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Publisher: John Wiley and Sons   (Total: 1589 journals)

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Showing 1 - 200 of 1589 Journals sorted alphabetically
Abacus     Hybrid Journal   (Followers: 12, SJR: 0.48, h-index: 22)
About Campus     Hybrid Journal   (Followers: 5)
Academic Emergency Medicine     Hybrid Journal   (Followers: 65, SJR: 1.385, h-index: 91)
Accounting & Finance     Hybrid Journal   (Followers: 47, SJR: 0.547, h-index: 30)
ACEP NOW     Free   (Followers: 1)
Acta Anaesthesiologica Scandinavica     Hybrid Journal   (Followers: 52, SJR: 1.02, h-index: 88)
Acta Archaeologica     Hybrid Journal   (Followers: 164, SJR: 0.101, h-index: 9)
Acta Geologica Sinica (English Edition)     Hybrid Journal   (Followers: 3, SJR: 0.552, h-index: 41)
Acta Neurologica Scandinavica     Hybrid Journal   (Followers: 5, SJR: 1.203, h-index: 74)
Acta Obstetricia et Gynecologica Scandinavica     Hybrid Journal   (Followers: 15, SJR: 1.197, h-index: 81)
Acta Ophthalmologica     Hybrid Journal   (Followers: 6, SJR: 0.112, h-index: 1)
Acta Paediatrica     Hybrid Journal   (Followers: 56, SJR: 0.794, h-index: 88)
Acta Physiologica     Hybrid Journal   (Followers: 6, SJR: 1.69, h-index: 88)
Acta Polymerica     Hybrid Journal   (Followers: 9)
Acta Psychiatrica Scandinavica     Hybrid Journal   (Followers: 35, SJR: 2.518, h-index: 113)
Acta Zoologica     Hybrid Journal   (Followers: 7, SJR: 0.459, h-index: 29)
Acute Medicine & Surgery     Hybrid Journal   (Followers: 4)
Addiction     Hybrid Journal   (Followers: 35, SJR: 2.086, h-index: 143)
Addiction Biology     Hybrid Journal   (Followers: 14, SJR: 2.091, h-index: 57)
Adultspan J.     Hybrid Journal   (SJR: 0.127, h-index: 4)
Advanced Energy Materials     Hybrid Journal   (Followers: 27, SJR: 6.411, h-index: 86)
Advanced Engineering Materials     Hybrid Journal   (Followers: 26, SJR: 0.81, h-index: 81)
Advanced Functional Materials     Hybrid Journal   (Followers: 51, SJR: 5.21, h-index: 203)
Advanced Healthcare Materials     Hybrid Journal   (Followers: 14, SJR: 0.232, h-index: 7)
Advanced Materials     Hybrid Journal   (Followers: 268, SJR: 9.021, h-index: 345)
Advanced Materials Interfaces     Hybrid Journal   (Followers: 6, SJR: 1.177, h-index: 10)
Advanced Optical Materials     Hybrid Journal   (Followers: 7, SJR: 2.488, h-index: 21)
Advanced Science     Open Access   (Followers: 5)
Advanced Synthesis & Catalysis     Hybrid Journal   (Followers: 17, SJR: 2.729, h-index: 121)
Advances in Polymer Technology     Hybrid Journal   (Followers: 13, SJR: 0.344, h-index: 31)
Africa Confidential     Hybrid Journal   (Followers: 21)
Africa Research Bulletin: Economic, Financial and Technical Series     Hybrid Journal   (Followers: 13)
Africa Research Bulletin: Political, Social and Cultural Series     Hybrid Journal   (Followers: 10)
African Development Review     Hybrid Journal   (Followers: 33, SJR: 0.275, h-index: 17)
African J. of Ecology     Hybrid Journal   (Followers: 16, SJR: 0.477, h-index: 39)
Aggressive Behavior     Hybrid Journal   (Followers: 15, SJR: 1.391, h-index: 66)
Aging Cell     Open Access   (Followers: 11, SJR: 4.374, h-index: 95)
Agribusiness : an Intl. J.     Hybrid Journal   (Followers: 3, SJR: 0.627, h-index: 14)
Agricultural and Forest Entomology     Hybrid Journal   (Followers: 16, SJR: 0.925, h-index: 43)
Agricultural Economics     Hybrid Journal   (Followers: 45, SJR: 1.099, h-index: 51)
AIChE J.     Hybrid Journal   (Followers: 32, SJR: 1.122, h-index: 120)
Alcoholism and Drug Abuse Weekly     Hybrid Journal   (Followers: 7)
Alcoholism Clinical and Experimental Research     Hybrid Journal   (Followers: 7, SJR: 1.416, h-index: 125)
Alimentary Pharmacology & Therapeutics     Hybrid Journal   (Followers: 33, SJR: 2.833, h-index: 138)
Alimentary Pharmacology & Therapeutics Symposium Series     Hybrid Journal   (Followers: 3)
Allergy     Hybrid Journal   (Followers: 51, SJR: 3.048, h-index: 129)
Alternatives to the High Cost of Litigation     Hybrid Journal   (Followers: 3)
American Anthropologist     Hybrid Journal   (Followers: 148, 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: 92, SJR: 2.325, h-index: 51)
American J. of Economics and Sociology     Hybrid Journal   (Followers: 29, SJR: 0.211, h-index: 26)
American J. of Hematology     Hybrid Journal   (Followers: 34, SJR: 1.761, h-index: 77)
American J. of Human Biology     Hybrid Journal   (Followers: 12, SJR: 1.018, h-index: 58)
American J. of Industrial Medicine     Hybrid Journal   (Followers: 16, SJR: 0.993, h-index: 85)
American J. of Medical Genetics Part A     Hybrid Journal   (Followers: 16, SJR: 1.115, h-index: 61)
American J. of Medical Genetics Part B: Neuropsychiatric Genetics     Hybrid Journal   (Followers: 4, SJR: 1.771, h-index: 107)
American J. of Medical Genetics Part C: Seminars in Medical Genetics     Partially Free   (Followers: 6, SJR: 2.315, h-index: 79)
American J. of Physical Anthropology     Hybrid Journal   (Followers: 37, SJR: 1.41, h-index: 88)
American J. of Political Science     Hybrid Journal   (Followers: 276, SJR: 5.101, h-index: 114)
American J. of Primatology     Hybrid Journal   (Followers: 15, SJR: 1.197, h-index: 63)
American J. of Reproductive Immunology     Hybrid Journal   (Followers: 3, SJR: 1.347, h-index: 75)
American J. of Transplantation     Hybrid Journal   (Followers: 17, SJR: 2.792, h-index: 140)
American J. on Addictions     Hybrid Journal   (Followers: 9, SJR: 0.843, h-index: 57)
Anaesthesia     Hybrid Journal   (Followers: 138, SJR: 1.404, h-index: 88)
Analyses of Social Issues and Public Policy     Hybrid Journal   (Followers: 9, SJR: 0.397, h-index: 18)
Analytic Philosophy     Hybrid Journal   (Followers: 18)
Anatomia, Histologia, Embryologia: J. of Veterinary Medicine Series C     Hybrid Journal   (Followers: 3, SJR: 0.295, h-index: 27)
Anatomical Sciences Education     Hybrid Journal   (Followers: 1, SJR: 0.633, h-index: 24)
Andrologia     Hybrid Journal   (Followers: 2, SJR: 0.528, h-index: 45)
Andrology     Hybrid Journal   (Followers: 2, SJR: 0.979, h-index: 14)
Angewandte Chemie     Hybrid Journal   (Followers: 220)
Angewandte Chemie Intl. Edition     Hybrid Journal   (Followers: 222, SJR: 6.229, h-index: 397)
Animal Conservation     Hybrid Journal   (Followers: 41, SJR: 1.576, h-index: 62)
Animal Genetics     Hybrid Journal   (Followers: 8, SJR: 0.957, h-index: 67)
Animal Science J.     Hybrid Journal   (Followers: 6, SJR: 0.569, h-index: 24)
Annalen der Physik     Hybrid Journal   (Followers: 5, SJR: 1.46, h-index: 40)
Annals of Anthropological Practice     Partially Free   (Followers: 2, SJR: 0.187, h-index: 5)
Annals of Applied Biology     Hybrid Journal   (Followers: 7, SJR: 0.816, h-index: 56)
Annals of Clinical and Translational Neurology     Open Access   (Followers: 1)
Annals of Human Genetics     Hybrid Journal   (Followers: 9, SJR: 1.191, h-index: 67)
Annals of Neurology     Hybrid Journal   (Followers: 47, SJR: 5.584, h-index: 241)
Annals of Noninvasive Electrocardiology     Hybrid Journal   (Followers: 1, SJR: 0.531, h-index: 38)
Annals of Public and Cooperative Economics     Hybrid Journal   (Followers: 8, SJR: 0.336, h-index: 23)
Annals of the New York Academy of Sciences     Hybrid Journal   (Followers: 5, SJR: 2.389, h-index: 189)
Annual Bulletin of Historical Literature     Hybrid Journal   (Followers: 13)
Annual Review of Information Science and Technology     Hybrid Journal   (Followers: 14)
Anthropology & Education Quarterly     Hybrid Journal   (Followers: 25, SJR: 0.72, h-index: 31)
Anthropology & Humanism     Hybrid Journal   (Followers: 17, SJR: 0.137, h-index: 3)
Anthropology News     Hybrid Journal   (Followers: 15)
Anthropology of Consciousness     Hybrid Journal   (Followers: 11, SJR: 0.172, h-index: 5)
Anthropology of Work Review     Hybrid Journal   (Followers: 11, SJR: 0.256, h-index: 5)
Anthropology Today     Hybrid Journal   (Followers: 89, SJR: 0.545, h-index: 15)
Antipode     Hybrid Journal   (Followers: 49, SJR: 2.212, h-index: 69)
Anz J. of Surgery     Hybrid Journal   (Followers: 8, SJR: 0.432, h-index: 59)
Anzeiger für Schädlingskunde     Hybrid Journal   (Followers: 1)
Apmis     Hybrid Journal   (Followers: 1, SJR: 0.855, h-index: 73)
Applied Cognitive Psychology     Hybrid Journal   (Followers: 70, SJR: 0.754, h-index: 69)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 7, SJR: 0.632, h-index: 58)
Applied Psychology     Hybrid Journal   (Followers: 206, SJR: 1.023, h-index: 64)
Applied Psychology: Health and Well-Being     Hybrid Journal   (Followers: 49, SJR: 0.868, h-index: 13)
Applied Stochastic Models in Business and Industry     Hybrid Journal   (Followers: 5, SJR: 0.613, h-index: 24)
Aquaculture Nutrition     Hybrid Journal   (Followers: 14, SJR: 1.025, h-index: 55)
Aquaculture Research     Hybrid Journal   (Followers: 31, SJR: 0.807, h-index: 60)
Aquatic Conservation Marine and Freshwater Ecosystems     Hybrid Journal   (Followers: 36, SJR: 1.047, h-index: 57)
Arabian Archaeology and Epigraphy     Hybrid Journal   (Followers: 11, SJR: 0.453, h-index: 11)
Archaeological Prospection     Hybrid Journal   (Followers: 12, SJR: 0.922, h-index: 21)
Archaeology in Oceania     Hybrid Journal   (Followers: 13, SJR: 0.745, h-index: 18)
Archaeometry     Hybrid Journal   (Followers: 27, SJR: 0.809, h-index: 48)
Archeological Papers of The American Anthropological Association     Hybrid Journal   (Followers: 15, SJR: 0.156, h-index: 2)
Architectural Design     Hybrid Journal   (Followers: 25, SJR: 0.261, h-index: 9)
Archiv der Pharmazie     Hybrid Journal   (Followers: 3, SJR: 0.628, h-index: 43)
Archives of Drug Information     Hybrid Journal   (Followers: 5)
Archives of Insect Biochemistry and Physiology     Hybrid Journal   (SJR: 0.768, h-index: 54)
Area     Hybrid Journal   (Followers: 12, SJR: 0.938, h-index: 57)
Art History     Hybrid Journal   (Followers: 245, SJR: 0.153, h-index: 13)
Arthritis & Rheumatology     Hybrid Journal   (Followers: 52, 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: 15)
Asia & the Pacific Policy Studies     Open Access   (Followers: 16)
Asia Pacific J. of Human Resources     Hybrid Journal   (Followers: 320, SJR: 0.494, h-index: 19)
Asia Pacific Viewpoint     Hybrid Journal   (Followers: 1, SJR: 0.616, h-index: 26)
Asia-Pacific J. of Chemical Engineering     Hybrid Journal   (Followers: 8, SJR: 0.345, h-index: 20)
Asia-pacific J. of Clinical Oncology     Hybrid Journal   (Followers: 6, SJR: 0.554, h-index: 14)
Asia-Pacific J. of Financial Studies     Hybrid Journal   (SJR: 0.241, h-index: 7)
Asia-Pacific Psychiatry     Hybrid Journal   (Followers: 4, SJR: 0.377, h-index: 7)
Asian Economic J.     Hybrid Journal   (Followers: 8, SJR: 0.234, h-index: 21)
Asian Economic Policy Review     Hybrid Journal   (Followers: 4, SJR: 0.196, h-index: 12)
Asian J. of Control     Hybrid Journal   (SJR: 0.862, h-index: 34)
Asian J. of Endoscopic Surgery     Hybrid Journal   (SJR: 0.394, h-index: 7)
Asian J. of Organic Chemistry     Hybrid Journal   (Followers: 6, SJR: 1.443, h-index: 19)
Asian J. of Social Psychology     Hybrid Journal   (Followers: 5, SJR: 0.665, h-index: 37)
Asian Politics and Policy     Hybrid Journal   (Followers: 12, SJR: 0.207, h-index: 7)
Asian Social Work and Policy Review     Hybrid Journal   (Followers: 5, SJR: 0.318, h-index: 5)
Asian-pacific Economic Literature     Hybrid Journal   (Followers: 5, SJR: 0.168, h-index: 15)
Assessment Update     Hybrid Journal   (Followers: 4)
Astronomische Nachrichten     Hybrid Journal   (Followers: 2, SJR: 0.701, h-index: 40)
Atmospheric Science Letters     Open Access   (Followers: 29, SJR: 1.332, h-index: 27)
Austral Ecology     Hybrid Journal   (Followers: 15, SJR: 1.095, h-index: 66)
Austral Entomology     Hybrid Journal   (Followers: 9, SJR: 0.524, h-index: 28)
Australasian J. of Dermatology     Hybrid Journal   (Followers: 8, SJR: 0.714, h-index: 40)
Australasian J. On Ageing     Hybrid Journal   (Followers: 6, SJR: 0.39, h-index: 22)
Australian & New Zealand J. of Statistics     Hybrid Journal   (Followers: 14, SJR: 0.275, h-index: 28)
Australian Accounting Review     Hybrid Journal   (Followers: 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: 47, SJR: 0.814, h-index: 49)
Australian and New Zealand J. of Public Health     Hybrid Journal   (Followers: 11, SJR: 0.82, h-index: 62)
Australian Dental J.     Hybrid Journal   (Followers: 7, SJR: 0.482, h-index: 46)
Australian Economic History Review     Hybrid Journal   (Followers: 5, SJR: 0.171, h-index: 12)
Australian Economic Papers     Hybrid Journal   (Followers: 31, SJR: 0.23, h-index: 9)
Australian Economic Review     Hybrid Journal   (Followers: 6, SJR: 0.357, h-index: 21)
Australian Endodontic J.     Hybrid Journal   (Followers: 3, SJR: 0.513, h-index: 24)
Australian J. of Agricultural and Resource Economics     Hybrid Journal   (Followers: 3, SJR: 0.765, h-index: 36)
Australian J. of Grape and Wine Research     Hybrid Journal   (Followers: 5, SJR: 0.879, h-index: 56)
Australian J. of Politics & History     Hybrid Journal   (Followers: 14, SJR: 0.203, h-index: 14)
Australian J. of Psychology     Hybrid Journal   (Followers: 18, SJR: 0.384, h-index: 30)
Australian J. of Public Administration     Hybrid Journal   (Followers: 406, SJR: 0.418, h-index: 29)
Australian J. of Rural Health     Hybrid Journal   (Followers: 5, SJR: 0.43, h-index: 34)
Australian Occupational Therapy J.     Hybrid Journal   (Followers: 72, SJR: 0.59, h-index: 29)
Australian Psychologist     Hybrid Journal   (Followers: 12, SJR: 0.331, h-index: 31)
Australian Veterinary J.     Hybrid Journal   (Followers: 21, SJR: 0.459, h-index: 45)
Autism Research     Hybrid Journal   (Followers: 36, SJR: 2.126, h-index: 39)
Autonomic & Autacoid Pharmacology     Hybrid Journal   (SJR: 0.371, h-index: 29)
Banks in Insurance Report     Hybrid Journal   (Followers: 1)
Basic & Clinical Pharmacology & Toxicology     Hybrid Journal   (Followers: 11, SJR: 0.539, h-index: 70)
Basic and Applied Pathology     Open Access   (Followers: 2, SJR: 0.113, h-index: 4)
Basin Research     Hybrid Journal   (Followers: 5, SJR: 1.54, h-index: 60)
Bauphysik     Hybrid Journal   (Followers: 2, SJR: 0.194, h-index: 5)
Bauregelliste A, Bauregelliste B Und Liste C     Hybrid Journal  
Bautechnik     Hybrid Journal   (Followers: 1, SJR: 0.321, h-index: 11)
Behavioral Interventions     Hybrid Journal   (Followers: 9, SJR: 0.297, h-index: 23)
Behavioral Sciences & the Law     Hybrid Journal   (Followers: 24, SJR: 0.736, h-index: 57)
Berichte Zur Wissenschaftsgeschichte     Hybrid Journal   (Followers: 10, SJR: 0.11, h-index: 5)
Beton- und Stahlbetonbau     Hybrid Journal   (Followers: 2, SJR: 0.493, h-index: 14)
Biochemistry and Molecular Biology Education     Hybrid Journal   (Followers: 6, SJR: 0.311, h-index: 26)
Bioelectromagnetics     Hybrid Journal   (Followers: 1, SJR: 0.568, h-index: 64)
Bioengineering & Translational Medicine     Open Access  
BioEssays     Hybrid Journal   (Followers: 10, SJR: 3.104, h-index: 155)
Bioethics     Hybrid Journal   (Followers: 14, SJR: 0.686, h-index: 39)
Biofuels, Bioproducts and Biorefining     Hybrid Journal   (Followers: 1, SJR: 1.725, h-index: 56)
Biological J. of the Linnean Society     Hybrid Journal   (Followers: 16, SJR: 1.172, h-index: 90)
Biological Reviews     Hybrid Journal   (Followers: 4, SJR: 6.469, h-index: 114)
Biologie in Unserer Zeit (Biuz)     Hybrid Journal   (Followers: 41, 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: 44, SJR: 0.415, h-index: 55)
Biotechnology and Bioengineering     Hybrid Journal   (Followers: 141, SJR: 1.633, h-index: 146)
Biotechnology J.     Hybrid Journal   (Followers: 14, SJR: 1.185, h-index: 51)
Biotechnology Progress     Hybrid Journal   (Followers: 39, SJR: 0.736, h-index: 101)
Biotropica     Hybrid Journal   (Followers: 20, SJR: 1.374, h-index: 71)
Bipolar Disorders     Hybrid Journal   (Followers: 9, SJR: 2.592, h-index: 100)
Birth     Hybrid Journal   (Followers: 38, SJR: 0.763, h-index: 64)
Birth Defects Research Part A : Clinical and Molecular Teratology     Hybrid Journal   (Followers: 2, SJR: 0.727, h-index: 77)
Birth Defects Research Part B: Developmental and Reproductive Toxicology     Hybrid Journal   (Followers: 6, SJR: 0.468, h-index: 47)
Birth Defects Research Part C : Embryo Today : Reviews     Hybrid Journal   (SJR: 1.513, h-index: 55)
BJOG : An Intl. J. of Obstetrics and Gynaecology     Partially Free   (Followers: 243, SJR: 2.083, h-index: 125)

