanoparticles as Highly CO
           Tolerant Catalysts
    • Authors: Aaron Garg; Maria Milina, Madelyn Ball, Daniela Zanchet, Sean T. Hunt, James A. Dumesic, Yuriy Roman-Leshkov
      Abstract: Core-shell architectures offer an effective way to tune and enhance the properties of noble metal catalysts. Here, we demonstrate the synthesis of Pt shell on titanium tungsten nitride core nanoparticles (Pt/TiWN) by high temperature ammonia nitridation of a parent core-shell carbide material (Pt/TiWC). X-ray photoelectron spectroscopy revealed significant core-level shifts for Pt shells supported on TiWN cores, corresponding to increased stabilization of the Pt valence d-states. The modulation of the electronic structure of the Pt shell by the nitride core translated into enhanced CO tolerance during hydrogen electrooxidation in the presence of CO. The ability to control shell coverage and vary the heterometallic composition of the shell and nitride core opens up attractive opportunities to synthesize a broad range of new materials with tunable catalytic properties.
      PubDate: 2017-05-25T10:20:29.351838-05:
      DOI: 10.1002/ange.201704632
  • A Unified Continuous Flow Assembly Line Synthesis of Highly Substituted
           Pyrazoles and Pyrazolines
    • Authors: Joshua Britton; Timothy F Jamison
      Abstract: A rapid and modular continuous flow synthesis of highly functionalized fluorinated pyrazoles and pyrazolines has been developed. Flowing fluorinated amines through sequential reactor coils mediates diazoalkane formation and [3+2] cycloaddition to generate more than 30 azoles in a telescoped fashion. Pyrazole cores are then sequentially modified through additional reactor modules performing N-alkylation and arylation, deprotection, and amidation to install broad molecular diversity in short order. Continuous flow synthesis enables the safe handling of diazoalkanes at elevated temperatures, and the use of aryl alkyne dipolarphiles under catalyst free conditions. This assembly line synthesis provides a flexible approach for the synthesis of agrochemicals and pharmaceuticals, as demonstrated by a four-step, telescoped synthesis of measles therapeutic, AS-136A, in a total residence time of 31.7 min (1.76 g h-1).
      PubDate: 2017-05-25T09:20:36.884442-05:
      DOI: 10.1002/ange.201704529
  • Cytoprotective Encapsulation of Individual Jurkat T Cells within Durable
           TiO2 Shells for T Cell Therapy
    • Authors: Wongu Youn; Eun Hyea Ko, Mi-Hee Kim, Matthew Park, Daewha Hong, Gulaim A. Seisenbaeva, Vadim G. Kessler, Insung S. Choi
      Abstract: Lymphocytes, such as T cells and natural killer (NK) cells, have therapeutic promises in adoptive cell transfer (ACT) therapy, where the cells are activated and expanded in vitro, and then infused into a patient. However, the in vitro preservation of labile lymphocytes during transfer, manipulation, and storage has been one of the bottlenecks in the development and commercialization of therapeutic lymphocytes. Herein, we suggest a "cell-in-shell" (a.k.a. artificial spore) strategy to enhance the cell viability in the practical settings, while maintaining biological activities for therapeutic efficacy. A durable titanium oxide (TiO2) shell is formed on individual Jurkat T cells, and the CD3 and other antigens on cell surfaces remain accessible to the antibodies. Interleukin-2 (IL-2) secretion is also not hampered by the shell formation. This work suggests a chemical toolbox for effectively preserving lymphocytes in vitro and developing the lymphocyte-based cancer immunotherapy.
      PubDate: 2017-05-25T03:20:23.534663-05:
      DOI: 10.1002/ange.201703886
  • Acoustic Emission from Organic Martensites
    • Authors: Manas K. Panda; Martin Etter, Robert Dinnebier, Pance Naumov
      Abstract: In salient effects, still crystals of solids that switch between phases acquire a momentum and are autonomously propelled due to rapid release of elastic energy accrued during a latent structural transition induced by heat, light or mechanical stimulation. Herein we report that when the mechanical reconfiguration is induced by change of temperature in thermosalient crystals, bursts of detectable acoustic waves are generated prior to their self-actuation. The results provide compelling evidence that the thermosalient transitions in organic and organic-containing crystals are molecular analogues of the martensitic transitions in some metals and metal alloys such as steel and shape memory alloys. Within a broader context, the results reveal that akin to metallic bonding, the intermolecular interactions in molecular solids are capable of gradual accrual and sudden release of substantial amount of strain during anisotropic thermal expansion.
      PubDate: 2017-05-24T21:20:30.46388-05:0
      DOI: 10.1002/ange.201702359
  • Highly Luminescent and Ultra-stable CsPbBr3 Pervoskite Quantum
           Dots-silica/alumina Monolith
    • Authors: Zhichun Li; Long Kong, Shouqiang Huang, Liang Li
      Abstract: We successfully prepared QDs-silica/alumina monolith (QDs-SAM) by a simple sol-gel reaction of Al-Si single precursors with CsPbBr3 QDs blended in toluene solution, without adding water and catalyst. The resultant transparent monolith exhibits high photoluminescence quantum yields (PLQY) up to 90%, and good photostability under strong illumination of blue light for 300 h. We demonstrated that the preliminary ligand exchange of didodecyl dimethyl ammonium bromide (DDAB) was very important to protect CsPbBr3 QDs from the surface damages during sol-gel reaction, which not only allowed us to maintain the original optical properties of CsPbBr3 QDs but also avoided the aggregation of QDs and make the monolith transparent. The CsPbBr3 QDs-SAM in powder form was easily mixed into resins and applied as color-converting layer with curing on blue light-emitting diodes (LED), and showed a high luminous efficacy of 80 lm/w and a narrow emission with a full width at half maximum (FWHM) of 25 nm.
      PubDate: 2017-05-24T21:20:26.680234-05:
      DOI: 10.1002/ange.201703264
  • Mechanism-Based Enantiodivergence in Manganese Reduction Catalysis: A
           Chiral Pincer Complex for the Highly Enantioselective Hydroboration of
    • Authors: Lutz Gade; Hubert Wadepohl, Vladislav Vasilenko, Clemens K Blasius
      Abstract: A manganese alkyl complex containing a chiral "boxmi" pincer ligand is a precatalyst for a catalyst of unprecedented activity and selectivity in the enantioselective hydroboration of ketones producing preparatively useful chiral alcohols in excellent yields and up to>99 %ee. It is applicable for both aryl alkyl and dialkyl ketone reduction under mild conditions (TOF>450 h-1 at -40°C) and an earth abundant base metal catalyst which operates at very low catalyst loadings (as low as 0.1 mol%) and with a high level of functional group tolerance. We provide evidence for the existence of two distinct mechanistic pathways for manganese-catalyzed hydride transfer and elaborate their role for enantiocontrol in the selectivity-determining step.
      PubDate: 2017-05-24T11:20:23.371465-05:
      DOI: 10.1002/ange.201704184
  • Enantioselective Nickel-Catalyzed Intramolecular Allylic Alkenylations
           Enabled by Reversible Alkenylnickel E/Z Isomerization
    • Authors: Connor Yap; Gabriel MJ Lenagh-Snow, Somnath N Karad, William Lewis, Louis J Diorazio, Hon Wai Lam
      Abstract: Enantioselective nickel-catalyzed arylative cyclizations of substrates containing a Z-allylic phosphate tethered to an alkyne are described. These reactions give multisubstituted chiral aza- and carbocycles, and are initiated by the addition of an arylboronic acid to the alkyne, followed by cyclization of the resulting alkenylnickel species onto the allylic phosphate. The reversible E/Z isomerization of the alkenylnickel species is essential for the success of the reactions.
      PubDate: 2017-05-24T10:21:38.799181-05:
      DOI: 10.1002/ange.201703380
  • Molecular Graph Paper
    • Authors: Marcin Lindner; Michal Valášek, Marcel Mayor, Timo Frauhammer, Wulf Wulfhekel, Lukas Gerhard
      Abstract: We present a self-assembled template of tetraphenylmethane-based variants on a Au(111) surface which feature a periodic lateral arrangement of acetyl groups sticking out of the molecular film. Using the tip of a scanning tunneling microscope, this acetyl group can be removed in a spatially controlled way without a significant effect on the remaining molecular assembly. The chemically modified molecule can readily be distinguished from the original ones such that information can be engraved in the molecular film. Both the modified nature of an individual molecule and the order of the molecular film are shown to persist at room temperature. We show that the mesh size of this molecular graph paper can be tuned by varying the length of the molecular spacer group so that writing and reading information on the nanoscale with variable letter size becomes possible.
      PubDate: 2017-05-24T09:30:22.008325-05:
      DOI: 10.1002/ange.201703586
  • Essential Reagents for Organic Synthesis. Herausgegeben von Philip L.
           Fuchs, André B. Charette, Tomislav Rovis und Jeffrey W. Bode.
    • Authors: Scott A. Snyder
      Abstract: John Wiley and Sons, Hoboken 2016. 640 S., Broschur, 115.00 $.—ISBN 978-1119278306
      PubDate: 2017-05-24T08:31:17.246035-05:
      DOI: 10.1002/ange.201703968
  • Assessing the Influence of Mutation on GTPase Transition States by using
           X-ray Crystallography, 19F NMR, and DFT Approaches
    • Authors: Yi Jin; Robert W. Molt, Erika Pellegrini, Matthew J. Cliff, Matthew W. Bowler, Nigel G. J. Richards, G. Michael Blackburn, Jonathan P. Waltho
      Abstract: We report X-ray crystallographic and 19F NMR studies of the G-protein RhoA complexed with MgF3−, GDP, and RhoGAP, which has the mutation Arg85′Ala. When combined with DFT calculations, these data permit the identification of changes in transition state (TS) properties. The X-ray data show how Tyr34 maintains solvent exclusion and the core H-bond network in the active site by relocating to replace the missing Arg85′ sidechain. The 19F NMR data show deshielding effects that indicate the main function of Arg85′ is electronic polarization of the transferring phosphoryl group, primarily mediated by H-bonding to O3G and thence to PG. DFT calculations identify electron-density redistribution and pinpoint why the TS for guanosine 5′-triphosphate (GTP) hydrolysis is higher in energy when RhoA is complexed with RhoGAPArg85′Ala relative to wild-type (WT) RhoGAP. This study demonstrates that 19F NMR measurements, in combination with X-ray crystallography and DFT calculations, can reliably dissect the response of small GTPases to site-specific modifications.Finger weg: Mutagenes Entfernen eines Arginin-Fingers aus dem GTPase-aktivierenden Protein RhoGAP ändert Kristallstrukturen und transponierte 19F-NMR-Daten für MgFx-Komplexe als Übergangszustandsanaloga. Die Ergebnisse werden durch Dichtefunktionalrechnungen der Elektronenverteilung im Übergangzustand bestätigt. Insgesamt deuten die Daten auf einen späteren, stärker dissoziativen Übergangszustand für den Phosphoryltransfer hin.
      PubDate: 2017-05-24T08:31:12.817521-05:
      DOI: 10.1002/ange.201703074
  • Supramolecular Interfacial Polymerization: A Controllable Method of
           Fabricating Supramolecular Polymeric Materials
    • Authors: Bo Qin; Shuai Zhang, Qiao Song, Zehuan Huang, Jiang-Fei Xu, Xi Zhang
      Abstract: A new method of supramolecular polymerization at the water–oil interface is developed. As a demonstration, an oil-soluble supramonomer containing two thiol end groups linked by two ureidopyrimidinone units and a water-soluble monomer bearing two maleimide end groups are employed. Supramolecular interfacial polymerization can be implemented by a thiol–maleimide click reaction at the water–chloroform interface to obtain supramolecular polymeric films. The glass transition temperature of such supramolecular polymers can be well-tuned by simply changing the polymerization time and temperature. It is highly anticipated that this work will provide a facile and general approach to realize control over supramolecular polymerization by transferring the preparation of supramolecular polymers from solutions to water–oil interfaces and construct supramolecular materials with well-defined properties.Grenzkontrolle: Eine supramolekulare Polymerisation an der Wasser-Öl-Grenzfläche mit vielen Vorteilen wurde entwickelt: Sie ist leicht ausführbar, nicht von Molverhältnis und Monomerkonzentration abhängig und auch für nichtmischbare Monomere geeignet. Mithilfe dieses Verfahrens lassen sich supramolekulare Materialien mit definierten und einstellbaren Eigenschaften erzeugen.
      PubDate: 2017-05-24T08:31:04.59415-05:0
      DOI: 10.1002/ange.201703572
  • Bert M. Weckhuysen geehrt/MRS Outstanding Young Investigator
           Award/VAAM-Forschungspreis für Tobias J. Erb
    • PubDate: 2017-05-24T08:31:00.857489-05:
      DOI: 10.1002/ange.201704713
  • Steuerung der Produktverteilung und der Mechanismen der thermischen
           Aktivierung von Methan durch Ligandeneffekte und elektrische Felder
    • Authors: Lei Yue; Jilai Li, Shaodong Zhou, Xiaoyan Sun, Maria Schlangen, Sason Shaik, Helmut Schwarz
      Abstract: Die Bindung von Acetonitril an zweiatomiges [ZnO].+ führt bei der thermischen Aktivierung von Methan in der Gasphase zu einem unerwarteten Wechsel der Reaktionsmechanismen und einer Umverteilung der Produkte. Theoretischen Studien zufolge spielt die starke Metall-Kohlenstoff-Bindung bei der ligandenfreien [ZnO].+-Spezies eine bedeutende Rolle für die Rückbindung des CH3.-Radikals an das Metallzentrum; hierdurch wird die kompetitive Bildung von CH3., OH. und CH3OH ermöglicht. Diese Wechselwirkung wird durch einen CH3CN-Liganden drastisch reduziert, was mechanistisch zu einem Wechsel von der bei [ZnO].+/CH4 dominierenden protonengekoppelten Elektronenübertragung zum klassischen Wasserstoffatomtransfer, gefolgt von der ausschließlichen Abspaltung von CH3., führt. Dieser Ligandeneffekt kann durch das gerichtete externe elektrische Feld einer negativen Punktladung gut modelliert werden.Ein einfacher Ligand schaltet zwei von drei Reaktionskanälen des Paares [ZnO].+/CH4 aus, sodass beim System [(CH3CN)ZnO].+/CH4 nur noch die Wasserstoffatomabstraktion abläuft. Dieser bemerkenswerte Ligandeneffekt kann gut durch ein gerichtetes externes elektrisches Feld modelliert werden. PCSET: protonengekoppelter Einelektronentransfer; OEEF: gerichtetes externes elektrisches Feld; HAT: Wasserstoffatomtransfer.
      PubDate: 2017-05-24T08:30:49.686271-05:
      DOI: 10.1002/ange.201703485
  • Confining Excitation Energy in Er3+-Sensitized Upconversion Nanocrystals
           through Tm3+-Mediated Transient Energy Trapping
    • Authors: Qiushui Chen; Xiaojie Xie, Bolong Huang, Liangliang Liang, Sanyang Han, Zhigao Yi, Yu Wang, Ying Li, Dianyuan Fan, Ling Huang, Xiaogang Liu
      Abstract: A new class of lanthanide-doped upconversion nanoparticles are presented that are without Yb3+ or Nd3+ sensitizers in the host lattice. In erbium-enriched core–shell NaErF4:Tm (0.5 mol %)@NaYF4 nanoparticles, a high degree of energy migration between Er3+ ions occurs to suppress the effect of concentration quenching upon surface coating. Unlike the conventional Yb3+-Er3+ system, the Er3+ ion can serve as both the sensitizer and activator to enable an effective upconversion process. Importantly, an appropriate doping of Tm3+ has been demonstrated to further enhance upconversion luminescence through energy trapping. This endows the resultant nanoparticles with bright red (about 700-fold enhancement) and near-infrared luminescence that is achievable under multiple excitation wavelengths. This is a fundamental new pathway to mitigate the concentration quenching effect, thus offering a convenient method for red-emitting upconversion nanoprobes for biological applications.Teamwork: Normalerweise können Kern-Schale-Strukturen die Lumineszenzlöschung durch Energieverluste an Gitterdefekten im Inneren von Nanokristallen nicht verhindern. Er3+-sensibilisierte Nanokristalle mit Tm3+-vermitteltem transientem Energieeinfang (NaErF4:Tm@NaYF4) zeigen nun eine hoch effiziente aufwärtskonvertierte Emission. Diese Nanomaterialien geben bei Anregung bei mehreren Wellenlängen rotes Licht und NIR-Strahlung ab.
      PubDate: 2017-05-24T08:30:47.022965-05:
      DOI: 10.1002/ange.201703012
  • Instant Hydrogelation Inspired by Inflammasomes
    • Authors: Huaimin Wang; Zhaoqianqi Feng, Alvin Lu, Yujie Jiang, Hao Wu, Bing Xu
      Abstract: Based on the recent near-atomic structures of the PYRIN domain of ASC in the protein filament of inflammasomes and the observation that the active form of vitamin B6 (pyridoxal phosphate, P5P) modulates the self-assembly of ASC, we rationally designed an N-terminal capped nonapeptide (Nap-FFKKFKLKL, 1) to form supramolecular nanofibers consisting of α-helix. The addition of P5P to the solution of 1 results in a hydrogel almost instantly (about 4 seconds). Several other endogenous small molecules (for example, pyridoxal, folinic acid, ATP, and AMP) also convert the solution of 1 into a hydrogel. As the demonstration of correlating assemblies of peptides and the relevant protein epitopes, this work illustrates a bioinspired approach to develop supramolecular structures modulated by endogenous small molecules.Vitamin B6 und ähnliche endogene niedermolekulare Substanzen induzieren die sofortige Hydrogelbildung peptidischer Epitope von Inflammasomen. Somit konnte die Aggregation von Peptiden mit den relevanten Proteinepitopen für die supramolekulare Hydrogelbildung korreliert werden.
      PubDate: 2017-05-24T08:30:43.282111-05:
      DOI: 10.1002/ange.201702783
  • The Dynamic Multisite Interactions between Two Intrinsically Disordered
    • Authors: Shaowen Wu; Dongdong Wang, Jin Liu, Yitao Feng, Jingwei Weng, Yu Li, Xin Gao, Jianwei Liu, Wenning Wang
      Abstract: Protein interactions involving intrinsically disordered proteins (IDPs) comprise a variety of binding modes, from the well-characterized folding upon binding to dynamic fuzzy complexes. To date, most studies concern the binding of an IDP to a structured protein, while the interaction between two IDPs is poorly understood. In this study, NMR, smFRET, and molecular dynamics (MD) simulation are combined to characterize the interaction between two IDPs, the C-terminal domain (CTD) of protein 4.1G and the nuclear mitotic apparatus (NuMA) protein. It is revealed that CTD and NuMA form a fuzzy complex with remaining structural disorder. Multiple binding sites on both proteins were identified by molecular dynamics and mutagenesis studies. This study provides an atomic scenario in which two IDPs bearing multiple binding sites interact with each other in dynamic equilibrium. The combined approach employed here could be widely applicable for investigating IDPs and their dynamic interactions.Chaotisches Duo: NMR- und Einzelmolekül-FRET-Studien offenbaren in Kombination mit Moleküldynamiksimulationen, dass die intrinsisch ungeordneten Proteine 4.1G-CTD und NuMA einen dynamischen Komplex bilden, in dem beide Komponenten ungeordnet bleiben (siehe Bild). Die Wechselwirkung zweier Proteine mit multiplen Bindestellen führt dabei zu einem dynamischen Gleichgewicht.
      PubDate: 2017-05-24T08:30:38.696459-05:
      DOI: 10.1002/ange.201701883
  • Trapping a Silicon(I) Radical with Carbenes: A Cationic cAAC–Silicon(I)
           Radical and an NHC–Parent-Silyliumylidene Cation
    • Authors: Yan Li; Yuk-Chi Chan, Bi-Xiang Leong, Yongxin Li, Emma Richards, Indu Purushothaman, Susmita De, Pattiyil Parameswaran, Cheuk-Wai So
      Abstract: The trapping of a silicon(I) radical with N-heterocyclic carbenes is described. The reaction of the cyclic (alkyl)(amino) carbene [cAACMe] (cAACMe=:C(CMe2)2(CH2)NAr, Ar=2,6-iPr2C6H3) with H2SiI2 in a 3:1 molar ratio in DME afforded a mixture of the separated ion pair [(cAACMe)2Si:.]+I− (1), which features a cationic cAAC–silicon(I) radical, and [cAACMe−H]+I−. In addition, the reaction of the NHC–iodosilicon(I) dimer [IAr(I)Si:]2 (IAr=:C{N(Ar)CH}2) with 4 equiv of IMe (:C{N(Me)CMe}2), which proceeded through the formation of a silicon(I) radical intermediate, afforded [(IMe)2SiH]+I− (2) comprising the first NHC–parent-silyliumylidene cation. Its further reaction with fluorobenzene afforded the CAr−H bond activation product [1-F-2-IMe-C6H4]+I− (3). The isolation of 2 and 3 confirmed the reaction mechanism for the formation of 1. Compounds 1–3 were analyzed by EPR and NMR spectroscopy, DFT calculations, and X-ray crystallography.Ungewöhnliche Intermediate: Die Reaktion eines cyclischen Alkylaminocarbens mit H2SiI2 ergibt ein getrenntes Ionenpaar, das einen cAAC-Silicium(I)-Radikalkomplex enthält (siehe Schema, links). Andererseits führt die Umsetzung des NHC-Iodsilicium(I)-Dimers [IAr(I)Si:]2 mit einem weiteren NHC zum einem NHC-koordinierten Stamm-Silyliumylidenkation (rechts).
      PubDate: 2017-05-24T08:30:36.352518-05:
      DOI: 10.1002/ange.201702760
  • Photoredoxkatalyse durch sensibilisierten Elektronentransfer
    • Authors: Indrajit Ghosh; Rizwan S. Shaikh, Burkhard König
      Abstract: Photosynthetische Organismen nutzen Antennenchromophore zur Lichtabsorption und übertragen die Anregungsenergie auf Reaktionszentren, in denen Redoxreaktionen ablaufen. Bei der chemischen Photokatalyse mit sichtbarem Licht wird dagegen nur ein einziges Molekül, der Photoredoxkatalysator, genutzt, um Licht zu absorbieren und die Redoxprozesse auszuführen. Wir berichten hier über eine Zwei-Zentren-Photoredoxkatalyse, bei der – in Analogie zum Energiefluss des biologischen Vorbilds – die Aufgaben der Lichtenergieabsorption und des Elektronentransfers auf zwei Moleküle verteilt werden: Ru(bpy)3Cl2 absorbiert sichtbares Licht und überträgt die Energie auf aromatische Kohlenwasserstoffe, an denen die Redoxreaktion abläuft. Dieser sensibilisierte Elektronentransfer ermöglicht die Nutzung von Aromaten, wie Anthracen oder Pyren, die selbst kein sichtbares Licht absorbieren, für die Photoredoxkatalyse. Die praktische Anwendung des Verfahrens zeigen wir anhand von Kohlenstoff-Kohlenstoff- und Kohlenstoff-Heteroatom-Bindungsknüpfungen.Naturnahe Aufgabenteilung: Eine Zwei-Zentren-Photoredoxkatalyse wird vorgestellt, bei der Ru(bpy)3Cl2 sichtbares Licht absorbiert und die dadurch gewonnene Energie auf aromatische Kohlenwasserstoffe überträgt, an denen eine Redoxreaktion abläuft. Auf diese Weise wurden (Hetero)Arylhalogenide für C-C- und C-Heteroatom-Kupplungen aktiviert.
      PubDate: 2017-05-24T08:30:34.84563-05:0
      DOI: 10.1002/ange.201703004
  • Betaine Catalysis for Hierarchical Reduction of CO2 with Amines and
           Hydrosilane To Form Formamides, Aminals, and Methylamines
    • Authors: Xiao-Fang Liu; Xiao-Ya Li, Chang Qiao, Hong-Chen Fu, Liang-Nian He
      Abstract: An efficient, sustainable organocatalyst, glycine betaine, was developed for the reductive functionalization of CO2 with amines and diphenylsilane. Methylamines and formamides were obtained in high yield by tuning the CO2 pressure and reaction temperature. Based on identification of the key intermediate, that is, the aminal, an alternative mechanism for methylation involving the C0 silyl acetal and aminal is proposed. Furthermore, reducing the CO2 amount afforded aminals with high yield and selectivity. Therefore, betaine catalysis affords products with a diversified energy content that is, formamides, aminals and methylamines, by hierarchical two-, four- and six-electron reduction, respectively, of CO2 coupled with C−N bond formation.Unter Glycinbetain-Katalyse kann CO2 reduktiv mit Aminen und Diphenylsilan funktionalisiert werden. Der organokatalytische Ansatz liefert Produkte mit vielfältigem Energiegehalt – Formamide, Aminale und Methylamine – durch hierarchische Zwei-, Vier- bzw. Sechs-Elektronen-Reduktion von CO2 und C-N-Bindungsbildung.
      PubDate: 2017-05-24T08:30:32.483142-05:
      DOI: 10.1002/ange.201702734
  • Evidence of Structure Sensitivity in the Fischer–Tropsch Reaction on
           Model Cobalt Nanoparticles by Time-Resolved Chemical Transient Kinetics
    • Authors: Walter T. Ralston; Gérôme Melaet, Tommy Saephan, Gabor A. Somorjai
      Abstract: The Fischer–Tropsch process, or the catalytic hydrogenation of carbon monoxide (CO), produces long chain hydrocarbons and offers an alternative to the use of crude oil for chemical feedstocks. The observed size dependence of cobalt (Co) catalysts for the Fischer–Tropsch reaction was studied with colloidally prepared Co nanoparticles and a chemical transient kinetics reactor capable of measurements under non-steady-state conditions. Co nanoparticles of 4.3 nm and 9.5 nm diameters were synthesized and tested under atmospheric pressure conditions and H2/CO=2. Large differences in carbon coverage (ΘC) were observed for the two catalysts: the 4.3 nm Co catalyst has a ΘC less than one while the 9.5 nm Co catalyst supports a ΘC greater than two. The monomer units present on the surface during reaction are identified as single carbon species for both sizes of Co nanoparticles, and the major CO dissociation site is identified as the B5-B geometry. The difference in activity of Co nanoparticles was found to be a result of the structure sensitivity caused by the loss of these specific types of sites at smaller nanoparticle sizes.Lieber etwas größer: Die größenabhängige Aktivität von Cobalt-Nanopartikeln in Fischer-Tropsch-Synthesen hängt mit dem Verschwinden von Kohlenmonoxid-Dissoziationsplätzen auf kleinen Nanopartikeln zusammen. Kinetische Transientenexperimente und Synchrotronspektroskopie belegen eine stärkere Kohlenstoffakkumulation auf großen Nanopartikeln. Die Kohlenmonoxid-Dissoziationsplätze befinden sich an (221)-Stufen auf kubisch-flächenzentriertem Cobalt.
      PubDate: 2017-05-24T08:30:25.154503-05:
      DOI: 10.1002/ange.201701186
  • Strain stiffening hydrogels through self-assembly and covalent fixation of
           semi-flexible fibers
    • Authors: Rint P. Sijbesma; Marcos Fernandez-Castano Romera, Clément Guibert, Ilja K. Voets, Cornelis Storm
      Abstract: Biomimetic, strain-stiffening materials are reported, made through self-assembly and covalent fixation of small building blocks to form fibrous hydrogels able to stiffen by an order of magnitude in response to applied stress. The gels consist of semi-flexible rodlike micelles of bisurea bolaamphiphiles with oligo(ethylene oxide) (EO) outer blocks and a polydiacetylene (PDA) backbone. The micelles are fibers composed of 9-10 ribbons. A gelation method based on Cu-catalyzed azide-alkyne cycloaddition (CuAAC) was developed that leads to strain-stiffening hydrogels with unusual yet universal linear and nonlinear stress-strain response. Upon gelation, the X-ray scattering profile is unchanged, suggesting that crosslinks are formed at random positions along the fiber contour without fiber bundling. The work expands the current knowledge about the design principles and chemistries needed to achieve fully synthetic, biomimetic soft matter with on-demand, targeted mechanical properties.
      PubDate: 2017-05-24T05:20:31.460964-05:
      DOI: 10.1002/ange.201704046
  • Photocatalytic Nanosheet Lithography: A New Concept for Photolithography
           based on Organically Modified Photoactive 2D Nanosheets
    • Authors: Pirmin Ganter; Bettina Valeska Lotsch
      Abstract: Harvesting the properties of nanosheets is not only crucial from a fundamental perspective, but also for the development of novel functional devices based on 2D nanosheets. Here, we demonstrate the processing of organically modified TBAxH1-xCa2Nb3O10 nanosheets into photonic thin films and study their colorimetric sensing properties in response to various aqueous and organic solvent vapors. Building on the enhanced solvent accessibility of TBA-containing nanosheets and their photocatalytic activity under UV irradiation, we develop a new concept for photocatalytic lithography using TBAxH1-xCa2Nb3O10 nanosheets as a negative photoresist to obtain high-fidelity micron-scale patterns of robust inorganic nanosheets. Photocatalytic nanosheet lithography (PNL) therefore adds a new resist-free, resource efficient direct patterning technique to the toolbox of photolithography.
      PubDate: 2017-05-24T04:20:36.736896-05:
      DOI: 10.1002/ange.201703149
  • Ag Films with Hierarchical Chiralities
    • Authors: Shunai Che; Liguo Ma, Yuanyuan Cao, Yingying Duan, Lu Han
      Abstract: Preparing chiral metallic films is one of the primary challenges in materials science. Although physical fabrication methods for metal films with singular and large-sized chirality exist, chemical preparation of that with multi-structured chirality from atomic to larger scales have not been reported yet. Here, we report the chiral molecule-induced formation of chiral Ag films on a copper substrate through a redox reaction. Three levels of chirality were identified, primary twisted 'nanoflakes' with atomic crystal lattices, secondary helical stacking of these nanoflakes to form 'nanoplates' and tertiary micrometre-sized 'circinate' consisting of chiral arranged nanoplates. The chiral Ag films exhibited multiple plasmonic absorption- and scattering-based optical activities at UV-visible wavelengths based on their hierarchical chiralities; and showed chiral catalytic selectivity for amino acids in electrochemical reactions based on their primary atomic crystal lattices.