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Journal Cover Angewandte Chemie International Edition
  [SJR: 6.229]   [H-I: 397]   [222 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1433-7851 - ISSN (Online) 1521-3773
   Published by John Wiley and Sons Homepage  [1589 journals]
  • Hierarchical Hollow Nanoprisms Based on Ultrathin Ni-Fe Layered Double
           Hydroxide Nanosheets with Enhanced Electrocatalytic Activity towards
           Oxygen Evolution
    • Authors: Le Yu; Jing Fan Yang, Bu Yuan Guan, Yan Lu, Xiong Wen (David) Lou
      Abstract: The oxygen evolution reaction (OER) is involved in various renewable energy systems, such as water-splitting cells and metal–air batteries. Ni-Fe layered double hydroxides (LDHs) have been reported as promising OER electrocatalysts in alkaline electrolytes. The rational design of advanced nanostructures for Ni-Fe LDHs is highly desirable to optimize their electrocatalytic performance. Herein, we report a facile self-templated strategy for the synthesis of novel hierarchical hollow nanoprisms composed of ultrathin Ni-Fe LDH nanosheets. Tetragonal nanoprisms of nickel precursors were first synthesized as the self-sacrificing template. Afterwards, these Ni precursors were consumed during the hydrolysis of iron(II) sulfate for the simultaneous growth of a layer of Ni-Fe LDH nanosheets on the surface. The resultant Ni-Fe LDH hollow prisms with large surface areas manifest high electrocatalytic activity towards the OER with low overpotential, small Tafel slope, and remarkable stability.A self-templated strategy enables the synthesis of hierarchical hollow nanoprisms composed of ultrathin Ni-Fe layered double hydroxide (LDH) nanosheets. During the hydrolysis of iron(II) sulfate, prism-like Ni precursors are dissolved and converted into a shell of Ni-Fe LDH on their surface. Owing to structural and compositional advantages, these hollow nanoprisms display enhanced electrochemical activity in the oxygen evolution reaction.
      PubDate: 2017-12-14T05:51:05.365432-05:
      DOI: 10.1002/anie.201710877
       
  • Driving Chemistry and Europe
    • Authors: Gilberte Chambaud
      Abstract: “… Mobility that favors individual exchanges between researchers is extremely important for the scientific community. The merging of scientific publications within a consortium of European journals and the creation of the European Chemistry Congresses have been major successes …” Read more in the Guest Editorial by Gilberte Chambaud.
      PubDate: 2017-12-14T04:40:47.574452-05:
      DOI: 10.1002/anie.201709947
       
  • Bimetallic Ag-Pt sub-nanometer supported clusters as highly efficient and
           robust oxidation catalysts
    • Authors: Fabio R. Negreiros; Avik Halder, Chunrong Yin, Akansha Singh, Giovanni Barcaro, Luca Sementa, Eric C. Tyo, Michael J. Pellin, Stephan Bartling, Karl-Heinz Meiwes-Broer, Sönke Seifert, Prasenjiy Sen, Sandeep Nigam, Chiranjib Majumder, Nobuyuki Fukui, Hisato Yasumatsu, Stefan Vajda, Alessandro Fortunelli
      Abstract: A combined experimental and theoretical investigation of Ag-Pt sub-nanometer clusters as heterogeneous catalysts in the COCO2 reaction (COox) is presented. Ag9Pt2 and Ag9Pt3 clusters are size-selected in the gas phase, deposited on an ultrathin amorphous alumina support, and tested as catalysts experimentally under realistic conditions and via first-principles simulations at realistic coverage. In situ GISAXS/TPRx demonstrates that the clusters neither sinter nor deactivate even after prolonged exposure to reactants at high temperature, and present comparable, extremely high COox catalytic efficiency. Such high activity and stability are ascribed to a synergic role of Ag and Pt in ultranano-aggregates, in which Pt anchors the clusters to the support and binds and activates two CO molecules, while Ag binds and activates O2, and Ag/Pt surface proximity disfavors poisoning by CO or oxidized species.
      PubDate: 2017-12-14T04:35:23.254342-05:
      DOI: 10.1002/anie.201709784
       
  • The molecular structure of gauche-1,3-butadiene: Experimental proof of
           non-planarity
    • Authors: Joshua Baraban; Marie-Aline Martin-Drumel, P. Bryan Changala, Sandra Eibenberger, Matthew Nava, David Patterson, John F Stanton, G. Barney Ellison, Michael C McCarthy
      Abstract: The planarity of the second stable conformer of 1,3-butadiene - the archetypal diene for the Diels- Alder reaction, in which a planar conjugated diene and a dienophile combine to form a ring - is not established. The most recent high level calculations predict the species to adopt a twisted, gauche structure due to steric interactions between the inner terminal hydrogens rather than a planar, cis structure favored by the conjugation of the doubled bonds. Here we unambiguously prove experimentally that the structure cis-1,3-butadiene is indeed gauche with a substantial dihedral angle of 34°, in excellent agreement with theory. Observation of two tunneling components indicates that the molecule undergoes facile interconversion between two equivalent enantiomeric forms. Comparison of experimentally determined structures for gauche-and trans-butadiene provides an opportunity to examine the effects of conjugation and steric interactions.
      PubDate: 2017-12-14T04:07:37.441012-05:
      DOI: 10.1002/anie.201709966
       
  • Smart Solid Electrolyte Interphase Layer for Long Life Lithium Metal
           Anodes
    • Authors: Nian-Wu Li; Yang Shi, Ya-Xia Yin, Xian-Xiang Zeng, Jin-Yi Li, Cong-Ju Li, Li-Jun Wan, Rui Wen, Yu-Guo Guo
      Abstract: Lithium (Li) metal is a promising anode material for high-energy density batteries. However, the unstable and static solid electrolyte interphase (SEI) can be destroyed by the dynamic Li plating/stripping behavior on the Li anode surface, leading to side reactions and Li dendrites growth. Herein, we design a smart Li polyacrylic acid (LiPAA) SEI layer with high stretchability to address the dynamic Li plating/stripping processes by the self-adapting interface regulation, which is demonstrated by in situ AFM process. With the high binding ability and excellent stability of LiPAA polymer, the smart SEI can significantly reduce the side reactions and improve the safety property markedly. The stable cycling of 700 h is achieved in the LiPAA-Li LiPAA-Li symmetrical cell. The innovative strategy of self-adapting SEI design is broadly applicable, conceptually providing admirable opportunities for Li metal anodes.
      PubDate: 2017-12-14T00:06:38.005046-05:
      DOI: 10.1002/anie.201710806
       
  • Dynamic Covalent Chemistry within Biphenyl Scaffolds: Reversible Covalent
           Bonding, Control of Selectivity, and Chirality Sensing with One Single
           System
    • Authors: Cailing Ni; Daijun Zha, Hebo Ye, Yu Hai, Yuntao Zhou, Eric Anslyn, Lei You
      Abstract: Axial chirality is a prevalent and important phenomenon in chemistry. Herein we report a combination of dynamic covalent chemistry and axial chirality for the development of a universal platform toward binding and chirality sensing of multiple classes of mononucleophiles. An equilibrium between open aldehyde and its cyclic hemiaminal within biphenyl derivatives enables the dynamic incorporation of a broad range of alcohols, thiols, primary amines, and secondary amines with high efficiency. The selectivity toward different classes of nucleophiles was also achieved by regulating the distinct reactivity of the system with external stimuli. Through induced helicity as a result of central-to-axial chirality transfer the handedness and enantiomeric excess values of chiral monoalcohol and monoamine analytes can be reported via circular dichroism. The generality of the strategies introduced herein should find applications in many aspects, including assembly, sensing, and labeling.
      PubDate: 2017-12-13T21:42:39.229835-05:
      DOI: 10.1002/anie.201711602
       
  • Controlling the polymer microstructure in anionic polymerization by
           compartmentalization
    • Authors: Elisabeth Rieger; Jan Blankenburg, Eduard Grune, Manfred Wagner, Katharin Landfester, Frederik Roman Wurm
      Abstract: An ideal random anionic copolymerization is forced to gradient structures by physical separation of two monomers in emulsion compartments. One monomer (M) is preferably soluble in the droplets, while the other one (D) prefers the continuous phase of a DMSO-in-cyclohexane emulsion. The living anionic copolymerization of two activated aziridines is thus confined to the DMSO compartments as polymerization occurs selectively in the droplets. Dilution of the continuous phase adjusts the local concentration of monomer D in the droplets and thus the gradient of the resulting copolymer. The copolymerizations in emulsion are monitored by real-time 1H NMR kinetics, proving a change of the reactivity ratios of both monomers upon dilution of the continuous phase from ideal random to adjustable gradients by simple dilution. This model system will allow the preparation of copolymer libraries in the future in a one-pot, one-shot reaction, without any sequential monomer addition.
      PubDate: 2017-12-13T21:42:26.385335-05:
      DOI: 10.1002/anie.201710417
       