      PubDate: 2017-05-24T03:21:00.692094-05:
      DOI: 10.1002/ange.201701994
  • Monofluoromethyl-Substituted Sulfonium Ylides: Electrophilic
           Monofluoromethylating Reagents with Broad Substrate Scopes
    • Authors: Yafei Liu; Long Lu, Qilong Shen
      Abstract: Two electrophilic monofluoromethylating reagents S-monofluoromethyl-S-phenyl-bis(carbomethoxy) methylide sulfonium ylide 3a and S-monofluoromethyl-S-(4-nitrophenyl)-bis(carbo -methoxy) methylide sulfonium ylide 3b and their reactions with a variety of nucleophiles such as alcohols and malonate derivatives, sulfonic and carboxylic acids, phenols, amides, and nitrogen of heteroarenes under mild conditions were described. Mechanistic studies by employing deuterated reagents 3a-D2/3b-D2 suggest that these monofluoromethylating reactions proceed via an electrophilic substitution pathway.
      PubDate: 2017-05-23T23:20:26.391245-05:
      DOI: 10.1002/ange.201704175
  • Cofactor-Free, Direct Photoactivation of Enoate Reductases for Asymmetric
           Reduction of C=C Bonds
    • Authors: Sahng Ha Lee; Da Som Choi, Milja Pesic, Yang Woo, Caroline Paul, Frank Hollmann, Chan Beum Park
      Abstract: Enoate reductases from the family of Old Yellow Enzymes (OYEs) can catalyze stereoselective trans-hydrogenation of activated C=C bonds. Here, we report visible light-driven activation of OYEs through NAD(P)H-free, direct transfer of photoexcited electrons from xanthene dyes to the prosthetic flavin moiety. Our spectroscopic and electrochemical analyses verified spontaneous association of rose bengal and its derivatives with OYEs. Illumination of a white light-emitting-diode triggered photoreduction of OYEs by xanthene dyes, which facilitated the enantioselective reduction of C=C bonds in the absence of NADH. The photoenzymatic conversion of 2-methylcyclohexenone resulted in enantiopure (ee>99%) (R)-2-methylcyclohenanone with conversion yields as high as 80-90%. The photobiocatalytic platform was successfully applied to different homologues of OYEs. This work demonstrates a simple and versatile way of activating OYEs by direct coupling of OYE-catalysis with molecular photocatalysis.
      PubDate: 2017-05-23T22:20:24.630529-05:
      DOI: 10.1002/ange.201702461
  • Recent progress of first principles calculations in CH3NH3PbI3 perovskite
           solar cells
    • Authors: Sining Yun; Xiao Zhou, Jacky Even, Anders Hagfeldt
      Abstract: Hybrid halide perovskite solar cells (PSCs) exceeding 22% power conversion efficiencies (PCEs) have attracted considerable global attention due to the intrinsic nature of perovskite. Although we all know about that perovskite plays a significant role in the operation of PSCs, the fundamental theories associated with perovskite have not been resolved by the exponential increase in research effort. This raises questions about whether the first-principles calculations are sufficiently addressing the underlying issues in perovskite. In this minireview, we assess the current understanding of structural and electronic properties, defects, ionic diffusion, and shift current for CH3NH3PbI3 perovskite based on the first-principles calculations, and the effect of ionic transport on the hysteresis of current-voltage curves in PSCs. The shift current connected to the possible presence of ferroelectricity is also discussed. The current state-of-the-art and some open questions regarding PSCs are also highlighted, and the benefits, challenges, and potentials of perovskite for use in PSCs are especially stressed.
      PubDate: 2017-05-23T21:20:38.617763-05:
      DOI: 10.1002/ange.201702660
  • Secondary Structure-Driven Self-Assembly of Reactive Polypept(o)ides:
           Controlling Size, Shape and Function of Core Cross-Linked Nanostructures
    • Authors: Kristina Klinker; Olga Schäfer, David Huesmann, Tobias Bauer, Leon Capelôa, Lydia Braun, Natascha Stergiou, Meike Schinnerer, Anjaneyulu Dirisala, Kanjiro Miyata, Kensuke Osada, Horacio Cabral, Kazunori Kataoka, Matthias Barz
      Abstract: Achieving precise control over morphology and function of polymeric nanoparticles during self-assembly remains a challenge in material as well as bio-medical sciences, especially when all these properties can be controlled independently. Herein, we report on nanostructures derived from amphiphilic block copolypept(o)ides by secondary structure directed self-assembly, presenting a strategy to adjust core polarity separately from particle preparation in a bio-reversible fashion. The peptide-inherent process of secondary structure-formation allows for the synthesis of spherical and worm-like core cross-linked architectures from the same block copolymer, introducing a simple yet powerful approach to versatile peptide-based nanoparticles.
      PubDate: 2017-05-23T21:20:29.004445-05:
      DOI: 10.1002/ange.201702624
  • A high-valent non heme μ-oxo MnIV dimer generated from a
           thiolate-bound MnII complex and O2
    • Authors: Carole Duboc; Deborah Brazzolotto, Fabián G. Cantú Reinhard, Julian Smith-Jones, Marius Retegan, Lucia Amidani, Abayomi S. Faponle, Kallol Ray, Christian Philouze, Sam P. de Visser, Marcello Gennari
      Abstract: This study deals with the unprecedented reactivity of dinuclear non heme MnII-thiolate complexes with O2, which dependent on the protonation state of the initial MnII dimer selectively generates either a di-μ-oxo or μ-oxo-μ-hydroxo MnIV complex. Both dimers have been characterized by different techniques including single-crystal X-ray diffraction and mass spectrometry. Oxygenation reactions carried out with labeled 18O2 unambiguously shows that the oxygen atoms present in the MnIV dimers originate from O2. Based on experimental observations and DFT calculations, evidence is provided that these MnIV species comproportionate with a MnII precursor to yield μ-oxo and/or μ-hydroxo MnIII dimers. Our work highlights the delicate balance of reaction conditions to control the synthesis of non heme high-valent μ-oxo and μ-hydroxo Mn species from MnII precursors and O2.
      PubDate: 2017-05-23T21:20:24.280511-05:
      DOI: 10.1002/ange.201703215
  • α-Radical Phosphines: Synthesis, Structure and Reactivity
    • Authors: Manuel Alcarazo; Lianghu Gu, Yiying Zheng, Estela Haldón, Richard Goddard, Eckhard Bill, Walter Thiel
      Abstract: A series of phosphines featuring a persistent radical were synthesized in two steps by condensation of dialkyl-/diarylchlorophosphines with stable cyclic (alkyl)(amino)carbenes (cAACs) followed by one-electron reduction of the corresponding cationic intermediates. Structural, spectroscopic and computational data indicate that the spin density in these phosphines is mainly localized on the original carbene carbon from the cAAC fragment; thus, it remains in the α-position to the central phosphorus. The potential of these α-radical phosphines to serve as spin-labeled ligands is demonstrated through the preparation of several Au(I) derivatives, which were also structurally characterized by single-crystal X-ray diffraction.
      PubDate: 2017-05-23T10:20:55.752389-05:
      DOI: 10.1002/ange.201704185
  • Frontispiz: The Structure of the Elusive Simplest Dipeptide Gly-Gly
    • Authors: Carlos Cabezas; Marcelino Varela, José L. Alonso
      Abstract: Dipeptidstrukturen In der Zuschrift auf S. 6520 ff. präsentieren J. L. Alonso et al. experimentelle Daten zur Struktur des einfachsten Dipeptids – Gly-Gly –, erhalten durch die Verwendung von Laserablation und FT-Mikrowellenspektroskopie in einer Überschallexpansion.
      PubDate: 2017-05-23T08:52:51.140035-05:
      DOI: 10.1002/ange.201782361
  • Absolute Minimal Sampling of Homonuclear 2D NMR TOCSY Spectra for
           High-Throughput Applications of Complex Mixtures
    • Authors: Alexandar Hansen; Da-Wei Li, Cheng Wang, Rafael Bruschweiler
      Abstract: Modern applications of 2D NMR spectroscopy to diagnostic screening, metabolomics, quality control, and other high-throughput applications are often limited by the time-consuming sampling requirements along the indirect time domain t1. 2D Total Correlation Spectroscopy (TOCSY) provides unique spin-connectivity information for the analysis of a large number of compounds in complex mixtures, but standard methods typically require>100 t1-increments for an accurate spectral reconstruction, rendering these experiments ineffective for high-throughput applications. Here, we demonstrate for a complex metabolite mixture how absolute minimal sampling (AMS), based on direct fitting of resonance frequencies and amplitudes in the time domain, yields an accurate spectral reconstruction of TOCSY spectra using as few as 16 t1-points. This permits the rapid collection of homonuclear 2D NMR experiments at high resolution with measurement times that previously were the realm of 1D experiments only.
      PubDate: 2017-05-23T08:20:35.701943-05:
      DOI: 10.1002/ange.201703587
  • Synthesis of Aldehydes by Organocatalytic Formylation Reactions of Boronic
           Acids with Glyoxylic Acid
    • Authors: Wei Wang; He Huang, Chenguang Yu, Xiangmin Li, Yongqiang Zhang, Yueteng Zhang, Xiaobei Chen, Patrick S. Mariano, Hexin Xie
      Abstract: We report a conceptually novel organocatalytic strategy for formylation of boronic acids, in which a new reactivity is engineered into the α-amino acid forming Petasis reaction occurring between aryl boron acids, amines and glyoxylic acid. The feasibility and preparative power of the protocol was demonstrated by its use to prepare aldehydes from broadly accessible aryl and alkenyl boronic acids, glyoxylic acid, and the cheap N-alkylaniline derivatives, tetrahydroquinoline and indoline, as catalysts. Furthermore, the operational simplicity of the process, which is performed by simply mixing these reagents under ambient conditions, and its ability to generate structurally diverse and valued aryl, heteroaryl and α,β-unsaturated aldehydes containing a wide array of functional groups, demonstrates the practical utility of the newly unveiled synthetic strategy.
      PubDate: 2017-05-23T08:20:27.378793-05:
      DOI: 10.1002/ange.201703127
  • Crystalline Hollow Microrods for Site-Selective Enhancement of Nonlinear
    • Authors: Bing Chen; Wei Kong, Yong Liu, Yunhao Lu, Mingyu Li, Xvsheng Qiao, Xianping Fan, Feng Wang
      Abstract: A class of one-dimensional hollow microstructure is described, which was formed by a kinetically controlled crystal growth process. A hexagonal-phase NaYbF4 microrod comprising isolated holes along the longitudinal axis was synthesized by a one-pot hydrothermal method with the assistance of citrate ligands. The structural void feature modulates light intensity across the microrods as a result of interference arising from light scattering and reflection by the inner walls. A single crystal comprising a structural void was doped with upconverting lanthanide ions. Upon near-infrared excitation of the doped crystal spatially resolvable optical codes were produced.Hohle Mikrokristalle von hexagonalem NaYbF4 erzeugen eine nichtlineare Photolumineszenz bei Bestrahlung mit Nahinfrarotlicht. Streuung und Reflexion an den Innenwänden der strukturierten Mikrostäbe modulieren die Lichtintensität in den verschiedenen Bereichen der Struktur. Durch Dotierung mit aufwärtskonvertierenden Lanthanoidionen werden räumlich aufgelöste optische Codes erhalten.
      PubDate: 2017-05-23T08:05:33.868725-05:
      DOI: 10.1002/ange.201703600
  • Sulfation of the Human Cytomegalovirus Protein UL22A Enhances Binding to
           the Chemokine RANTES
    • Authors: Xiaoyi Wang; Julie Sanchez, Martin J. Stone, Richard J. Payne
      Abstract: UL22A is an 83 amino acid chemokine-binding protein produced by human cytomegalovirus that likely assists the virus in dampening the host antiviral response. We proposed that UL22A is sulfated on two tyrosine residues and tested this hypothesis through the chemical synthesis of a small library of differentially sulfated protein variants. The (sulfo)proteins were efficiently prepared using a novel β-selenoleucine motif to facilitate one-pot ligation–deselenization chemistry. Tyrosine sulfation of UL22A proved critical for RANTES binding, with the doubly sulfated variant exhibiting an improvement in binding of 2.5 orders of magnitude compared to the unmodified protein.Fein abgestimmt: Für das Chemokin-Bindeprotein UL22A wurde eine posttranslationale Sulfatierung an zwei Tyrosinresten vorhergesagt. Eine Bibliothek sulfatierter UL22A-Proteine wurde mithilfe eines Eintopfverfahrens durch eine β-Selenoleucin-vermittelte Peptidligation und anschließende Deselenierung aufgebaut. Experimenten zufolge verstärkt die Sulfatierung der Tyrosinreste die Bindungsaffinität für das Chemokin RANTES deutlich.
      PubDate: 2017-05-23T08:03:05.812099-05:
      DOI: 10.1002/ange.201703059
  • Chemische Struktur und Biosynthese der Crocagine, polycyclischer Peptide
           ribosomalen Ursprungs aus Chondromyces crocatus
    • Authors: Konrad Viehrig; Frank Surup, Carsten Volz, Jennifer Herrmann, Antoine Abou Fayad, Sebastian Adam, Jesko Köhnke, Dirk Trauner, Rolf Müller
      Abstract: Sekundärmetabolom-Analysen in dem myxobakteriellen Naturstoffproduzenten Chondromyces crocatus Cm c5 führten zur Isolierung und Charakterisierung der Crocagine, neuartiger polycyclischer Peptide mit Tetrahydropyrrolo[2,3-b]indol-Grundgerüst. Der zugehörige Gencluster wurde durch eine Kombination aus gezielter Mutagenese und In-vitro-Experimenten zugeordnet. Auf Grundlage der Ergebnisse konnte ein Biosyntheseschema für die Crocagine erstellt werden. Diese Naturstoffe werden aus den drei C-terminalen Aminosäuren eines Vorläuferpeptides gebildet und gehören daher zu einer neuen Klasse der ribosomal gebildeten und posttranslational modifizierten Peptide (RiPPs). Weiterhin konnte gezeigt werden, dass Crocagin A an das Regulatorprotein CsrA (“carbon storage regulator”) bindet, wodurch dessen Bindung an seine RNA-Wechselwirkungspartner unterdrückt wird.RiPPs aus einem Myxobakterium: Das ungewöhnliche tetracyclische Peptidgrundgerüst der Crocagine entstammt einem ribosomal synthetisierten Vorläuferpeptid. Isolierung, Strukturaufklärung, Mutagenese des Produzenten und In-vitro-Experimente werden vorgestellt.
      PubDate: 2017-05-23T07:56:00.080571-05:
      DOI: 10.1002/ange.201612640
  • Common Fibril Structures Imply Systemically Conserved Protein Misfolding
           Pathways In Vivo
    • Authors: Karthikeyan Annamalai; Falk Liberta, Marie-Theres Vielberg, William Close, Hauke Lilie, Karl-Heinz Gührs, Angelika Schierhorn, Rolf Koehler, Andreas Schmidt, Christian Haupt, Ute Hegenbart, Stefan Schönland, Matthias Schmidt, Michael Groll, Marcus Fändrich
      Abstract: Systemic amyloidosis is caused by the misfolding of a circulating amyloid precursor protein and the deposition of amyloid fibrils in multiple organs. Chemical and biophysical analysis of amyloid fibrils from human AL and murine AA amyloidosis reveal the same fibril morphologies in different tissues or organs of one patient or diseased animal. The observed structural similarities concerned the fibril morphology, the fibril protein primary and secondary structures, the presence of post-translational modifications and, in case of the AL fibrils, the partially folded characteristics of the polypeptide chain within the fibril. Our data imply for both analyzed forms of amyloidosis that the pathways of protein misfolding are systemically conserved; that is, they follow the same rules irrespective of where inside one body fibrils are formed or accumulated.Generelles Fehlverhalten: In verschiedenen Geweben ein und desselben Körpers bilden Polypeptidketten dieselben Amyloidfibrillenstrukturen. Diese Beobachtung deutet darauf hin, dass die Art und Weise der Proteinfehlfaltung in vivo konserviert ist.
      PubDate: 2017-05-23T07:36:24.742572-05:
      DOI: 10.1002/ange.201701761
  • Surface Modification of Two-Dimensional Metal-Organic Layers Creates
           Biomimetic Catalytic Microenvironments for Selective Oxidation
    • Authors: Wenjie Shi; Lingyun Cao, Hua Zhang, Xin Zhou, Bing An, Zekai Lin, Ruihan Dai, Jianfeng Li, Cheng Wang, Wenbin Lin
      Abstract: Microenvironments in enzymes play crucial roles in controlling the activities and selectivities of reaction centers. Herein we report the tuning of the catalytic microenvironments of metal-organic layers (MOLs), a two-dimensional version of metal-organic frameworks (MOFs) with thickness down to a monolayer, to control product selectivities. By modifying the secondary building units (SBUs) of MOLs with monocarboxylic acids such as gluconic acid, we successfully changed the hydrophobicity/hydrophilicity around the active sites and fine-tuned the selectivity in photocatalytic oxidation of tetrahydrofuran (THF) to exclusively afford butyrolactone (BTL), likely via prolonging residence time of reaction intermediates in the hydrophilic microenvironment of catalytic centers. Our work highlights new opportunities in using functional MOLs as highly tunable and selective two-dimensional catalytic materials.
      PubDate: 2017-05-23T07:20:39.972032-05:
      DOI: 10.1002/ange.201703675
  • A Designed Approach to Enantiodivergent Enamine Catalysis
    • Authors: Mathew Vetticatt; Juliet Macharia, Victor Wambua, Yun Hong, Lawrence Harris, Jennifer S Hirschi, Gary B. Evans
      Abstract: The rational design and implementation of enantiodivergent enamine catalysis is reported. A simple secondary amine catalyst, 2-methyl-L-proline, and its tetrabutylammonium salt function as an enantiodivergent catalyst pair delivering opposite enantiomers of α-functionalized aldehyde products in excellent enantioselectivities. This novel concept of 'designed enantiodivergence' is applied to the enantioselective α-amination, aldol and α-aminoxylation/α-hydroxyamination reactions of aldehydes.
      PubDate: 2017-05-23T07:20:36.002614-05:
      DOI: 10.1002/ange.201703919
  • Multiple hydrogen bonding enables the self-healing of sensors for
           human-machine interaction
    • Authors: Jie Cao; Canhui Lu, Jian Zhuang, Manxiao Liu, Xinxing Zhang, Yanmei Yu, Qingchuan Tao
      Abstract: Despite its widespread use in signal collection, flexible sensor has been rarely used in human-machine interaction due to its indistinguishable signal, poor reliability and stability when suffered from unavoidable scratches and/or mechanical cuts. Here, we demonstrate a highly sensitive and self-healing sensor enabled by multiple hydrogen bonding network and nanostructured conductive network. The nanostructured supramolecular sensor displays extremely fast (~15 s) and repeatable self-healing ability with high healing efficiency (93% after the 3rd healing process). It can precisely detect tiny human motions, demonstrating highly distinguishable and reliable signals even after cutting-healing and bending over 20000 cycles. Furthermore, a human-machine interaction system is integrated to develop a facial expression control system and an electronic larynx, aiming to control the robot to assist the patient's daily life and help the dumb to realize real-time speaking.
      PubDate: 2017-05-23T07:20:32.269839-05:
      DOI: 10.1002/ange.201704217
  • Frozen Acrylamide Gels as Dynamic Nuclear Polarization Matrices.
    • Authors: Jasmine Viger-Gravel; Pierrick Berruyer, David Gajan, Jean-Marie Basset, Anne Lesage, Paul Tordo, Olivier Ouari, Lyndon Emsley
      Abstract: We show that aqueous acrylamide gels can be used to provide dynamic nuclear polarization (DNP) NMR signal enhancements of around 200 at 9.4 T and 100 K. The enhancements are shown to increase with cross linker concentration and low concentrations of the AMUPol biradical. We show that this DNP matrix can be used in situations where conventional incipient wetness methods fail, such as to obtain DNP surface enhanced NMR spectra from inorganic nanoparticles. In particular, we obtain 113Cd spectra from CdTe-COOH NPs in minutes. The spectra clearly indicate a highly-disordered cadmium rich surface.
      PubDate: 2017-05-23T06:21:24.899764-05:
      DOI: 10.1002/ange.201703758
  • SERS- and Electrochemically-Active 3D Plasmonic Liquid Marble for
           Molecular-Level Spectroelectrochemical Investigation of Microliter
    • Authors: Charlynn Koh; Hiang Kwee Lee, Gia Chuong Phan-Quang, Xuemei Han, Mian Rong Lee, Zhe Yang, Xing Yi Ling
      Abstract: Liquid marbles are emerging microreactors due to their isolated environment and flexibility of materials used. Herein, we demonstrate plasmonic liquid marble (PLM) as the smallest spectroelectrochemical microliter-scale reactor for concurrent spectro- and electrochemical analyses. We exploit PLM's three-dimensional Ag shell as bifunctional surface-enhanced Raman scattering (SERS) platform and working electrode for redox process modulation. The combination of SERS and electrochemistry (EC) capability enable in situ molecular read-out of transient electrochemical species, and elucidation of potential-dependent and multi-step reaction dynamics. The 3D configuration of our PLM-based EC-SERS system exhibits 2-fold and 10-fold superior electrochemical and SERS performance than conventional 2D platforms. The rich molecular-level electrochemical insights and excellent EC-SERS capabilities offered by our 3D spectroelectrochemical system is pertinent in charge transfer processes.
      PubDate: 2017-05-23T05:20:25.326464-05:
      DOI: 10.1002/ange.201704433
  • DNA barcoding meets nanotechnology: development of a smart universal tool
           for food authentication
    • Authors: Paola Valentini; Andrea Galimberti, Valerio Mezzasalma, Fabrizio De Mattia, Maurizio Casiraghi, Massimo Labra, Pier Paolo Pompa
      Abstract: Food trade globalization and the growing demand for selected food varieties have led to the intensification of adulteration cases, especially in the form of species substitution/mixing with cheaper taxa. This phenomenon acquired huge economic impact and sometimes even public health implications. DNA barcoding represents a well-proven molecular tool to assess the authenticity of food items, although its diffusion is hampered by analytical constraints and timeframes that are often prohibitive for food market. To address such issues, we have introduced a new technology, named NanoTracer, which allows for rapid and naked-eye molecular traceability of any food, employing limited instrumentation and cost-effective reagents. Moreover, unlike sequencing, this method allows to identify not only the substitution of a fine ingredient, but also its dilution with cheaper ones.
      PubDate: 2017-05-23T04:20:31.95028-05:0
      DOI: 10.1002/ange.201702120
  • Induced-fit recognition of CCG trinucleotide repeats by a nickel
           chromomycin complex results in large-scale DNA deformation
    • Authors: Wen-Hsuan Tseng; Chung-Ke Chang, Pei-Ching Wu, Nien-Jen Hu, Gene-Hsiang Lee, Ching-Cherng Tzeng, Stephen Neidle, Ming-Hon Hou
      Abstract: Small-molecule compounds targeting trinucleotide repeats in DNA have considerable potential as therapeutic or diagnostic agents against many neurological diseases. NiII(Chro)2 (Chro = chromomycin A3) was found to bind specifically to the minor groove of (CCG)n repeats in duplex DNA, with unique fluorescence features that may serve as a probe for disease detection. Crystallographic studies have revealed that the specificity originates from the large-scale spatial rearrangement of the DNA structure, including extrusion of consecutive bases and backbone distortions, with a sharp bending of the duplex accompanied by conformational changes in the Ni(II) chelate itself. The DNA deformation of CCG repeats upon binding forms a GGCC tetranucleotide tract, which is recognized by NiII(Chro)2. The extruded cytosine and last guanine nucleotides form water-mediated hydrogen bonds which aid in ligand recognition. The recognition can be accounted for by the classic induced-fit paradigm.
      PubDate: 2017-05-23T03:20:29.057905-05:
      DOI: 10.1002/ange.201703989
  • Total Synthesis of (±)-Waihoensene
    • Authors: Hee-Yoon Lee; Hongsoo Lee, Taek Kang
      Abstract: The first total synthesis of waihoensene, a tetracyclic diterpene containing an angular triquinane and a six-membered ring, with four contiguous quaternary carbon atoms, was achieved through the tandem cycloaddition reaction of an allenyl diazo substrate containing a six-membered ring via trimethylenemethane (TMM) diyl intermediate.
      PubDate: 2017-05-23T03:20:27.859486-05:
      DOI: 10.1002/ange.201704492
  • Enantioselective Dearomative Difunctionalization of Indoles by
           Palladium-Catalyzed Heck/Sonogashira Sequence
    • Authors: Ren-Rong Liu; Yong-Gang Wang, Ying-Long Li, Bing-Bing Huang, Ren-Xiao Liang, Yi-Xia Jia
      Abstract: Palladium-catalyzed enantioselective dearomative arylalkynylation of N-substituted indoles, through a Heck/Sonogashira sequence, was established using a new BINOL-based phosphoramidite as the chiral ligand. A wide range of 2,3-disubstituted indolines, bearing vicinal quaternary and tertiary stereocenters, were efficiently constructed in one step with excellent enantioselectivities (up to 97 % ee) and diastereoselectivities (>20:1).Funktionalisierung in Stereo: Eine hoch enantioselektive desaromatisierende Arylalkinylierung von N-substituierten Indolen durch Alkine wird durch eine Kombination aus Palladium und einem chiralen BINOL-Phosphoramidit-Ligand katalysiert. Vielfältige 2,3-disubstituierte Indoline mit benachbarten tertiären und quartären Stereozentren sind hoch enantio- und diastereoselektiv in einer Stufe erhältlich.
      PubDate: 2017-05-23T03:05:52.404518-05:
      DOI: 10.1002/ange.201703833
  • Modified Tetrathiafulvalene as an Organic Conductor for Improving
           Performances of Li−O2 Batteries
    • Authors: Jinqiang Zhang; Bing Sun, Yufei Zhao, Katja Kretschmer, Guoxiu Wang
      Abstract: Large over-potentials owing to the sluggish kinetics of battery reactions have always been the drawbacks of Li−O2 batteries, which lead to short cycle life. Although redox mediators have been intensively investigated to overcome this issue, side-reactions are generally induced by the solvated nature of redox mediators. Herein, we report an alternative method to achieve more efficient utilization of tetrathiafulvalene (TTF) in Li−O2 batteries. By coordinating TTF+ with LiCl during charging, an organic conductor TTF+Clx− precipitate covers Li2O2 to provide an additional electron-transfer pathway on the surface, which can significantly reduce the charge over-potential, improve the energy efficiency of Li−O2 batteries, and eliminate side-reactions between the lithium metal anode and TTF+. When a porous graphene electrode is used, the Li−O2 battery combined with TTF and LiCl shows an outstanding performance and prolonged cycle life.Eine Prise Salz: TTF+Clx− scheidet sich auf der Oberfläche des Entladungsprodukts Li2O2 ab, wenn LiCl beim Laden zu einem Tetrathiafulvalen-haltigen Elektrolyten gegeben wird. Dieser Prozess verringert effizient das Risiko von Nebenreaktionen und verbessert die Zyklenleistung von Li-O2-Batterien.
      PubDate: 2017-05-23T03:05:50.559407-05:
      DOI: 10.1002/ange.201703784
  • Ein ungesättigtes Chinolon-N-oxid von Pseudomonas aeruginosa moduliert
           Wachstum und Virulenz von Staphylococcus aureus
    • Authors: Dávid Szamosvári; Thomas Böttcher
      Abstract: Chemische Wechselwirkungen zwischen konkurrierenden Bakterien sind von großer Bedeutung für den Verlauf von Erkrankungen des Menschen. D. Szamosvári und T. Böttcher berichten in ihrer Zuschrift (
      DOI : 10.1002/ange.201702944) über ein ungesättigtes Chinolon-N-oxid aus Pseudomonas aeruginosa, welches das Wachstum und die Virulenz von Staphylococcus aureus mit beispielloser Effizienz und Aktivität beeinflusst. Diese Ergebnisse werfen ein neues Licht auf die Modulation des Verhaltens konkurrierender Stämme durch einen wichtigen Metaboliten von P. aeruginosa.
      PubDate: 2017-05-23T03:05:47.936719-05:
  • Total Synthesis of Aplydactone by a Conformationally Controlled C−H
    • Authors: Chenguang Liu; Renzhi Chen, Yang Shen, Zhanhao Liang, Yuhui Hua, Yandong Zhang
      Abstract: A concise, protecting-group-free total synthesis of the unusual brominated sesquiterpene aplydactone is described. Our synthesis features a [2+2] photocycloaddition, a Wolff ring contraction, an unusual remote C−H functionalization to establish the highly strained tetracyclic core, and a hydrogen-atom transfer (HAT) reaction to access the bromine-containing stereocenter. A finely tuned conformation of the α-diazoketone precursor is the key for the success of the late-stage transannular C−H insertion to deliver a bridged six-membered ring and a quaternary stereocenter (C6) between two quaternary carbon atoms (C1 and C7).HAT Vorteile: Eine schutzgruppenfreie Totalsynthese von Aplydacton nutzt eine transannulare C-H-Insertion in einem sechsgliedrigen Ring und einen Wasserstoffatomtransfer (HAT). Rechnungen zufolge ist eine genau abgestimmte Konformation entscheidend für den Erfolg der anspruchsvollen C-H-Insertion.