  • Artificial Cysteine S-Glycosylation Induced by Per-O-Acetylated Unnatural
           Monosacharides during Metabolic Glycan Labeling
    • Authors: Wei Qin; Ke Qin, Xinqi Fan, Linghang Peng, Weiyao Hong, Yuntao Zhu, Pinou Lv, Yifei Du, Rongbing Huang, Mengting Han, Bo Cheng, Yuan Liu, Wen Zhou, Chu Wang, Xing Chen
      Abstract: Here we report an unexpected, non-enzymatic cysteine S-glycosylation induced by per-O-acetylated monosaccharides and their clickable analogs on various proteins. This artificial S-glycosylation broadly compromises the specificity and validity of metabolic glycan labeling in living cells using per-O-acetylated azido and alkynyl sugars, which has been overlooked in the field for decades. We demonstrate that free unnatural sugars can avoid the artifacts and by using N-azidoactylgalactosamine, we provide a corrected list of O-GlcNAcylated proteins and O-GlcNAc sites in HeLa cells.
      PubDate: 2017-12-13T12:35:39.227184-05:
      DOI: 10.1002/anie.201711710
       
  • A New Mechanism for β-Lactamases: Class D Enzymes Degrade 1β-Methyl
           Carbapenems via Lactone Formation
    • Authors: Christopher T. Lohans; Emma van Groesen, Kiran Kumar, Catherine L. Tooke, James Spencer, Robert S. Paton, Jürgen Brem, Christopher Schofield
      Abstract: β-Lactamases threaten the clinical use of carbapenems, considered antibiotics of last resort. The classical mechanism of serine carbapenemase activity proceeds via hydrolysis of an acyl-enzyme intermediate. We show that class D β-lactamases also degrade clinically used 1β-methyl-substituted carbapenems via the unprecedented formation of a carbapenem-derived β-lactone. β-Lactone formation results from the nucleophilic attack of the carbapenem hydroxyethyl side chain onto the ester carbonyl of the acyl-enzyme intermediate. The carbapenem-derived lactone products inhibit both serine β-lactamases (particularly class D) and metallo-β-lactamases. These results define a new mechanism for the class D carbapenemases, in which a hydrolytic water molecule is not required.
      PubDate: 2017-12-13T11:42:52.462769-05:
      DOI: 10.1002/anie.201711308
       
  • Isolation of a Reactive Tricoordinate alpha-Oxo Gold Carbene Complex
    • Authors: Abdallah Zeineddine; Feriel Rekhroukh, E. Daiann Sosa Carrizo, Sonia Mallet-Ladeira, Karinne Miqueu, Abderrahmane Amgoune, Didier Bourissou
      Abstract: The [(P,P)Au=C(Ph)CO2Et]+ complex 3 [where (P,P) is an o-carboranyl diphosphine ligand] was prepared by diazo decomposition at -40°C. It is the first alpha-oxo gold carbene complex to be characterized. Its crystallographic structure was determined and DFT calculations have been performed, unraveling the key influence of the chelating (P,P) ligand. The gold center is tricoordinate and the electrophilicity of the carbene center is reduced. Complex 3 mimics transient alpha-oxo gold carbenes in a series of catalytic transformations, and enables to support the critical role of electrophilicity in the chemoselectivity of phenol functionalization (O-H vs C-H insertion).
      PubDate: 2017-12-13T09:35:47.518731-05:
      DOI: 10.1002/anie.201711647
       
  • Jan C. M van Hest
    • PubDate: 2017-12-13T09:15:20.250705-05:
      DOI: 10.1002/anie.201712084
       
  • Near-Infrared Light-Driven Hydrogen Evolution from Water Using a
           Polypyridyl Triruthenium Photosensitizer
    • Authors: Yutaro Tsuji; Keiya Yamamoto, Kosei Yamauchi, Ken Sakai
      Abstract: The evolution of H2 by near-infrared light irradiation is an unprecedented phenomenon that makes use of an extended wavelength range of the solar spectrum. In their Communication (
      DOI : 10.1002/anie.201708996), K. Sakai et al. report photocatalytic H2 evolution using a polypyridyl triruthenium photosensitizer with light-harvesting properties. The photosensitizer promotes H2 evolution under light irradiation at 700–800 nm.
      PubDate: 2017-12-13T09:06:16.66801-05:0
       
  • Integrated Transmission Electron and Single-Molecule Fluorescence
           Microscopy Correlates Reactivity with Ultrastructure in a Single Catalyst
           Particle
    • Authors: Frank C. Hendriks; Sajjad Mohammadian, Zoran Ristanović, Sam Kalirai, Florian Meirer, Eelco T. C. Vogt, Pieter C. A. Bruijnincx, Hans C. Gerritsen, Bert M. Weckhuysen
      Abstract: Two “superheroes” in high-resolution chemical imaging, namely single-molecule fluorescence microscopy and transmission electron microscopy, have been combined in the same set-up to facilitate correlative analysis. In their Communication (
      DOI : 10.1002/anie.201709723), H. C. Gerritsen, B. M. Weckhuysen et al. show the validity of this approach by studying structure–activity relationships in a single catalyst particle. Differences in reactivity exist among active components with identical structural features.
      PubDate: 2017-12-13T09:06:14.498287-05:
       
  • Microtubular Self-Assembly of Covalent Organic Frameworks
    • Authors: Bappaditya Gole; Vladimir Stepanenko, Sabrina Rager, Matthias Grüne, Dana D. Medina, Thomas Bein, Frank Würthner, Florian Beuerle
      Abstract: Despite significant progress in the synthesis of covalent organic frameworks (COFs), reports on the precise construction of template-free nano- and microstructures of such materials have been rare. In the quest for dye-containing porous materials, a novel conjugated framework DPP-TAPP-COF with an enhanced absorption capability up to λ=800 nm has been synthesized by utilizing reversible imine condensations between 5,10,15,20-tetrakis(4-aminophenyl)porphyrin (TAPP) and a diketopyrrolopyrrole (DPP) dialdehyde derivative. Surprisingly, the obtained COF exhibited spontaneous aggregation into hollow microtubular assemblies with outer and inner tube diameters of around 300 and 90 nm, respectively. A detailed mechanistic investigation revealed the time-dependent transformation of initial sheet-like agglomerates into the tubular microstructures.Rolling up the COFs: Tetraphenylporphyrins and diketopyrrolopyrroles have been incorporated as functional dye components in covalent organic frameworks by means of reversible imine condensations. Upon formation, these crystalline polymers spontaneously self-assemble to form hollow microtubes.
      PubDate: 2017-12-13T09:06:12.401696-05:
      DOI: 10.1002/anie.201708526
       
  • Electrobiorefineries: Unlocking the synergy of electrochemical and
           microbial conversions
    • Authors: Falk Harnisch; Carolin Urban
      Abstract: Lead-in: An integrated biobased economy urges an alliance of the two realms "chemical production" and "electric power". The concept of electrobiorefineries provides a blueprint for such an alliance agreement. Joining the forces of microbial and electrochemical conversions in electrobiorefineries allows interfacing the production, storage, and exploitation of electricity as well as biobased chemicals. Electrobiorefineries are a technological evolution of biorefineries by means of the addition of (bio)electrochemical transformations. This interfacing of microbial and electrochemical conversions will result in synergies affecting the whole process line, like enlarging the product portfolio, increasing the productivity, or exploiting new feedstock. A special emphasis is given to the utilization of oxidative and reductive electroorganic reactions of microbially produced intermediates that may serve as privileged building blocks.
      PubDate: 2017-12-13T08:06:56.628175-05:
      DOI: 10.1002/anie.201711727
       
  • Abderrahmane Amgoune
    • PubDate: 2017-12-13T08:06:48.998162-05:
      DOI: 10.1002/anie.201712422
       
  • A π-Conjugation Extended Viologen as a Two-Electron Storage Anolyte for
           Total Organic Aqueous Redox Flow Batteries
    • Authors: Jian Luo; Bo Hu, Camden Debruler, Tianbiao Leo Liu
      Abstract: Extending the conjugation of viologen by a planar thiazolo[5,4-d]thiazole (TTz) framework and functionalizing the pyridinium with hydrophilic ammonium groups yielded a highly water-soluble π-conjugation extended viologen, 4,4′-(thiazolo[5,4-d]thiazole-2,5-diyl)bis(1-(3-(trimethylammonio)propyl)pyridin-1-ium) tetrachloride, [(NPr)2TTz]Cl4 , as a novel two-electron storage anolyte for aqueous organic redox flow battery (AORFB) applications. Its physical and electrochemical properties were systematically investigated. Paired with 4-trimethylammonium-TEMPO (NMe-TEMPO) as catholyte, [(NPr)2TTz]Cl4 enables a 1.44 V AORFB with a theoretical energy density of 53.7 Wh L−1. A demonstrated [(NPr)2TTz]Cl4/NMe-TEMPO AORFB delivered an energy efficiency of 70 % and 99.97 % capacity retention per cycle.On the fast track: A highly water-soluble π-conjugation extended viologen has been developed as a novel two-electron storage anolyte to enable a 1.44 V total organic neutral aqueous redox flow battery.
      PubDate: 2017-12-13T08:06:47.570941-05:
      DOI: 10.1002/anie.201710517
       
  • Martin D. Smith
    • PubDate: 2017-12-13T08:06:35.290151-05:
      DOI: 10.1002/anie.201712087
       
  • Solubility-Parameter-Guided Solvent Selection to Initiate Ostwald Ripening
           for Interior Space-Tunable Structures with Architecture-Dependent
           Electrochemical Performance
    • Authors: Baoguang Mao; Donglei Guo, Jinwen Qin, Tao Meng, Xin Wang, Minhua Cao
      Abstract: Despite significant advancement in preparing various hollow structures by Ostwald ripening, one common problem is the intractable uncontrollability of initiating Ostwald ripening due to the complexity of the reaction processes. Here, a new strategy on Hansen solubility parameter (HSP)-guided solvent selection to initiate Ostwald ripening is proposed. Based on this comprehensive principle for solvent optimization, N,N-dimethylformamide (DMF) was screened out, achieving accurate synthesis of interior space-tunable MoSe2 spherical structures (solid, core–shell, yolk-shell and hollow spheres). The resultant MoSe2 structures exhibit architecture-dependent electrochemical performances towards hydrogen evolution reaction and sodium-ion batteries. This pre-solvent selection strategy can effectively provide researchers great possibility in efficiently synthesizing various hollow structures. This work paves a new pathway for deeply understanding Ostwald ripening.Hollow inorganic structures: Solubility-parameter-guided solvent selection to initiate Ostwald ripening has been used to achieve accurate synthesis of interior space-tunable MoSe2 hollow structures in N,N-dimethylformamide. The resultant MoSe2 structures show closely architecture-dependent electrochemical performances towards hydrogen evolution reaction and sodium-ion batteries.
      PubDate: 2017-12-13T08:06:33.923679-05:
      DOI: 10.1002/anie.201710378
       
  • The Narrowest Band Gap Ever Observed in Molecular Ferroelectrics:
           Hexane-1,6-diammonium Pentaiodobismuth(III)
    • Authors: Han-Yue Zhang; Zhenhong Wei, Peng-Fei Li, Yuan-Yuan Tang, Wei-Qiang Liao, Heng-Yun Ye, Hu Cai, Ren-Gen Xiong
      Abstract: Narrow band gaps and excellent ferroelectricity are intrinsically paradoxical in ferroelectrics as the leakage current caused by an increase in the number of thermally excited carriers will lead to a deterioration of ferroelectricity. A new molecular ferroelectric, hexane-1,6-diammonium pentaiodobismuth (HDA-BiI5), was now developed through band gap engineering of organic–inorganic hybrid materials. It features an intrinsic band gap of 1.89 eV, and thus represents the first molecular ferroelectric with a band gap of less than 2.0 eV. Simultaneously, low-temperature solution processing was successfully applied to fabricate high-quality ferroelectric thin films based on HDA-BiI5, for which high-precision controllable domain flips were realized. Owing to its narrow band gap and excellent ferroelectricity, HDA-BiI5 can be considered as a milestone in the exploitation of molecular ferroelectrics, with promising applications in high-density data storage and photovoltaic conversion.The molecular ferroelectric hexane-1,6-diammonium pentaiodobismuth displays a narrow band gap of 1.89 eV. Low-temperature solution processing enabled the fabrication of high-quality flexible ferroelectric thin films.
      PubDate: 2017-12-13T08:06:12.514011-05:
      DOI: 10.1002/anie.201709588
       
  • Nanoscale Trimetallic Metal–Organic Frameworks Enable Efficient Oxygen
           Evolution Electrocatalysis
    • Authors: Fei-Long Li; Qi Shao, Xiaoqing Huang, Jian-Ping Lang
      Abstract: Metal–organic frameworks (MOFs) are a class of promising materials for diverse heterogeneous catalysis, but they are usually not directly employed for oxygen evolution electrocatalysis. Most reports focus on using MOFs as templates to in situ create efficient electrocatalysts through annealing. Herein, we prepared a series of Fe/Ni-based trimetallic MOFs (Fe/Ni/Co(Mn)-MIL-53 accordingly to the Material of Institute Lavoisier) by solvothermal synthesis, which can be directly adopted as highly efficient electrocatalysts. The Fe/Ni/Co(Mn)-MIL-53 shows a volcano-type oxygen evolution reaction (OER) activity as a function of compositions. The optimized Fe/Ni2.4/Co0.4-MIL-53 can reach a current density of 20 mA cm−2 at low overpotential of 236 mV with a small Tafel slope of 52.2 mV dec−1. In addition, the OER performance of these MOFs can be further enhanced by directly being grown on nickel foam (NF).Multimetallic MOFs with modulated compositions have been successfully synthesized and directly adopted as efficient oxygen evolution reaction (OER) catalysts (MOFs=metal–organic frameworks). The Fe/Ni/Co/(Mn)-MIL-53 catalyst exhibits a volcano-type OER activity as a function of compositions. The optimized Fe/Ni/Mn0.4-MIL-53/NF catalyst is highly active and ultrastable towards OER catalysis.
      PubDate: 2017-12-13T07:37:03.391375-05:
      DOI: 10.1002/anie.201711376
       