      PubDate: 2017-05-23T03:05:44.761181-05:
      DOI: 10.1002/ange.201703803
  • Total Synthesis of (±)-Corymine
    • Authors: Benxiang Zhang; Xiaoqing Wang, Chao Cheng, Deqian Sun, Chaozhong Li
      Abstract: The first total synthesis of the hexacyclic indole alkaloid (±)-corymine is described. Starting from the readily available N-protected tryptamine, the title compound was achieved in 21 steps in 3.4 % overall yield. Key steps of the synthesis include: a) the addition of a malonate to a 3-bromooxindole to afford 3,3-disubstituted oxindole, b) the formation of a 12-membered cyclic enol ether by intramolecular O-propargylation, immediately followed by propargyl Claisen rearrangement to provide the α-allenyl ketone stereospecifically, c) DMDO oxidation to install a hydroxy group in a highly stereoselective manner, and d) the SmI2-mediated reductive C−O bond cleavage to remove the α-keto carboxyl group.In 21 Stufen ausgehend von N-Nosyl-geschütztem Tryptamin ist (±)-Corymin durch Totalsynthese zugänglich. Dabei erzeugt eine intramolekulare O-Propargylierung einen 12-gliedrigen cyclischen Enolether, und eine stereospezifische Propargyl-Claisen-Umlagerung führt anschließend zu der wichtigen 3-Vinylidenazocan-Zwischenstufe.
      PubDate: 2017-05-23T03:00:26.175315-05:
      DOI: 10.1002/ange.201704086
  • Chain Multiplication of Fatty Acids to Precise Telechelic Polyethylene
    • Authors: Timo Witt; Manuel Häußler, Stefanie Kulpa, Stefan Mecking
      Abstract: Starting from common monounsaturated fatty acids, a strategy is revealed that provides ultra-long aliphatic α,ω-difunctional building blocks by a sequence of two scalable catalytic steps that virtually double the chain length of the starting materials. The central double bond of the α,ω-dicarboxylic fatty acid self-metathesis products is shifted selectively to the statistically much-disfavored α,β-position in a catalytic dynamic isomerizing crystallization approach. “Chain doubling” by a subsequent catalytic olefin metathesis step, which overcomes the low reactivity of this substrates by using waste internal olefins as recyclable co-reagents, yields ultra-long-chain α,ω-difunctional building blocks of a precise chain length, as demonstrated up to a C48 chain. The unique nature of these structures is reflected by unrivaled melting points (Tm=120 °C) of aliphatic polyesters generated from these telechelic monomers, and by their self-assembly to polyethylene-like single crystals.Verdoppelter Einsatz: Einfach ungesättigte Fettsäuren dienen als Ausgangsmaterial für definierte, sehr lange aliphatische α,ω-difunktionalisierte Bausteine. Dies gelingt über eine Sequenz aus zwei skalierbaren katalytischen Umsetzungen: Isomerisierung und „Kettenlängenverdoppelung”.
      PubDate: 2017-05-23T02:50:55.946942-05:
      DOI: 10.1002/ange.201702796
  • Self-Optimization of the Active Site of Molybdenum Disulfide by an
           Irreversible Phase Transition during Photocatalytic Hydrogen Evolution
    • Authors: Longlu Wang; Xia Liu, Jinming Luo, Xidong Duan, John Crittenden, Chengbin Liu, Shuqu Zhang, Yong Pei, Yunxiong Zeng, Xiangfeng Duan
      Abstract: The metallic 1T-MoS2 has attracted considerable attention as an effective catalyst for hydrogen evolution reactions (HERs). However, the fundamental mechanism about the catalytic activity of 1T-MoS2 and the associated phase evolution remain elusive and controversial. Herein, we prepared the most stable 1T-MoS2 by hydrothermal exfoliation of MoS2 nanosheets vertically rooted into rigid one-dimensional TiO2 nanofibers. The 1T-MoS2 can keep highly stable over one year, presenting an ideal model system for investigating the HER catalytic activities as a function of the phase evolution. Both experimental studies and theoretical calculations suggest that 1T phase can be irreversibly transformed into a more active 1T′ phase as true active sites in photocatalytic HERs, resulting in a “catalytic site self-optimization”. Hydrogen atom adsorption is the major driving force for this phase transition.Ein irreversibler Phasenübergang in MoS2 während der photokatalytischen Wasserstoffentwicklung wird durch die Absorption von Wasserstoffatomen angetrieben. Die verzerrte Struktur konnte durch Spannung und Schwefel-Leerstellen stabilisiert werden. Die Verbesserung der katalytischen Aktivität durch den Phasenübergang stellt einen Selbstoptimierungsmechanismus dar.
      PubDate: 2017-05-23T02:46:28.089235-05:
      DOI: 10.1002/ange.201703066
  • Base-Selective Five- versus Six-Membered Ring Annulation in
           Palladium-Catalyzed C–C Coupling Cascade Reactions: New Access to
           Electron-Poor Polycyclic Aromatic Dicarboximides
    • Authors: Sabine Seifert; David Schmidt, Kazutaka Shoyama, Frank Würthner
      Abstract: Palladium-catalyzed base-selective annulation of dibromonaphthalimide to different aryl boronate esters by combined Suzuki–Miyaura cross-coupling and direct C−H arylation afforded a series of new five- and six-membered ring annulated electron-poor polycyclic aromatic hydrocarbons. Cesium carbonate (Cs2CO3) as auxiliary base in these C−C coupling cascade reactions led exclusively to six-membered ring annulation, while the use of organic base diazabicycloundecene (DBU) afforded the corresponding five-membered ring annulated products. This base-dependent selective mode of annulation is attributed to different mechanistic pathways directed by the applied base. The selective annulation was revealed by single crystal X-ray analysis of the respective five- and six-membered ring annulated products. The optical and redox properties of the new polycyclic aromatic dicarboximides were characterized by UV/Vis absorption and fluorescence spectroscopy and cyclic voltammetry.Polycyclen: Elektronenarme polycyclische aromatische Kohlenwasserstoffe werden durch Pd-katalysierte Kupplungsreaktionen erhalten. Abhängig von der Hilfsbase findet dabei eine selektive Fünf- oder Sechsring-Anellierung statt.
      PubDate: 2017-05-23T02:46:03.699184-05:
      DOI: 10.1002/ange.201702889
  • Biocatalytic Friedel–Crafts Acylation and Fries Reaction
    • Authors: Nina G. Schmidt; Tea Pavkov-Keller, Nina Richter, Birgit Wiltschi, Karl Gruber, Wolfgang Kroutil
      Abstract: The Friedel–Crafts acylation is commonly used for the synthesis of aryl ketones, and a biocatalytic version, which may benefit from the chemo- and regioselectivity of enzymes, has not yet been introduced. Described here is a bacterial acyltransferase which can catalyze Friedel–Crafts C-acylation of phenolic substrates in buffer without the need of CoA-activated reagents. Conversions reach up to>99 %, and various C- or O-acyl donors, such as DAPG or isopropenyl acetate, are accepted by this enzyme. Furthermore the enzyme enables a Fries-like rearrangement reaction of resorcinol derivatives. These findings open an avenue for the development of alternative and selective C−C bond formation methods.Die biokatalytische Acylierung von Resorcinen durch eine Acyltransferase liefert die C-acylierten Produkte. Diese biochemische Friedel-Crafts-Acylierung nutzt einfache aktivierte Ester, z. B. Isopropenylacetat, als Acylquellen. Das Enzym ermöglicht außerdem eine Fries-artige Umlagerung.
      PubDate: 2017-05-23T02:42:46.524352-05:
      DOI: 10.1002/ange.201703270
  • Die Kohlenmonoxid-Dehydrogenase reduziert Cyanat zu Cyanid
    • Authors: Alexandre Ciaccafava; Daria Tombolelli, Lilith Domnik, Jae-Hun Jeoung, Holger Dobbek, Maria-Andrea Mroginski, Ingo Zebger, Peter Hildebrandt
      Abstract: Die Kohlenmonoxid-Dehydrogenase (CODH) hat eine hohe Umweltrelevanz aufgrund ihrer Fähigkeit, CO2 biokatalytisch zu reduzieren. Trotz intensiver Bemühungen in den vergangenen Jahrzehnten ist der katalytische Mechanismus der CODH noch nicht vollständig aufgeklärt. In einer spektroskopischen und theoretischen Studie präsentieren wir nun erste Beweise für eine Reduktion von Cyanat (NCO−) zu Cyanid (CN−) am C-Cluster. Das Addukt bleibt am katalytischen Zentrum gebunden und bildet den so genannten CN−-inhibierten Zustand. Interessanterweise findet diese Umwandlung nicht in Kristallen von CODHIICh statt, was anhand des Fehlens der entsprechenden CN-Streckschwingungsbanden belegt werden kann. Die Transformation von NCO−, eines Inhibitors des Cred2-Zustands der CODH, könnte den CO2-Umsatz nachahmen und auf diese Weise neue Perspektiven für die Aufklärung des genauen katalytischen Mechanismus der CODH bieten.O-Verlust: Der C-Cluster der Kohlenmonoxid-Dehydrogenase katalysiert die Reduktion von Cyanat zu Cyanid. Das Addukt bleibt am katalytischen Zentrum in Form des so genannten Cyanid-inhibierten Zustands gebunden. So kann die CO2-Transformation nachgestellt werden, und es eröffnen sich neue Perspektiven hinsichtlich der Aufklärung des Katalysemechanismus.
      PubDate: 2017-05-23T02:42:41.442348-05:
      DOI: 10.1002/ange.201703225
  • Rapid Production of High-Purity Hydrogen Fuel through Microwave-Promoted
           Deep Catalytic Dehydrogenation of Liquid Alkanes with Abundant Metals
    • Authors: Xiangyu Jie; Sergio Gonzalez-Cortes, Tiancun Xiao, Jiale Wang, Benzhen Yao, Daniel R. Slocombe, Hamid A. Al-Megren, Jonathan R. Dilworth, John M. Thomas, Peter P. Edwards
      Abstract: Hydrogen as an energy carrier promises a sustainable energy revolution. However, one of the greatest challenges for any future hydrogen economy is the necessity for large scale hydrogen production not involving concurrent CO2 production. The high intrinsic hydrogen content of liquid-range alkane hydrocarbons (including diesel) offers a potential route to CO2-free hydrogen production through their catalytic deep dehydrogenation. We report here a means of rapidly liberating high-purity hydrogen by microwave-promoted catalytic dehydrogenation of liquid alkanes using Fe and Ni particles supported on silicon carbide. A H2 production selectivity from all evolved gases of some 98 %, is achieved with less than a fraction of a percent of adventitious CO and CO2. The major co-product is solid, elemental carbon.Stop CO2! Die mikrowellenunterstützte katalytische tiefe Dehydrierung von flüssigen Alkenen mit Eisen- und Nickel-Katalysatoren liefert CO2-freien Wasserstoff. Die Ergebnisse zeigen einen Weg für die Dekarbonisierung von fossilen Brennstoffen auf.
      PubDate: 2017-05-23T02:36:12.161577-05:
      DOI: 10.1002/ange.201703489
  • Facile Access to NaOC≡As and Its Use as an Arsenic Source to Form
           Germylidenylarsinidene Complexes
    • Authors: Shenglai Yao; Yves Grossheim, Arseni Kostenko, Ernesto Ballestero-Martínez, Stefan Schutte, Mark Bispinghoff, Hansjörg Grützmacher, Matthias Driess
      Abstract: A facile, one-pot synthesis of [Na(OC≡As)(dioxane)x] (x=2.3–3.3) in 78 % yield is reported through the reaction of arsine gas with dimethylcarbonate in the presence of NaOtBu and 1,4-dioxane. It has been employed for the synthesis of the first arsaketenyl-functionalized germylene [LGeAsCO] (2, L=CH[CMeN(Dipp)]2; Dipp=2,6-iPr2C6H3) from the reaction with LGeCl (1). Upon exposure to ambient light, 2 undergoes CO elimination to form the 1,3-digerma-2,4-diarsacyclobutadiene [L2Ge2As2] (3), which contains a symmetric Ge2As2 ring with ylide-like Ge=As bonds. Remarkably, the CO ligand located at the arsenic center of 2 can be exchanged with PPh3 or an N-heterocyclic carbene iPrNHC donor (iPrNHC=1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene) to afford the novel germylidenylarsinidene complexes [LGe-AsPPh3] (4) and [LGe-As(iPrNHC)] (5), respectively, demonstrating transition-metal-like ligand substitution at the arsinidene-like As atom. The formation of 2–5 and their electronic structures have been studied by DFT calculations.Germanium trifft auf Arsen: Ausgehend von Arsin führt eine Eintopfsynthese bequem zu Na(OC≡As), das mit einem Chloro(β-diketiminato)germylen unter Bildung des Arsaketenyl-funktionalisierten Germylens 1 reagiert. Diese Verbindung spaltet CO ab und geht über das intermediäre Arsagermin 2 in das isolierbare 1,3-Digerma-2,4-diarsacyclobutadien 3 über, das sich durch Ylid-artige Ge=As-Bindungen auszeichnet.
      PubDate: 2017-05-23T02:36:06.992593-05:
      DOI: 10.1002/ange.201703731
  • Construction of Chiral Tetrahydro-β-Carbolines: Asymmetric
           Pictet–Spengler Reaction of Indolyl Dihydropyridines
    • Authors: Shou-Guo Wang; Zi-Lei Xia, Ren-Qi Xu, Xi-Jia Liu, Chao Zheng, Shu-Li You
      Abstract: A highly efficient synthesis of the enantioenriched tetrahydro-β-carbolines was developed by using a chiral phosphoric acid catalyzed Pictet–Spengler reaction of indolyl dihydropyridines. The reaction proceeds under mild reaction conditions to afford the desired chiral tetrahydro-β-carbolines in good to excellent yields (up to 96 %) and high enantioselectivities (up to 99 % ee). With this method, a formal synthesis of tangutorine and a total synthesis of deplancheine were achieved in a highly efficient manner.Lange bekannt, aber nicht veraltet: Die Titelreaktion mit einem chiralen Phosphorsäurederivat als Katalysator liefert unter milden Bedingungen Tetrahydro-β-carboline in guten bis hervorragenden Ausbeuten und mit hohen Enantioselektivitäten. Die Methode wurde in einer formalen Synthese von Tangutorin und in einer Totalsynthese von Deplanchein eingesetzt.
      PubDate: 2017-05-23T02:35:49.029149-05:
      DOI: 10.1002/ange.201703178
  • Selektive, narzisstische Selbstsortierung bei der Synthese von
           metallorganischen Strukturen mit Poly-NHC-Liganden
    • Authors: Narayan Sinha; Tristan T. Y. Tan, Eduardo Peris, F. Ekkehardt Hahn
      Abstract: Narzisstische Selbstsortierung wurde bei der Eintopfsynthese von drei metallorganischen molekularen Zylindern des Typs [M3{L-(NHC)3}2](PF6)3 (M=Ag+, Au+; L=Benzol, Triphenylamin oder 1,3,5-Triphenylbenzol) ausgehend von L-(NHC)3 und Silber(I)- oder Gold(I)-Ionen beobachtet. Die molekularen Zylinder enthalten stets nur einen Typ der Tris-NHC-Liganden, ohne dass Heteroligand-Verbindungen zu detektieren sind. Die Transmetallierung der Tris-NHC-Liganden von Ag+ auf Au+ in einer Eintopfreaktion verläuft unter Erhaltung der supramolekularen Strukturen. Selbstsortierung wurde auch bei der Eintopfreaktion von Benzol-verbrückten Tris- und Tetrakis-NHC-Liganden mit Ag2O beobachtet. Die vorliegende Studie überträgt erstmals narzisstische Selbstsortierung von Metall-Ligand-Wechselwirkungen in Werner-Komplexen auf metallorganische Derivate.Perfekte Sortierung! Narzisstische Selbstsortierung wurde bei der Eintopfreaktion von drei unterschiedlichen trigonalen Trisimidazolium-Salzen mit Ag2O beobachtet. Die Reaktion lieferte drei zylinderartige Dreikernkomplexe, die jeweils zwei identische Tris-NHC-Liganden enthalten. Selbstsortierung wurde auch beim nachfolgenden Metallionenaustausch der Tris-NHC-Liganden beobachtet, der die drei Silber(I)-Komplexen in drei Gold(I)-Komplexe überführt.
      PubDate: 2017-05-23T02:20:30.664881-05:
      DOI: 10.1002/ange.201702637
  • A Membrane-Free Neutral pH Formate Fuel Cell Enabled by a Selective Nickel
           Sulfide Oxygen Reduction Catalyst
    • Authors: Bing Yan; Nolan M. Concannon, Jarrod D. Milshtein, Fikile R. Brushett, Yogesh Surendranath
      Abstract: Polymer electrolyte membranes employed in contemporary fuel cells severely limit device design and restrict catalyst choice, but are essential for preventing short-circuiting reactions at unselective anode and cathode catalysts. Herein, we report that nickel sulfide Ni3S2 is a highly selective catalyst for the oxygen reduction reaction in the presence of 1.0 m formate. We combine this selective cathode with a carbon-supported palladium (Pd/C) anode to establish a membrane-free, room-temperature formate fuel cell that operates under benign neutral pH conditions. Proof-of-concept cells display open circuit voltages of approximately 0.7 V and peak power values greater than 1 mW cm−2, significantly outperforming the identical device employing an unselective platinum (Pt) cathode. The work establishes the power of selective catalysis to enable versatile membrane-free fuel cells.Ein hochselektiver Katalysator: Nickelsulfid (Ni3S2) katalysiert selektiv die Sauerstoffreduktion (ORR) in einer 1.0 m Formiatlösung, was zu einer bei neutralem pH-Wert operierenden, membranlosen Formiat-Brennstoffzelle führt. Die Ni3S2-Pd-Brennstoffzelle erreicht eine höhere Leerlaufspannung und Leistungsdichte als eine Pt-Pd-Konfiguration.
      PubDate: 2017-05-23T02:20:29.053875-05:
      DOI: 10.1002/ange.201702578
  • Beispiellose Verstärkung von Kohlenstoffsignalen in der
    • Authors: György Pintér; Harald Schwalbe
      Abstract: Grenzen durchbrechen: Eine 1000-fache Verstärkung von 13C-Signalen in der Flüssigphasen-NMR-Spektroskopie wurde durch dynamische Kernpolarisation (DNP) bei hohem Magnetfeld und bei Raumtemperatur erzielt. Die früher vorhergesagte Obergrenze für Hochfeld-DNP in flüssiger Phase wurde damit deutlich übertroffen.
      PubDate: 2017-05-23T02:20:23.484366-05:
      DOI: 10.1002/ange.201702766
  • Unexpected Direct Synthesis of N-Vinyl Amides through Vinyl
           Azide–Enolate [3+2] Cycloaddition
    • Authors: Hans Choi; Harry J. Shirley, Paul A. Hume, Margaret A. Brimble, Daniel P. Furkert
      Abstract: The unexpected synthesis of industrially important N-vinyl amides directly from aldehydes and α,β-unsaturated N-vinyl amides from esters is reported. This reaction probably proceeds through an initial [3+2] azide–enolate cycloaddition involving a vinyl azide generated in situ. A survey of the reaction scope and preliminary mechanistic findings supported by quantum computational analysis are reported, with implications for the future development of atom-efficient amide synthesis. Intriguingly, this study suggests that (cautious) reevaluation of azidoethene as a synthetic reagent may be warranted.Einen zweiten Blick wert: Industriell wichtige N-Vinylamide wurden direkt aus Aldehyden/Estern und 1-Azido-2-iodethan synthetisiert. Quantenchemische Rechnungen stützen den vorgeschlagenen Mechanismus einer [3+2]-Cycloaddition des aus dem Aldehyd oder Ester gebildeten Enolats mit einem in situ erzeugten Vinylazid (siehe Schema). Eine Neubewertung von Azidoethen als atomeffizientes Synthesereagens scheint lohnend.
      PubDate: 2017-05-23T02:15:39.128082-05:
      DOI: 10.1002/ange.201702727
  • Morphologische Kontrolle von heteroleptischen cis- und
    • Authors: Witold M. Bloch; Julian J. Holstein, Wolf Hiller, Guido H. Clever
      Abstract: Die kontrollierte integrative Selbstsortierung metallosupramolekularer Strukturen eröffnet Möglichkeiten, mehr Komplexität und Funktion in eine einzelne selbstassemblierte Struktur einzuführen. Wir klären hier die Beziehung zwischen der Geometrie von drei Ligandkomponenten und der Morphologie von drei selbstsortierten heteroleptischen [Pd2L2L′2]4+-Käfigen auf. So ergibt die Pd-vermittelte Assemblierung von zwei doppelt-einzähnigen Pyridyl-Liganden mit einem nativen Bisswinkel von 75° und 120° einen cis-[Pd2L2L′2]4+-Käfig, wohingegen die gleiche Reaktion von zwei Liganden mit Bisswinkeln von 75° und 60° den letzteren Liganden in eine anti-Konformation zwingt. Dies führt zu einem heteroleptischen trans-[Pd2(anti-L)2L′2]4+-Käfig mit der Topologie einer “zweifach verbrückten Acht”. Jede der heteroleptischen Strukturen ist durch eine Käfig-zu-Käfig-Umwandlung ihrer homoleptischen Vorstufen zugänglich. Die Morphologie der [Pd2L2L′2]-Käfige kann durch selektiven Ligandenaustausch gezielt gesteuert werden.Eine doppelt verbrückte Acht: Die integrative Selbstsortierung geometrisch unterschiedlicher Liganden und Käfige wird zugunsten der Bildung neuartiger [Pd2L2L′2]-Strukturen gesteuert. In einem Beispiel zeigt die Röntgenstrukturanalyse die Topologie einer „doppelt verbrückten Acht” – ein für metallosupramolekulare Strukturen bislang unbekanntes Motiv. Ferner wurde eine morphologische Kontrolle über die Struktur der Käfige durch hoch selektive Ligandaustauschreaktionen erreicht.
      PubDate: 2017-05-23T02:15:29.444268-05:
      DOI: 10.1002/ange.201702573
  • Mild, Redox-Neutral Formylation of Aryl Chlorides through the
           Photocatalytic Generation of Chlorine Radicals
    • Authors: Matthew K. Nielsen; Benjamin J. Shields, Junyi Liu, Michael J. Williams, Michael J. Zacuto, Abigail G. Doyle
      Abstract: We report a redox-neutral formylation of aryl chlorides that proceeds through selective 2-functionalization of 1,3-dioxolane through nickel and photoredox catalysis. This scalable benchtop approach provides a distinct advantage over traditional reductive carbonylation in that no carbon monoxide, pressurized gas, or stoichiometric reductant is employed. The mild conditions give unprecedented scope from abundant and complex aryl chloride starting materials.Bewusst mild: Aromatische Aldehyde entstehen aus leicht verfügbaren Arylchloriden durch Nickel-photokatalysierte C-H-Funktionalisierung in preiswertem 1,3-Dioxolan als Lösungsmittel. Milde Reaktionsbedingungen und der Verzicht auf Kohlenmonoxid-Überdruck oder stöchiometrischen Einsatz von Reduktionsmitteln bedingen eine gute Verträglichkeit mit funktionellen Gruppen und eine große Substratbreite.
      PubDate: 2017-05-23T02:05:49.263032-05:
      DOI: 10.1002/ange.201702079
  • Inhibierung des humanen B12-verarbeitenden Enzyms CblC durch
           Antivitamine B12 – Kristallstruktur des inaktiven ternären Komplexes
           mit dem Kosubstrat Glutathion
    • Authors: Markus Ruetz; Aranganathan Shanmuganathan, Carmen Gherasim, Agnes Karasik, Robert Salchner, Christoph Kieninger, Klaus Wurst, Ruma Banerjee, Markos Koutmos, Bernhard Kräutler
      Abstract: Antivitamine B12 gewinnen als robuste B12-Dummys zunehmend biomedizinisches Interesse. Das potenzielle Antivitamin B12 2,4-Difluorphenylethinylcobalamin (F2PhEtyCbl) wurde hergestellt, und seine 3D-Struktur in Lösung und im Kristall wurde untersucht. Das chemisch inerte F2PhEtyCbl zeigte sich gegen Thermolyse seiner Co-C-Bindung bei 100 °C resistent, war stabil bei Bestrahlung mit (hellem) Tageslicht und blieb auch bei längerer Aufbewahrung in wässriger Lösung bei Raumtemperatur intakt. Es wurde vom humanen B12-verarbeitenden Enzym CblC in Gegenwart des Kosubstrats Glutathion (GSH) mit hoher Affinität (KD=130 nm) gebunden. F2PhEtyCbl stabilisierte den ternären Komplex von CblC mit GSH und widerstand der Verarbeitung. Die Kristallstruktur dieses Komplexes lieferte erste Einblicke in die Wechselwirkungen eines Antivitamins B12 mit CblC sowie in die Anordnung von GSH und Base-off-Cobalamin im aktiven Zentrum dieses blockierten Enzyms.Antivitamin in Aktion: Antivitamine B12 sind vom Vitamin abstammende „B12-Dummys”. Ein neues, robustes Antivitamin B12 wurde bei der Inhibierung von CblC biochemisch analysiert, dem humanen B12-verarbeitenden Schlüsselenzym. Die Kristallstruktur des inaktivierten Enzym-Komplexes ermöglichte detaillierte Einblicke in das mit Cobalamin und dem Kosubstrat Glutathion vollbeladene CblC.
      PubDate: 2017-05-23T02:05:45.644189-05:
      DOI: 10.1002/ange.201701583
  • A Structurally Characterized Fluoroalkyne
    • Authors: Lewis M. Hall; David P. Tew, Natalie E. Pridmore, Adrian C. Whitwood, Jason M. Lynam, John M. Slattery
      Abstract: The facile synthesis of a stable and isolable compound with a fluoroalkynyl group, M−C≡CF, is reported. Reaction of [Ru(C≡CH)(η5-C5Me5)(dppe)] with an electrophilic fluorinating agent (NFSI) results in the formation of the fluorovinylidene complex [Ru(=C=CHF)(η5-C5Me5)(dppe)][N(SO2Ph)2]. Subsequent deprotonation with LiN(SiMe3)2 affords the fluoroalkynyl complex [Ru(C≡CF)(η5-C5Me5)(dppe)]. In marked contrast to the rare and highly reactive examples of fluoroalkynes that have been reported previously, this compound can be readily isolated and structurally characterized. This has allowed the structure and bonding in the CCF motif to be explored. Further electrophilic fluorination of this species yields the difluorovinylidene complex [Ru(C=CF2)(η5-C5Me5)(dppe)][N(SO2Ph)2].Schickes Fluor: Im Unterschied zu anderen fluorierten Alkinen ist strukturell charakterisiertes {M−C≡CF} lange stabil. Strukturanalyse, Spektroskopie und Rechnungen offenbaren eine beträchtliche kinetische Stabilisierung durch einen Halbsandwich-Ruthenium-Substituenten. Weitere Fluorierung bietet einen bequemen Zugang zu einem seltenen Beispiel eines Difluorvinylidenkomplexes.
      PubDate: 2017-05-23T02:05:40.840108-05:
      DOI: 10.1002/ange.201702401
  • Direct Nucleophilic Substitution Reaction of Cage B−H Bonds by Grignard
           Reagents: A Route to Regioselective B4-Alkylation of o-Carboranes
    • Authors: Cen Tang; Jiji Zhang, Zuowei Xie
      Abstract: Direct nucleophilic substitution reaction of cage B−H bonds of o-carboranes by Grignard reagents in the absence of any transition metals has been achieved for the first time, and leads to the regioselective synthesis of a series of 4-alkyl-1,2-diaryl-o-carboranes in very high yields. The presence of two electron-withdrawing aryl groups on the cage carbon atoms is crucial to realizing the reaction. The regioselectivity is controlled by both electronic and steric factors. This work represents a new strategy for the development of methods for carborane functionalization.Auch ohne Übergangsmetall liefert die Titelreaktion ihre Produkte, 4-Alkyl-1,2-diaryl-o-carborane, in hohen Ausbeuten. Zwei elektronenziehende Arylgruppen an den beiden Kohlenstoffatomen des Käfigs sind entscheidend für das Gelingen der Reaktion, deren Regioselektivität sowohl durch elektronische als auch sterische Faktoren gesteuert wird.
      PubDate: 2017-05-23T02:05:36.921473-05:
      DOI: 10.1002/ange.201702347
  • Self-Assembly of Conjugated Metallopolymers with Tunable Length and
           Controlled Regiochemistry
    • Authors: Jake L. Greenfield; Felix J. Rizzuto, Ieva Goldberga, Jonathan R. Nitschke
      Abstract: Self-assembled materials can be designed to express useful optoelectronic properties; however, achieving structural control is a necessary precondition for the optimization of desired properties. Here we report a simple, metal-templated polymerization process that generates helical metallopolymer strands over 75 repeat units long (28 kDa) from a single bifunctional monomer and CuI. The resulting polymer consists of a double helix of two identical conjugated organic strands enclosing a central column of metal ions. The length of this metallopolymer can be controlled by adding monofunctional subcomponents to end-cap the conjugated ligands. The use of ditopic and bulky monotopic subcomponents, respectively, allows a head-to-head or head-to-tail double helix to be generated. Spectroscopic measurements of different polymer lengths demonstrate how control over polymer length leads to control over the electronic and luminescent properties of the resulting material, thereby enabling tunable white-light emission.Verdrilltes „Kupferkabel”: Die Selbstorganisation von difunktionellen Subkomponenten um einen CuI-Kern ergibt ein langes, doppelhelikales Metallopolymer. Endgruppen wurden genutzt, um die Regiochemie der beiden Stränge innerhalb des Polymers einzustellen. Über die Stöchiometrie von Monomer und Endgruppe lässt sich die Polymerlänge ändern, was eine abstimmbare Weißlichtemission ermöglicht.