  • Total Synthesis of (6R,10R,13R,14R,16R,17R,19S,20R,21R,24S,
           25S,28S,30S,32R,33R,34R,36S,37S,39R)-Azaspiracid-3 Reveals Non-Identity
           with the Natural Product
    • Authors: Nathaniel T. Kenton; Daniel Adu-Ampratwum, Antony A. Okumu, Zhigao Zhang, Yong Chen, Son Nguyen, Jianyan Xu, Yue Ding, Pearse McCarron, Jane Kilcoyne, Frode Rise, Alistair L. Wilkins, Christopher O. Miles, Craig J. Forsyth
      Abstract: A convergent and stereoselective total synthesis of the previously assigned structure of azaspiracid-3 has been achieved by a late-stage Nozaki–Hiyama–Kishi coupling to form the C21−C22 bond with the C20 configuration unambiguously established from l-(+)-tartaric acid. Postcoupling steps involved oxidation to an ynone, modified Stryker reduction of the alkyne, global deprotection, and oxidation of the resulting C1 primary alcohol to the carboxylic acid. The synthetic product matched naturally occurring azaspiracid-3 by mass spectrometry, but differed both chromatographically and spectroscopically.A convergent and stereospecific total synthesis of the previously assigned structure of the marine neurotoxin azaspiracid-3 reveals non-identity with the natural product. Therefore structural revision of the primary azaspiracids is necessary.
      PubDate: 2017-12-13T07:26:35.897564-05:
      DOI: 10.1002/anie.201711006
       
  • Ronald Breslow (1931–2017)
    • Authors: Alanna Schepartz; Robert Bergman, Robert H. Grubbs
      Abstract: Ronald Breslow, Samuel Latham Mitchill Professor of Chemistry at Columbia University, passed away on October 25, 2017, at the age of 86. Breslow made remarkable contributions to the fields of physical-organic and bioorganic chemistry, including biological and biomimetic transformations, and the use of molecular recognition to control reaction selectivity.
      PubDate: 2017-12-13T07:26:01.27017-05:0
      DOI: 10.1002/anie.201711641
       
  • Evidence for Triplet Sensitization in the Visible-Light-Induced
           [2+2] Photocycloaddition of Eniminium Ions
    • Authors: Fabian M. Hörmann; Tim S. Chung, Elsa Rodriguez, Matthias Jakob, Thorsten Bach
      Abstract: Εniminium ions were prepared from the corresponding α,β-unsaturated carbonyl compounds (enones and enals), and were found to be promoted to their respective triplet states by energy transfer. The photoexcited intermediates underwent intra- or intermolecular [2+2] photocycloaddition in good yields (50–78 %) upon irradiation at λ=433 nm or λ=457 nm. Iridium or ruthenium complexes with a sufficiently high triplet energy were identified as efficient catalysts (2.5 mol % catalyst loading) for the reaction. The intermolecular [2+2] photocycloaddition of an eniminium ion derived from a chiral secondary amine proceeded with high enantioselectivity (88 % ee).The energy is the limit: The [2+2] photocycloaddition of iminium ions 1 is catalyzed by iridium or ruthenium complexes and proceeds via triplet energy transfer. The intermediate iminium ions 2 are hydrolyzed to the respective carbonyl compounds such as aldehyde 3, which was formed in 78 % yield from a chiral eniminium ion precursor.
      PubDate: 2017-12-13T07:25:45.546853-05:
      DOI: 10.1002/anie.201710441
       
  • Total Synthesis of (+)-Sarcophytin
    • Authors: Leonardo J. Nannini; Suren J. Nemat, Erick M. Carreira
      Abstract: A total synthesis of the cembranoid (+)-sarcophytin is presented, featuring a Diels–Alder cycloaddition of an enone as the dienophile with an ester-derived dienoate. The study highlights a peculiar geometric preference for the Z dienoate to furnish the cycloadduct. The endgame involves a reaction cascade, including lactone opening, alcohol oxidation, and ketone epimerization to complete an efficient synthesis. A salient feature of the synthesis is the resulting reassignment of the absolute configuration, which corrects the previously reported nominal structure.All right now: A total synthesis of the cembranoid (+)-sarcophytin is presented, featuring a Diels–Alder cycloaddition of an enone and Z dienoate. A reaction cascade, including lactone opening, alcohol oxidation, and ketone epimerization, completes an efficient synthesis. Reassignment of the absolute configuration of the natural product corrects the previously reported nominal structure.
      PubDate: 2017-12-13T07:20:51.428943-05:
      DOI: 10.1002/anie.201711372
       
  • The Ideal Ionic Liquid Salt Bridge for the Direct Determination of Gibbs
           Energies of Transfer of Single Ions, Part I: The Concept
    • Authors: Valentin Radtke; Andreas Ermantraut, Daniel Himmel, Thorsten Koslowski, Ivo Leito, Ingo Krossing
      Abstract: We describe a procedure for the thermodynamicallyrigorous, experimental determination of the Gibbs Energy of Transferof single ions between solvents. The method is based on potentialdifference measurements between two electrochemical half cells withdifferent solvents connected by an ideal Ionic Liquid Salt Bridge(ILSB). We discuss the specific requirements for the IL with regard tothe procedure, ensuring that the Liquid Junction Potentials (LJP) atboth ends of the ILSB cancel largely. The remaining parts of the LJPscan be determined by separate emf measurements. No extrathermodynamicassumptions are necessary for this procedure. Theaccuracy of the measurements depends amongst others on the"ideality" of the used IL, as shown in our companion paper Part II.
      PubDate: 2017-12-13T05:13:41.33192-05:0
      DOI: 10.1002/anie.201707333
       
  • Direct asymmetric Michael reaction of α,β-unsaturated aldehydes and
           ketones catalyzed by two secondary amine catalysts
    • Authors: Yujiro Hayashi; Nariyoshi Umekubo
      Abstract: Direct asymmetric Michael reaction of α,β-unsaturated aldehydes and ketones proceeds in the presence of two pyrrolidine-type catalysts, such as diphenylprolinol silyl ether and hydroxyproline, to afford synthetically useful δ-keto aldehydes with excellent diastereo- and enantioselectivities. Although there are several iminium ions and enamines in the reaction mixture, an iminium ion generated from the former catalyst reacts preferentially with an enamine generated from the latter catalyst.
      PubDate: 2017-12-13T05:12:59.471171-05:
      DOI: 10.1002/anie.201710085
       
  • The Ideal Ionic Liquid Salt Bridge for the Direct Determination of Gibbs
           Energies of Transfer of Single Ions, Part II: Evaluation of the Role of
           Ion Solvation and Ion Mobilities
    • Authors: Andreas Ermantraut; Valentin Radtke, Niklas Gebel, Daniel Himmel, Thorsten Koslowski, Ivo Leito, Ingo Krossing
      Abstract: An important intermediate goal to evaluate our concept for the assumption-free determination of single ion Gibbs transfer energies ΔtrG°(i, S1> S2) is presented: We executed the crucial steps a) and b) of the methodology, described in Part I of this treatise, exemplarily for Ag+ and Cl− with S1 being water and S2 being acetonitrile. The experiments showed that virtually all parts of the liquid junction potentials (LJPs) at both ends of a salt bridge cancel, if the bridge electrolyte is an "ideal" ionic liquid - one with nearly identical diffusion of anion and cation. This holds for [N2225]+[NTf2]- in the pure IL, but also in water and acetonitrile solution. Emf measurements of solvate cells between S1 and S2 gave Nernstian behavior for Ag+-concentration cells and constant like cell potentials for solutions with five tested Ag+-counterions.
      PubDate: 2017-12-13T05:12:29.54904-05:0
      DOI: 10.1002/anie.201707334
       
  • Live-Cell Protein Sulfonylation Based on Proximity-driven N-Sulfonyl
           Pyridone Chemistry
    • Authors: Kazuya Matsuo; Yuki Nishikawa, Marie Masuda, Itaru Hamachi
      Abstract: The development of bioorthogonal approaches for labeling of endogenous proteins under the multimolecular crowding conditions of live cells is highly desirable for the analysis and engineering of proteins without using genetic manipulation. N-Sulfonyl pyridone (SP) is reported as a new reactive group for protein sulfonylation. The ligand-directed SP chemistry was able to modify not only purified proteins in vitro, but also endogenous ones on the surface of and inside live cells selectively and rapidly, which allowed to convert endogenous proteins to FRET-based biosensors in situ.Ligand-directed N-sulfonyl pyridone chemistry afforded the specific sulfonylation of endogenous proteins without disturbing their original nature. This chemical strategy allowed the simple conversion of endogenous proteins in live cell habitats into semisynthetic FRET biosensors for the analysis of the dynamic process in protein–ligand (small molecule) interactions.
      PubDate: 2017-12-13T04:51:33.478142-05:
      DOI: 10.1002/anie.201707972
       
  • Ultrathin Graphdiyne Nanosheets Grown In Situ on Copper Nanowires and
           Their Performance as Lithium-Ion Battery Anodes
    • Authors: Hong Shang; Zicheng Zuo, Liang Li, Fan Wang, Huibiao Liu, Yongjun Li, Yuliang Li
      Abstract: A method is presented for the scalable preparation of high-quality graphdiyne nanotubes and ultrathin graphdiyne nanosheets (average thickness: ca. 1.9 nm) using Cu nanowires as a catalyst. For the storage of Li+ ions, the graphdiyne nanostructures show a high capacity of 1388 mAh g−1 and high rate performance (870 mA h g−1 at 10 A g−1, and 449.8 mA h g−1 at 20 A g−1) with robust stability, demonstrating outstanding overall potential for its applications.A copper nanowire was used for large-scale preparation of ultrathin graphdiyne nanosheets (1.9 nm), and the growth properties were investigated. The ability of the ultrathin graphdiyne nanosheets to store lithium ions was impressive (1380 mAh g−1). Diffusion: in-plane (blue arrow), out-of-plane (red).
      PubDate: 2017-12-13T04:46:15.040834-05:
      DOI: 10.1002/anie.201711366
       
  • CO Hydrogenation on Cobalt-Based Catalysts: Tin Poisoning Unravels CO in
           Hollow Sites as a Main Surface Intermediate
    • Authors: Anaëlle Paredes-Nunez; Davide Lorito, Laurence Burel, Debora Motta-Meira, Giovanni Agostini, Nolven Guilhaume, Yves Schuurman, Frederic Meunier
      Abstract: Site poisoning is a powerful method to unravel the nature of active sites or reaction intermediates. The nature of the intermediates involved in the hydrogenation of CO was unraveled by poisoning alumina-supported cobalt catalysts with various concentrations of tin. The rate of formation of the main reaction products (methane and propylene) was found to be proportional to the concentration of multi-bonded CO, likely located in hollow sites. The specific rate of decomposition of these species was sufficient to account for the formation of the main products. These hollow-CO are proposed to be main reaction intermediates in the hydrogenation of CO under the reaction conditions used here, while linear CO are mostly spectators.Site poisoning by tin was used to reveal the nature of the intermediates involved in CO hydrogenation on alumina-supported cobalt catalysts. The rate of formation of methane and propylene was proportional to the concentration of multiply bonded CO, likely located in hollow sites. These CO are proposed to be main reaction intermediates in the hydrogenation of CO under the reaction conditions, while linear CO are mostly spectators.
      PubDate: 2017-12-13T04:46:04.62784-05:0
      DOI: 10.1002/anie.201710301
       
  • Photoactivated N-Acyliminoiodinanes Applied to Amination: an
           ortho-Methoxymethyl Group Stabilizes Reactive Precursors
    • Authors: Yusuke Kobayashi; Sota Masakado, Yoshiji Takemoto
      Abstract: N-Acyliminoiodinanes were characterized for the first time by X-ray structural analysis. The ortho-methoxymethyl group and the carbonyl oxygen coordinate to the iodine atom of the iminoiodinane. Activation of the N-acyliminoiodinane was achieved by photoirradiation at 370 nm, thereby enabling reaction with various silyl enol ethers to give α-aminoketone derivatives in good to high yield. N-sulfonyliminoiodinanes bearing ortho substituents were used in photoinduced amination.N-Acyliminoiodinanes stabilized by an ortho-methoxymethyl group are activated toward reactivity with various silyl enol ethers upon photoirradiation (370 nm), and produce α-aminoketone derivatives in good to high yield. The photoinduced amination reaction extends to N-sulfonyliminoiodinanes bearing ortho substituents. PG=protecting group.
      PubDate: 2017-12-13T04:46:00.105736-05:
      DOI: 10.1002/anie.201710277
       
  • Hierarchical Hollow Nanoprisms Based on Ultrathin Ni-Fe Layered Double
           Hydroxide Nanosheets with Enhanced Electrocatalytic Activity towards
           Oxygen Evolution
    • Authors: Le Yu; Jing Fan Yang, Bu Yuan Guan, Yan Lu, Xiong Wen (David) Lou
      Abstract: Ni-Fe layered double hydroxides (LDHs) are promising oxygen evolution reaction (OER) electrocatalysts in alkaline electrolytes. In their Communication (
      DOI : 10.1002/anie.201710877), X. W. Lou and co-workers report a facile self-templated strategy for the synthesis of hierarchical hollow nanoprisms composed of ultrathin Ni-Fe LDH nanosheets. These hollow prisms with large surface areas display high electrocatalytic activity towards the OER, with a low overpotential, a small Tafel slope, and remarkable stability.
      PubDate: 2017-12-13T04:41:07.817896-05:
       
  • Stephan Irle
    • PubDate: 2017-12-13T03:55:43.426355-05:
      DOI: 10.1002/anie.201712472
       
  • A Metal–Organic Framework with Exceptional Activity for C−H
           Bond Amination
    • Authors: Le Wang; Douglas W. Agnew, Xiao Yu, Joshua S. Figueroa, Seth M. Cohen
      Abstract: The development of catalysts capable of fast, robust C−H bond amination under mild conditions is an unrealized goal despite substantial progress in the field of C−H activation in recent years. A Mn-based metal–organic framework (CPF-5) is described that promotes the direct amination of C−H bonds with exceptional activity. CPF-5 is capable of functionalizing C−H bonds in an intermolecular fashion with unrivaled catalytic stability producing>105 turnovers.A Mn-based MOF (metal–organic framework) with a unique active site catalyzes C−H amination under mild conditions. Importantly, the catalyst displays an exceptional and unprecedented TON of>120 000, which is about 4 orders of magnitude greater than any other state-of-the-art C−H amination catalysts.
      PubDate: 2017-12-13T03:55:41.19034-05:0
      DOI: 10.1002/anie.201709420
       