      PubDate: 2017-05-23T02:01:27.939771-05:
      DOI: 10.1002/ange.201702320
  • Dotierte Halbleiter-Nanokristalle: Lumineszenz, plasmonische und
           magnetische Eigenschaften
    • Authors: Narayan Pradhan; Samrat Das Adhikari, Angshuman Nag, D. D. Sarma
      Abstract: Der Einbau bereits weniger Fremdatome in Halbleiter-Nanokristalle kann zu einer drastischen Änderung der Eigenschaften oder gar dem Auftreten gänzlich neuer Eigenschaften führen. Zum Beispiel haben Mid-Gap-Zustände, die durch Dotierung generiert werden, einen enormen Einfluss auf die photokatalytische Aktivität und oberflächenkontrollierte Redoxreaktionen. Fremdatome/Dotanden erzeugen neue Emissionszentren, ermöglichen thermometrisches optisches Schaltverhalten, erhöhen die Lebensdauer der angeregten Zustände von FRET-Donoren und erzeugen niederenergetische Absorptionen induziert durch lokalisierte Oberflächenplasmonenresonanzen. Dotierte Nanokristalle werden seit kurzem außerdem als Materialien für die Umwandlung von Sonnenenergie erforscht. Ferner werden auch die elektrischen und magnetischen Eigenschaften des Wirtmaterials durch Dotierung stark verändert. Diese vorteilhaften fremdatominduzierten Modifikationen machen dotierte Nanokristalle mit passenden Dotand-Wirt-Paaren zu geeigneten Kandidaten für die gezielte Herstellung von Materialien mit bestimmten Eigenschaften für eine breite Auswahl von Technologien. Die Zusammenhänge zwischen den Eigenschaften von Halbleiter-Nanokristallen und ihrer Dotierung sind Gegenstand dieses Aufsatzes.„Doping”-Kontrolle: Dotierte Halbleiter-Nanokristalle kombinieren den Einfluss der Dotierung mit dem Quanten-Confinement-Effekt des Nanokristalls. Dieser Aufsatz diskutiert jüngste Entwicklungen bei der Synthese, Lumineszenz, Photokatalyse, Photovoltaik, Plasmonik sowie den magnetischen und magneto-optischen Eigenschaften dotierter Halbleiter-Nanokristalle.
      PubDate: 2017-05-23T01:50:37.471459-05:
      DOI: 10.1002/ange.201611526
  • Single-Atom Electrocatalysts
    • Authors: Chengzhou Zhu; Shaofang Fu, Qiurong Shi, Dan Du, Yuehe Lin
      Abstract: Recent years have witnessed the increasing production of the sustainable and renewable energy. The limitations of electrochemical performances are closely associated with the search for highly efficient electrocatalysts with more rational control of size, shape, composition and structure. Specifically, the rapidly emerging studies on single-atom catalysts (SACs) have sparked new interests in electrocatalysis because of the unique properties such as high catalytic activity, selectivity and 100% atom utilization. In this review, we introduce the innovative synthesis and advanced characterizations of SACs and primarily focus on their electrochemical applications in oxygen reduction/evolution reaction, hydrogen evolution reaction, hydrocarbon conversion reactions for fuel cells (methanol, ethanol and formic acid electrooxidation) and other related fields. Significantly, this unique single atom-depended electrocatalytic performance together with the underlying mechanism will also be discussed. Furthermore, future research directions and challenges are proposed to further realize the ultimate goal of tailoring single-atoms for electrochemical applications.
      PubDate: 2017-05-23T01:20:43.808715-05:
      DOI: 10.1002/ange.201703864
  • From Extended-Nano Fluidics to an Autonomous Solar Light Driven Micro Fuel
           Cell Device
    • Authors: Yuriy Pihosh; Jin Uemura, Ivan Turkevych, Kazuma Mawatari, Yutaka Kazoe, Adelina Smirnova, Takehiko Kitamori
      Abstract: Autonomous micro/nano mechanical, chemical and biomedical sensors require persistent power sources scaled to their size. Realization of autonomous micro-power sources is a challenging task, as it requires combination of wireless energy supply, conversion, storage and delivery to the sensor. In this work, we realized solar light driven power source that consists of a micro fuel cell (μFC) and a photocatalytic micro fuel generator (μFG) integrated on a single microfluidic chip. The μFG produces hydrogen by photocatalytic water splitting under solar light. The hydrogen is then consumed by the μFC to generate electricity. Importantly, the byproduct water returns back to the photocatalytic μFG via recirculation loop without losses. Functionality of both devices relies on novel phenomena in extended-nano fluidic channels that ensure ultra-fast proton transport. As a proof of concept, we demonstrate that μFG/μFC source achieves remarkable energy density of ~17.2 mWh cm-2 at room temperature.
      PubDate: 2017-05-23T00:20:35.787593-05:
      DOI: 10.1002/ange.201703227
  • A Tunable Ionic Diode based on Biomimetic Structure-Tailorable Nanochannel
    • Authors: Kai Xiao; Lu Chen, Zhen Zhang, Ganhua Xie, Pei Li, Xiang-Yu Kong, Liping Wen, Lei Jiang
      Abstract: In this work, we reported a tunable ionic diode based on biomimetic structure-tailorable nanochannels, with the precise ions transport characteristics from ohmic behaviour to bidirectional rectification as well as the gating properties. The forward/reverse directions of the ionic diode and the degree of rectification can be well regulated by combining the patterned surface charge and the sophisticated structure. This system creates an ideal platform for precise transportation of ions and molecules, and anticipates to have potential applications in analytical sciences.
      PubDate: 2017-05-22T22:20:24.735516-05:
      DOI: 10.1002/ange.201704137
  • Rhodium-Catalyzed Enantioselective Radical Addition of CX4 Reagents to
    • Authors: Joseph M. Ready; Bo Chen, Cheng Fang, Peng Liu
      Abstract: We describe an enantioselective addition of Br-CX3 (X = Cl or Br) to terminal olefins that introduces a trihalomethyl group and generates optically active secondary bromides. Computational and experimental evidence supports an asymmetric atom transfer radical addition (ATRA) mechanism in which the stereodetermining step involves outer-sphere bromine abstraction from a (bisphosphine)Rh(II)BrCl complex by a benzylic radical intermediate. Beyond the synthetic utility, this mechanism appears unprecedented in asymmetric catalysis.
      PubDate: 2017-05-22T10:21:53.917358-05:
      DOI: 10.1002/ange.201704074
  • Eight-Electron Silver and Mixed Gold/Silver Nanoclusters Stabilized by
           Se-Donor Ligands
    • Authors: Wan-Ting Chang; Po-Yi Lee, Jian-Hong Liao, Samia Kahlal, Jean-Yves Saillard, Chen-Wei Liu
      Abstract: The first atomically and structurally precise silver-nanoclusters stabilized by Se-donor ligands, [Ag20{Se2P(OiPr)2}12] (3) and [Ag21{Se2P(OEt)2}12]+(4), have been isolated by ligand replacement reaction of [Ag20{S2P(OiPr)2}12] (1) and [Ag21{S2P(OiPr)2}12]+ (2), respectively. Further, doping reactions of 4 with Au(PPh3)Cl resulted in the formation of [AuAg20{Se2P(OEt)2}12]+, (5). Structures of 3, 4 and 5 were determined by single crystal X-ray diffraction. The anatomy of cluster 3 with an Ag20 core having C3 symmetry is very similar to that of its dithiophosphate analogue 1. Clusters 4 and 5 exhibit an Ag21 and Au@Ag20 core of Oh symmetry composed of eight silver capping atoms in a cubic arrangement and encapsulating an Ag13 and Au@Ag12 centered icosahedron, respectively. Both ligand exchange and heteroatom doping result in significant changes in optical and emissive properties for chalcogen-passivated silver nanoparticles, which have been theoretically proved as 8-electron superatoms.
      PubDate: 2017-05-22T09:20:40.493355-05:
      DOI: 10.1002/ange.201704800
  • Phenotypic Identification of a Novel Autophagy Inhibitor Chemotype
           Targeting Lipid Kinase VPS34
    • Authors: Herbert Waldmann; Lucas Robke, Luca Laraia, Marjorie A. Carnero Corrales, Georgios Konstantinidis, Makoto Muroi, André Richters, Michael Winzker, Tobias Engbring, Stefano Tomassi, Nobumoto Watanabe, Hiroyuki Osada, Daniel Rauh, Yaowen Wu, Julian Engel
      Abstract: Autophagy is a critical regulator of cellular homeostasis and metabolism. Interference with this process is considered a new approach for the treatment of disease, in particular cancer and neurological disorders. Therefore, novel small molecule autophagy modulators are in high demand. We describe the discovery of autophinib, a potent autophagy inhibitor with a novel chemotype. Autophinib was identified by means of a phenotypic assay monitoring formation of autophagy-induced puncta indicating accumulation of lipidated cytosolic protein LC3 on the autophagosomal membrane. Target identification and validation revealed that autophinib inhibits autophagy induced by starvation or Rapamycin by targeting the lipid kinase VPS34.
      PubDate: 2017-05-22T09:20:33.730958-05:
      DOI: 10.1002/ange.201703738
  • Catalytic Electrophilic Alkylation of p-Quinones via a Redox Chain
    • Authors: Xiao-Long Xu; Zhi Li
      Abstract: Allylation and benzylation of p-quinones is achieved by an unusual redox chain reaction. Mechanistic studies suggest that the trace existence of hydroquinone initiates a redox chain reaction that consists of a Lewis acid-catalyzed Friedel-Crafts alkylation and a subsequent redox equilibrium that regenerates hydroquinone. The electrophiles could be various allylic and benzylic esters. Addition of Hantzsch ester as initiator improves the efficiency of the reaction.
      PubDate: 2017-05-22T08:20:28.873419-05:
      DOI: 10.1002/ange.201702885
  • A Modular Flow Design for the meta-Selective C−H Arylation of
    • Authors: Hannes P. L. Gemoets; Gabriele Laudadio, Kirsten Verstraete, Volker Hessel, Timothy Noël
      Abstract: Described herein is an effective and practical modular flow design for the meta-selective C−H arylation of anilines. The design consists of four continuous-flow modules (i.e., diaryliodonium salt synthesis, meta-selective C−H arylation, inline copper extraction, and aniline deprotection) which can be operated either individually or consecutively to provide direct access to meta-arylated anilines. With a total residence time of 1 hour, the desired product could be obtained in high yield and excellent purity without the need for column chromatography, and the residual copper content meets the standards for parenterally administered pharmaceutical substances.meta-Arylierte Aniline sind wichtige Bestandteile zahlreicher wertvoller Chemikalien. Ein Flussverfahren mit vier Schlüsselschritten führt zu diesen Verbindungen: Synthese eines Diaryliodoniumsalzes, meta-selektive C-H-Arylierung sowie Entfernen des Kupferkatalysators und Abspaltung der Schutzgruppe. Jedes Modul für sich hat großes Potenzial, und ihre Kombination liefert die Produkte in kurzer Zeit mit guter Reinheit.
      PubDate: 2017-05-22T08:00:51.910034-05:
      DOI: 10.1002/ange.201703369
  • Discovery of EGF Receptor Inhibitors that are Selective for the
           d746-750/T790M/C797S Mutant through Structure-Based de Novo Design
    • Authors: Hwangseo Park; Hoi-Yun Jung, Shinmee Mah, Sungwoo Hong
      Abstract: Next-generation epidermal growth factor receptor (EGFR) inhibitors against the d746-750/T790M/C797S mutation were discovered through two-track virtual screening and de novo design. A number of nanomolar inhibitors were identified using 2-aryl-4-aminoquinazoline as the molecular core and the modified binding energy function involving a proper dehydration term, which provides important structural insight into the key principles for high inhibitory activities against the d746-750/T790M/C797S mutant. Furthermore, some of these EGFR inhibitors showed a greater than 1000-fold selectivity for the d746-750/T790M/C797S mutant over the wild type, as well as nanomolar activity against the mutant.Selektiv gegen die Mutante: Inhibitoren gegen die d746-750/T790M/C797S-Mutation des epidermalen Wachstumsfaktorrezeptors (EGFR) wurden mithilfe von virtuellem Screening und De-novo-Design entdeckt. Einige nanomolar wirksame 2-Aryl-4-aminochinazoline waren um den Faktor>1000 selektiver für die Tripelmutante im Vergleich zum Wildtyp. Die hoch aktive Inhibition beruht auf verstärkten Wechselwirkungen an der ATP-Bindestelle.
      PubDate: 2017-05-22T08:00:49.034577-05:
      DOI: 10.1002/ange.201703389
  • Catalytic Asymmetric [3+1]-Cycloaddition Reaction of Ylides with
           Electrophilic Metallo-enolcarbene Intermediates
    • Authors: Yongming Deng; Lynée A. Massey, Peter Y. Zavalij, Michael P. Doyle
      Abstract: The first asymmetric [3+1]-cycloaddition was successfully achieved by copper(I) triflate/double-sidearmed bisoxazoline complex catalyzed reactions of β-triisopropylsilyl-substituted enoldiazo compounds with sulfur ylides. This methodology delivered a series of chiral cyclobutenes in good yields with high enantio- and diastereoselectivities (up to 99 % ee, and>20:1 d.r.). Additionally, the [3+1]-cycloaddition of catalytically generated metallo-enolcarbenes was successfully extended to reaction with a stable benzylidene dichlororuthenium complex.Drei plus eins: β-Triisopropylsilyl-substituierte Enoldiazoverbindungen reagieren mit Schwefel-Yliden in Gegenwart eines Komplexes aus Kupfer(I)-triflate und einem Bisoxazolin mit zwei Seitenarmen zu Cyclobutenen (siehe Schema). Eine asymmetrische Variante liefert die Produkte hoch enantio- und diastereoselektiv sowie in guten Ausbeuten.
      PubDate: 2017-05-22T08:00:36.149892-05:
      DOI: 10.1002/ange.201704069
  • Redox-Sensitive Stomatocyte Nanomotors: Destruction and Drug Release in
           the Presence of Glutathione
    • Authors: Yingfeng Tu; Fei Peng, Paul B. White, Daniela A. Wilson
      Abstract: The development of artificial nanomotor systems that are stimuli-responsive is still posing many challenges. Herein, we demonstrate the self-assembly of a redox-responsive stomatocyte nanomotor system, which can be used for triggered drug release under biological reducing conditions. The redox sensitivity was introduced by incorporating a disulfide bridge between the hydrophilic poly(ethylene glycol) block and the hydrophobic polystyrene block. When incubated with the endogenous reducing agent glutathione at a concentration comparable to that within cells, the external PEG shells of these stimuli-responsive nanomotors are cleaved. The specific bowl-shaped stomatocytes aggregate after the treatment with glutathione, leading to the loss of motion and triggered drug release. These novel redox-responsive nanomotors can not only be used for remote transport but also for drug delivery, which is promising for future biomedical applications.Ein redoxempfindlicher Stomatocyt-förmiger Nanomotor wurde durch den Einbau von Disulfidbrücken zwischen den hydrophilen PEG- und hydrophoben PS-Blöcken des Copolymers erhalten. Wird dieser in vitro mit dem endogenen Reduktionsmittel Glutathion inkubiert, werden die externen PEG-Schalen des Nanomotors abgespalten, wodurch die Beweglichkeit verloren geht und Wirkstofffreisetzung möglich wird.
      PubDate: 2017-05-22T07:41:01.861701-05:
      DOI: 10.1002/ange.201703276
  • Gold-Catalyzed Cadiot–Chodkiewicz-Type Cross-Coupling of Terminal
           Alkynes with Alkynyl Hypervalent Iodine Reagents: Highly Selective
           Synthesis of Unsymmetrical 1,3-Diynes
    • Authors: Xiangdong Li; Xin Xie, Ning Sun, Yuanhong Liu
      Abstract: A new and efficient method for the synthesis of unsymmetrical 1,3-butadiynes by gold-catalyzed C(sp)–C(sp) cross-coupling of terminal alkynes with alkynyl hypervalent iodine(III) reagents has been developed. The reaction features high selectivity and efficiency, mild reaction conditions, wide substrate scope, and functional-group compatibility, and is a highly attractive complement to existing methods. Mechanistic studies reveal that formation of a phenanthrolinyl-ligated gold(I) complex is crucial for the efficiency and selectivity of the target transformation.Kein Hype: Eine neue Methode zur Ausführung der Titelreaktion ermöglicht hohe Selektivität und Effizienz bei milden Bedingungen, mit einem großen Spektrum an Substraten und funktionellen Gruppen. Mechanistischen Studien zufolge ist die Bildung eines Phenanthrolinyl-Gold(I)-Komplexes von entscheidender Bedeutung für eine selektive Transformation.
      PubDate: 2017-05-22T07:40:59.027698-05:
      DOI: 10.1002/ange.201702833
  • Observation of CH⋅⋅⋅π Interactions between Methyl and Carbonyl
           Groups in Proteins
    • Authors: Frédéric A. Perras; Dominique Marion, Jérôme Boisbouvier, David L. Bryce, Michael J. Plevin
      Abstract: Protein structure and function is dependent on myriad noncovalent interactions. Direct detection and characterization of these weak interactions in large biomolecules, such as proteins, is experimentally challenging. Herein, we report the first observation and measurement of long-range “through-space” scalar couplings between methyl and backbone carbonyl groups in proteins. These J couplings are indicative of the presence of noncovalent C−H⋅⋅⋅π hydrogen-bond-like interactions involving the amide π network. Experimentally detected scalar couplings were corroborated by a natural bond orbital analysis, which revealed the orbital nature of the interaction and the origins of the through-space J couplings. The experimental observation of this type of CH⋅⋅⋅π interaction adds a new dimension to the study of protein structure, function, and dynamics by NMR spectroscopy.Die Masse macht's: Lösungsphasen-NMR-Spektroskopie und DFT-Rechnungen belegen die Existenz schwacher, wasserstoffbrückenartiger CH⋅⋅⋅π-Wechselwirkungen in Proteinen zwischen Methyldonorgruppen und peptidgebundenen Akzeptorgruppen (siehe Bild). Da eine große Zahl von CH⋅⋅⋅πCO-Wechselwirkungen in Proteinen vorhanden ist, liefern sie wahrscheinlich einen wichtigen Beitrag zur Proteinstruktur, -dynamik und -funktion.
      PubDate: 2017-05-22T07:40:55.269403-05:
      DOI: 10.1002/ange.201702626
  • Deprotonation of a Seemingly Hydridic Diborane(6) to Build a B−B
    • Authors: Thomas Kaese; Hendrik Budy, Michael Bolte, Hans-Wolfram Lerner, Matthias Wagner
      Abstract: Deprotonation of the doubly arylene-bridged diborane(6) derivative 1H2 with (Me3Si)3CLi or (Me3Si)2NK gives the B−B σ-bonded species M[1H] in essentially quantitative yields (THF, room temperature; M=Li, K, arylene=4,4′-di-tert-butyl-2,2′-biphenylylene). With nBuLi as the base, the yield of Li[1H] drops to 20 % and the 1,1-bis(9-borafluorenyl)butane Li[2H] is formed as a side product (30 %). In addition to the 1,1-butanediyl fragment, the two boron atoms of Li[2H] are linked by a μ-H bridge. In the closely related molecule Li[3H], the corresponding μ-H atom can be abstracted with (Me3Si)3CLi to afford the B−B-bonded conjugated base Li2[3] (THF, 150 °C; 15 %). Li[1H] and Li[2H] were characterized by NMR spectroscopy and X-ray crystallography.Ungeahnte Fähigkeiten: Eine B-B-Bindung entsteht bei der Deprotonierung eines doppelt arylenverbrückten Diboran(6)-Derivats. Diese Reaktion belegt, dass Organoborane nicht zwingend hydridisch sein müssen, und sie zeigt neue Wege zu elektronenpräzisen Diboranen auf.
      PubDate: 2017-05-22T07:40:51.957746-05:
      DOI: 10.1002/ange.201702393
  • Oxidative Neutralization of Mustard-Gas Simulants in an On-Board Flow
           Device with In-Line NMR Monitoring
    • Authors: Baptiste Picard; Boris Gouilleux, Thomas Lebleu, Jacques Maddaluno, Isabelle Chataigner, Maël Penhoat, François-Xavier Felpin, Patrick Giraudeau, Julien Legros
      Abstract: The fast and effective neutralization of the mustard-gas simulant 2-chloroethyl ethyl sulfide (CEES) using a simple and portable continuous flow device is reported. Neutralization takes place through a fully selective sulfoxidation by a stable source of hydrogen peroxide (alcoholic solution of urea–H2O2 adduct/MeSO3H freshly prepared). The reaction progress can be monitored with an in-line benchtop NMR spectrometer, allowing a real-time adjustment of reaction conditions. Inherent features of millireactors, that is, perfect control of mixing, heat and reaction time, allowed the neutralization of 25 g of pure CEES within 46 minutes in a 21.5 mL millireactor (tR=3.9 minutes). This device, which relies on affordable and nontoxic reagents, fits into a suitcase, and can be deployed by police/military forces directly on the attack site.Das Senfgas-Simulans (2-Chlorethyl)ethylsulfid (CEES) wurde durch selektive Oxidation zu Sulfoxid (CEESO) unter kontinuierlichem Fluss mit Inline-Überwachung vollständig neutralisiert. Reines CEES (25 g) wurde innerhalb von 46 Minuten in einem 21.5-mL-Reaktor fast vollständig in CEESO umgewandelt. Das Flow-Gerät ist klein genug, um mitgeführt und direkt am Ort der chemischen Bedrohung eingesetzt werden zu können.
      PubDate: 2017-05-22T07:35:36.086195-05:
      DOI: 10.1002/ange.201702744
  • Direct Hydroxylation of Benzene to Phenol by Cytochrome P450BM3 Triggered
           by Amino Acid Derivatives
    • Authors: Osami Shoji; Sota Yanagisawa, Joshua Kyle Stanfield, Kazuto Suzuki, Zhiqi Cong, Hiroshi Sugimoto, Yoshitsugu Shiro, Yoshihito Watanabe
      Abstract: Selective hydroxylation of benzene to phenol, without formation of side products resulting from overoxidation, was catalyzed by cytochrome P450BM3 (P450BM3) with the assistance of amino acid derivatives as decoy molecules. The catalytic turnover rate and the total turnover number reached 259 min-1P450BM3-1 and 40,200 P450BM3-1 when N-heptyl-L-proline modified with L-phenyl alanine (C7-L-Pro-L-Phe) was used as the decoy molecule. This work shows that amino acid derivatives that have a totally different structure from fatty acids can be used as decoy molecules for aromatic hydroxylation by wild-type P450BM3. This methodology for nonnative substrate hydroxylation by wild-type P450BM3 has the potential to expand the utility of P450BM3 for biotransformations.
      PubDate: 2017-05-22T06:20:42.124022-05:
      DOI: 10.1002/ange.201703461
  • Self-Assembled Biomimetic Chloroplast Coupled Photoenzymatic Reaction for
           Sustainable Synthesis of Fuel
    • Authors: Xuehai Yan; Kai Liu, Chengqian Yuan, Qianli Zou, Zengchun Xie
      Abstract: Prototypes of biosystems provide good blueprints for the design and creation of biomimetic systems. However, mimicking both the sophisticated natural structures and their complex biological functions still remains a great challenge. Herein, biomimetic chloroplasts have been fabricated by one-step bio-inspired amino acid mineralization and simultaneous integration of catalytically active units. Hierarchically structured crystals are obtained by metal ion-directed self-assembly of cystine (the oxidized dimer form of the amino acid cysteine), with porous structure and stacking nanorods, which show similar architectural principles to chloroplasts. Porphyrin and enzyme molecules can be both encapsulated in the crystal during mineralization, endowing photocatalytic and enzymatic activity to the crystal, achieving efficient and sustainable synthesis of hydrogen and aldehyde via coupled photoenzymatic reaction.
      PubDate: 2017-05-22T06:20:38.193272-05:
      DOI: 10.1002/ange.201704678
  • Selected Copper-Based Reactions for C-N, C-O, C-S and C-C Bond Formation
    • Authors: Dawei Ma; Subhajit Bhunia, Govind Goroba Pawar, S. Vijay Kumar, Yongwen Jiang
      Abstract: The metal catalyzed cross-coupling reactions are one of the most important transformations in organic synthesis. Copper catalysis has received great attention due to its low toxicity and inexpensive nature. However, traditional Ullmann-type coupling reactions suffered from limited substrate scope and harsh reaction conditions. The introduction of some bidentate ligands such as amino acids, diamines, 1,3-diketones and oxalic diamides during the past two decades has totally changed its scenario, allowing the coupling reactions of aryl halides and nucleophiles to take place at both low reaction temperatures and catalytic loadings. The reaction scope has also been greatly expanded and makes this copper-based cross coupling attractive in both academia and industry. This review will summarize the latest progress in developing the useful reaction conditions for coupling of (hetero)aryl halides with different nucleophiles. Additionally, recent advances on Cu-catalyzed coupling reactions with aryl boronates and Cu-based trifluoromethylations of aromatic electrophiles will be introduced.
      PubDate: 2017-05-22T02:20:26.211446-05:
      DOI: 10.1002/ange.201701690
  • Structural basis for copper-oxygen mediated C-H bond activation by the
           formylglycine-generating enzyme
    • Authors: Marcel Meury; Matthias Knop, Florian P. Seebeck
      Abstract: The formylglycine-generating enzyme (FGE) is a unique copper-protein that catalyzes oxygen-dependent C-H activation. We describe 1.66 Å- and 1.28 Å-resolution crystal structures of FGE from Thermomonospora curvata in complex with either Ag (I) or Cd (II) providing definitive evidence for a high-affinity metal-binding site in this enzyme. The structures reveal a bis-cysteine linear coordination of the monovalent metal, and tetrahedral coordination of the bivalent metal. Similar coordinational change may occur in the active enzyme as a result of Cu (I)/(II) redox cycling. Complexation of copper by two cysteines is common among copper-trafficking proteins, but is unprecedented for redox-active copper-enzymes or synthetic copper catalysts.
      PubDate: 2017-05-22T00:20:26.937612-05:
      DOI: 10.1002/ange.201702901
  • Reversing polarity: Carbonyl α-aminations with nitrogen nucleophiles
    • Authors: Aurelien de la Torre; Veronica Tona, Nuno Maulide
      Abstract: The synthesis of alpha-amino carbonyl compounds is an important challenge in synthesis en route to biologically essential structures. While classical approaches involve the use of enol or enolate chemistries in combination with an electrophilic source of nitrogen, those strategies usually necessitate further transformations in order to reach the desired targets. In recent years, a new approach arose involving the direct use of nucleophilic sources of nitrogen along with an oxidant. This advantageously leads in one-pot to the biologically relevant alpha-amino compounds, without further transformation required. This Minireview highlights the recent advances in the emerging field of oxidative alpha-amination reactions using nucleophilic sources of nitrogen.
      PubDate: 2017-05-20T10:50:24.96581-05:0
      DOI: 10.1002/ange.201702937
  • Black Tungsten Nitride as Metallic Photocatalyst for Overall Water
           Splitting Operable at up to 765 nm
    • Authors: Yu Lei Wang; Ting Nie, Yu Hang Li, Xue Lu Wang, Li Rong Zheng, Ai Ping Chen, Xue Qing Gong, Huagui Yang
      Abstract: Semiconductor photocatalysts are hardly to be employed for overall water splitting beyond 700 nm, owing to both thermodynamic aspects and activation barriers. Metallic materials as photocatalysts are known to overcome this limitation through interband transitions for creating electron-hole pairs, however, the application of metallic photocatalysts for overall water splitting has never been fulfilled. Here we report, for the first time, that the black tungsten nitride can be employed as metallic photocatalyst for overall water splitting at wavelengths of up to 765 nm. Experimental and theoretical results together confirm that metallic properties play a substantial role in exhibiting photocatalytic activity under red-light irradiation for tungsten nitride. This work represents the first red-light responsive photocatalyst for overall water splitting, and may open a promising venue in searching of metallic materials as efficient photocatalysts for solar energy utilization.
      PubDate: 2017-05-19T11:45:28.712081-05:
      DOI: 10.1002/ange.201702943
  • Enantiopure cycloiridiated complexes bearing a pentahelicenic
           N-heterocyclic carbene and displaying long-lived circularly-polarized
    • Authors: Jeanne Crassous; Nora Hellou, Monika Srebro-Hooper, Ludovic Favereau, Francesco Zinna, Elsa Caytan, Loic Toupet, Vincent Dorcet, Marion Jean, Nicolas Vanthuyne, Gareth Williams, Lorenzo Di Bari, Jochen Autschbach
      Abstract: A fused pi-helical N-heterocyclic (NHC) system has been prepared and examined through its diastereoisomerically pure cycloiridiated complexes. The latter display light-green phosphorescence with i) unusually long lifetimes and ii) circular polarization that depends on both the helical-NHC P/M and the iridium delta/lambda stereochemistry. These unprecedented features are attributed to extended pi-conjugation within helical carbenic ligand and efficient helicene-NHC-Ir interaction.
      PubDate: 2017-05-19T09:50:41.905586-05:
      DOI: 10.1002/ange.201704263
  • Methylammonium-Mediated Evolution of Mixed-Organic-Cation Perovskite Thin
           Films: A Dynamic Composition-Tuning Process
    • Authors: Chongwen Li; Yuanyuan Zhou, Li Wang, Yue Chang, Yingxia Zong, Lioz Etgar, Guanglei Cui, Nitin P. Padture, Shuping Pang
      Abstract: Methylammonium-mediated phase-evolution behavior of FA1−xMAxPbI3 mixed-organic-cation perovskite (MOCP) is studied. It is found that by simply enriching the MOCP precursor solutions with excess methylammonium cations, the MOCPs form via a dynamic composition-tuning process that is key to obtaining MOCP thin films with superior properties. This simple chemical approach addresses several key challenges, such as control over phase purity, uniformity, grain size, composition, etc., associated with the solution-growth of MOCP thin films with targeted compositions.Unter Kontrolle: Dünne Filme eines FA1−xMAxPbI3-Iodidperowskits mit gemischten organischen Kationen (MOCP) wurden synthetisiert. Bei Anreicherung der Vorstufenlösungen mit Methylammoniumkationen läuft die MOCP-Bildung über einen dynamisch kontrollierten Prozess ab, der entscheidend für die Bildung dünner Filme mit überlegenen Eigenschaften, exakter Zusammensetzung, exzellenter Uniformität und hohen Korngrößen ist.