  • Frontispiece: Facile Supramolecular Processing of Carbon Nanotubes and
           Polymers for Electromechanical Sensors
    • Authors: Chae Bin Kim; Ki Beom Jeong, Beom Joo Yang, Jong-Won Song, Bon-Cheol Ku, Seunghyun Lee, Seoung-Ki Lee, Chiyoung Park
      Abstract: Supramolecular Gels A supramolecular, non-volatile eutectic liquid can form bucky gels with carbon nanotubes upon grinding. In their Communication on page 16180 ff. S. Lee, S.-K. Lee, C. Park show the resulting viscoelastic conductor behaves as a self-healing electromechanical sensor.
      PubDate: 2017-12-13T03:08:34.782084-05:
      DOI: 10.1002/anie.201785161
       
  • Co(II)-Based Metalloradical Activation of 2-(Diazomethyl)pyridines for
           Radical Transannulation and Cyclopropanation
    • Authors: Buddhadeb Chattopadhyay; Satyajit Roy, Sandip Kumar Das
      Abstract: A new catalytic method for the denitrogenative transannulation/cyclopropanation of in-situ generated 2-(diazomethyl)pyridines is described via a cobalt-catalyzed radical activation mechanism. The method has been developed by taking advantage of the inherent property of Co(III)-carbene radical intermediate. This is the first report for the denitrogenative transannulation/cyclopropanation via radical activation mechanism, which is supported by various control experiments. For synthetic application of this metalloradical approach, it has been showcased by the short total synthesis of ()-monomorine.
      PubDate: 2017-12-13T01:39:02.66174-05:0
      DOI: 10.1002/anie.201711209
       
  • CO oxidation on metal-supported monolayer oxide films: Do we know which
           phase (interface) is active'
    • Authors: Ke Zhang; Linfei Li, Shamil Shaikhutdinov, Hans-Joachim Freund
      Abstract: Ultrathin ("monolayer") films of transition metal oxides grown on metal substrates have recently received considerable attention as promising catalytic materials, in particular for low-temperature CO oxidation. The reaction rate on such systems often increases when the film only partially covers the support, and the effect is commonly attributed to the formation of active sites at the metal/oxide boundary. By studying the structure and reactivity of FeO(111) films on Pt(111), here we show that, independently of the film coverage, CO oxidation takes place at the interface between reduced and oxidized phases in the oxide film formed under reaction conditions. The promotional role of a metal support is to ease formation of the reduced phase via reaction between CO adsorbed on metal and oxygen at the oxide island edge.
      PubDate: 2017-12-13T01:38:00.11686-05:0
      DOI: 10.1002/anie.201710934
       
  • Surface Molding of Microscale Hydrogels with Microactuation Functionality
    • Authors: John J. Bowen; Mark A. Rose, Abhiteja Konda, Stephen A. Morin
      Abstract: This work describes the fabrication of numerous hydrogel microstructures, μ-gels, via a process called "surface molding"—chemically patterned elastomeric assembly substrates were used to organize and manipulate the geometry of liquid prepolymer microdroplets, which, following photo-initiated crosslinking, maintained the desired morphology. By adjusting the state of strain during the crosslinking process, a continua of structures could be created using one pattern. These arrays of μ-gels have stimuli-responsive properties that are directly applicable to actuation where the basis shape and array geometry of the μ-gels can be used to rationally generate microactuators with programmed motions. As a method, "surface molding," represents a powerful addition to the soft lithographic toolset that can be readily applied to the simultaneous synthesis of large numbers of geometrically and functionally distinct polymeric microstructures.
      PubDate: 2017-12-12T22:15:23.338902-05:
      DOI: 10.1002/anie.201710612
       
  • Selective C-H Halogenations with a Highly Fluorinated Manganese Porphyrin
    • Authors: Gang Li; Andrew Dilger, Peter Cheng, William Ewing, John T. Groves
      Abstract: Selective C-H functionalizations of aliphatic molecules remain a challenge in organic synthesis. While radical chain halogenations provide an efficient way to access many halogenated molecules, application of typical protocols to selectively halogenate electron-deficient and strained aliphatic molecules are rare. Herein, we report selective C-H chlorinations and fluorinations that use an electron-deficient manganese pentafluorophenyl porphyrin catalyst, Mn(TPFPP)Cl. This catalyst displays superior properties for aliphatic halogenations of recalcitrant, electron-deficient and strained substrates with unique regio- and stereoselectivity. In operando UV-vis analyses indicate that an oxoMn(V) species is responsible for hydrogen atom abstraction. The observed stereoselectivity results from steric interactions between the bulky porphyrin ligand and the intermediate substrate radical in the halogen rebound step.
      PubDate: 2017-12-12T22:12:51.617765-05:
      DOI: 10.1002/anie.201710676
       
  • Kinetic Dearomatization Strategy for an Expedient Biomimetic Route to the
           Bielschowskysin Skeleton.
    • Authors: Stephane Roche; Paul Scesa, Medhi Wangpaichitr, Niramol Savaraj, Lyndon West
      Abstract: Bielschowskysin (1), the flagship of the furanocembranoid-derived diterpene family has attracted attention from chemists owing to its intriguing and daunting polycyclic architecture and medicinal potential against lung cancer. The high level of functionalization of 1 poses a considerable challenge to synthesis. Herein a stereoselective furan dearomatization strategy of furanocembranoids was achieved via the intermediacy of chlorohydrins. The stereochemical course of the kinetic dearomatization was established and the C-3 configuration of the resulting exo-enol ether intermediates proved to be essential to complete the late-stage transannular [2+2] photocycloaddition. Overall, this biomimetic strategy starting from the natural product acerosolide (9) featured an unprecedented regio- and highly stereoselective furan dearomatization which enabled a rapid access to the pivotal exo-enol ethers en route to the intricate bielschowskyane skeleton.
      PubDate: 2017-12-12T15:06:08.585937-05:
      DOI: 10.1002/anie.201711780
       
  • Catalytic Asymmetric Synthesis of Trifluoromethylated γ-Amino Acids via
           Umpolung Addition of Trifluoromethyl Imines to Carboxylic Acid Derivatives
           
    • Authors: Bin Hu; Li Deng
      Abstract: Enabled by the discovery of novel cinchona alkaloid-derived chiral phase-transfer catalysts, highly chemo-, regio-, diastereo- and enantioselective umpolung additions of trifluoromethyl imines to α, β-unsaturated N-acylpyrroles were realized. With a catalyst loading ranging from 0.2 to 5.0 mol%, this new catalytic asymmetric transformation provides facile and high-yield access to highly enantiomerically enriched chiral trifluoromethylated γ-amino acids and γ-lactams.
      PubDate: 2017-12-12T14:06:26.981257-05:
      DOI: 10.1002/anie.201710915
       
  • Electron-Precise Actinide-Pnictide (An-Pn) Bonds Spanning Non-Metal,
           Metalloid, and Metal Combinations (An = U, Th; Pn = P, As, Sb, Bi)
    • Authors: Stephen Liddle; Thomas Rookes, Elizabeth Wildman, Gabor Balazs, Benedict Gardner, Ashley Wooles, Matthew Gregson, Floriana Tuna, Manfred Scheer
      Abstract: We report the synthesis and characterisation of the compounds [An(TrenDMBS){Pn(SiMe3)2}] and [An(TrenTIPS){Pn(SiMe3)2}] [TrenDMBS = N(CH2CH2NSiMe2But)3, An = U, Pn = P, As, Sb, Bi; An = Th, Pn = P, As; TrenTIPS = N(CH2CH2NSiPri3)3, An = U, Pn = P, As, Sb; An = Th, Pn = P, As, Sb]. The U-Sb and Th-Sb moieties are unprecedented examples of any kind of An-Sb molecular bond, and the U-Bi bond is the first electron-precise one. The Th-Bi combination was too unstable to isolate, underscoring the fragility of these linkages. However, the U-Bi complex is the heaviest electron-precise pairing of two elements involving an actinide on a macroscopic scale under ambient conditions, and this is exceeded only by An-An pairings prepared under cryogenic matrix isolation conditions. Thermolysis and photolysis experiments suggest that the U-Pn bonds degrade by hemolytic bond cleavage, whereas the more redox robust thorium compounds engage in an acid-base/dehydrocoupling route.
      PubDate: 2017-12-12T13:35:35.446002-05:
      DOI: 10.1002/anie.201711824
       
  • Encapsulation of Homogeneous Catalysts in Mesoporous Materials Using
           Diffusion-Limited Atomic Layer Deposition
    • Authors: Shufang Zhang; Bin Zhang, Haojie Liang, Yequn Liu, Yan Qiao, Yong Qin
      Abstract: The heterogenization of homogeneous metal complex catalysts has attracted great attention. Herein, we report the encapsulation of metal complexes into nanochannels of mesoporous materials by coating metal oxides at/near the pore entrance via diffusion-limited atomic layer deposition (ALD) to produce a "hollow plug". The pore size of the hollow plug is precisely controlled on the sub-nanometer scale by the number of ALD cycles to fit various metal complexes with different molecular sizes. Typically, Co or Ti complexes are successfully encapsulated into the nanochannels of SBA-15, SBA-16 and MCM-41. The encapsulated Co and Ti catalysts show excellent catalytic activity and reusability in the hydrolytic kinetic resolution of epoxides and asymmetric cyanosilylation of carbonyl compounds, respectively. This ALD-assisted encapsulation method can be extended to the encapsulation of other homogeneous catalysts into different mesoporous materials for various heterogeneous reactions.
      PubDate: 2017-12-12T13:00:27.890343-05:
      DOI: 10.1002/anie.201712010
       
  • CO2 to terpenes - autotrophic and electroautotrophic α-humulene
           production with Cupriavidus necator
    • Authors: Thomas Krieg; Anne Sydow, Sonja Faust, Ina Huth, Dirk Holtmann
      Abstract: Herein, we demonstrate that CO2 can be converted by an engineered "Knallgas" bacterium (Cupriavidus necator) to the terpene α-humulene. Heterologous expression of the mevalonate pathway and α-humulene synthase resulted in a production of approx. 10 mg α-humulene per gram cell dry mass (CDM) under heterotrophic conditions. This first example of chemolithoautotrophic production of a terpene from carbon dioxide, hydrogen and oxygen is a promising starting point for the production of different high value terpene compounds from abundant and simple raw materials. Furthermore, the production system was used to produce 17 mg α-humulene per gram CDM from CO2 and electrical energy in microbial electrosynthesis (MES) mode. Due to the fact that the system can convert CO2 by using electrical energy from solar energy it opens a new route to artificial photosynthetic systems.
      PubDate: 2017-12-12T12:07:01.211631-05:
      DOI: 10.1002/anie.201711302
       
  • pH resistant monodispersed polymer-lipid nanodiscs
    • Authors: Thirupathi Ravula; Nathaniel Z Hardin, Sudheer Ramadugu, Sarah J Cox, Ayyalusamy Ramamoorthy
      Abstract: Polymer lipid nanodiscs have provided an invaluable system for structural and functional studies of membrane proteins in their near-native environment. In spite of the recent advances in the development and usage of polymer lipid nanodisc systems, lack of control over size and poor tolerance to pH and divalent metal ions are major limitations for further applications. Here we report a facile modification of a low molecular weight styrene maleic acid copolymer to form monodispersed lipid bilayer nanodiscs that show ultra-stability towards a pH range of 2.5 to 10 and divalent metal ion concentration. The macro-nanodiscs (>20 nm diameter) show magnetic-alignment properties that can be exploited for high-resolution structural studies of membrane proteins using well-established solid-state NMR techniques. As demonstrated in this study, the new polymer, SMA-QA, is a robust membrane mimetic tool that offers significant advantages over currently reported nanodisc systems.
      PubDate: 2017-12-12T11:36:49.434676-05:
      DOI: 10.1002/anie.201712017
       
  • Three-Component Enantioselective Cyclization Reaction Catalyzed by an
           Unnatural Amino Acid Derivative
    • Authors: María de Gracia Retamosa; Andrea Ruiz-Olalla, Tamara Bello, Abel de Cózar, Fernando P. Cossío
      Abstract: A new diastereo- and enantioselective three-component cyclization reaction is described. The reaction takes place between a ketone, a carboxylic acid, and a nitroalkene to yield a bicyclic octahydro-2H-indol-2-one scaffold possessing three chiral centers. This reaction involves a rearrangement of the nitro group under simple thermal conditions. A plausible mechanism is proposed for this new reaction based on DFT calculations and isotope-labeling experiments. A new concise enantioselective synthesis of the alkaloid (+)-pancracine is presented as an example of the potential of this novel organocatalytic cyclization reaction in the synthesis of natural products.Brand new cycle: The unnatural and densely substituted l-proline ester XL catalyzes the formation of bicyclic γ-lactams possessing three new chiral centers. This new reaction has no equivalent in organocatalytic, enzymatic, or organometallic chemistry and can be used in the synthesis of complex natural products.
      PubDate: 2017-12-12T08:59:23.476502-05:
      DOI: 10.1002/anie.201708952
       
  • The Chemical Record Lectureship for Michael Grätzel / Baizer Award for
           Flavio Maran / And also in the News
    • PubDate: 2017-12-12T08:58:59.001638-05:
      DOI: 10.1002/anie.201712406
       
  • A General Synthesis of Porous Carbon Nitride Films with Tunable Surface
           Area and Photophysical Properties
    • Authors: Guiming Peng; Lidan Xing, Jesús Barrio, Michael Volokh, Menny Shalom
      Abstract: Graphitic carbon nitride (g-CN) has emerged as a promising material for energy-related applications. However, exploitation of g-CN in practical devices is still limited owing to difficulties in fabricating g-CN films with adjustable properties and high surface area. A general and simple pathway is reported to grow highly porous and large-scale g-CN films with controllable chemical and photophysical properties on various substrates using the doctor blade technique. The growth of g-CN films, ascribed to the formation of a supramolecular paste, comprises g-CN monomers in ethylene glycol, which can be cast on different substrates. The g-CN composition, porosity, and optical properties can be tuned by the design of the supramolecular paste, which upon calcination results in a continuous porous g-CN network. The strength of the porous structure is demonstrated by high electrochemically active surface area, excellent dye adsorption and photoelectrochemical and photodegradation properties.An efficient, easy, and general method for growing highly porous and large-scale carbon nitride (g-CN) networks on various substrates using the doctor blade technique is introduced. The g-CN films have high electrochemical active surface area, excellent dye adsorption, and good photoelectrochemical and photodegradation properties. This method opens opportunities for exploitation of g-CN in electronic and photoelectronic devices.
      PubDate: 2017-12-12T08:53:42.524359-05:
      DOI: 10.1002/anie.201711669
       
  • Ion–Solvent Complexes Promote Gas Evolution from Electrolytes on a
           Sodium Metal Anode
    • Authors: Xiang Chen; Xin Shen, Bo Li, Hong-Jie Peng, Xin-Bing Cheng, Bo-Quan Li, Xue-Qiang Zhang, Jia-Qi Huang, Qiang Zhang
      Abstract: Lithium and sodium metal batteries are considered as promising next-generation energy storage devices due to their ultrahigh energy densities. The high reactivity of alkali metal toward organic solvents and salts results in side reactions, which further lead to undesirable electrolyte depletion, cell failure, and evolution of flammable gas. Herein, first-principles calculations and in situ optical microscopy are used to study the mechanism of organic electrolyte decomposition and gas evolution on a sodium metal anode. Once complexed with sodium ions, solvent molecules show a reduced LUMO, which facilitates the electrolyte decomposition and gas evolution. Such a general mechanism is also applicable to lithium and other metal anodes. We uncover the critical role of ion–solvent complexation for the stability of alkali metal anodes, reveal the mechanism of electrolyte gassing, and provide a mechanistic guidance to electrolyte and lithium/sodium anode design for safe rechargeable batteries.Safe rechargeable batteries: Ion–solvent complexes in alkali metal batteries have been studied by first-principles calculations and in situ optical microscopy. The ion–solvent complexes have low LUMOs and are readily reduced on an alkali metal anode. A general mechanism for organic electrolyte decomposition and gas evolution was discovered.
      PubDate: 2017-12-12T08:53:18.584971-05:
      DOI: 10.1002/anie.201711552
       
  • A Six-Oxidase Cascade for Tandem C−H Bond Activation Revealed by
           Reconstitution of Bicyclomycin Biosynthesis
    • Authors: Song Meng; Wei Han, Juan Zhao, Xiao-Hong Jian, Hai-Xue Pan, Gong-Li Tang
      Abstract: As a commercial antibiotic, bicyclomycin (BCM) is currently the only known natural product targeting the transcription termination factor rho. It belongs to a family of highly functionalized diketopiperazine (DKP) alkaloids and bears a unique O-bridged bicyclo[4.2.2]piperazinedione ring system, a C1 triol, and terminal exo-methylene groups. We have identified and characterized the BCM biosynthetic pathway by heterologous biotransformations, in vitro biochemical assays, and one-pot enzymatic synthesis. A tRNA-dependent cyclodipeptide synthase guides the heterodimerization of leucine and isoleucine to afford the DKP precursor; subsequently, six redox enzymes, including five α-ketoglutarate/Fe2+-dependent dioxygenases and one cytochrome P450 monooxygenase, regio- and stereoselectively install four hydroxy groups (primary, secondary, and two tertiary), an exo-methylene moiety, and a medium-sized bridged ring through the functionalization of eight unactivated C−H bonds.Enzymatic characterization of the biosynthesis of the antibiotic bicyclomycin revealed a tRNA-dependent cyclodipeptide synthase for the heterodimerization of Leu and Ile to afford the diketopiperazine precursor. Subsequently, six redox enzymes activate eight unactivated C−H bonds through regio- and stereoselective hydroxylation, alkenylation, heterocyclization, and desaturation/epoxidation.
      PubDate: 2017-12-12T08:53:12.35678-05:0
      DOI: 10.1002/anie.201710529
       
  • Can Coordination-Driven Supramolecular Self-Assembly Reactions Be
           Conducted from Fully Aliphatic Linkers'
    • Authors: Mehdi Elsayed Moussa; Sloane Evariste, Barbara Krämer, Régis Réau, Manfred Scheer, Christophe Lescop
      Abstract: The reaction between a preassembled CuI bimetallic molecular clip with a short intermetallic distance and a series of fully aliphatic cyano-capped ditopic linkers with increasing lengths was investigated. It is shown that, depending on the length of the ditopic linkers, the rational design of unprecedented supramolecular compact metallacycles containing fully aliphatic walls is possible. The specific preorganized molecular arrangement of the molecular clip used favors stabilizing interlinker London dispersion interactions, which allow, as the length of the linkers increases, the selective formation of discrete compact metallacycles at the expense of 1D coordination polymers. The generalizability of this approach was demonstrated by the reaction of fully aliphatic cyano-capped linkers with two other types of preassembled CuI bimetallic molecular clips that also had short intermetallic distances.Give them a sense of direction: Cyano-capped fully aliphatic linkers underwent supramolecular assembly with preorganized CuI dimers with short intermetallic distances to form different types of metallacycles and 1D coordination polymers depending on the length of the linkers (see picture). Stabilizing London dispersion interactions between the methylene units made the selective self-assembly of such linkers with nondirectional backbones possible.
      PubDate: 2017-12-12T08:52:44.681395-05:
      DOI: 10.1002/anie.201709119
       
  • Asymmetric Synthesis of 2H-Azirines with a Tetrasubstituted Stereocenter
           by Enantioselective Ring Contraction of Isoxazoles
    • Authors: Kazuhiro Okamoto; Atsushi Nanya, Akira Eguchi, Kouichi Ohe
      Abstract: Highly strained 2H-azirines with a tetrasubstituted stereocenter were synthesized by the enantioselective isomerization of isoxazoles with a chiral diene–rhodium catalyst system. The effect of ligands and the coordination behavior support the proposed catalytic cycle in which the coordination site is fixed in favor of efficient enantiodiscrimination by a bulky substituent of the ligand. In silico studies also support the existence of a rhodium–imido complex as a key intermediate for enantiodiscrimination.Coping well under the strain: Highly strained 2H-azirines with tetrasubstituted stereocenters were synthesized with high enantioselectivity by the N−O bond-cleaving isomerization of isoxazoles in the presence of a chiral diene–rhodium catalyst (see scheme). This asymmetric ring contraction of isoxazoles proceeded under mild reaction conditions to give 2-alkoxycarbonyl 2H-azirines with various substituents, including halogen groups.
      PubDate: 2017-12-12T08:52:14.513502-05:
      DOI: 10.1002/anie.201710920
       
  • Distal Weak Coordination of Acetamides in Ruthenium(II)-Catalyzed
           C−H Activation Processes
    • Authors: Qingqing Bu; Torben Rogge, Vladislav Kotek, Lutz Ackermann
      Abstract: C−H activations with challenging arylacetamides were accomplished by versatile ruthenium(II) biscarboxylate catalysis. The distal C−H functionalization offers ample scope—including twofold oxidative C−H functionalizations and alkyne hydroarylations—through facile base-assisted internal electrophilic-type substitution (BIES) C−H ruthenation by weak O-coordination.From a distance: A versatile RuII-catalyzed method permits facile distal C−H activation of weakly O-coordinating arylacetamides via a six-membered ruthenacycle intermediate. The scope of the reaction includes primary, secondary, and tertiary amides.
      PubDate: 2017-12-12T08:51:48.677289-05:
      DOI: 10.1002/anie.201711108
       
  • The Catalytic Asymmetric Mukaiyama-Michael Reaction of Silyl Ketene
           Acetals with α,β-Unsaturated Methyl Esters
    • Authors: Benjamin List; Tim Gatzenmeier, Philip S. J. Kaib, Julia B. Lingnau, Richard Goddard
      Abstract: α,β-Unsaturated esters are readily available but challenging substrates to activate in asymmetric catalysis. We now describe an efficient, general, and highly enantioselective Mukaiyama-Michael reaction of silyl ketene acetals with α,β-unsaturated methyl esters, catalyzed by a silylium imidodiphosphorimidate (IDPi) Lewis acid.
      PubDate: 2017-12-12T08:37:24.327942-05:
      DOI: 10.1002/anie.201712088
       
  • Introducing Chiral Bifunctional Phosphine-Carboxylate Ligands for
           Palladium(0)-Catalyzed Enantioselective C-H Arylation
    • Authors: Lei Yang; Markus Neuburger, Olivier Baudoin
      Abstract: Previous enantioselective Pd0-catalyzed C-H activation reactions proceeding via the concerted metalation-deprotonation mechanism employed either a chiral ancillary ligand, a chiral base, or a bimolecular mixture thereof. This study describes the development of new chiral bifunctional ligands based on a binaphthyl scaffold and incorporating both a phosphine and a carboxylic acid moiety. The optimal ligand provided high yields and enantioselectivities for the desymmetrizing C(sp2)-H arylation leading to 5,6-dihydrophenanthridines, whereas the corresponding monofunctional ligands showed low enantioselectivities. The bifunctional system proved applicable to a range of substituted dihydrophenanthridines, and allowed the parallel kinetic resolution of racemic substrates.
      PubDate: 2017-12-12T06:03:25.270628-05:
      DOI: 10.1002/anie.201712061
       
  • Enantioselective Synthesis of N,S-Acetals by an Oxidative Pummerer-Type
           Transformation using Phase-Transfer Catalysis
    • Authors: Souvagya Biswas; Koji Kubota, Manuel Orlandi, Mathias Turberg, Dillon H. Miles, Matthew S. Sigman, F. Dean Toste
      Abstract: Reported is the first enantioselective oxidative Pummerer-type transformation using phase-transfer catalysis to deliver enantioenriched sulfur-bearing heterocycles. This reaction includes the direct oxidation of sulfides to a thionium intermediate, followed by an asymmetric intramolecular nucleophilic addition to form chiral cyclic N,S-acetals with moderate to high enantioselectivites. Deuterium-labelling experiments were performed to identify the stereodiscrimination step of this process. Further analysis of the reaction transition states, by means of multidimensional correlations and DFT calculations, highlight the existence of a set of weak noncovalent interactions between the catalyst and substrate that govern the enantioselectivity of the reaction.Aye, aye, CAPT: The first catalytic enantioselective Pummerer-type transformation has been developed employing chiral-anion phase-transfer catalysis (CAPT). This chemical transformation allows facile construction of a wide variety of enantioenriched cyclic N,S-acetal motifs which were previously difficult to access.
      PubDate: 2017-12-12T04:41:11.286837-05:
      DOI: 10.1002/anie.201711277
       
  • On the Use of Polyelectrolytes and Polymediators in Organic
           Electrosynthesis
    • Authors: Benjamin Schille; Niels Ole Giltzau, Robert Francke
      Abstract: Although organic electrosynthesis is generally considered to be a green method, the necessity for excess amounts of supporting electrolyte constitutes a severe drawback. Furthermore, the employment of redox mediators results in an additional separation problem. In this context, we have explored the applicability of soluble polyelectrolytes and polymediators with the TEMPO-mediated transformation of alcohols into carbonyl compounds as a test reaction. Catalyst benchmarking based on cyclic voltammetry studies indicated that the redox-active polymer can compete with molecularly defined TEMPO species. Alcohol oxidation was also highly efficient on a preparative scale, and our polymer-based approach allowed for the separation of both mediator and supporting electrolyte in a single membrane filtration step. Moreover, we have shown that both components can be reused multiple times.Combining electrosynthesis with membrane filtration: The attachment of a TEMPO mediator and a supporting electrolyte to soluble polymers enables the selective anodic conversion of alcohols into carbonyl compounds and allows for efficient recovery/recycling of the mediator and the salt by membrane filtration.
      PubDate: 2017-12-12T04:33:03.720395-05:
      DOI: 10.1002/anie.201710659
       
  • Desktop NMR and Its Applications From Materials Science To Organic
           Chemistry
    • Authors: Bernhard Blümich; Kawarpal Singh
      Abstract: NMR spectroscopy is an indispensable method of analysis in chemistry, which until recently suffered from high demands for space, high costs for acquisition and maintenance, and operational complexity. This has changed with the introduction of compact NMR spectrometers suitable for small-molecule analysis on the chemical workbench. These spectrometers contain permanent magnets giving rise to proton NMR frequencies between 40 and 80 MHz. The enabling technology is to make small permanent magnets with homogeneous fields. Tabletop instruments with inhomogeneous fields have been in use for over 40 years for characterizing food and hydrogen-containing materials by relaxation and diffusion measurements. Related NMR instruments measure these parameters in the stray field outside the magnet. They are used to inspect the borehole walls of oil wells and to test objects nondestructively. The state-of-the-art of NMR spectroscopy, imaging and relaxometry with compact instruments is reviewed.NMR spectroscopy is known not only for its outstanding analytical power but also for the large size and costs of the instruments. In recent years, the family of instruments with bulky superconducting magnets has been complemented with compact tabletop and portable devices suitable for small-molecule analysis and nondestructive materials testing. The state of the art of compact NMR instruments is reviewed and illustrated with selected examples.
      PubDate: 2017-12-12T04:32:03.028748-05:
      DOI: 10.1002/anie.201707084
       
  • Computational Chemistry: The Fate of Current Methods and Future Challenges
    • Authors: Stefan Grimme; Peter R. Schreiner
      Abstract: “Where do we go from here'” is the underlying question regarding the future (perhaps foreseeable) developments in computational chemistry. Although this young discipline has already permeated practically all of chemistry, it is likely to become even more powerful with the rapid development of computational hard- and software.
      PubDate: 2017-12-12T04:31:56.820978-05:
      DOI: 10.1002/anie.201709943
       
  • Macrolide Synthesis trough Intramolecular Oxidative Cross-Coupling of
           Alkenes
    • Authors: Bing Jiang; Meng Zhao, Shu-Sen Li, Yun-He Xu, Teck-Peng Loh
      Abstract: A RhIII-catalyzed intramolecular oxidative cross-coupling between double bonds for the synthesis of macrolides is described. Under the optimized reaction conditions, macrocycles containing a diene moiety can be formed in reasonable yields and with excellent chemo- and stereoselectivity. This method provides an efficient approach to synthesize macrocyclic compounds containing a 1,3-conjugated diene structure.Two pair: A RhIII-catalyzed intramolecular oxidative cross-coupling between double bonds for the synthesis of macrolides is described. Under the optimized conditions, macrocycles containing a diene moiety can be formed in reasonable yields and with excellent chemo- and stereoselectivity. This provides efficient access to macrocyclic compounds containing 1,3-conjugated dienes.
      PubDate: 2017-12-12T04:31:31.226976-05:
      DOI: 10.1002/anie.201710601
       