      PubDate: 2017-05-19T07:17:25.311032-05:
      DOI: 10.1002/ange.201704188
  • Non-Pincer-Type Manganese Complexes as Efficient Catalysts for the
           Hydrogenation of Esters
    • Authors: Robbert van Putten; Evgeny A. Uslamin, Marcel Garbe, Chong Liu, Angela Gonzalez-de-Castro, Martin Lutz, Kathrin Junge, Emiel J. M. Hensen, Matthias Beller, Laurent Lefort, Evgeny A. Pidko
      Abstract: Eine mangankatalysierte Esterreduktion wird durch Abstimmen der Reaktivität der MnI-Spezies mit einfachen zweizähnigen P,N-Liganden und einer Alkoxidbase möglich. E. A. Pidko et al. stellen in ihrer Zuschrift ( hochaktive Mn-Katalysatoren für die selektive Esterhydrierung vor. Die Aktivität der Katalysatoren ist das Resultat einer feinen Balance zwischen den katalytischen und desaktivierenden Reaktionswegen in Abhängigkeit vom Lösungsmittel, der Base und den Reaktionsbedingungen.
      PubDate: 2017-05-19T07:06:22.987673-05:
      DOI: 10.1002/ange.201704502
  • Significant Enhancement of C2H2/C2H4 Separation by a Photochromic
           Diarylethene Unit: A Temperature- and Light-Responsive Separation Switch
    • Authors: Cong Bin Fan; Le Gong, Ling Huang, Feng Luo, Rajamani Krishna, Xian Feng Yi, An Min Zheng, Le Zhang, Shou Zhi Pu, Xue Feng Feng, Ming Biao Luo, Guo Cong Guo
      Abstract: Selektive Adsorption und Trennung durch photochrome Metall-organische Gerüste (MOFs) lassen sich bisher nur in seltenen Fällen allein durch externe Reize einstellen. In ihrer Zuschrift ( setzen F. Luo, G.-C. Guo und Mitarbeiter eine photochrome Diarylethen-Einheit zur lichtresponsiven Steuerung von Selektivität und Trennverhalten ein. Dadurch erhalten sie eine hoch selektive Adsorption, zum Beispiel im System C2H2/C2H4.
      PubDate: 2017-05-19T07:06:21.96921-05:0
      DOI: 10.1002/ange.201704765
  • A Membrane-Free Neutral pH Formate Fuel Cell Enabled by a Selective Nickel
           Sulfide Oxygen Reduction Catalyst
    • Authors: Bing Yan; Nolan M. Concannon, Jarrod D. Milshtein, Fikile R. Brushett, Yogesh Surendranath
      Abstract: Eine membranlose Brennstoffzelle beruht auf der Selektivität von Katalysatoren an der Anode und Kathode. In ihrer Zuschrift (
      DOI : 10.1002/ange.201702578) zeigen Y. Surendranath et al., dass N3S2 die Sauerstoffreduktion (ORR) in Gegenwart einer hohen Formiatkonzentration selektiv katalysiert. Im Verbund mit dem bekannten Formiat-Oxidationskatalysator Pd/C ermöglicht der selektive ORR-Katalysator Ni3S2 die Konstruktion einer membranlosen Formiat-Brennstoffzelle, die bei neutralem pH-Wert funktioniert und eine bessere Leistung als die Pt-Pd-Zelle erbringt.
      PubDate: 2017-05-19T07:06:20.878625-05:
  • A Long-Life Lithium–Air Battery in Ambient Air with a Polymer
           Electrolyte Containing a Redox Mediator
    • Authors: Ziyang Guo; Chao Li, Jingyuan Liu, Yonggang Wang, Yongyao Xia
      Abstract: Lithium–air batteries when operated in ambient air generally exhibit poor reversibility and cyclability, because of the Li passivation and Li2O2/LiOH/Li2CO3 accumulation in the air electrode. Herein, we present a Li–air battery supported by a polymer electrolyte containing 0.05 m LiI, in which the polymer electrolyte efficiently alleviates the Li passivation induced by attacking air. Furthermore, it is demonstrated that I−/I2 conversion in polymer electrolyte acts as a redox mediator that facilitates electrochemical decomposition of the discharge products during recharge process. As a result, the Li–air battery can be stably cycled 400 times in ambient air (relative humidity of 15 %), which is much better than previous reports. The achievement offers a hope to develop the Li–air battery that can be operated in ambient air.Eine Sauerstoff atmende Elektrode: Eine an Luft langlebige Lithium-Luft-Batterie wurde unter Verwendung eines den Redoxmediator I−/I2 enthaltenden Gelpolymerelektrolyts entwickelt (siehe Bild). Das Polymerelektrolyt und der Redoxmediator mindern die durch angreifende Luft hervorgerufene Passivierung des Lithiums und verbessern die Lade-Entlade-Effizienz der Batterie.
      PubDate: 2017-05-19T07:06:20.004383-05:
      DOI: 10.1002/ange.201701290
  • An Aggregating Amphiphilic Squaraine: A Light-up Probe That Discriminates
           Parallel G-Quadruplexes
    • Authors: Vincenzo Grande; Filippo Doria, Mauro Freccero, Frank Würthner
      Abstract: G-quadruplexes (G4s) are peculiar DNA or RNA tertiary structures that are involved in the regulation of many biological events within mammalian cells, bacteria, and viruses. Although their role as versatile therapeutic targets has been emphasized for 35 years, G4 selectivity over ubiquitous double-stranded DNA/RNA, as well as G4 differentiation by small molecules, still remains challenging. Here, a new amphiphilic dicyanovinyl-substituted squaraine, SQgl, is reported to act as an NIR fluorescent light-up probe discriminating an extensive panel of parallel G4s while it is non-fluorescent in the aggregated state. The squaraine can form an unconventional sandwich π-complex binding two quadruplexes, which leads to a strongly fluorescent (ΦF=0.61) supramolecular architecture. SQgl is highly selective against non-quadruplex and non-parallel G4 sequences without altering their topology, as desired for applications in selective in vivo high-resolution imaging and theranostics.Bevorzugt parallel: Ein amphiphiles Squarain, das in Wasser nicht fluoreszierende Aggregate bildet, wurde als NIR-Sonde mit hoher Selektivität für parallele G-Quadruplexe (G4s) entwickelt. Die starke Fluoreszenz ist auf die Bildung eines ungewöhnlichen Sandwich-π-Komplexes zwischen dem Squarain und zwei parallelen G4s zurückzuführen.
      PubDate: 2017-05-19T07:06:17.250668-05:
      DOI: 10.1002/ange.201702096
  • Mechanical Deformation Accelerates Protein Ageing
    • Authors: Jessica Valle-Orero; Jaime Andrés Rivas-Pardo, Rafael Tapia-Rojo, Ionel Popa, Daniel J. Echelman, Shubhasis Haldar, Julio M. Fernández
      Abstract: A hallmark of tissue ageing is the irreversible oxidative modification of its proteins. We show that single proteins, kept unfolded and extended by a mechanical force, undergo accelerated ageing in times scales of minutes to days. A protein forced to be continuously unfolded completely loses its ability to contract by folding, becoming a labile polymer. Ageing rates vary among different proteins, but in all cases they lose their mechanical integrity. Random oxidative modification of cryptic side chains exposed by mechanical unfolding can be slowed by the addition of antioxidants such as ascorbic acid, or accelerated by oxidants. By contrast, proteins kept in the folded state and probed over week-long experiments show greatly reduced rates of ageing. We demonstrate a novel approach whereby protein ageing can be greatly accelerated: the constant unfolding of a protein for hours to days is equivalent to decades of exposure to free radicals under physiological conditions.Beschleunigte Alterung tritt auf, wenn ein Protein lange Zeit durch Anwendung von Kraft in einem ungefalteten Zustand gehalten wird. Nach 20 h verliert es die Fähigkeit, sich wieder zu falten. Der Grund hierfür ist die Exposition kryptischer Seitenketten gegenüber der oxidativen Umgebung. Der Prozess lässt sich durch Antioxidantien stark verlangsamen. Diese Art von oxidativen Schäden sind ein Kennzeichen für den Verlust an Gewebeelastizität beim Altern.
      PubDate: 2017-05-19T07:06:14.751745-05:
      DOI: 10.1002/ange.201703630
  • Biofunktionale Mikrogel-basierte Dünger zur kontrollierten Blattdüngung
           mit Nährstoffen auf Pflanzen
    • Authors: Richard A. Meurer; Steffen Kemper, Sandra Knopp, Thomas Eichert, Felix Jakob, Heiner E. Goldbach, Ulrich Schwaneberg, Andrij Pich
      Abstract: Die Blattdüngung mit Mikronährstoffen (z. B. Fe3+) bei Pflanzen über einen längeren Zeitraum ist anspruchsvoll und oft aufgrund unzureichender Regenbeständigkeit nicht möglich. Intelligente Versorgungssysteme, die eine Freisetzung von Mikronährstoffen über mehrere Wochen ermöglichen, würden innovative und nachhaltige Lösungen zur Verbesserung der Pflanzengesundheit und der Lebensmittelproduktion im Allgemeinen liefern. Wir berichten über ein neues Versorgungssystem zur Blattdüngung basierend auf funktionalen, pH-ansprechbaren Biohybrid-Mikrogelen, die orthogonale Funktionalitäten als Träger der Mikronährstoffe und zum Einsatz von Peptiden (bezeichnet als Ankerpeptide) als Haftungspromotoren auf der Blattoberfläche besitzen. Die Ankerpeptide binden an hydrophobe Oberflächen, bevorzugt an die wachsartigen “Inseln” auf der Blattoberfläche. Unser System benötigt keine Hilfsmittel und kann in wässriger Dispersion beladen, aufbewahrt und angewendet werden. Wir beschreiben sowohl die Synthese und Funktionalisierung der Mikrogele als auch deren Beladung mit Fe3+ Ionen. Abschließend wird ein erfolgreicher Nachweis der Wirksamkeit an Gurkenpflanzen, die an Eisenmangel leiden, präsentiert.Intelligente Versorgungssysteme für die Pflanzendüngung mit Mikronährstoffen bieten nachhaltige Möglichkeiten zur Verbesserung der Pflanzengesundheit und der Lebensmittelproduktion. Neuartige Biohybrid-Mikrogele mit eisenbindenden Liganden und Ankerpeptiden als Haftungspromotoren wurden als Nährstoffträger entwickelt. Ein Wirkungsnachweis an Eisen-defizienten Gurkenpflanzen wird präsentiert.
      PubDate: 2017-05-19T07:06:04.351767-05:
      DOI: 10.1002/ange.201701620
  • Enzymatic engineering of live bacterial cell surface using butelase 1
    • Authors: Xiaobao Bi; Juan Yin, Giang K. T. Nguyen, Chang Rao, Nurashikin Bte Abdul Halim, Xinya Hemu, James P. Tam, Chuan-Fa Liu
      Abstract: We show that butelase-mediated ligation (BML) can be used to modify live bacterial cell surfaces with diverse cargo molecules. Surface-displayed butelase recognition motif NHV was first introduced at the C-terminal end of the anchoring protein OmpA on E. coli cells. This then served as a handle of BML for the functionalization of E. coli cell surfaces with fluorescein and biotin tags, a tumor-associated monoglycosylated peptide and mCherry protein. The cell-surface ligation reaction was achieved at low concentrations of butelase and the labeling substrates. Furthermore, the fluorescein-labeled bacterial cells were used to show the interactions with cultured HeLa cells and with macrophages in live transgenic zebrafish, capturing the latter's powerful phagocytic effect in action. Together these results highlight the usefulness of butelase 1 in live bacterial cell surface engineering for novel applications.
      PubDate: 2017-05-19T06:25:51.050375-05:
      DOI: 10.1002/ange.201703317
  • Tris(perfluorotolyl)borane - a Boron Lewis Superacid
    • Authors: Norbert Werner Mitzel; Jan Schwabedissen, Leif Körte, Marcel Soffner, Sebastian Blomeyer, Christian Reuter, Yury Vishnevskiy, Beate Neumann, Georg Stammler
      Abstract: Tris(tetrafluoro-4-(trifluoromethyl)phenyl)borane (BTolF) was prepared by reacting boron tribromide with tetrameric F3CC6F4-Cu(I). The latter was generated from F3CC6F4MgBr and copper(I) bromide. Lewis acidities of BTolF evaluated by the Gutmann-Beckett method and calculated fluoride ion affinities are 9 and 10%, respecttively, higher than that of tris(penta-fluorophenyl)borane (BCF) and even higher than that of SbF5. The molecular structures of BTolF and BCF were determined by gas electron diffraction, that of BTolF also by single crystal X-ray diffraction.
      PubDate: 2017-05-19T05:51:04.925401-05:
      DOI: 10.1002/ange.201704097
  • Synthesis of Highly Substituted Pyridines via Copper-Catalyzed
           Condensation of Oximes and α,β-Unsaturated Imines
    • Authors: Wei Wen Tan; Yew Jin Ong, Naohiko Yoshikai
      Abstract: A copper-catalyzed condensation reaction of oxime acetates and α,β-unsaturated ketimines into pyridine derivatives is reported. The reaction features mild conditions, high functional group compatibility, and high regioselectivity with respect to unsymmetrical oxime acetates, thus allowing for the preparation of a wide range of polysubstituted pyridines, many of which are not readily accessible by conventional condensation methods.
      PubDate: 2017-05-19T05:50:59.880409-05:
      DOI: 10.1002/ange.201704378
  • Double-Caging Linker for AND-Type Fluorogenic Construction of
           Protein/Antibody Bioconjugates and in situ Quantification
    • Authors: Shiyong Liu; Guhuan Liu, Guohai Shi, Haoyue Sheng, Yanyan Jiang, Haojun Liang
      Abstract: We report on in situ fluorescent quantification of the conjugation efficiency between azide-terminated synthetic polymers/ imaging probes and thiol-functionalized antibodies/proteins/peptides, by utilizing a doubly caged profluorescent and heterodifunctional core molecule (C1) as the self-sorting bridging unit. Orthogonal dual 'click' coupling of C1 with azide- and thiol-functionalized precursors leads to highly fluorescent bioconjugates, whereas single click products of C1 remain essentially nonfluorescent. This 'AND' logic gate-type fluorogenic feature also enables further integration with FRET processes. For the construction of antibody-probe conjugates from an anti-carcinoembryonic antigen and a quinone-caged profluorescent naphthalimide derivative, the dual 'click' coupling process with C1 can be conveniently monitored via emission turn-on of C1, whereas prominent changes in FRET ratios occur for antibody-probe conjugates when triggered by specific tumor-associated enzymes.
      PubDate: 2017-05-19T05:50:56.351034-05:
      DOI: 10.1002/ange.201702748
  • Silica-Polypyrrole Hybrids as High-Performance Metal-Free Electrocatalysts
           for Hydrogen Evolution Reaction in Neutral Media
    • Authors: Jin-Xian Feng; Han Xu, Sheng-Hua Ye, Gangfeng Ouyang, Ye-Xiang Tong, Gao-Ren Li
      Abstract: Constructing inorganic-organic hybrids with high abilities of water adsorption and activation will lead to significant enhancement of electrocatalytic activity for hydrogen evolution reaction (HER) in neutral media that is environmentally benign. Here we report SiO2-polypyrrole (PPy) hybrid nanotubes supported on carbon fibers (CFs) (SiO2/PPy NTs-CFs) as low-cost and high-performance electrocatalysts for HER in neutral media. Because of the strong electronic interactions between SiO2 and PPy, SiO2 uniquely serves as the centers of water adsorption and activation, and accordingly it will obviously promote HER. SiO2/PPy NTs-CFs as metal-free electrocatalysts achieve high catalytic performance for HER in neutral media, such as low onset potential, small Tafel slope and excellent long-term durability.
      PubDate: 2017-05-18T23:07:01.67704-05:0
      DOI: 10.1002/ange.201702934
  • Bandgap Engineering of Lead-Free Double Perovskite Cs2AgBiBr6 through
           Trivalent Metal Alloying
    • Authors: Kezhao Du; Weiwei Meng, Xiaoming Wang, Yanfa Yan, David B. Mitzi
      Abstract: The double perovskite family, A2MIMIIIX6, represents a promising route to overcome the lead toxicity issue confronting current photovoltaic (PV) standout, CH3NH3PbI3. Given the generally large indirect bandgap within most known double perovskites, bandgap engineering provides an important approach for targeting outstanding PV performance within this family. Using Cs2AgBiBr6 as host, we demonstrate bandgap engineering through alloying of InIII/SbIII. Cs2Ag(Bi1-xMx)Br6 (M = In, Sb) accommodates up to 75% InIII with increased bandgap, and up to 37.5% SbIII with reduced bandgap—i.e., enabling ~0.41 eV bandgap modulation through introduction of the two metals, with smallest value of 1.86 eV for Cs2Ag(Bi0.625Sb0.375)Br6. Band structure calculations indicate that opposite bandgap shift directions associated with Sb/In substitution arise from different atomic configurations for these atoms. Associated photoluminescence and environmental stability of the three-metal systems are also assessed.
      PubDate: 2017-05-18T20:45:44.69072-05:0
      DOI: 10.1002/ange.201703970
  • Quantifying hydrogen-bond populations in DMSO/water mixtures
    • Authors: Carlos R Baiz; Kwang-Im Oh, Kavya Rajesh, John F Stanton
      Abstract: Dimethyl sulfoxide (DMSO) disrupts the hydrogen-bond networks in water. DMSO's widespread uses as a cosolvent, along with its unusual attributes, have inspired numerous studies. In this study, infrared absorption spectroscopy of the S=O stretch combined with molecular dynamics and quantum chemistry models were used to directly quantify DMSO/water hydrogen bond populations in binary mixtures. Singly H-bonded species are dominant at 10 mol%, due to strong DMSO-water interactions. We found an unexpected increase in non-hydrogen-bonded DMSO near the eutectic point (~35 mol%) which also correlates with several abnormalities in the solution's bulk properties. We find evidence for three distinct regimes: 1. Strong DMSO-water interactions (90 mol%). We propose a "step in" mechanism, which involves hydrogen bonding between water and the DMSO aggregate species.
      PubDate: 2017-05-18T14:50:25.926228-05:
      DOI: 10.1002/ange.201704162
  • Optochemical Control of Biological Processes in Cells and Animals
    • Authors: Nicholas Ankenbruck; Taylor Courtney, Yuta Naro, Alexander Deiters
      Abstract: Achieving precise control of biological function represents a crucial tool for studying the mechanisms of cellular processes. Naturally, these processes occur in a strict spatially and temporally regulated fashion. In order to generate accurate models, the tools used to study these processes must also operate with high spatiotemporal resolution. To this end, the use of light as a conditional stimulus has found extensive applications for the activation and deactivation of small molecules, proteins, peptides, and oligonucleotides. Harnessing light has enabled significant advances in both research applications and holds promise toward clinical studies. This review showcases many of the most recent applications and methodology developments of optical control of biology. It focuses on the most recent developments in utilizing chemistry to optically manipulate living systems such as cells and animals.
      PubDate: 2017-05-18T14:45:36.907013-05:
      DOI: 10.1002/ange.201700171
  • Perovskite solar cells from the atomic to the film level
    • Authors: Michael Saliba; Juan-Pablo Correa-Baena, Michael Graetzel, Anders Hagfeldt, Antonio Abate
      Abstract: Organic-inorganic perovskites have made tremendous progress in recent years due to exceptional material properties such as high panchromatic absorption, charge carrier diffusion lengths and a sharp optical band edge. The combination of high-quality semiconductor with low-cost deposition techniques seems to be a match made in heaven creating great excitement and anticipation far beyond the academic ivory tower. This is particularly true for perovskite solar cells (PSCs) that have shown unprecedented gains in efficiency and stability over a time span of just 5 years. Now there are serious efforts for commercialisation with the hope that PSCs can make a major impact in generating inexpensive, sustainable solar electricity.In this review, we will focus on materials and devices from the atomic to the thin film level to highlight the remaining challenges and to anticipate the future developments of PSCs.
      PubDate: 2017-05-18T14:45:25.356819-05:
      DOI: 10.1002/ange.201703226
  • Asymmetric Synthesis of Secondary and Tertiary Boronic Esters
    • Authors: Varinder Kumar Aggarwal; Beatrice Collins, Claire Wilson, Eddie Myers
      Abstract: Non-racemic chiral boronic esters are recognised as immensely valuable building blocks in modern organic synthesis. Their stereospecific transformation into a variety of functional group - from amines and halides to arenes and alkynes - along with their air and moisture stability, has established them as an important target for asymmetric synthesis. Efforts towards the stereoselective synthesis of secondary and tertiary alkyl boronic esters have spanned over five decades and are underpinned by a wealth of reactivity platforms, drawing on the unique and varied reactivity of boron. This review summarizes strategies for the asymmetric synthesis of alkyl boronic esters, from the seminal hydroboration methods of H. C. Brown to the current state of the art.
      PubDate: 2017-05-18T12:46:02.844105-05:
      DOI: 10.1002/ange.201701963
  • Nanojunction polymer photoelectrode for efficient charge transport and
    • Authors: Qiushi Ruan; Wenjun Luo, Jijia Xie, Yiou Wang, Xu Liu, Zhiming Bai, Claire J Carmalt, Junwang Tang
      Abstract: A novel nanojunction archiecture of metal-free photoanode, composed of B-doped carbon nitride nanolayer and bulk carbon nitride has been fabricated by a one-step construction approach. This type of nanojunction overcomes a few intrinsic drawbacks of carbon nitride film, e.g. severe bulk charge recombination and slow charge transfer. For the optium sample, the top layer of the nanojunction has a depth of ca. 100 nm and the bottom layer is ca. 900 nm. The nanojunction photoanode results into a 10 fold higher photocurrent than bulk graphitic carbon nitride and an extremely high incident photon-to-current efficiency (IPCE) of ca. 10% at 400 nm, which to the best of our knowledge is the highest for G-CN based polymer photoanodes in the absence of any sacrificial reagents. The EIS, MS and IMPS spectroscopies all prove such enhancement is mainly due to more than 10 times faster charge seperation rate and nearly 3 times higher conductivity due to the nanojunction architcutre.
      PubDate: 2017-05-18T09:50:56.343221-05:
      DOI: 10.1002/ange.201703372
  • High-Dimensional Neural Network Potentials for Complex Systems
    • Authors: Jörg Behler
      Abstract: Modern simulation techniques have reached a level of maturity, which allows addressing a wide range of problems in chemistry and materials science. Unfortunately, the application of first principles methods with predictive power is still limited to rather small systems, and in spite of the rapid evolution of computer hardware no fundamental change of this situation can be expected. Consequently, to reach an atomic level understanding of complex systems, the development of more efficient but equally reliable atomistic potentials has received considerable attention in recent years. A promising new development has been the introduction of machine learning (ML) methods to describe the atomic interactions. Once trained to electronic structure data, ML potentials can accelerate computer simulations by several orders of magnitude, while quantum mechanical accuracy is preserved. In this article, the methodology of an important class of ML potentials employing artificial neural networks is reviewed.
      PubDate: 2017-05-18T09:50:54.275271-05:
      DOI: 10.1002/ange.201703114
  • Lithium Bond Chemistry in Lithium-Sulfur Batteries
    • Authors: Ting-Zheng Hou; Wen-Tao Xu, Xiang Chen, Hong-Jie Peng, Jia-Qi Huang, Qiang Zhang
      Abstract: Lithium-sulfur (Li-S) battery is a promising high-energy-density energy storage system. The strong anchoring of intermediates is widely accepted to retard the shuttle of polysulfides in a working battery. However, the understanding of the intrinsic chemistry is still deficient. Inspired by the concept of hydrogen bond, herein we focus on the Li bond chemistry in Li-S batteries through sophisticated quantum chemical calculations, in combination with 7Li nuclear magnetic resonance (NMR). Identified as Li bond, the strong dipole-dipole interaction between Li polysulfides and Li-S cathode materials originates from the electron-rich donors (e.g., pyridinic nitrogen (pN)), and enhanced by the inductive and conjugative effect of scaffold materials with π-electrons (e.g., graphene). The chemical shift of Li polysulfides in 7Li NMR, being both theoretically predicted and experimentally verified, is suggested to serve as a quantitative descriptor of Li bond strength.
      PubDate: 2017-05-18T09:50:50.654652-05:
      DOI: 10.1002/ange.201704324
  • Titelbild: Mo2B4O9—Connecting Borate and Metal-Cluster Chemistry
           (Angew. Chem. 23/2017)
    • Authors: Martin K. Schmitt; Oliver Janka, Rainer Pöttgen, Christopher Benndorf, Marcos de Oliveira, Hellmut Eckert, Florian Pielnhofer, Amadeus-Samuel Tragl, Richard Weihrich, Bastian Joachim, Dirk Johrendt, Hubert Huppertz
      Pages: 6443 - 6443
      Abstract: Mo2B4O9 vereint zwei Forschungsfelder – Boratchemie und Metallcluster –, denn es ist das erste Borat, das Übergangsmetallcluster in der Kristallstruktur enthält. Wie H. Huppertz und Mitarbeiter in ihrer Zuschrift auf S. 6549 zeigen, ebnete ein gezielter Reduktionsprozess in einem Hochdruckexperiment den Weg zu dieser neuen Substanzklasse.
      PubDate: 2017-05-09T07:25:40.516095-05:
      DOI: 10.1002/ange.201703990
  • Innentitelbild: Solvent-Assisted Metal Metathesis: A Highly Efficient and
           Versatile Route towards Synthetically Demanding Chromium Metal–Organic
           Frameworks (Angew. Chem. 23/2017)
    • Authors: Jun-Hao Wang; Ying Zhang, Mian Li, Shu Yan, Dan Li, Xian-Ming Zhang
      Pages: 6444 - 6444
      Abstract: Robustheit und Porosität machen Chrom(III)-basierte Metall-organische Gerüste (Cr-MOFs) zu verheißungsvollen Materialien, jedoch ist ihre Synthese relativ schwierig. In der Zuschrift auf S. 6578 ff. beschreiben J. H. Wang, X. M. Zhang et al. die Synthese verschiedener Cr-MOFs aus den entsprechenden Fe-MOFs durch solvensvermittelten Metallaustausch unter milden Bedindungen. Die effiziente und flexible Methode bietet einen exzellenten Ansatz für die Synthese stabiler MOFs.
      PubDate: 2017-04-27T19:03:02.236186-05:
      DOI: 10.1002/ange.201703997
  • Graphisches Inhaltsverzeichnis: Angew. Chem. 23/2017
    • Pages: 6447 - 6462
      PubDate: 2017-05-23T08:52:47.788185-05:
      DOI: 10.1002/ange.201782311
  • Top-Beiträge aus unseren Schwesterzeitschriften: Angew. Chem. 23/2017
    • Pages: 6466 - 6469
      PubDate: 2017-05-23T08:52:46.28621-05:0
      DOI: 10.1002/ange.201782313
  • Distinguished Women in Chemistry or Chemical Engineering der IUAPC 2017
    • Pages: 6471 - 6471
      PubDate: 2017-05-11T08:10:26.691846-05:
      DOI: 10.1002/ange.201704276
  • Gerd Becker (1940–2017)
    • Authors: Werner Uhl; Sumati Panicker
      Pages: 6472 - 6472
      Abstract: Gerd Becker, Emeritus der Universität Stuttgart, ist am 10. Januar 2017 verstorben. Becker war ein Pionier der Phosphorchemie; seine Arbeiten zu Phosphorverbindungen mit Doppel- und Dreifachbindungen zu Kohlenstoffatomen verletzten die klassischen Vorstellungen über die Bindung zwischen Hauptgruppenelementen und führten zu Anwendungen in der Übergangsmetallchemie wie in der organischen Synthese.
      PubDate: 2017-04-28T04:45:30.465013-05:
      DOI: 10.1002/ange.201703696
  • Oxidative Cross-Coupling Reactions. Von Aiwen Lei, Wei Shi, Chao Liu, Wei
           Liu, Hua Zhang und Chuan He.
    • Authors: Jin-Heng Li
      Pages: 6473 - 6473
      Abstract: Wiley-VCH, Weinheim, 2016. 229 S., geb., 129.00 €.—ISBN 978-3527336883
      PubDate: 2017-04-13T10:57:39.560343-05:
      DOI: 10.1002/ange.201703272
  • Hydroniumionenbatterien: eine nachhaltige Lösung zur
    • Authors: Yun-hai Zhu; Xu Yang, Xin-bo Zhang
      Pages: 6476 - 6478
      Abstract: Hydroniumionen sind zum ersten Mal reversibel in einer Elektrode aus kristallinem 3,4,9,10-Perylentetracarbonsäuredianhydrid (PTCDA) gespeichert worden. Dabei wurde ein äußerst reversibles Lade-Entlade-Verhalten von PTCDA in einem wässrigen sauren Elektrolyten aus 1 m H2SO4 beobachtet. Die Kapazität und die Betriebspotentiale ähneln denen der Natriumionen-Speicherung in der gleichen Elektrode.
      PubDate: 2017-04-18T06:50:36.264393-05:
      DOI: 10.1002/ange.201702160
  • On-Chip-Mikrosuperkondensatoren aus Koordinationspolymeren zur
    • Authors: Liang Huang; Liming Dai
      Pages: 6479 - 6481
      Abstract: Miniaturisierte Elektronik: On-Chip-Mikrosuperkondensatoren (MSCs) zur AC-Netzfilterung basierend auf Koordinationspolymergerüsten wurden durch eine einfache schichtweise Methode hergestellt. Die On-Chip-MSCs zeigen einen niedrigen Impedanzphasenwinkel von −73° bei 120 Hz und eine hohe Leistungsdichte von bis zu 1323 W cm−3 bei einer niedrigen Relaxationszeitkonstanten von 0.27 ms.