  • Highly Branched Polymers with Layered Structures that Mimic
           Light-Harvesting Processes
    • Authors: Yi Shi; Xiaosong Cao, Daqiao Hu, Haifeng Gao
      Abstract: Hyperbranched polymers (HBPs) with decorated donor and acceptor chromophores in different domains were constructed to demonstrate the function of light harvesting in a polymeric nanostructure. Taking advantage of our recently developed chain-growth copper-catalyzed azide–alkyne cycloaddition polymerization, two structural parameters in the HBPs, for example, the molar ratio of the acceptor Coumarin 343 in the core to the donor Coumarin 2 on the periphery, and the average distance between these two layers, could be independently varied in a one-pot synthesis. The results demonstrated an efficient energy transfer from the excited Coumarin 2 to the ground-state Coumarin 343 in the core, with the efficiency of the energy transfer reaching as high as 98 %. The excited Coumarin 343, after receiving energy from donor Coumarin 2 emitted higher fluorescence intensity than when directly excited, indicating an observed light concentration effect from the periphery dye to the central dye in one polymer structure.Hyperbranched polymers (HBPs) with decorated donor (Coumarin 2, C2) and acceptor (Coumarin 343, C343) chromophores in different domains were constructed by chain-growth copper-catalyzed azide–alkyne cycloaddition polymerization (CuAACP) to demonstrate the function of light harvesting in a polymeric nanostructure. The efficiency of the energy transfer extended up to 98 %.
      PubDate: 2017-12-12T04:30:47.771953-05:
      DOI: 10.1002/anie.201709492
       
  • Copper-Catalyzed Enantioselective Markovnikov Protoboration of α-Olefins
           Enabled by a Buttressed NHC Ligand
    • Authors: Yuan Cai; Xin-Tuo Yang, Shuo-Qing Zhang, Feng Li, Yu-Qing Li, Lin-Xin Ruan, Xin Hong, Shi-Liang Shi
      Abstract: We report herein a highly enantioselective copper-catalyzed Markovnikov protoboration of unactivated terminal alkenes. A variety of simple and abundant feedstock α-olefins bearing a diverse array of functional groups and heterocyclic substituents can be applied in this process, which proceeds under mild conditions at ambient temperature to provide expedient access to enantioenriched alkylboronic esters in good regioselectivity and with excellent enantiocontrol. Critical to the success of the protocol was the development and application of a novel, sterically hindered N-heterocyclic carbene, (R,R,R,R)-ANIPE, as the ligand for copper.
      PubDate: 2017-12-12T02:48:58.09126-05:0
      DOI: 10.1002/anie.201711229
       
  • Visualization of Heterogeneous Oxygen Storage Behavior in Three-Way
           Catalyst Pt/Ce2Zr2Ox Particles by Hard X-ray Spectro-Ptychography
    • Authors: Makoto Hirose; Nozomu Ishiguro, Kei Shimomura, Nicolas Burdet, Hirosuke Matsui, Mizuki Tada, Yukio Takahashi
      Abstract: The cerium density and valence in micrometer-size Pt/Ce2Zr2Ox (x=7-8) three-way catalyst particles were successfully mapped by hard X-ray spectro-ptychography (ptychographic-XAFS). The analysis of correlation between the Ce density and valence in ptychographic-XAFS images suggested the existence of several oxidation behaviors in the oxygen storage process in the Ce2Zr2Ox particles. Ptychographic-XAFS will open up the nanoscale chemical imaging and structural analysis of heterogeneous catalysts.
      PubDate: 2017-12-11T23:52:46.439376-05:
      DOI: 10.1002/anie.201710798
       
  • Interfacial nanoprecipitation toward stable and responsive microbubbles
           and their use as a resuscitative fluid
    • Authors: Yifeng Peng; Raymond Seekell, Alexis Cole, Jemima Lamothe, Andrew Lock, Sarah van den Bosch, Xiaoqi Tang, John Kheir, Brian Polizzotti
      Abstract: : We report a new approach to prepare stable microbubbles (MBs) via interfacial nanoprecipitation of bioabsorbable polymers at air/liquid interface. This facile method offers robust control over MBs morphology and chemo-physical properties by simple chemical modifications. This approach is amenable to large-scale manufacturing, and is useful to develop functional MBs for advanced biomedical applications. To demonstrate this, we created a MB-based intravenous oxygen carrier that undergoes pH-triggered self-elimination. Intravenous injection of past MBs increase the risk of pulmonary vascular obstruction. However, we show, for the first time, that our current design supersedes previous MBs, as they 1) yielded no evidence of acute risks in rodents, and 2) improved the survival in a disease model of asphyxial cardiac arrest (from 0 to 100%), a condition that affects more than 100,000 in-hospital patients, carrying a ~90% mortality.
      PubDate: 2017-12-11T21:50:45.675471-05:
      DOI: 10.1002/anie.201711839
       
  • Emissive synthetic cofactors: enzymatic interconversions of tzA analogues
           of ATP, NAD+, NADH, NADP+ and NADPH
    • Authors: Yitzhak Tor; François Hallé, Andrea Fin, Alexander R Rovira
      Abstract: A series of enzymatic transformations, which generate visibly emissive isofunctional cofactors based on an isothiazolo[4,3-d]pyrimidine analogue of adenosine (tzA), is described. Nicotinamide adenylyl transferase condenses nicotinamide mononucleotide and tzATP to yield NtzAD+, which can be enzymatically phosphorylated by NAD+ kinase and ATP or tzATP to the corresponding NtzADP+. The latter can be engaged in NADP-specific coupled enzymatic transformations involving conversion to NtzADPH by glucose-6-phosphate dehydrogenase and reoxidation to NtzADP+ by glutathione reductase. The NtzADP+/NtzADPH cycle can be monitored in real time by fluorescence spectroscopy.
      PubDate: 2017-12-11T12:51:23.294199-05:
      DOI: 10.1002/anie.201711935
       
  • Transition-Metal-Catalyzed Selective Functionalization of C(sp3)-H Bonds
           in Natural Products
    • Authors: Rashad R Karimov; John F. Hartwig
      Abstract: Direct functionalization of natural products is important for studying structure-activity and structure-property relationships of these molecules. Recent advances in transition-metal-catalyzed functionalizations of C(sp3)-H bonds, the most abundant yet inert bonds in natural products, have been shown to create natural product derivatives selectively. Strategies to achieve such transformation are reviewed.
      PubDate: 2017-12-11T12:51:20.432037-05:
      DOI: 10.1002/anie.201710330
       
  • A bioresistant nitroxide spin label for in-cell EPR spectroscopy: in vitro
           and in oocytes protein structural dynamics studies.
    • Authors: Ganesan Karthikeyan; Alessio Bonucci, Gilles Casano, Guillaume Gerbaud, Sébastien Abel, Virginie Thomé, Laurent Kodjabachian, Axel Magalon, Bruno Guigliarelli, Valérie Belle, Olivier Ouari, Elisabetta Mileo
      Abstract: Approaching proteins structural dynamics and protein-protein interactions in the cellular environment is a fundamental challenge. Due to its absolute sensitivity and to its selectivity to paramagnetic species, Site-Directed Spin Labeling (SDSL) combined with Electron Paramagnetic Resonance (EPR) has the potential to evolve into an efficient method to follow conformational changes in proteins directly inside cells. Until now, the use of nitroxyde-based spin labels for in-cell studies has represented a major hurdle because of their short persistence in the cellular context. In this work we present the design and synthesis of the first maleimido-proxyl-based spin label (M-TETPO) resistant towards reduction and being efficient to probe protein dynamics by continuous wave and pulsed EPR. In particular, the extended lifetime of M-TETPO enabled the study of structural features of a chaperone in the absence and presence of its binding partner at endogenous concentration directly inside cells.
      PubDate: 2017-12-11T11:20:46.752424-05:
      DOI: 10.1002/anie.201710184
       
  • Building Organic/Inorganic Hybrid Interphases for Fast Interfacial
           Transport in Rechargeable Metal Batteries
    • Authors: Qing Zhao; Zhengyuan Tu, Shuya Wei, Kaihang Zhang, Snehashis Choudhury, Xiaotun Liu, Lynden Archer
      Abstract: We report a facile, in-situ synthesis to create durable, hybrid Solid-electrolyte interphases (SEI) on metal anodes. Composed of Si-interlinked molecules that host LiCl salt, the hybrid SEI exhibit fast charge-transfer kinetics and high exchange current densities. By means of electrochemical analysis and direct optical visualization of Li and Na deposition in symmetric Li/Li and Na/Na cells, it is further shown that the hybrid SEI enables excellent morphological control at relatively high current densities (3-5 mA/cm2) and even for notoriously unstable Na metal anodes. We investigate benefits of the fast interfacial transport attributes of the SEI in Li-S cells. It is found that stable electrochemical cycling is achieved in galvanostatic studies at rates as high as 2 C. Our work provides a promising path towards rational design of multi-functional, elastic SEI that overcomes the most serious limitations of spontaneously formed interphases on high-capacity metal anodes.
      PubDate: 2017-12-11T10:20:55.738649-05:
      DOI: 10.1002/anie.201711598
       
  • Triple Bonds Between Iron and Heavier Group 15 Elements in AFe(CO)3−
           (A=As, Sb, Bi) Complexes
    • Authors: Jia-Qi Wang; Chaoxian Chi, Han-Shi Hu, Luyan Meng, Mingbiao Luo, Jun Li, Mingfei Zhou
      Abstract: Heteronuclear transition-metal–main-group-element carbonyl complexes of AsFe(CO)3−, SbFe(CO)3−, and BiFe(CO)3− were produced by a laser vaporization supersonic ion source in the gas phase, and were studied by mass-selected IR photodissociation spectroscopy and advanced quantum chemistry methods. These complexes have C3v structures with all of the carbonyl ligands bonded on the iron center, and feature covalent triple bonds between bare Group 15 elements and Fe(CO)3−. Chemical bonding analyses on the whole series of AFe(CO)3− (A=N, P, As, Sb, Bi, Mc) complexes indicate that the valence orbitals involved in the triple bonds are hybridized 3d and 4p atomic orbitals of iron, leading to an unusual (dp–p) type of transition-metal–main-group-element multiple bonding. The σ-type three-orbital interaction between Fe 3d/4p and Group 15 np valence orbitals plays an important role in the bonding and stability of the heavier AFe(CO)3− (A=As, Sb, Bi) complexes.Going for the triple: IR photodissociation spectroscopy and quantum chemical calculations were performed on the complexes AFe(CO)3− (A=As, Sb, Bi). These studies reveal that the complexes contain a (dp–p) type of A−Fe triple bonding.
      PubDate: 2017-12-11T09:28:12.866513-05:
      DOI: 10.1002/anie.201709875
       
  • Magnetic Actuation of Drops and Liquid Marbles Using a Deformable
           Paramagnetic Liquid Substrate
    • Authors: Jacopo Vialetto; Masayuki Hayakawa, Nikita Kavokine, Masahiro Takinoue, Subramanyan Namboodiri Varanakkottu, Sergii Rudiuk, Manos Anyfantakis, Mathieu Morel, Damien Baigl
      Abstract: The magnetic actuation of deposited drops has mainly relied on volume forces exerted on the liquid to be transported, which is poorly efficient with conventional diamagnetic liquids such as water and oil, unless magnetosensitive particles are added. Herein, we describe a new and additive-free way to magnetically control the motion of discrete liquid entities. Our strategy consists of using a paramagnetic liquid as a deformable substrate to direct, using a magnet, the motion of various floating liquid entities, ranging from naked drops to liquid marbles. A broad variety of liquids, including diamagnetic (water, oil) and nonmagnetic ones, can be efficiently transported using the moderate magnetic field (ca. 50 mT) produced by a small permanent magnet. Complex trajectories can be achieved in a reliable manner and multiplexing potential is demonstrated through on-demand drop fusion. Our paramagnetofluidic method advantageously works without any complex equipment or electric power, in phase with the necessary development of robust and low-cost analytical and diagnostic fluidic devices.Playing drops and marbles: Small magnets are used to precisely drive the motion of floating drops and liquid marbles, made of water, oil or nonmagnetic fluids, and without the use of magnetosensitive particles for the first time. Digital microfluidic operations such as transport along complex trajectories and programmed drop fusion are demonstrated.
      PubDate: 2017-12-11T09:23:10.808546-05:
      DOI: 10.1002/anie.201710668
       
  • para-Xylene Ultra-selective Zeolite MFI Membranes Fabricated from
           Nanosheet Monolayers at the Air–Water Interface
    • Authors: Donghun Kim; Mi Young Jeon, Benjamin L. Stottrup, Michael Tsapatsis
      Abstract: The control of membrane morphology and microstructure is crucial to improve the separation performance of molecular-sieve membranes. This can be enabled by making thin, dense, and uniform seed-crystal coatings, which are then intergrown into continuous membranes. Herein, we show a novel and simple floating particle coating method can give closely packed monolayers of zeolite nanosheets on nonporous or porous supports. The zeolite nanosheet monolayer is formed at the air–water interface in a conical Teflon trough. As the water in the trough is drained, the monolayer is deposited on a support placed below. Membranes prepared by gel-free secondary growth of the nanosheets deposited by this method show unprecedented ultra-selective performance for separation of para- from ortho-xylene (separation factor>10 000).The membrane drain: A uniform and dense MFI nanosheet monolayer from an air–water interface is transferred onto a porous support by a new monolayer deposition method using a conical trough which drains. The high-coverage nanosheet seed coating, and subsequent intergrowth gives a thin, oriented, and low-defect-density membrane, which exhibits ultra-selective (separation factor>10 000) performance for xylene isomer separation.
      PubDate: 2017-12-11T09:20:53.649074-05:
      DOI: 10.1002/anie.201708835
       