      PubDate: 2017-04-11T08:20:25.095846-05:
      DOI: 10.1002/ange.201702868
  • Übergangsmetallkatalysierte Nutzung von Methanol als C1-Quelle in der
           organischen Synthese
    • Authors: Kishore Natte; Helfried Neumann, Matthias Beller, Rajenahally V. Jagadeesh
      Pages: 6482 - 6492
      Abstract: Methanol ist als Lösungsmittel, als billiges Reagenz und als nachhaltiger Grundstock für wertvolle Chemikalien, Pharmazeutika und Werkstoffe von Nutzen. Unter den verschiedenen Anwendungen ist der Gebrauch von Methanol als C1-Quelle für die Bildung von C-C-, C-N- und C-O-Bindungen nach wie vor in der organischen Synthese und in der Arzneimittelforschung wichtig. Besonders die C-, N- und O-Methylierung ist von zentralem Interesse, weil die resultierenden Strukturmotive in Naturstoffen sowie in Fein- und Großchemikalien vorkommen. In diesem Minireview fassen wir die Nutzung von Methanol als C1-Quelle für Methylierungen, Methoxylierungen, Formylierungen, Methoxycarbonylierungen und die oxidative Methylesterbildung zusammen.Nachhaltige C1-Quelle: Methanol ist ein bevorzugter Ausgangsstoff für Chemikalien, Materialien und Moleküle für die Lebenswissenschaften. Überdies ist es ein nachhaltiger Grundstock und ein billiges Reagenz für Methylierungen und Methoxylierungen, Methoxycarbonylierungen und die oxidative Bildung von Methylestern, unter anderem bei der Herstellung von Formamiden, Harnstoffderivaten, Ethern, Estern und Heterocyclen.
      PubDate: 2017-04-25T06:25:51.570509-05:
      DOI: 10.1002/ange.201612520
  • Synthetische Biologie – die Synthese der Biologie
    • Authors: Simon Ausländer; David Ausländer, Martin Fussenegger
      Pages: 6494 - 6519
      Abstract: Die synthetische Biologie befasst sich mit der gezielten Konstruktion von lebenden Biomaschinen aus standardisierten Komponenten, die vordefinierte Aufgaben in einer (selbst-)kontrollierten Weise ausführen können. Unterschiedliche Forschungsstrategien und interdisziplinäre Ansätze werden verfolgt, um technische Prinzipien in die Biologie zu implementieren. Die “top-down”-Strategie greift auf die enorme Diversität der Natur zurück, um natürliche Komponenten künstlich in genetischen, metabolischen oder signalweiterleitenden Netzwerken mit vorhersehbaren und kontrollierbaren Eigenschaften zusammenzuführen. Dieser hauptsächlich von der Anwendung her gedachte Ansatz bringt lebende Fabriken hervor, die Wirkstoffe, Treibstoffe, Biomaterialien und Feinchemikalien produzieren. Man bekommt lebende Pillen an die Hand, bestehend aus konstruierten Zellen mit der Fähigkeit, Krankheiten in vivo autonom zu entdecken und zu behandeln. Im Gegensatz dazu versucht man in der “bottom-up”-Strategie, sich von bestehenden lebenden Systemen unabhängig zu machen und biologische Systeme von Grund auf neu zu entwerfen. So sollen künstliche biologische Gebilde synthetisiert werden, die es in der Natur nicht gibt. Dieser eher wissensgetriebene Ansatz untersucht die Rekonstruktion minimaler biologischer Systeme, die grundlegende biologische Phänomene wie Selbstorganisation, Selbstreplikation und Selbsterhaltung hervorbringen können. Die Synthese künstlicher biologischer Einheiten wie synthetischer Nucleotide oder Aminosäuren und ihr Einbau in Polymere im Inneren lebender Zellen stellt gegenwärtig die Grenze zwischen natürlichen und künstlichen biologischen Systemen dar. Insbesondere Entwurf und Synthese ganzer Genome in vitro und ihre Übertragung in Wirtzellen sowie die Anwendung effizienter genomweiter Manipulationstechniken deuten auf die Zukunft der synthetischen Biologie: die Erschaffung lebender Designerzellen mit maßgeschneiderten erwünschten Eigenschaften für Biomedizin und Biotechnologie.Aufregende Zeiten für die synthetische Biologie: Zellen werden konstruiert, um Wirkstoffe und Biokraftstoffe zu produzieren, ganze Genome werden synthetisiert, Proteine und DNA-Moleküle werden mit nichtnatürlichen Funktionen ausgestattet, und die Fortschritte der Molekularbiologie werden wahrscheinlich die Biomedizin und Biotechnologie revolutionieren. Dieser Aufsatz fasst diese verschiedenen Forschungsfelder der synthetischen Biologie zusammen.
      PubDate: 2017-04-25T08:38:30.152467-05:
      DOI: 10.1002/ange.201609229
  • The Structure of the Elusive Simplest Dipeptide Gly-Gly
    • Authors: Carlos Cabezas; Marcelino Varela, José L. Alonso
      Pages: 6520 - 6525
      Abstract: Among the hundreds of peptide compounds for which conformations have been determined by using different spectroscopic techniques, the structure of the simplest dipeptide glycylglycine (Gly-Gly) is conspicuously absent. Herein, for the first time, solid samples of Gly-Gly have been vaporized by laser ablation and three different structures have been revealed in a supersonic expansion by Fourier transform microwave spectroscopy. The intramolecular hydrogen bonding interactions that stabilize the observed forms have been established based on the 14N nuclear quadrupole hyperfine structure. We have illustrated how conformer interconversion distorts the equilibrium conformational distribution, giving rise to missing conformers in the conformational landscape.Die Konformationslandschaft des einfachsten Dipeptids, Glycylglycin (Gly-Gly), wurde durch Kopplung von Laserablation und Fourier-Transformations-Mikrowellenspektroskopie aufgeklärt. Drei identifizierte Konformere fügen sich zusammen mit wegen Umwandlungsprozessen nicht beobachteten Konformeren zum ersten Übersichtsbild der Gly-Gly-Struktur, die zu einem gewissen Ausmaß dynamisch ist.
      PubDate: 2017-04-28T04:45:35.438528-05:
      DOI: 10.1002/ange.201702425
  • Elusive Terminal Copper Arylnitrene Intermediates
    • Authors: Abolghasem (Gus) Bakhoda; Quan Jiang, Jeffery A. Bertke, Thomas R. Cundari, Timothy H. Warren
      Pages: 6526 - 6530
      Abstract: We report herein three new modes of reactivity between arylazides N3Ar with a bulky copper(I) β-diketiminate. Addition of N3ArX3 (ArX3=2,4,6-X3C6H2; X=Cl or Me) to [iPr2NN]Cu(NCMe) results in triazenido complexes from azide attack on the β-diketiminato backbone. Reaction of [iPr2NN]Cu(NCMe) with bulkier azides N3Ar leads to terminal nitrenes [iPr2NN]Cu]=NAr that dimerize via formation of a C−C bond at the arylnitrene p-position to give the dicopper(II) diketimide 4 (Ar=2,6-iPr2C6H3) or undergo nitrile insertion to give diazametallocyclobutene 8 (Ar=4-Ph-2,6-iPr2C6H2). Importantly, reactivity studies reveal both 4 and 8 to be “masked” forms of the terminal nitrenes [iPr2NN]Cu=NAr that undergo nitrene group transfer to PMe3, tBuNC, and even into a benzylic sp3 C−H bond of ethylbenzene.Versuche zur Isolierung von terminalen Arylnitrenen [Cu]=NAr ergeben ein Dikupferdiketimid (siehe Schema, links) durch reversible C-C-Kupplung in der para-Position der NAr-Gruppe oder ein Diazametallacyclobuten durch Acetonitril-Insertion (rechts). Experimentelle und theoretische Studien zeigen, dass beide Zwischenstufen als „maskierte” Quellen für das terminale Nitren [Cu]=NAr dienen, das Nitren-Transfer zu PMe3, CNtBu und benzylischen C-H-Bindungen eingeht.
      PubDate: 2017-05-04T04:30:47.329262-05:
      DOI: 10.1002/ange.201611275
  • Intramolecular Cross-Linking: Addressing Mechanochemistry with a
           Bioinspired Approach
    • Authors: Avishai Levy; Feng Wang, Arad Lang, Or Galant, Charles E. Diesendruck
      Pages: 6531 - 6534
      Abstract: Many of the attractive properties in polymers are a consequence of their high molecular weight and therefore, scission of chains due to mechanochemistry leads to deterioration in properties and performance. Intramolecular cross-links are systematically added to linear chains, slowing down mechanochemical degradation to the point where the chains become virtually invincible to shear in solution. Our approach mimics the immunoglobulin-like domains of Titin, whose structure directs mechanical force towards the scission of sacrificial intramolecular hydrogen bonds, absorbing mechanical energy while unfolding. The kinetics of the mechanochemical reactions supports this hypothesis, as the polymer properties are maintained while high rates of mechanochemistry are observed. Our results demonstrate that polymers with intramolecular cross-links can be used to make solutions which, even under severe shear, maintain key properties such as viscosity.Standhafte Polymere: Zufällige intramolekulare kovalente Vernetzungen in Einzelketten-Polymernanopartikeln brechen bevorzugt bei Ultraschallbehandlung, sodass die Polymere in Lösung mechanochemisch resistent werden. Wird eine bestimmte Vernetzungsdichte überschritten, so bleiben die Nanopartikel bei Scherung in Lösung praktisch unverändert.
      PubDate: 2017-05-02T10:43:04.029494-05:
      DOI: 10.1002/ange.201612242
  • Partial Reduction and Selective Transfer of Hydrogen Chloride on Catalytic
           Gold Nanoparticles
    • Authors: Judit Oliver-Meseguer; Antonio Doménech-Carbó, Mercedes Boronat, Antonio Leyva-Pérez, Avelino Corma
      Pages: 6535 - 6539
      Abstract: HCl in solution accepts electron density from Au NPs and partially reduces at room temperature, as occurs with other simple diatomic molecules, such as O2 and H2. The activation can be run catalytically in the presence of alkynes to give exclusively E-vinyl chlorides, after the regio- and stereoselective transfer of HCl. Based also on this method, vinyl chloride monomer (VCM) can be produced in a milder and greener way than current industrial processes.Reduziert und aktiviert: Chlorwasserstoff wird von substratgebundenen Gold-Nanopartikeln bei Raumtemperatur partiell reduziert. Durch regio- und stereoselektive katalytische Addition an Alkine sind E-α-Vinylchloride zugänglich. Außerdem gelingt die kontinuierliche Synthese des Monomers Vinylchlorid aus Acetylen.
      PubDate: 2017-04-28T02:51:07.587222-05:
      DOI: 10.1002/ange.201700282
  • Synthesis of Intrinsically Disordered Fluorinated Peptides for Modular
           Design of High-Signal 19F MRI Agents
    • Authors: Steven E. Kirberger; Sofia D. Maltseva, Joseph C. Manulik, Samuel A. Einstein, Bradley P. Weegman, Michael Garwood, William C. K. Pomerantz
      Pages: 6540 - 6544
      Abstract: 19F MRI is valuable for in vivo imaging due to the only trace amounts of fluorine in biological systems. Because of the low sensitivity of MRI however, designing new fluorochemicals remains a significant challenge for achieving sufficient 19F signal. Here, we describe a new class of high-signal, water-soluble fluorochemicals as 19F MRI imaging agents. A polyamide backbone is used for tuning the proteolytic stability to avoid retention within the body, which is a limitation of current state-of-the-art perfluorochemicals. We show that unstructured peptides containing alternating N-ϵ-trifluoroacetyllysine and lysine provide a degenerate 19F NMR signal. 19F MRI phantom images provide sufficient contrast at micromolar concentrations, showing promise for eventual clinical applications. Finally, the degenerate high signal characteristics were retained when conjugated to a large protein, indicating potential for in vivo targeting applications, including molecular imaging and cell tracking.Ungeordnete Symmetrie: Eine neue Klasse von wasserlöslichen, peptidbasierten fluorierten Molekülen als Kontrastmittel für die 19F-Kernspintomographie wird beschrieben. Die Synthesestrategie nutzt eine alternierende Abfolge von positiven Ladungen und fluorierten Aminosäuren, die zu einem ungeordneten Peptid mit überlappenden 19F-Resonanzen führen, die ein einzelnes, intensives Signal für die Verwendung als 19F-MRI-Reagens ergeben.
      PubDate: 2017-05-04T04:30:32.818525-05:
      DOI: 10.1002/ange.201700426
  • An Organic Semiconductor Organized into 3D DNA Arrays by
           “Bottom-up” Rational Design
    • Authors: Xiao Wang; Ruojie Sha, Martin Kristiansen, Carina Hernandez, Yudong Hao, Chengde Mao, James W. Canary, Nadrian C. Seeman
      Pages: 6545 - 6548
      Abstract: A 3D array of organic semiconductors was assembled using a DNA scaffold. An octameric aniline molecule (“octaniline”) was incorporated into a DNA building block based on a dimeric tensegrity triangle. The construct self-assembled to form a 3D crystal. Reversible redox conversion between the pernigraniline and leucoemeraldine states of the octaniline is retained in the crystal. Protonic doping gave emeraldine salt at pH 5, corresponding to the conductive form of polyaniline. Redox cycling within the crystal was visualized by color changes and Raman microscopy. The ease of conversion between the octaniline states suggests that it is a viable electronic switch within a unique 3D structure.Vorhersehen und sehen: Drei Dekaden nach der Vorhersage wurden Moleküle eines organischen Halbleiters (Octaanilin) durch rationales Design in eine DNA-Nanostruktur eingebunden, die sich zu einem makroskopischen Kristall zusammenlagert (siehe Bild). Die Oxidations- und Leitfähigkeitszustände des Octaanilins lassen sich im Inneren des Kristalls einfach kontrollieren und durch entsprechende Farbänderungen sichtbar machen.
      PubDate: 2017-05-03T06:50:34.346757-05:
      DOI: 10.1002/ange.201700462
  • Mo2B4O9—Connecting Borate and Metal-Cluster Chemistry
    • Authors: Martin K. Schmitt; Oliver Janka, Rainer Pöttgen, Christopher Benndorf, Marcos de Oliveira, Hellmut Eckert, Florian Pielnhofer, Amadeus-Samuel Tragl, Richard Weihrich, Bastian Joachim, Dirk Johrendt, Hubert Huppertz
      Pages: 6549 - 6553
      Abstract: We report on the first thoroughly characterized molybdenum borate, which was synthesized in a high-pressure/high-temperature experiment at 12.3 GPa/1300 °C using a Walker-type multianvil apparatus. Mo2B4O9 incorporates tetrahedral molybdenum clusters into an anionic borate crystal structure—a structural motif that has never been observed before in the wide field of borate crystal chemistry. The six bonding molecular orbitals of the [Mo4] tetrahedron are completely filled with 12 electrons, which are fully delocalized over the four molybdenum atoms. This finding is in agreement with the results of the magnetic measurements, which confirmed the diamagnetic character of Mo2B4O9. The two four-coordinated boron sites can be differentiated in the 11B MAS-NMR spectrum because of the strongly different degrees of local distortions. Experimentally obtained IR and Raman bands were assigned to vibrational modes based on DFT calculations.Zwei Forschungsfelder werden vereint: Unter den kristallinen Boraten ist Mo2B4O9 das erste, dessen Kristallstruktur Übergangsmetallcluster enthält. Die [Mo4O4]-Heterocuban-Einheiten bestehen aus einem Tetraeder aus Molybdänatomen mit Sauerstoffatomen oberhalb seiner Flächen. Durch einen Reduktionsprozess in einem Hochdruckexperiment wird eine neuartige Substanzklasse eröffnet.
      PubDate: 2017-04-21T03:16:05.178684-05:
      DOI: 10.1002/ange.201701891
  • Direct Experimental Evidence for Halogen–Aryl π Interactions in
           Solution from Molecular Torsion Balances
    • Authors: Han Sun; André Horatscheck, Vera Martos, Max Bartetzko, Ulrike Uhrig, Dieter Lentz, Peter Schmieder, Marc Nazaré
      Pages: 6554 - 6558
      Abstract: We dissected halogen–aryl π interactions experimentally using a bicyclic N-arylimide based molecular torsion balances system, which is based on the influence of the non-bonded interaction on the equilibria between folded and unfolded states. Through comparison of balances modulated by higher halogens with fluorine balances, we determined the magnitude of the halogen–aryl π interactions in our unimolecular systems to be larger than −5.0 kJ mol−1, which is comparable with the magnitude estimated in the biomolecular systems. Our study provides direct experimental evidence of halogen–aryl π interactions in solution, which until now have only been revealed in the solid state and evaluated theoretically by quantum-mechanical calculations.Gewichtiger Beweis: Molekulare Torsionswaagen mit einem N-Arylimid und einer zusätzlichen aromatischen Gruppe bieten ein direktes experimentelles Maß für Halogen-Aryl-Wechselwirkungen in Lösung (siehe Bild). Für die Stärke der Halogen-Aryl-Wechselwirkungen in den hier beschriebenen Systemen wird ein Wert größer −5.0 kJ mol−1 ermittelt.
      PubDate: 2017-04-28T02:55:48.726541-05:
      DOI: 10.1002/ange.201700520
  • Enhancing Light Absorption and Charge Transfer Efficiency in Carbon Dots
           through Graphitization and Core Nitrogen Doping
    • Authors: Benjamin C. M. Martindale; Georgina A. M. Hutton, Christine A. Caputo, Sebastian Prantl, Robert Godin, James R. Durrant, Erwin Reisner
      Pages: 6559 - 6563
      Abstract: Single-source precursor syntheses have been devised for the preparation of structurally similar graphitic carbon dots (CDs), with (g-N-CD) and without (g-CD) core nitrogen doping for artificial photosynthesis. An order of magnitude improvement has been realized in the rate of solar (AM1.5G) H2 evolution using g-N-CD (7950 μmolH2 (gCD)−1 h−1) compared to undoped CDs. All graphitized CDs show significantly enhanced light absorption compared to amorphous CDs (a-CD) yet undoped g-CD display limited photosensitizer ability due to low extraction of photogenerated charges. Transient absorption spectroscopy showed that nitrogen doping in g-N-CD increases the efficiency of hole scavenging by the electron donor and thereby significantly extends the lifetime of the photogenerated electrons. Thus, nitrogen doping allows the high absorption coefficient of graphitic CDs to be translated into high charge extraction for efficient photocatalysis.Kohlenstoffpunkte wurden für die solare H2-Produktion untersucht, und mehrere zentrale Struktur-Aktivitäts-Beziehungen wurden ermittelt. Dotierung der Kernstruktur mit Stickstoff erweist sich als Strategie für die Beschleunigung von Ladungstransferreaktionen in graphitischen Kohlenstoffpunkten, die auch eine starke Lichtabsorption zeigen.
      PubDate: 2017-05-02T10:43:07.092308-05:
      DOI: 10.1002/ange.201700949
  • Structure-Selective Cation Exchange in the Synthesis of Zincblende MnS and
           CoS Nanocrystals
    • Authors: Julie L. Fenton; Raymond E. Schaak
      Pages: 6564 - 6567
      Abstract: The ability to selectively form one crystal structure among several options in a polymorphic system is an important goal in solid-state synthesis. Nanocrystal cation exchange, which proceeds rapidly under mild conditions, can retain key structural features and yield otherwise inaccessible phases, but the extent to which crystal structure can be retained and therefore selectively targeted during such reactions has been limited. Here, we show that nanocrystals of digenite Cu2−xS transform to zincblende MnS and CoS upon cation exchange. Zincblende MnS and CoS, which are metastable in bulk, retain both the tetrahedral cation coordination and cubic close packed anion sublattice of digenite Cu2−xS. Comparison with wurtzite MnS and CoS, which have been accessed previously through analogous cation exchange of roxbyite Cu2−xS, demonstrates the selective formation of the related zincblende vs. wurtzite polymorphs by cation exchange of structurally distinct templates.Diese Struktur, nicht die andere! Digenit-Nanokristalle (Cu2−xS) wurden durch Kationenaustausch in MnS und CoS mit Zinkblende-Struktur überführt – und obwohl die Produkte metastabile Verbindungen im kristallinen Zustand sind, bleiben die Anionen- und Kationenuntergitter erhalten. Auf diesem Syntheseweg können nun mehrere Phasen im gleichen System selektiv und rational erzeugt werden.
      PubDate: 2017-05-02T10:43:09.400734-05:
      DOI: 10.1002/ange.201701087
  • Enhanced Catalytic Activity of Cobalt Porphyrin in CO2 Electroreduction
           upon Immobilization on Carbon Materials
    • Authors: Xin-Ming Hu; Magnus H. Rønne, Steen U. Pedersen, Troels Skrydstrup, Kim Daasbjerg
      Pages: 6568 - 6572
      Abstract: In a comparative study of the electrocatalytic CO2 reduction, cobalt meso-tetraphenylporphyrin (CoTPP) is used as a model molecular catalyst under both homogeneous and heterogeneous conditions. In the former case, employing N,N-dimethylformamide as solvent, CoTPP performs poorly as an electrocatalyst giving low product selectivity in a slow reaction at a high overpotential. However, upon straightforward immobilization of CoTPP onto carbon nanotubes, a remarkable enhancement of the electrocatalytic abilities is seen with CO2 becoming selectively reduced to CO (>90 %) at a low overpotential in aqueous medium. This effect is ascribed to the particular environment created by the aqueous medium at the catalytic site of the immobilized catalyst that facilitates the adsorption and further reaction of CO2. This work highlights the significance of assessing an immobilized molecular catalyst from more than homogeneous measurements alone.Heterogen versus homogen: Wird Cobalt-meso-tetraphenylporphyrin (CoTTP) auf Kohlenstoffnanoröhren immobilisiert, resultiert eine bemerkenswert erhöhte katalytische Aktivität in der CO2-Elektroreduktion, mit [CoITPP]− als der aktiven Spezies. Der hier beschriebene Ansatz zur Heterogenisierung ermöglicht die einfache Durchmusterung und Evaluierung molekularer Katalysatoren unter heterogenen Bedingungen.
      PubDate: 2017-05-03T06:50:28.663464-05:
      DOI: 10.1002/ange.201701104
  • Reversible Supracolloidal Self-Assembly of Cobalt Nanoparticles to Hollow
           Capsids and Their Superstructures
    • Authors: Nonappa; Johannes S. Haataja, Jaakko V. I. Timonen, Sami Malola, Peter Engelhardt, Nikolay Houbenov, Manu Lahtinen, Hannu Häkkinen, Olli Ikkala
      Pages: 6573 - 6577
      Abstract: The synthesis and spontaneous, reversible supracolloidal hydrogen bond-driven self-assembly of cobalt nanoparticles (CoNPs) into hollow shell-like capsids and their directed assembly to higher order superstructures is presented. CoNPs and capsids form in one step upon mixing dicobalt octacarbonyl (Co2CO8) and p-aminobenzoic acid (pABA) in 1,2-dichlorobenzene using heating-up synthesis without additional catalysts or stabilizers. This leads to pABA capped CoNPs (core ca. 5 nm) with a narrow size distribution. They spontaneously assemble into tunable spherical capsids (d≈50–200 nm) with a few-layered shells, as driven by inter-nanoparticle hydrogen bonds thus warranting supracolloidal self-assembly. The capsids can be reversibly disassembled and reassembled by controlling the hydrogen bonds upon heating or solvent exchanges. The superparamagnetic nature of CoNPs allows magnetic-field-directed self-assembly of capsids to capsid chains due to an interplay of induced dipoles and inter-capsid hydrogen bonds. Finally, self-assembly on air–water interface furnishes lightweight colloidal framework films.Cobalt-Kettchen: Ein templatfreier und reversibler suprakolloidaler Selbstorganisationsprozess ordnet superparamagnetische Cobalt-Nanopartikel zu hohlen Kapsidkugeln an, die wiederum Strukturen höherer Ordnung aufbauen.
      PubDate: 2017-04-28T04:51:17.699788-05:
      DOI: 10.1002/ange.201701135
  • Solvent-Assisted Metal Metathesis: A Highly Efficient and Versatile Route
           towards Synthetically Demanding Chromium Metal–Organic Frameworks
    • Authors: Jun-Hao Wang; Ying Zhang, Mian Li, Shu Yan, Dan Li, Xian-Ming Zhang
      Pages: 6578 - 6582
      Abstract: Chromium(III)-based metal–organic frameworks (Cr-MOFs) are very attractive in a wide range of investigations because of their robustness and high porosity. However, reports on Cr-MOFs are scarce owing to the difficulties in their direct synthesis. Recently developed postsynthetic routes to obtain Cr-MOFs suffered from complicated procedures and a lack of general applicability. Herein, we report a highly efficient and versatile strategy, namely solvent-assisted metal metathesis, to obtain Cr-MOFs from a variety of FeIII-MOFs, including several well-known MOFs and a newly synthesized one, through judicious selection of a coordinating solvent. The versatility of this strategy was demonstrated by producing Cr-MIL-100, Cr-MIL-142A/C, Cr-PCN-333, and Cr-PCN-600 from their FeIII analogues and Cr-SXU-1 from a newly synthesized MOF precursor, Fe-SXU-1, in acetone as the solvent under very mild conditions. We have thus developed a general approach for the preparation of robust Cr-MOFs, which are difficult to synthesize by direct methods.Verchromt: Ein effizienter und flexibler Ansatz für die Synthese von Chrom(III)-basierten Metall-organischen Gerüsten (Cr-MOFs) aus unterschiedlichen FeIII-MOFs durch solvensvermittelten Metallaustausch wurde entwickelt. Diese Prozesse laufen in einem koordinierenden Lösungsmittel (Aceton) unter sehr milden Bedingungen ab.
      PubDate: 2017-04-07T02:51:31.833591-05:
      DOI: 10.1002/ange.201701217
  • Chromatin Regulates Genome Targeting with Cisplatin
    • Authors: Emmanouil Zacharioudakis; Poonam Agarwal, Alexandra Bartoli, Nathan Abell, Lavaniya Kunalingam, Valérie Bergoglio, Blerta Xhemalce, Kyle M. Miller, Raphaël Rodriguez
      Pages: 6583 - 6587
      Abstract: Cisplatin derivatives can form various types of DNA lesions (DNA-Pt) and trigger pleiotropic DNA damage responses. Here, we report a strategy to visualize DNA-Pt with high resolution, taking advantage of a novel azide-containing derivative of cisplatin we named APPA, a cellular pre-extraction protocol and the labeling of DNA-Pt by means of click chemistry in cells. Our investigation revealed that pretreating cells with the histone deacetylase (HDAC) inhibitor SAHA led to detectable clusters of DNA-Pt that colocalized with the ubiquitin ligase RAD18 and the replication protein PCNA. Consistent with activation of translesion synthesis (TLS) under these conditions, SAHA and cisplatin cotreatment promoted focal accumulation of the low-fidelity polymerase Polη that also colocalized with PCNA. Remarkably, these cotreatments synergistically triggered mono-ubiquitination of PCNA and apoptosis in a RAD18-dependent manner. Our data provide evidence for a role of chromatin in regulating genome targeting with cisplatin derivatives and associated cellular responses.Die Behandlung von Krebszellen mit Cisplatinderivaten und einem Histondeacetylase(HDAC)-Hemmer führt zur Bildung von Clustern platinierter DNA-Läsionen, die die Transläsionssynthese und den Apoptose-Signalweg synergistisch aktivieren. Die Befunde verweisen auf eine Rolle des Chromatins in der Regulation von Gentargeting mit Cisplatinderivaten und assoziierten zellulären Antworten.
      PubDate: 2017-05-05T06:44:56.155138-05:
      DOI: 10.1002/ange.201701144
  • Fullerene C70 as a Nanoflask that Reveals the Chemical Reactivity of
           Atomic Nitrogen
    • Authors: Yuta Morinaka; Rui Zhang, Satoru Sato, Hidefumi Nikawa, Tatsuhisa Kato, Ko Furukawa, Michio Yamada, Yutaka Maeda, Michihisa Murata, Atsushi Wakamiya, Shigeru Nagase, Takeshi Akasaka, Yasujiro Murata
      Pages: 6588 - 6591
      Abstract: To investigate the intrinsic reactivity of atomic nitrogen, which had previously been accomplished only by examining its decay in the gas phase using special equipment, a nitrogen atom was inserted into a series of molecule-encapsulating C60 and C70 fullerenes. Among the studied endofullerenes, H2@C70 was able to encapsulate an additional nitrogen atom within the fullerene cage under radiofrequency plasma conditions. The product was analyzed by ESR spectroscopy and mass spectrometry in solution, which revealed that the nitrogen atom with a quartet ground state does not react but weakly interact with the H2 molecule, thus demonstrating the utility of such fullerenes as “nanoflasks”.Eine schwache Wechselwirkung: Atomarer Stickstoff wurde in einer Serie von endohedralen C60- und C70-Fullerenen verkapselt, um die intrinsische Reaktivität des N-Atoms zu untersuchen. Unter den untersuchten Endofullerenen nahm H2@C70 ein zusätzliches N-Atom in seinen Fullerenkäfig unter Radiofrequenzplasma-Bedingungen auf. Das erhaltene Produkt wurde mittels ESR-Spektroskopie und Massenspektrometrie in Lösung analysiert.
      PubDate: 2017-05-02T10:42:53.248331-05:
      DOI: 10.1002/ange.201701158
  • Activatable Singlet Oxygen Generation from Lipid Hydroperoxide
           Nanoparticles for Cancer Therapy
    • Authors: Zijian Zhou; Jibin Song, Rui Tian, Zhen Yang, Guocan Yu, Lisen Lin, Guofeng Zhang, Wenpei Fan, Fuwu Zhang, Gang Niu, Liming Nie, Xiaoyuan Chen
      Pages: 6592 - 6596
      Abstract: Reactive oxygen species (ROS)-induced apoptosis is a widely practiced strategy for cancer therapy. Although photodynamic therapy (PDT) takes advantage of the spatial–temporal control of ROS generation, the meticulous participation of light, photosensitizer, and oxygen greatly hinders the broad application of PDT as a first-line cancer treatment option. An activatable system has been developed that enables tumor-specific singlet oxygen (1O2) generation for cancer therapy, based on a Fenton-like reaction between linoleic acid hydroperoxide (LAHP) tethered on iron oxide nanoparticles (IO NPs) and the released iron(II) ions from IO NPs under acidic-pH condition. The IO-LAHP NPs are able to induce efficient apoptotic cancer cell death both in vitro and in vivo through tumor-specific 1O2 generation and subsequent ROS mediated mechanism. This study demonstrates the effectiveness of modulating biochemical reactions as a ROS source to exert cancer death.Singulett-Sauerstoff wird in einer aktivierbaren biochemischen Reaktion aus einem Lipidhydroperoxid erzeugt, bei der Eisen(II)-Ionen aus Eisenoxid-Nanopartikeln katalytisch wirken. Auf dieser Grundlage wurde ein neuartiger Ansatz zur Krebstherapie entwickelt, der sowohl in vitro als auch in vivo eine vielversprechende Krebszell-Apoptose herbeiführte.
      PubDate: 2017-05-04T04:36:30.155257-05:
      DOI: 10.1002/ange.201701181
  • Color-Change Photoswitching of an Alkynylpyrene Excimer Dye
    • Authors: Ke Min Chan; Dominik K. Kölmel, Shenliang Wang, Eric T. Kool
      Pages: 6597 - 6601
      Abstract: We describe a photoswitchable DNA-based dimeric dye that visibly changes fluorescence from green to blue upon UV irradiation. A novel bis-alkyne-dependent [2+2+2] cycloaddition is proposed as a mechanism for the color change in air. The photoinduced structural switching results in spatial separation of stacked pyrene units, thereby causing selective loss of the excimer emission. We demonstrate and suggest several applications for this novel photoswitch.DNA-basierter Photoschalter: Ein DNA-basiertes dimeres Farbstoffmolekül wechselt unter UV-Licht seine Farbe von Grün nach Blau. Eine neuartige [2+2+2]-Cycloaddition eines Bis(alkins) mit Sauerstoff wird als Mechanismus für den Farbumschlag an der Luft vorgeschlagen (siehe Bild).
      PubDate: 2017-05-05T01:20:41.015082-05:
      DOI: 10.1002/ange.201701235
  • Tyrosine or Tryptophan' Modifying a Metalloradical Catalytic Site by
           Removal of the Cys–Tyr Cross-Link in the Galactose 6-Oxidase Homologue
    • Authors: Amanda K. Chaplin; Caterina Bernini, Adalgisa Sinicropi, Riccardo Basosi, Jonathan A. R. Worrall, Dimitri A. Svistunenko
      Pages: 6602 - 6606
      Abstract: The concerted redox action of a metal ion and an organic cofactor is a unique way to maximize the catalytic power of an enzyme. An example of such synergy is the fungal galactose 6-oxidase, which has inspired the creation of biomimetic copper oxidation catalysts. Galactose 6-oxidase and its bacterial homologue, GlxA, possess a metalloradical catalytic site that contains a free radical on a covalently linked Cys–Tyr and a copper atom. Such a catalytic site enables for the two-electron oxidation of alcohols to aldehydes. When the ability to form the Cys–Tyr in GlxA is disrupted, a radical can still be formed. Surprisingly, the radical species is not the Tyr residue but rather a copper second-coordination sphere Trp residue. This is demonstrated through the introduction of a new algorithm for Trp-radical EPR spectra simulation. Our findings suggest a new mechanism of free-radical transfer between aromatic residues and that the Cys–Tyr cross-link prevents radical migration away from the catalytic site.Bindung gebrochen und immer noch radikal: Radikalische Kupfer-Oxidasen verfügen über einen ungewöhnlichen Cys-Tyr-Redoxkofaktor. Dieser enthält ein stabiles Proteinradikal, das für ihre katalytische Aktivität entscheidend ist. Nach dem Bruch der Cys-Tyr-Bindung verbleibt immer noch ein Radikal, erstaunlicherweise aber nicht an Tyr, sondern an einem π-gestapelten Trp-Rest.
      PubDate: 2017-05-02T10:42:45.164733-05:
      DOI: 10.1002/ange.201701270
  • Oligonucleotide-Addressed Covalent 3′-Terminal Derivatization of Small
           RNA Strands for Enrichment and Visualization
    • Authors: Aleksandr Osipenko; Alexandra Plotnikova, Milda Nainytė, Viktoras Masevičius, Saulius Klimašauskas, Giedrius Vilkaitis
      Pages: 6607 - 6610
      Abstract: The HEN1 RNA 2′-O-methyltransferase plays important roles in the biogenesis of small non-coding RNAs in plants and proved a valuable tool for selective transfer of functional groups from cofactor analogues onto miRNA and siRNA duplexes in vitro. Herein, we demonstrate the versatile HEN1-mediated methylation and alkylation of small RNA strands in heteroduplexes with a range of complementary synthetic DNA oligonucleotides carrying user-defined moieties such as internal or 3′-terminal extensions or chemical reporter groups. The observed DNA-guided covalent functionalization of RNA broadens our understanding of the substrate specificity of HEN1 and paves the way for the development of novel chemo-enzymatic tools with potential applications in miRNomics, synthetic biology, and nanomedicine.Vielseitige RNA-Markierungen: Eine Methode zur chemoenzymatischen Markierung von miRNAs und siRNAs beruht auf der Aktivität der 2′-O-Methyltransferase HEN1, funktionelle Gruppen an das 3′-Ende des RNA-Strangs in DNA/RNA-Heterodoppelsträngen zu transferieren. Die Methode ermöglicht vielseitige Synthesen von Einzel- oder dualen Reportern: Die eine Markierung wird präparativ in die DNA-Sonde eingebaut, die zweite wird mittels HEN1 kovalent an die Ziel-RNA gebunden.
      PubDate: 2017-05-04T04:36:47.86295-05:0
      DOI: 10.1002/ange.201701448
  • Synthesis and Bowl-in-Bowl Assembly of a Geodesic Phenylene Bowl
    • Authors: Koki Ikemoto; Ryo Kobayashi, Sota Sato, Hiroyuki Isobe
      Pages: 6611 - 6614
      Abstract: A phenylene multiring with a corannulenoidal skeleton was synthesized. Geodesic constraints over 20 phenylene panels resulted in its nanometer-sized, bowl-shaped molecular structure, which was unequivocally revealed by crystallographic analysis. The crystal structure also showed the presence of a bowl-in-bowl dimeric assembly, which was driven by entropic factors in solution.Nach Form sortiert: Bei der Kupplung trigonal-planarer Phenylene zu einem von fünf Sechsecken umgebenen Fünfeck bewirken geodätische Randbedingungen die Bildung einer nanometergroßen schalenförmigen Struktur. Die Packung der Moleküle wird durch Konkav-konvex-Erkennungsprozesse bestimmt. Die Formerkennung beruht auf einem Entropiegewinn bei der Anordnung der großen 120 π-Systeme.
      PubDate: 2017-04-12T06:40:53.770747-05:
      DOI: 10.1002/ange.201702063
  • Vesicle Origami: Cuboid Phospholipid Vesicles Formed by Template-Free
    • Authors: Frederik Neuhaus; Dennis Mueller, Radu Tanasescu, Sandor Balog, Takashi Ishikawa, Gerald Brezesinski, Andreas Zumbuehl
      Pages: 6615 - 6618
      Abstract: Phospholipid liposomes are archetypical self-assembled structures. To minimize the surface tension, the vesicles typically are spherical. Deciphering the bilayer code, the basic physical interactions between phospholipids would allow these molecules to be utilized as building blocks for novel, non-spherical structures. A 1,2-diamidophospholipid is presented that self-assembles into a cuboid structure. Owing to intermolecular hydrogen bonding, the bilayer membranes form an exceptionally tight subgel packing, leading to a maximization of flat structural elements and a minimization of any edges. These conditions are optimized in the geometrical structure of a cube. Surprisingly, the lateral surface pressure in the membrane is only one third of the value typically assumed for a bilayer membrane, questioning a long-standing rule-of-thumb.Würfelförmige Vesikel: Ein 1,2-Diamidophospholipid wird vorgestellt, das ohne Templat Phospholipid-Würfel bildet. Intermolekulare Wasserstoffbrücken formen die Doppelschichtmembranen in einen außergewöhnlich eng gepackten Subgel-Zustand, wobei ebene Strukturelemente maximiert und Kanten minimiert werden. Die Würfelform ist aus geometrischer Sicht optimal für diese Bedingungen.
      PubDate: 2017-04-26T06:30:48.045859-05:
      DOI: 10.1002/ange.201701634
  • Anaerobic Respiration on Self-Doped Conjugated Polyelectrolytes: Impact of
           Chemical Structure
    • Authors: Nathan D. Kirchhofer; Samantha R. McCuskey, Cheng-Kang Mai, Guillermo C. Bazan
      Pages: 6619 - 6622
      Abstract: We probe anaerobic respiration of bacteria in the presence of conjugated polyelectrolytes (CPEs). Three different CPEs were used to probe how structural variations impact biocurrent generation from Shewanella oneidensis MR-1. For the self-doped anionic CPE only, absorption spectroscopy shows that the addition of S. oneidensis MR-1 leads to the disappearance of the polaron (radical cation) band at>900 nm and an increase in the band at 735 nm due to the neutral species, consistent with electron transfer from microbe to polymer. Microbial three-electrode electrochemical cells (M3Cs) show an increase in the current generated by S. oneidensis MR-1 with addition of the self-doped CPE relative to other CPEs and controls. These experiments combined with in situ cyclic voltammetry suggest that the doped CPE facilitates electron transport to electrodes and reveal structure–function relationships relevant to developing materials for biotic/abiotic interfaces.Verbesserte Bioelektroden: Der abiotisch-biotische Grenzflächenkontaktwiderstand ist einer der limitierenden Parameter für das Leistungsverhalten bioelektronischer Funktionseinheiten. Anionische selbstdotierte konjugierte Polyelektrolyte verstärken die Stromerzeugung aus anodisch respirierenden Shewanella oneidensis MR-1, indem sie als leitfähige Erweiterung der Elektrode agieren und die Kolonisierung verstärken.
      PubDate: 2017-04-26T06:31:20.948359-05:
      DOI: 10.1002/ange.201701964
  • Crack-Free, Soft Wrinkles Enable Switchable Anisotropic Wetting
    • Authors: Dongjoon Rhee; Won-Kyu Lee, Teri W. Odom
      Pages: 6623 - 6627
      Abstract: Soft skin layers on elastomeric substrates are demonstrated to support mechano-responsive wrinkle patterns that do not exhibit cracking under applied strain. Soft fluoropolymer skin layers on pre-strained poly(dimethylsiloxane) slabs achieved crack-free surface wrinkling at high strain regimes not possible by using conventional stiff skin layers. A side-by-side comparison between the soft and hard skin layers after multiple cycles of stretching and releasing revealed that the soft skin layer enabled dynamic control over wrinkle topography without cracks or delamination. We systematically characterized the evolution of wrinkle wavelength, amplitude, and orientation as a function of tensile strain to resolve the crack-free structural transformation. We demonstrated that wrinkled surfaces can guide water spreading along wrinkle orientation, and hence switchable, anisotropic wetting was realized.Falten sind kein Grund zur Sorge: Weiche Überzugschichten eines fluorierten Polymers auf Elastomersubstraten werfen Falten, die ohne Abblättern oder Rissbildung wiederholt gestreckt und entspannt werden konnten. Ein direkter Vergleich mit herkömmlichen harten Überzugschichten belegt die Robustheit der Falten in der weichen Schicht und ihre einzigartigen Eigenschaften, etwa eine schaltbare anisotrope Wasserspreitung.
      PubDate: 2017-04-28T04:46:25.024225-05:
      DOI: 10.1002/ange.201701968
  • Lead-free Perovskite Materials (NH4)3Sb2IxBr9−x
    • Authors: Chuantian Zuo; Liming Ding
      Pages: 6628 - 6632
      Abstract: A family of perovskite light absorbers (NH4)3Sb2IxBr9−x (0≤x≤9) was prepared. These materials show good solubility in ethanol, a low-cost, hypotoxic, and environmentally friendly solvent. The light absorption of (NH4)3Sb2IxBr9−x films can be tuned by adjusting I and Br content. The absorption onset for (NH4)3Sb2IxBr9−x films changes from 558 nm to 453 nm as x changes from 9 to 0. (NH4)3Sb2I9 single crystals were prepared, exhibiting a hole mobility of 4.8 cm2 V−1 s−1 and an electron mobility of 12.3 cm2 V−1 s−1. (NH4)3Sb2I9 solar cells gave an open-circuit voltage of 1.03 V and a power conversion efficiency of 0.51 %.Bleifrei sind die Perowskit-Materialien (NH4)3Sb2IxBr9−x (0≤x≤9), die in Ethanol-Lösung erhalten wurden. Einkristalle von (NH4)3Sb2I9 wurden gezüchtet und strukturanalytisch charakterisiert. Solarzellen mit (NH4)3Sb2I9 als Lichtabsorber lieferten Leerlaufspannungen von 1.03 V und einen Wirkungsgrad von 0.51 %.
      PubDate: 2017-04-28T04:46:17.763081-05:
      DOI: 10.1002/ange.201702265
  • The Effect of Surface Site Ensembles on the Activity and Selectivity of
           Ethanol Electrooxidation by Octahedral PtNiRh Nanoparticles
    • Authors: Nina Erini; Vera Beermann, Martin Gocyla, Manuel Gliech, Marc Heggen, Rafal E. Dunin-Borkowski, Peter Strasser
      Pages: 6633 - 6638
      Abstract: Direct ethanol fuel cells are attractive power sources based on a biorenewable, high energy-density fuel. Their efficiency is limited by the lack of active anode materials which catalyze the breaking of the C−C bond coupled to the 12-electron oxidation to CO2. We report shape-controlled PtNiRh octahedral ethanol oxidation electrocatalysts with excellent activity and previously unachieved low onset potentials as low as 0.1 V vs. RHE, while being highly selective to complete oxidation to CO2. Our comprehensive characterization and in situ electrochemical ATR studies suggest that the formation of a ternary surface site ensemble around the octahedral Pt3Ni1Rhx nanoparticles plays a crucial mechanistic role for this behavior.Reine Formsache: Seit langem steht die effiziente und vollständige Elektrooxidation von Ethanol bei niedrigen Überspannungen im Fokus moderner Forschungsbemühungen. Die einzigartige Anordnung von ternären Pt-Ni-Rh-Ensembles auf definierten oktaedrischen {111}-Oberflächen zeigt nun erfolgversprechende Aktivitäten und eine gute Selektivität für diese Umwandlung.
      PubDate: 2017-04-28T04:51:02.073677-05:
      DOI: 10.1002/ange.201702332
  • Phenol-Catalyzed Discharge in the Aprotic Lithium-Oxygen Battery
    • Authors: Xiangwen Gao; Zarko P. Jovanov, Yuhui Chen, Lee R. Johnson, Peter G. Bruce
      Pages: 6639 - 6643
      Abstract: Discharge in the lithium-O2 battery is known to occur either by a solution mechanism, which enables high capacity and rates, or a surface mechanism, which passivates the electrode surface and limits performance. The development of strategies to promote solution-phase discharge in stable electrolyte solutions is a central challenge for development of the lithium-O2 battery. Here we show that the introduction of the protic additive phenol to ethers can promote a solution-phase discharge mechanism. Phenol acts as a phase-transfer catalyst, dissolving the product Li2O2, avoiding electrode passivation and forming large particles of Li2O2 product—vital requirements for high performance. As a result, we demonstrate capacities of over 9 mAh cm−2areal, which is a 35-fold increase in capacity compared to without phenol. We show that the critical requirement is the strength of the conjugate base such that an equilibrium exists between protonation of the base and protonation of Li2O2.Der Entladevorgang in Li-O2-Batterien verläuft entweder über einen erwünschten Lösungsphasenmechanismus oder über einen ungünstigen Oberflächenmechanismus, der die Elektrode passiviert. Phenol fördert den Lösungsmechanismus, indem es als Phasentransferkatalysator wirkt und das Li2O2-Produkt in Lösung bringt (siehe Bild), die Elektrodenpassivierung verhindert und große Li2O2-Partikel bildet – eine wichtige Anforderung für gute Batterieleistungen.
      PubDate: 2017-05-10T02:20:45.842957-05:
      DOI: 10.1002/ange.201702432
  • Amide-Directed C−H Sodiation by a Sodium Hydride/Iodide Composite
    • Authors: Yinhua Huang; Guo Hao Chan, Shunsuke Chiba
      Pages: 6644 - 6647
      Abstract: A new protocol for amide-directed ortho and lateral C−H sodiation is enabled by sodium hydride (NaH) in the presence of either sodium iodide (NaI) or lithium iodide (LiI). The transient organosodium intermediates could be transformed into functionalized aromatic compounds.Richtungsweisend: Eine Amid-gelenkte C-H-Natriierung in ortho-Stellung oder an einer Seitenkette gelingt mit Natriumhydrid (NaH) in Gegenwart von Natriumiodid (NaI) oder Lithiumiodid (LiI). Die transienten Organonatriumspezies wurden in funktionalisierte aromatische Produkte umgewandelt.
      PubDate: 2017-04-27T13:07:05.749468-05:
      DOI: 10.1002/ange.201702512
  • Preparation of Waterproof Organometal Halide Perovskite Photonic Crystal
    • Authors: Kun Chen; Stefan Schünemann, Harun Tüysüz
      Pages: 6648 - 6652
      Abstract: Herein, we report on an innovative method for the preparation of a series of organometal halide perovskite (OHP) photonic crystal beads with pronounced and tunable photonic stop bands by using self-assembled polystyrene spheres as a mold. After infiltration of the mold with OHP precursor solution and slow drying, the OHPs crystallized in the voids of the polystyrene arrays. By controlling the diameter of the polystyrene spheres, the photonic stop band of the OHPs could be precisely tuned. The overlap between the photonic stop band of the beads and the band gap of the OHPs enhances the light harvesting of the perovskite because of the slow photon effect, which arises from the photonic crystal beads. Moreover, the stability of the composite was greatly enhanced by coating with the transparent polymer PDMS without blocking the light propagation. The coated OHP photonic beads kept their composition even after having been in contact with water for 24 h.Wasserfeste Komposite aus organometallischen Halogenidperowskiten und photonischen Kristallpartikeln wurden hergestellt. Die Bandlücke des Perowskits und die Stoppbande der Kristallpartikel können so eingestellt werden, dass sie überlappen, wodurch die Lichtsammlung bei Bestrahlung mit sichtbarem Licht verbessert wird. Die Komposite waren nach Beschichtung mit PDMS auch in Wasser sehr stabil.
      PubDate: 2017-05-02T10:42:47.874426-05:
      DOI: 10.1002/ange.201702556
  • Pressure-Induced Polymerization of Acetylene: Structure-Directed
           Stereoselectivity and a Possible Route to Graphane
    • Authors: Jiangman Sun; Xiao Dong, Yajie Wang, Kuo Li, Haiyan Zheng, Lijuan Wang, George D. Cody, Christopher A. Tulk, Jamie J. Molaison, Xiaohuan Lin, Yufei Meng, Changqing Jin, Ho-kwang Mao
      Pages: 6653 - 6657
      Abstract: Geometric isomerism in polyacetylene is a basic concept in chemistry textbooks. Polymerization to cis-isomer is kinetically preferred at low temperature, not only in the classic catalytic reaction in solution but also, unexpectedly, in the crystalline phase when it is driven by external pressure without a catalyst. Until now, no perfect reaction route has been proposed for this pressure-induced polymerization. Using in situ neutron diffraction and meta-dynamic simulation, we discovered that under high pressure, acetylene molecules react along a specific crystallographic direction that is perpendicular to those previously proposed. Following this route produces a pure cis-isomer and more surprisingly, predicts that graphane is the final product. Experimentally, polycyclic polymers with a layered structure were identified in the recovered product by solid-state nuclear magnetic resonance and neutron pair distribution functions, which indicates the possibility of synthesizing graphane under high pressure.Von Acetylen zu Graphan: Neutronenbeugung und theoretische Studien geben Einblick in die Ursache für die hauptsächliche Bildung von cis-Polyacetylen bei der druckinduzierten Polymerisation von C2H2. Graphan wird als das Endprodukt vorhergesagt, und ein schichtartiges polycyclisches Polymer wurde experimentell als ein Intermediat zwischen Polyacetylen und Graphan identifiziert.
      PubDate: 2017-05-02T10:58:12.804119-05:
      DOI: 10.1002/ange.201702685
  • Switchable Site-Selective Catalytic Carboxylation of Allylic Alcohols with
    • Authors: Manuel van Gemmeren; Marino Börjesson, Andreu Tortajada, Shang-Zheng Sun, Keisho Okura, Ruben Martin
      Pages: 6658 - 6662
      Abstract: A switchable site-selective catalytic carboxylation of allylic alcohols has been developed in which CO2 is used with dual roles, both facilitating C−OH cleavage and as a C1 source. This protocol is characterized by its mild reaction conditions, absence of stoichiometric amounts of organometallic reagents, broad scope, and exquisite regiodivergency which can be modulated by the type of ligand employed.Doppelagent: In der Titelreaktion dient CO2 nicht nur als C1-Baustein, sondern es erleichtert auch die C-OH-Bindungsspaltung. Diese Kreuzkupplung zweier Elektrophile unter Beteiligung nichtgeschützter Alkohole ohne Zusatz stöchiometrischer Mengen an Organometallspezies hat eine große Anwendungsbreite. Überdies verläuft die Umsetzung regiodivergent und kann über den eingesetzten Ligandentyp gesteuert werden.
      PubDate: 2017-05-02T10:42:34.110844-05:
      DOI: 10.1002/ange.201702857
  • Non-Enzymatic RNA Backbone Proofreading through Energy-Dissipative
    • Authors: Angelica Mariani; John D. Sutherland
      Pages: 6663 - 6666
      Abstract: Non-enzymatic oligomerization of activated ribonucleotides leads to ribonucleic acids that contain a mixture of 2′,5′- and 3′,5′-linkages, and overcoming this backbone heterogeneity has long been considered a major limitation to the prebiotic emergence of RNA. Herein, we demonstrate non-enzymatic chemistry that progressively converts 2′,5′-linkages into 3′,5′-linkages through iterative degradation and repair. The energetic costs of this proofreading are met by the hydrolytic turnover of a phosphate activating agent and an acylating agent. With multiple rounds of this energy-dissipative recycling, we show that all-3′,5′-linked duplex RNA can emerge from a backbone heterogeneous mixture, thereby delineating a route that could have driven RNA evolution on the early earth.Übung macht den Meister: Auf einer Urerde ohne Enzyme könnten energiedissipative Kreisprozesse zur Korrektur und Wiederverwertung von Ribonukleinsäuren beigetragen haben. So ergibt sich ein plausibles Szenario für die präbiotische Evolution von RNA.
      PubDate: 2017-05-03T08:21:03.965285-05:
      DOI: 10.1002/ange.201703169
  • Mizoroki–Heck Cyclizations of Amide Derivatives for the Introduction
           of Quaternary Centers
    • Authors: Jose M. Medina; Jesus Moreno, Sophie Racine, Shuaijing Du, Neil K. Garg
      Pages: 6667 - 6671
      Abstract: We report non-decarbonylative Mizoroki–Heck reactions of amide derivatives. The transformation relies on the use of nickel catalysis and proceeds using sterically hindered tri- and tetrasubstituted olefins to give products containing quaternary centers. The resulting polycyclic or spirocyclic products can be obtained in good yields. Moreover, a diastereoselective variant of this method gives access to an adduct bearing vicinal, highly substituted sp3 stereocenters. These results demonstrate that amide derivatives can be used as building blocks for the assembly of complex scaffolds.Mehr Komplexität: Eine nicht-decarbonylierende Mizoroki-Heck-Reaktion von Boc-aktivierten Amid-Derivaten in Gegenwart eines Nickelkatalysators überführt sterisch gehinderte tri- und tetrasubstituierte Olefine in Produkte mit quartärem Kohlenstoffzentrum. Die Transformation ermöglicht die Verwendung von Amid-Derivaten als Bausteine für den Aufbau komplexer Molekülgerüste.
      PubDate: 2017-05-03T06:45:41.362401-05:
      DOI: 10.1002/ange.201703174
  • Crystallinity-Modulated Electrocatalytic Activity of a Nickel(II) Borate
           Thin Layer on Ni3B for Efficient Water Oxidation
    • Authors: Wen-Jie Jiang; Shuai Niu, Tang Tang, Qing-Hua Zhang, Xiao-Zhi Liu, Yun Zhang, Yu-Yun Chen, Ji-Hui Li, Lin Gu, Li-Jun Wan, Jin-Song Hu
      Pages: 6672 - 6677
      Abstract: The exploration of new efficient OER electrocatalysts based on nonprecious metals and the understanding of the relationship between activity and structure of electrocatalysts are important to advance electrochemical water oxidation. Herein, we developed an efficient OER electrocatalyst with nickel boride (Ni3B) nanoparticles as cores and nickel(II) borate (Ni-Bi) as shells (Ni-Bi@NB) via a very simple and facile aqueous reaction. This electrocatalyst exhibited a small overpotential of 302 mV at 10 mA cm−2 and Tafel slope of 52 mV dec−1. More interestingly, it was found that the OER activity of Ni-Bi@NB was closely dependent on the crystallinity of the Ni-Bi shells. The partially crystalline Ni-Bi catalyst exhibited much higher activity than the amorphous or crystalline analogues; this higher activity originated from the enhanced intrinsic activity of the catalytic sites. These findings open up opportunities to explore nickel(II) borates as a new class of efficient nonprecious metal OER electrocatalysts, and to improve the electrocatalyst performance by modulating their crystallinity.Abhängig von der Kristallinität ist die Aktivität eines neuen effizienten Elektrokatalysators für die Sauerstoffentwicklung (OER). Das Material besteht aus einer dünnen Nickel(II)-borat-Schicht auf Nickelborid(NB)-Nanopartikeln (Ni-Bi@NB; siehe Bild). Der partiell kristalline Ni-Bi-Katalysator überzeugt in der OER durch eine exzellente Leistung.
      PubDate: 2017-05-04T05:05:43.51327-05:0
      DOI: 10.1002/ange.201703183
  • Discovery of Hexagonal Structured Pd–B Nanocrystals
    • Authors: Keigo Kobayashi; Hirokazu Kobayashi, Mitsuhiko Maesato, Mikihiro Hayashi, Tomokazu Yamamoto, Satoru Yoshioka, Syo Matsumura, Takeharu Sugiyama, Shogo Kawaguchi, Yoshiki Kubota, Hiroshi Nakanishi, Hiroshi Kitagawa
      Pages: 6678 - 6682
      Abstract: We report on hexagonal close-packed (hcp) palladium (Pd)–boron (B) nanocrystals (NCs) by heavy B doping into face-centered cubic (fcc) Pd NCs. Scanning transmission electron microscopy–electron energy loss spectroscopy and synchrotron powder X-ray diffraction measurements demonstrated that the B atoms are homogeneously distributed inside the hcp Pd lattice. The large paramagnetic susceptibility of Pd is significantly suppressed in Pd–B NCs in good agreement with the reduction of density of states at Fermi energy suggested by X-ray absorption near-edge structure and theoretical calculations.Verhaltensänderung: Hexagonal dichtgepackte (hcp) Pd-B-Nanokristalle (NCs) wurden durch B-Dotierung in flächenzentriert kubische (fcc) Pd-NCs hergestellt. Analysen (HR-HAADF-STEM, EELS und Synchrotron-PXRD) der Pd-B-NCs belegen, dass die B-Atome homogen in einem hcp-Pd-Gitter verteilt sind. Die große paramagnetische Suszeptibilität der Pd-NCs ist in den Pd-B-NCs unterdrückt – in Übereinstimmung mit XANES-Messungen und theoretischen Studien, die eine Verringerung der Zustandsdichte am Fermi-Niveau voraussagen.
      PubDate: 2017-05-04T05:05:51.162149-05:
      DOI: 10.1002/ange.201703209
  • Iron Oxide Photoelectrode with Multidimensional Architecture for Highly
           Efficient Photoelectrochemical Water Splitting
    • Authors: Jin Soo Kang; Yoonsook Noh, Jin Kim, Hyelim Choi, Tae Hwa Jeon, Docheon Ahn, Jae-Yup Kim, Seung-Ho Yu, Hyeji Park, Jun-Ho Yum, Wonyong Choi, David C. Dunand, Heeman Choe, Yung-Eun Sung
      Pages: 6683 - 6688
      Abstract: Nanostructured metal oxide semiconductors have shown outstanding performances in photoelectrochemical (PEC) water splitting, but limitations in light harvesting and charge collection have necessitated further advances in photoelectrode design. Herein, we propose anodized Fe foams (AFFs) with multidimensional nano/micro-architectures as a highly efficient photoelectrode for PEC water splitting. Fe foams fabricated by freeze-casting and sintering were electrochemically anodized and directly used as photoanodes. We verified the superiority of our design concept by achieving an unprecedented photocurrent density in PEC water splitting over 5 mA cm−2 before the dark current onset, which originated from the large surface area and low electrical resistance of the AFFs. A photocurrent of over 6.8 mA cm−2 and an accordingly high incident photon-to-current efficiency of over 50 % at 400 nm were achieved with incorporation of Co oxygen evolution catalysts. In addition, research opportunities for further advances by structual and compositional modifications are discussed, which can resolve the low fill factoring behavior and improve the overall performance.Eine Photoelektrode aus anodisiertem Eisenschaum mit mehrdimensionaler Nano/Mikroarchitektur führt zu einer extrem hohen Photostromerzeugung und hohen faradayschen Effizienz in der Photoelektrolyse von Wasser. Die Morphologien der anodischen Eisenoxide und die Aktivierung der Photoelektrode durch Phasenübergangsphänomene wurden ebenfalls untersucht.
      PubDate: 2017-05-04T06:25:34.057627-05:
      DOI: 10.1002/ange.201703326
  • Enhanced Electrocatalytic Oxygen Evolution in Au–Fe Nanoalloys
    • Authors: Irene Vassalini; Laura Borgese, Michele Mariz, Stefano Polizzi, Giuliana Aquilanti, Paolo Ghigna, Andrea Sartorel, Vincenzo Amendola, Ivano Alessandri
      Pages: 6689 - 6693
      Abstract: Oxygen evolution reaction (OER) is the most critical step in water splitting, still limiting the development of efficient alkaline water electrolyzers. Here we investigate the OER activity of Au–Fe nanoalloys obtained by laser-ablation synthesis in solution. This method allows a high amount of iron (up to 11 at %) to be incorporated into the gold lattice, which is not possible in Au–Fe alloys synthesized by other routes, due to thermodynamic constraints. The Au0.89Fe0.11 nanoalloys exhibit strongly enhanced OER in comparison to the individual pure metal nanoparticles, lowering the onset of OER and increasing up to 20 times the current density in alkaline aqueous solutions. Such a remarkable electrocatalytic activity is associated to nanoalloying, as demonstrated by comparative examples with physical mixtures of gold and iron nanoparticles. These results open attractive scenarios to the use of kinetically stable nanoalloys for catalysis and energy conversion.Wasserspaltung: Au-Fe-Nanopartikel, die durch Laserablation in Lösung synthetisiert wurden, zeigen eine erhöhte Aktivität in der Sauerstoffentwicklung (siehe Diagramm). Die Ergebnisse liefern beste Aussichten für die Verwendung von Nanolegierungen in der Katalyse und Energieumwandlung.
      PubDate: 2017-05-02T10:47:50.518016-05:
      DOI: 10.1002/ange.201703387
  • Directing Reaction Pathways through Controlled Reactant Binding at
           Pd–TiO2 Interfaces
    • Authors: Jing Zhang; Bingwen Wang, Eranda Nikolla, J. Will Medlin
      Pages: 6694 - 6698
      Abstract: Recent efforts to design selective catalysts for multi-step reactions, such as hydrodeoxygenation (HDO), have emphasized the preparation of active sites at the interface between two materials having different properties. However, achieving precise control over interfacial properties, and thus reaction selectivity, has remained a challenge. Here, we encapsulated Pd nanoparticles (NPs) with TiO2 films of regulated porosity to gain a new level of control over catalyst performance, resulting in essentially 100 % HDO selectivity for two biomass-derived alcohols. This catalyst also showed exceptional reaction specificity in HDO of furfural and m-cresol. In addition to improving HDO activity by maximizing the interfacial contact between the metal and metal oxide sites, encapsulation by the nanoporous oxide film provided a significant selectivity boost by restricting the accessible conformations of aromatics on the surface.Die Nanomorphologie legt die Ausrichtung der Reaktantmoleküle in den aktiven Zentren eines Pd/TiO2-Katalysators fest. Das Resultat ist eine beispiellose Selektivität für die Hydrodeoxygenierung in der katalytischen Umwandlung von aus Biomasse stammenden aromatischen Alkoholen/Aldehyden und Phenolen.
      PubDate: 2017-05-04T06:25:28.748335-05:
      DOI: 10.1002/ange.201703669
  • Fluorophores for Excited-State Intramolecular Proton Transfer by an
           Yttrium Triflate Catalyzed Reaction of Isocyanides with Thiocarboxylic
    • Authors: Shuo Tong; Shun Zhao, Qing He, Qian Wang, Mei-Xiang Wang, Jieping Zhu
      Pages: 6699 - 6703
      Abstract: Discovery of new chemical reactivity of a given functional group can often result in innovative synthesis of important chemical entities that possess unprecedented properties. We designed and developed a one-step synthesis of 5-amino-4-carboxamidothiazoles 1 by an yttrium-triflate-catalyzed reaction of thiocarboxylic acids 2 with isocyanides 3. In this reaction, both reactants 2 and 3 deviated from their normal reactivities because of metal coordination. The resulting heterocycles are novel prototypical structures for the double ESIPT process. Some of them were excited by visible light irradiation and emitted fluorescence at the NIR region with large Stokes shift, high quantum yield, and strong solvatochromism.Farbenfrohe Reaktivität: Die Reaktion von Thiocarbonsäuren mit Isocyaniden in Anwesenheit einer katalytischen Menge von Yttriumtriflat ergab 5-Amino-4-carboxamidothiazole in guter bis exzellenter Ausbeute. Einige dieser Heterocyclen wurden mit sichtbarem Licht angeregt und emittierten Fluoreszenz im Nahinfrarotbereich mit einer großen Stokes-Verschiebung, hoher Quantenausbeute und einer starker positiver Solvatochromie.
      PubDate: 2017-04-13T12:11:14.318325-05:
      DOI: 10.1002/ange.201702488
  • A Rhodium(II)-Catalyzed Formal [4+1]-Cycloaddition toward Spirooxindole
           Pyrrolone Construction Employing Vinyl Isocyanates as 1,4-Dipoles
    • Authors: Jennifer L. Meloche; Brandon L. Ashfeld
      Pages: 6704 - 6708
      Abstract: A RhII-catalyzed, formal [4+1]-cycloaddition between diazooxindoles as electrophilic C1 synthons and 1,3-heterodienes for the construction of spirooxindole pyrrolones is described. Employing vinyl isocyanates as 1,4-dipoles, the cycloannulation occurs under relatively mild conditions and provides the corresponding pyrrolones in good to excellent yields.Einen Ring anstecken: Die Titelreaktion zwischen Diazooxindolen als elektrophilen C1-Bausteinen und 1,3-Heterodienen führt zum Aufbau von Spirooxindolpyrrolonen. Mit Vinylisocyanaten als 1,4-Dipolen läuft die Cycloanellierung unter milden Bedingungen ab, und die Pyrrolone werden in guten bis exzellenten Ausbeuten erhalten.
      PubDate: 2017-05-03T06:50:31.106491-05:
      DOI: 10.1002/ange.201701147
  • Total Synthesis of Rishirilide B by Organocatalytic Oxidative Kinetic
           Resolution: Revision of Absolute Configuration of (+)-Rishirilide B
    • Authors: Minami Odagi; Kota Furukori, Kan Takayama, Keiichi Noguchi, Kazuo Nagasawa
      Pages: 6709 - 6712
      Abstract: Described herein is the enantioselective syntheses of (+)- and (−)-rishirilide B from the corresponding optically active β-substituted tetralones, which were obtained by oxidative kinetic resolution based on α-hydroxylation in the presence of a chiral guanidine-bisurea bifunctional organocatalyst. Benzylic oxidation of the tetralones at C1 followed by regioselective isomerization of the oxabenzonorbornadiene structure led to rishirilide B. Our findings lead to the revision of the previously proposed (2R,3R,4R) absolute configuration of (+)-rishirilide B to (2S,3S,4S).Rekonfiguriert: Eine enantioselektive Synthese von (+)- und (−)-Rishirilid B über ein optisch aktives β-substituiertes Tetralon, das durch oxidative kinetische Racematspaltung mit einem Guanidin-Diharnstoff-Organokatalysator erhalten wurde, führt zur Revision der vorgeschlagenen Absolutkonfiguration von (+)-Rishirilid B zu (2S,3S,4S).
      PubDate: 2017-05-04T06:35:51.86045-05:0
      DOI: 10.1002/ange.201701431
  • A Short Synthesis of (±)-3-Demethoxyerythratidinone by Ligand-Controlled
           Selective Heck Cyclization of Equilibrating Enamines
    • Authors: Emma E. Blackham; Kevin I. Booker-Milburn
      Pages: 6713 - 6716
      Abstract: A short, 5-step total synthesis of (±)-3-demethoxyerythratidinone from a simple pyrrole derivative is described. Features include the formation of gram quantities of a key tricylic aziridine from a challenging photochemical cascade reaction through the use of flow photochemistry. The final step involved a highly unusual Heck cyclization whereby ligand control enabled efficient formation of the natural product in 69 % yield from the minor isomer present in an equilibrating mixture of labile enamines.Fünf Schritte zum Erfolg: Eine kurze Totalsynthese von (±)-3-Demethoxyerythratidinon (1) wurde mit einer Kombination aus Photochemie und Pd-katalysierter Heck-Cyclisierung vollendet. Ein entscheidender Aspekt war die präzise Kontrolle der Heck-Cyclisierung in einem äquilibrierenden Gemisch labiler Enamine durch die Wahl des Liganden.
      PubDate: 2017-05-04T04:50:28.545251-05:
      DOI: 10.1002/ange.201701775
  • Atroposelective Synthesis of Axially Chiral Biaryls by Palladium-Catalyzed
           Asymmetric C−H Olefination Enabled by a Transient Chiral Auxiliary
    • Authors: Qi-Jun Yao; Shuo Zhang, Bei-Bei Zhan, Bing-Feng Shi
      Pages: 6717 - 6721
      Abstract: Atroposelective synthesis of axially chiral biaryls by palladium-catalyzed C−H olefination, using tert-leucine as an inexpensive, catalytic, and transient chiral auxiliary, has been realized. This strategy provides a highly efficient and straightforward access to a broad range of enantioenriched biaryls in good yields (up to 98 %) with excellent enantioselectivities (95 to>99 % ee). Kinetic resolution of trisubstituted biaryls bearing sterically more demanding substituents is also operative, thus furnishing the optically active olefinated products with excellent selectivity (95 to>99 % ee, s-factor up to 600).Keine Anhänge: Die Titelreaktion nutzt tert-Leucin als ein transientes chirales Auxiliar und bietet effizienten Zugang zu enantiomerenangereicherten Biarylen in guten Ausbeuten (bis 98 %) und exzellenten Regioselektivitäten (bis>99 % ee). Bei trisubstituierten Biarylen mit sterisch anspruchsvolleren Substituenten läuft eine kinetische Racematspaltung ab, welche die optisch aktiven olefinierten Produkte mit exzellenter Selektivität (bis>99 % ee, s-Faktor bis 600) liefert.
      PubDate: 2017-05-04T05:01:25.74876-05:0
      DOI: 10.1002/ange.201701849
  • Insights Into How Heme Reduction Potentials Modulate Enzymatic Activities
           of a Myoglobin-based Functional Oxidase
    • Authors: Ambika Bhagi-Damodaran; Maximilian Kahle, Yelu Shi, Yong Zhang, Pia Ädelroth, Yi Lu
      Pages: 6722 - 6726
      Abstract: Heme-copper oxidase (HCO) is a class of respiratory enzymes that use a heme-copper center to catalyze O2 reduction to H2O. While heme reduction potential (E°′) of different HCO types has been found to vary>500 mV, its impact on HCO activity remains poorly understood. Here, we use a set of myoglobin-based functional HCO models to investigate the mechanism by which heme E°′ modulates oxidase activity. Rapid stopped-flow kinetic measurements show that increasing heme E°′ by ca. 210 mV results in increases in electron transfer (ET) rates by 30-fold, rate of O2 binding by 12-fold, O2 dissociation by 35-fold, while decreasing O2 affinity by 3-fold. Theoretical calculations reveal that E°′ modulation has significant implications on electronic charge of both heme iron and O2, resulting in increased O2 dissociation and reduced O2 affinity at high E°′ values. Overall, this work suggests that fine-tuning E°′ in HCOs and other heme enzymes can modulate their substrate affinity, ET rate and enzymatic activity.Die Vier-Elektronen-Reduktion von O2 zu H2O in Häm-Kupfer-Oxidase (HCO) erfordert eine effiziente Kontrolle des Elektronentransfers, der O2-Bindungs-/Dissoziationsraten und der O2-Affinität. Anhand eines funktionellen Modells der HCO wird gezeigt, dass das Häm-Reduktionspotential eine entscheidende Rolle bei der Kontrolle dieser Parameter, der elektronischen Eigenschaften von gebundenem O2 und damit der gesamten enzymatischen Aktivität spielt.
      PubDate: 2017-05-04T05:00:29.208068-05:
      DOI: 10.1002/ange.201701916
  • Synthesis of Layered Carbonitrides from Biotic Molecules for Photoredox
    • Authors: Can Yang; Bo Wang, Linzhu Zhang, Ling Yin, Xinchen Wang
      Pages: 6727 - 6731
      Abstract: The construction of layered covalent carbon nitride polymers based on tri-s-triazine units has been achieved by using nucleobases (adenine, guanine, cytosine, thymine and uracil) and urea to establish a two-dimensional semiconducting structure that allows band-gap engineering applications. This biomolecule-derived binary carbon nitride polymer enables the generation of energized charge carrier with light-irradiation to induce photoredox reactions for stable hydrogen production and heterogeneous organosynthesis of C−O, C−C, C−N and N−N bonds, which may enrich discussion on chemical reactions in prebiotic conditions by taking account of the photoredox function of conjugated carbonitride semiconductors that have long been considered to be stable HCN-derived organic macromolecules in space.Ein präbiotischer Photokatalysator' Graphitische Kohlenstoffnitride, die aus Nukleobasen und Harnstoff synthetisiert wurden, ermöglichen die Photoerzeugung von Ladungsträgern zur Auslösung von Photoredoxreaktionen für die H2-Produktion und die heterogene C-O-, C-C-, C-N- und N-N-Verknüpfung. Die Befunde bereichern das Konzept photochemischer Reaktionen in der präbiotischen Chemie.
      PubDate: 2017-05-04T05:05:30.8016-05:00
      DOI: 10.1002/ange.201702213
  • C−N Bond Activation and Ring Opening of a Saturated N-Heterocyclic
           Carbene by Lateral Alkali-Metal-Mediated Metalation
    • Authors: Alberto Hernán-Gómez; Alan R. Kennedy, Eva Hevia
      Pages: 6732 - 6735
      Abstract: Combining alkali-metal-mediated metalation (AMMM) and N-heterocyclic carbene (NHC) chemistry, a novel C−N bond activation and ring-opening process is described for these increasingly important NHC molecules, which are generally considered robust ancillary ligands. Here, mechanistic investigations on reactions of saturated NHC SIMes (SIMes=[:C{N(2,4,6-Me3C6H2)CH2}2]) with Group 1 alkyl bases suggest this destructive process is triggered by lateral metalation of the carbene. Exploiting co-complexation and trans-metal-trapping strategies with lower polarity organometallic reagents (Mg(CH2SiMe3)2 and Al(TMP)iBu2), key intermediates in this process have been isolated and structurally defined.Ko-lateralschaden: Die laterale Metallierung des gesättigten N-heterocyclischen Carbens [:C{N(2,4,6-Me3C6H2)CH2}2] (SIMes) löst einen destruktiven Prozess aus, der die Aktivierung der C-N-Bindung und die Ringöffnung des fünfgliedrigen heterocyclischen Rings induziert (siehe Schema).
      PubDate: 2017-05-10T07:30:55.726501-05:
      DOI: 10.1002/ange.201702246
  • Palladium-Catalyzed Regioselective Synthesis of 3-Arylindoles from
           N-Ts-Anilines and Styrenes
    • Authors: So Won Youn; Tae Yun Ko, Young Ho Jang
      Pages: 6736 - 6740
      Abstract: A Pd-catalyzed intermolecular oxidative annulation between N-Ts-anilines and styrenes was developed. This method offers a straightforward and robust approach to a wide range of 3-arylindoles using readily available starting materials with good functional-group tolerance and high regioselectivity and efficiency. Further elaboration of the products obtained from this process provided access to highly functionalized and structurally diverse indoles, for example, 3-(indol-3-yl)carbazoles, 1,9-dihydropyrrolo-[2,3-b]carbazoles, and 3′-aryl-3,5′-biindoles.Wichtige Ergänzung: Eine Pd-katalysierte intermolekulare oxidative Anellierung für die C-C/C-N-Bindungsbildung im Eintopfverfahren wurde entwickelt. Entgegen dem Regioselektivitätsmuster verwandter Methoden bietet diese Synthese effizienten Zugang zu den präparativ wertvollen 3-Arylindolen, die vormals aus Styrolen und Anilinen nicht zugänglich waren.
      PubDate: 2017-05-02T10:42:26.002816-05:
      DOI: 10.1002/ange.201702205
  • Palladium-Catalyzed Cascade sp2 C−H Functionalization/Intramolecular
    • Authors: Shu-Sen Chen; Min-Song Wu, Zhi-Yong Han
      Pages: 6741 - 6745
      Abstract: A chiral PdII-catalyzed cascade sp2 C−H functionalization/intramolecular asymmetric allylation reaction is reported. A new chiral sulfoxide–oxazoline (SOX) ligand bearing single chiral center on the sulfur was identified as the optimal ligand for the reaction, being efficient both in the C−H cleavage step and the stereocontrol of the allylation step. The broad scope of this method with respect to aryl ureas and 1,3-dienes enables the rapid construction of valuable chiral indoline derivatives with high yields and enantioselectivities (up to 99 % yield, up to 95:5 e.r.).Chiral und effizient: Für eine PdII-katalysierte Kaskade aus C(sp2)-H-Funktionalisierung und intramolekularer asymmetrischer Allylierung wurde ein chirales Sulfoxid-Oxazolin (SOX), das ausschließlich ein Schwefel-Chiralitätszentrum enthält, als optimaler Ligand identifiziert, der sowohl eine effiziente C-H-Bindungsspaltung als auch eine stereokontrollierte Allylierung vermittelt.
      PubDate: 2017-05-03T08:16:13.399929-05:
      DOI: 10.1002/ange.201702745
  • Copper(I)-Catalyzed Enantioselective Nucleophilic Borylation of Aliphatic
    • Authors: Koji Kubota; Shun Osaki, Mingoo Jin, Hajime Ito
      Pages: 6746 - 6750
      Abstract: A new method was developed for the first catalytic enantioselective borylation of aliphatic ketones. A variety of substrates reacted efficiently with bis(pinacolato)diboron in the presence of a copper(I)/chiral N-heterocyclic carbene complex catalyst to furnish optically active tertiary α-hydroxyboronates with moderate to high enantioselectivities (up to 94 % ee). Notably, the product could be converted into the chiral tertiary alcohol derivative using a stereospecific boron functionalization process. The theoretical study of the mechanism for the enantioselectivity is also described.Ketonfunktionalisierung: Die erste katalytische enantioselektive Borylierung von Ketonen wird vorgestellt. Eine Vielzahl von aliphatischen Ketonen reagiert effizient mit Bis(pinakolato)dibor in Gegenwart eines chiralen NHC/Kupfer(I)-Komplexes zu den entsprechenden tertiären α-Hydroxyboronatestern mit mittleren bis hohen Enantioselektivitäten.
      PubDate: 2017-05-03T06:45:53.249398-05:
      DOI: 10.1002/ange.201702826
  • Palladium-Catalyzed Enantioselective Redox-Relay Heck Alkynylation of
           Alkenols To Access Propargylic Stereocenters
    • Authors: Zhi-Min Chen; Christine S. Nervig, Ryan J. DeLuca, Matthew S. Sigman
      Pages: 6751 - 6754
      Abstract: An enantioselective redox-relay Heck alkynylation of di- and trisubstituted alkenols to construct propargylic stereocenters is disclosed using a new pyridine oxazoline ligand. This strategy allows direct access to chiral β-alkynyl carbonyl compounds employing allylic alcohol substrates in contrast to more traditional conjugate addition methods.Heck-Alkinylierung: Eine bequeme Redox-Relay-Heck-Strategie zur Synthese von enantiomerenangereicherten β-Alkinylcarbonylverbindungen aus Allylalkoholen wurde entwickelt. Trisubstituierte Allylalkohole sind auch vielversprechende Substrate für die Bildung von propargylischen quartären Stereozentren.
      PubDate: 2017-05-03T06:45:57.867118-05:
      DOI: 10.1002/ange.201703089
  • Unterschiedliche Reaktivität von As4 gegenüber Disilenen und
    • Authors: Andreas E. Seitz; Maria Eckhardt, Sakya S. Sen, Andreas Erlebach, Eugenia V. Peresypkina, Herbert W. Roesky, Marek Sierka, Manfred Scheer
      Pages: 6755 - 6759
      Abstract: Über die Aktivierung von gelbem Arsen mit dem Silylen [PhC(NtBu)2SiN(SiMe3)2] (1) und dem Disilen [(Me3Si)2N(η1-Me5C5)Si=Si(η1-Me5C5)N(SiMe3)2] (3) wird berichtet. Die Reaktion von As4 mit 1 führt zur präzedenzlosen As10-Käfigverbindung [(LSiN(SiMe3)2)3As10] (2) (L=PhC(NtBu)2) mit einem As7-Nortricyclan-Gerüst, das von Silicium(II)-bis(trimethylsilyl)amid-Substituenten enthaltenden Arsasilenresten stabilisiert wird. Dagegen wird die Verbindung [Cp*{(SiMe3)2N}SiAs]2 (4), die eine “Butterfly”-ähnliche Diarsadisilabicyclo[1.1.0]butan-Einheit enthält, durch die Reaktion von As4 mit dem Disilen 3 gebildet. Beide Verbindungen wurden durch Einkristall-Röntgenstrukturanalyse, NMR-Spektroskopie und Massenspektrometrie charakterisiert. Die Ergebnisse zeigen das unterschiedliche Reaktionsverhalten von gelbem Arsen (As4) im Vergleich zum weißen Phosphor (P4) in den Reaktionen mit den entsprechenden Silylenen und Disilenen.Die Reaktion von gelbem Arsen mit dem Silylen [PhC(NtBu)2SiN(SiMe3)2] und dem Disilen [(Me3Si)2N(η1-Me5C5)Si=Si(η1-Me5C5)N(SiMe3)2] ergibt eine As10-Käfigverbindung mit einem Nortricyclan-Gerüst bzw. ein Diarsadisila-„Butterfly”-Derivat. Diese Reaktionen zeigen das unterschiedliche Verhalten von gelbem Arsen (As4) und weißem Phosphor (P4) gegenüber entsprechenden Siliciumderivaten.
      PubDate: 2017-05-04T04:50:54.639622-05:
      DOI: 10.1002/ange.201701740
  • Mangan(I)-katalysierte regioselektive C-H-Allenierung: direkte Synthese
           von 2-Allenylindolen
    • Authors: Qingquan Lu; Steffen Greßies, Felix J. R. Klauck, Frank Glorius
      Pages: 6760 - 6764
      Abstract: Eine regioselektive und durch Mangan(I)-katalysierte C-H-Allenierung wird beschrieben. Diese ermöglicht einen einfachen Zugang zu einer Reihe von 2-Allenylindolen, auch im Grammmaßstab. Durch Chiralitätstransfer können bis zu 93 % ee erreicht werden. Mit leicht modifizierten Reaktionsbedingungen können außerdem zum ersten Mal Ketone direkt über Mangan(I)-katalysierte C-H-Aktivierung hergestellt werden. Mechanistische Untersuchungen unterstreichen die große Bedeutung der Koordination des Carbonat-Sauerstoffatoms an den Katalysator und des tertiären Kohlenstoffatoms.Magisches Mangan: Die Titelreaktion ermöglicht einen einfachen Zugang zu 2-Allenylindolen mit effizientem Chiralitätstransfer, außerdem lassen sich erstmals Ketone direkt durch eine MnI-katalysierte C-H-Aktivierung herstellen. Die Koordination des Carbonat-Sauerstoffatoms an den Mn-Katalysator und das tertiäre Kohlenstoffatom spielen eine entscheidende Rolle im Reaktionsmechanismus.
      PubDate: 2017-05-02T10:57:47.582495-05:
      DOI: 10.1002/ange.201701767
  • Die Biosynthese der β-Lacton-haltigen Proteasominhibitoren Belactosin
           und Cystargolid
    • Authors: Felix Wolf; Judith S. Bauer, Theresa M. Bendel, Andreas Kulik, Jörn Kalinowski, Harald Gross, Leonard Kaysser
      Pages: 6765 - 6769
      Abstract: Belactosine und Cystargolide sind von Actinobakterien produzierte Naturstoffe mit proteasominhibitorischen Eigenschaften. Beide weisen ein Peptidrückgrat aus zwei Aminosäuren sowie einen einzigartigen β-Lacton-Baustein auf. Hier wird eine detaillierte Untersuchung der Biosynthese der beiden Naturstoffe beschrieben. Die Identifizierung und Analyse der entsprechenden Gencluster weist darauf hin, dass beide Stoffe über seltene Aminosäure-Ligasen gebildet werden. Fütterungsversuche mit isotopenmarkierten Vorstufen und In-vitro-Biochemie zeigen einen bislang unbeschriebenen Mechanismus zur β-Lacton-Biosynthese, der sich aus der Leucin-Bildung ableitet und die Beteiligung eines Isopropylmalat-Synthase-ähnlichen Enzyms vorsieht.Der Weg zum Lacton: Die Biosynthese der peptidischen β-Lacton-haltigen Proteasominhibitoren Belactosin und Cystargolid folgt einem NRPS- und PKS-unabhängigen Syntheseweg. Ihr β-Lacton-Rest wird unter Mithilfe eines Isopropylmalat-Synthase-ähnlichen Enzyms in Analogie zur Leucin-Biosynthese gebildet. Die Bildung des Peptidrückgrats erfolgt durch eigenständige Aminosäuren-Ligasen.
      PubDate: 2017-04-28T02:51:14.517352-05:
      DOI: 10.1002/ange.201612076
  • Ultraschnelle Schichtablösung von Graphit zu qualitativ hochwertigem
           Graphen durch Nutzung von Wechselstrom
    • Authors: Sheng Yang; Antonio Gaetano Ricciardulli, Shaohua Liu, Renhao Dong, Martin R. Lohe, Alfons Becker, Marco A. Squillaci, Paolo Samorì, Klaus Müllen, Xinliang Feng
      Pages: 6770 - 6776
      Abstract: Um die Lücke zwischen Forschung im Labormaßstab und kommerzieller Anwendung zu schließen, ist die Massenproduktion von qualitativ hochwertigem Graphen unerlässlich. Hier wird eine skalierbare Exfolierungsstrategie beschrieben, die zur Herstellung von Graphenplättchen mit hohem Ertrag (75 %, 1–3 Schichten), geringer Defektdichte (C/O-Verhältnis von 21.2), sehr guter Verarbeitbarkeit in Lösung und hervorragenden elektronischen Eigenschaften (Loch-Mobilität von 430 cm2 V−1 s−1) führt. Durch die Anwendung von Wechselstrom erfolgt eine gleichzeitige Exfolierung an beiden Graphitelektroden, welche eine hohe Produktionsrate von über 20 g h−1 im Labormaßstab ermöglicht. Als Kathodenmaterial für Lithiumspeicher verfügen mit Graphen ummantelte LiFePO4-Partikel über eine hohe Kapazität von 167 mAh g−1 bei einer C-Rate von 1 nach 500 Zyklen.Graphen „aus der Steckdose”: Eine einfache, kostengünstige und hocheffiziente Methode zur Exfolierung von Graphit zu qualitativ hochwertigem Graphen mittels Wechselstrom wurde entwickelt. Das Verfahren besitzt großes Potenzial, um die Kluft zwischen Laborforschung und kommerzieller Anwendung zu überbrücken.
      PubDate: 2017-05-03T06:45:45.029511-05:
      DOI: 10.1002/ange.201702076
  • Innenrücktitelbild: Synthesis and Bowl-in-Bowl Assembly of a Geodesic
           Phenylene Bowl (Angew. Chem. 23/2017)
    • Authors: Koki Ikemoto; Ryo Kobayashi, Sota Sato, Hiroyuki Isobe
      Pages: 6777 - 6777
      Abstract: Eine kohlenstoffreiche geodätische Kuppel wurde durch Zusammenschluss von 20 trigonal-planar 1,3,5-verknüpften Phenylenen über 25 Biaryl-Bindungen konstruiert. H. Isobe et al. beschreiben in ihrer Zuschrift auf S. 6611 den Weg über die Kombination der Corannulenoide mit einem zentralen fünfeckigen Versatzstück zur geodätischen Nanoschale. Ein Konkav-konvex-Erkennungsmechanismus resultiert in der Bildung molekularer Schale-in-Schale-Dimere, die im Kristall und in Lösung vorliegen.
      PubDate: 2017-05-03T08:21:01.933461-05:
      DOI: 10.1002/ange.201703999
  • Rücktitelbild: Fluorophores for Excited-State Intramolecular Proton
           Transfer by an Yttrium Triflate Catalyzed Reaction of Isocyanides with
           Thiocarboxylic Acids (Angew. Chem. 23/2017)
    • Authors: Shuo Tong; Shun Zhao, Qing He, Qian Wang, Mei-Xiang Wang, Jieping Zhu
      Pages: 6778 - 6778
      Abstract: Die Eintopfsynthese …… von 5-Amino-4-carboxamidothiazolen durch die Yttriumtriflat-katalysierte Reaktion zwischen Thiocarbonsäuren und Isocyaniden wird von J. Zhu et al. in ihrer Zuschrift auf S. 6699 vorgestellt. Die erhaltenen Heterocyclen sind prototypische Strukturen für den doppelten intramolekularen Protonentransfer im angeregten Zustand (ESIPT) und könnten als Templat für die Synthese von ESICT-ESIPT-gekoppelten Molekülen dienen (CT=Ladungstransfer).
      PubDate: 2017-05-11T08:11:03.453845-05:
      DOI: 10.1002/ange.201703995
  • Makoto Yamashita
    • Pages: 6470 - 6470
      Abstract: „Ich verliere mein Zeitgefühl, wenn ich Kristallstrukturen löse. Das Wichtigste, was ich von meinen Eltern gelernt habe, ist Optimismus ...“ Dies und mehr von und über Makoto Yamashita finden Sie auf Seite 6470.
      PubDate: 2016-11-16T05:00:04.109637-05:
      DOI: 10.1002/ange.201610865
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