  • Light-driven C-H Oxygenation of Methane into Methanol and Formic Acid by
           Molecular Oxygen Using Perfluorinated Solvent
    • Authors: Kei Ohkubo; Kensaku Hirose
      Abstract: Chlorine dioxide radical (ClO2*) was found to act as an efficient oxidizing agent in the aerobic oxygenation of methane to methanol and formic acid under photoirradiation. Photochemical oxygenation of methane occurred in a two-phase system comprising perfluorohexane and water under ambient conditions (298 K, 1 atm). The yields of methanol and formic acid were 14% and 85%, respectively, with a methane conversion of 99% without formation of the further oxygenated products such as CO2 and CO. Ethane was also photochemically converted into ethanol (19%) and acetic acid (78%). The methane oxygenation is initiated by the photochemical Cl-O bond cleavage of ClO2* to generate Cl* and O2. The produced Cl* reacts with CH4 to form a methyl radical (CH3*). Finally, the oxygenated products such as methanol and formic acid were given by the radical chain reaction. A fluorous solvent plays an important role of inhibiting the deactivation of reactive radical species such as Cl* and CH3*.
      PubDate: 2017-12-11T08:22:22.854372-05:
      DOI: 10.1002/anie.201710945
       
  • ortho-Directing Chromium Arene Complexes as Efficient Mediators for
           Enantiospecific sp2-sp3 Cross-Coupling Reactions
    • Authors: Raphael Bigler; Varinder Kumar Aggarwal
      Abstract: A new strategy for the coupling of a broad scope of electronically diverse aromatics to boronic esters is reported. The coupling sequence, which relies on the directed ortho-lithiation of chromium arene complexes followed by boronate formation and oxidation, occurs with complete ortho-selectivity and enantiospecificity to give the coupling products in excellent yields and with high functional group tolerance. An intermediate chromium arene boronate complex was characterized by X-ray, NMR and IR to elucidate the reaction mechanism.
      PubDate: 2017-12-11T05:27:06.610005-05:
      DOI: 10.1002/anie.201711816
       
  • Magnetic Actuation of Drops and Liquid Marbles Using a Deformable
           Paramagnetic Liquid Substrate
    • Authors: Jacopo Vialetto; Masayuki Hayakawa, Nikita Kavokine, Masahiro Takinoue, Subramanyan Namboodiri Varanakkottu, Sergii Rudiuk, Manos Anyfantakis, Mathieu Morel, Damien Baigl
      Abstract: Like the flow of water from a fountain, the local deformation of a paramagnetic substrate enables the gravity-driven transport of a liquid. In their Communication (
      DOI : 10.1002/anie.201710668), D. Baigl et al. show that, using a magnet, the deformation of the substrate (illustrated by the deformed text) allows the manipulation of drops and liquid marbles (the dots of the letters “i”). This method does not rely on magnetosensitive particles and can be used with most conventional liquids such as water or oil.
      PubDate: 2017-12-11T05:04:05.691979-05:
       
  • Enantio- and Diastereoselective Cyclopropanation of 1-Alkenylboronates:
           Synthesis of 1-boryl-2,3-disubstituted Cyclopropanes
    • Authors: Pedro J. Pérez; Javier Carreras, Ana Caballero
      Abstract: A novel, highly enantio- and diastereoselective synthesis of 1-boryl-2,3-disubstituted cyclopropanes has been developed by means of the cyclopropanation of alkenylboronates with ethyl diazoacetate in the presence of catalytic amounts of a chiral copper-(I) complex. The products can also be directly accessed from alkynes through an operationally simple sequential hydroboration-cyclopropanation protocol. The resulting enantioenriched 1-boryl-2,3-disubstituted-cyclopropanes are versatile synthetic intermediates through further transformations at the carbon-boron bonds
      PubDate: 2017-12-11T03:51:40.914253-05:
      DOI: 10.1002/anie.201710415
       
  • Thioketone Directed Palladium(II)-Catalyzed C-H Arylation of Ferrocenes
           with Aryl Boronic Acids
    • Authors: Shuli You; Zhong-Jian Cai, Chen-Xu Liu, Qing Gu
      Abstract: A palladium(II)-catalyzed thioketone-chelation-assisted C-H direct arylation of ferrocenes is described. With thioketone as an efficient directing group, various mono- and di-aryl-substituted thiocarbonylferrocenes were obtained via Pd-catalyzed C-H direct functionalization reaction in high yields under mild and base-free conditions. Furthermore, the arylated thiocarbonylferrocene could undergo diverse transformations.
      PubDate: 2017-12-11T03:23:10.454104-05:
      DOI: 10.1002/anie.201711451
       
  • Dicarboxylic Acid Separation by Dynamic and Size-Matched Recognition in
           Solution and in the Solid State
    • Authors: Pierangelo Metrangolo; giancarlo terraneo, giuseppe resnati, tullio pilati, vijith kumar, alceo macchioni, gianluca ciancaleoni
      Abstract: Bis(trimethylammonium) alkane diiodides dynamically encapsulate dicarboxylic acids through intermolecular hydrogen bonds between the hosts' I- anions and the guests' carboxylic OH groups. A selective recognition is realized when the size of the I-∙∙∙HOOC-(CH2/CF2)n-COOH∙∙∙I- superanion matches the dication alkyl chain length. Dynamic recognition is demonstrated also in solution, where the presence of the size-matching organic salt boosts acid solubility profile thus allowing efficient mixture separation.
      PubDate: 2017-12-10T21:51:35.777698-05:
      DOI: 10.1002/anie.201711822
       
  • Photocatalytic Aerobic Phosphatation of Alkenes
    • Authors: Alexander Breder; Christian Depken, Felix Krätzschmar, Rene Rieger, Katharina Rode
      Abstract: A catalytic regime for the direct phosphatation of simple, non-polarized alkenes, using ordinary, non-activated phosphoric acid diesters as the phosphate source and O2 as the terminal oxidant, has been devised. The title method allows for the direct and highly econo-mic construction of a diverse range of allylic phosphate esters. From a conceptual viewpoint, the aerobic phosphatation is entirely complementary to traditional protocols for phosphate ester formation, which predominantly rely on the use of pre-functionalized or pre-activated reactants, such as alcohols and phosphoryl halides. The title transformation is enabled by the dual interplay of a photoredox- and a selenium-π-acid catalyst involving a sequence of single-electron-transfer processes.
      PubDate: 2017-12-08T09:00:36.851988-05:
      DOI: 10.1002/anie.201711599
       
  • Nanosheet Catalysis of Carbon Dioxide Photoreduction: Fundamentals and
           Challenges
    • Authors: Zhenyu Sun; Neetu Talreja, Hengcong Tao, John Texter, Jennifer Strunk, Martin Muhler, Jianfeng Chen
      Abstract: Transformation of CO2 into fuels and chemicals by using photocatalysis is a promising strategy to provide a long-term solution to mitigating global warming and energy supply problems. Achievements in photocatalysis during the last decade have sparked increased interest in using sunlight to reduce CO2. Traditional semiconductors used in photocatalysis (e.g. TiO2), are not suitable for the use in natural sunlight, and even under UV irradiation their performance is not sufficient. Some two-dimensional (2D) materials have recently been designed for catalytic reduction of CO2. These materials still require significant modification, which remains a challenge for photocatalytic process design. An overarching aim of this article is to summarize the literature reported on photocatalytic conversion of CO2 by various 2D materials in the liquid phase, with special attention given to development of novel 2D photocatalyst materials, to provide a basis to suggest improved materials.
      PubDate: 2017-12-08T07:26:32.964063-05:
      DOI: 10.1002/anie.201710509
       
  • The common Intermediates of Oxygen Evolution and Dissolution Reactions
           during Water Electrolysis on Iridium
    • Authors: Olga Kasian; Jan-Philipp Grote, Simon Geiger, Serhiy Cherevko, Karl J.J. Mayrhofer
      Abstract: Understanding the pathways of catalyst degradation during the oxygen evolution reaction is a cornerstone in development of efficient and stable electrolyzers, since even for most promising Ir based anodes the destined harsh conditions are detrimental. The dissolution mechanism has a complex nature and the correlation to the oxygen evolution reaction itself is still poorly understood. Here, hyphening a scanning flow cell with inductively coupled plasma and online electrochemical mass spectrometers, we in-situ monitor the oxygen evolution and degradation products of Ir and Ir-oxides. We show that at high anodic potentials several dissolution routes become possible, including formation of gaseous IrO3. On the basis of our experimental data possible pathways of oxygen evolution triggered dissolution of Ir are proposed, and the role of common intermediates for these reactions is discussed.
      PubDate: 2017-12-08T07:25:46.077319-05:
      DOI: 10.1002/anie.201709652
       
  • Conformational Selection of Dimethylarginine Recognition by the Survival
           Motor Neuron Tudor Domain
    • Authors: Shreyas Supekar; Anna C. Papageorgiou, Gerd Gemmecker, Raphael Peltzer, Mikael P. Johansson, Konstantinos Tripsianes, Michael Sattler, Ville R. I. Kaila
      Abstract: Tudor domains bind to dimethylarginine (DMA) residues, which are post-translational modifications that play a central role in gene regulation in eukaryotic cells. NMR spectroscopy and quantum calculations are combined to demonstrate that DMA recognition by Tudor domains involves conformational selection. The binding mechanism is confirmed by a mutation in the aromatic cage that perturbs the native recognition mode of the ligand. General mechanistic principles are delineated from the combined results, indicating that Tudor domains utilize cation–π interactions to achieve ligand recognition.The House of Tudor: The Tudor domain of the human survival motor neuron protein selectively recognizes stereoisomers of dimethylarginine residues within its aromatic ligand-binding cage using cation–π interactions. Stereoselectivity can be modulated by a single point mutation.
      PubDate: 2017-12-08T07:07:41.069828-05:
      DOI: 10.1002/anie.201708233
       
  • Stability of Residual Oxides in Oxide-Derived Copper Catalysts for
           Electrochemical CO2 Reduction Investigated with 18O Labeling
    • Authors: Yanwei Lum; Joel W. Ager
      Abstract: Oxide-derived (OD) Cu catalysts have high selectivity towards the formation of multi-carbon products (C2/C3) for aqueous electrochemical CO2 reduction (CO2R). It has been proposed that a large fraction of the initial oxide can be surprisingly resistant to reduction, and these residual oxides play a crucial catalytic role. The stability of residual oxides was investigated by synthesizing 18O-enriched OD Cu catalysts and testing them for CO2R. These catalysts maintain a high selectivity towards C2/C3 products (ca. 60 %) for up to 5 h in 0.1 m KHCO3 at −1.0 V vs. RHE. However, secondary-ion mass spectrometry measurements show that only a small fraction (
      PubDate: 2017-12-08T07:01:08.027936-05:
      DOI: 10.1002/anie.201710590
       
  • Highly Selective Manganese(I)/Lewis Acid Cocatalyzed Direct C−H
           Propargylation Using Bromoallenes
    • Authors: Can Zhu; Jonas Luca Schwarz, Sara Cembellín, Steffen Greßies, Frank Glorius
      Abstract: A manganese(I)/Lewis acid cocatalyzed direct C−H propargylation with high selectivity has been developed. BPh3 was discovered to not only promote the reactivity, but also enhance the selectivity. Secondary, tertiary, and even quaternary carbon centers at the propargylic position could be directly constructed. Both internal and terminal alkynes are easily accessible. The chirality was successfully transferred from an axially chiral allene to central chirality. The reactivity of the manganese catalyst in this reaction was found to be unique among transition metal catalysts.Proper(gylation)! In a highly selective manganese(I)/Lewis acid cocatalyzed direct C−H propargylation, BPh3 not only promotes the reactivity, but also enhances the selectivity. Secondary, tertiary, and even quaternary carbon centers at the propargylic position could be directly constructed. The reactivity of the manganese catalyst in this reaction is unique among transition metal catalysts.
      PubDate: 2017-12-08T07:01:01.656926-05:
      DOI: 10.1002/anie.201710835
       
  • Benjamin List
    • PubDate: 2017-12-08T06:55:25.158409-05:
      DOI: 10.1002/anie.201711047
       
  • Intramolecular Acetyl Transfer to Olefins by Catalytic C−C Bond
           Activation of Unstrained Ketones
    • Authors: Zi-Qiang Rong; Hee Nam Lim, Guangbin Dong
      Abstract: A rhodium-catalyzed intramolecular acetyl-group transfer has been achieved through a “cut and sew” process. The challenge arises from the existence of different competitive pathways. Preliminary success has been achieved with unstrained enones that contain a biaryl linker. The use of an electron-rich N-heterocycilc carbene (NHC) ligand is effective to inhibit undesired β-hydrogen elimination. Various 9,10-dihydrophenanthrene derivatives can be prepared with excellent functional-group compatibility. The 13C-labelling study suggests that the reaction begins with cleavage of the unstrained C−C bond, followed by migratory insertion and reductive elimination.Cross-stitch: A rhodium-catalyzed intramolecular acetyl-group transfer has been achieved by a cut and sew process. By using unstrained enones that contain a biaryl linker, C−C activation occurs with the assistance of a temporary directing group. Various 9,10-dihydrophenanthrene derivatives can be prepared with excellent functional-group compatibility.
      PubDate: 2017-12-08T05:24:29.608432-05:
      DOI: 10.1002/anie.201711394
       
  • A Chiral Halogen-Bonding [3]Rotaxane for the Recognition and Sensing of
           Biologically Relevant Dicarboxylate Anions
    • Authors: Jason Y. C. Lim; Igor Marques, Vítor Félix, Paul D. Beer
      Abstract: The unprecedented application of a chiral halogen-bonding [3]rotaxane host system for the discrimination of stereo- and E/Z geometric isomers of a dicarboxylate anion guest is described. Synthesised by a chloride anion templation strategy, the [3]rotaxane host recognises dicarboxylates through the formation of 1:1 stoichiometric sandwich complexes. This process was analysed by molecular dynamics simulations, which revealed the critical synergy of halogen and hydrogen bonding interactions in anion discrimination. In addition, the centrally located chiral (S)-BINOL motif of the [3]rotaxane axle component facilitates the complexed dicarboxylate species to be sensed via a fluorescence response.The discrimination between dicarboxylate stereo- and geometric isomers by a chiral halogen-bonding [3]rotaxane can be monitored in terms of the fluorescence response. Computational modelling studies revealed the critical synergy between the axle of the rotaxane host and macrocycle components in achieving dicarboxylate guest selectivity.
      PubDate: 2017-12-08T05:23:56.084452-05:
      DOI: 10.1002/anie.201711176
       
  • A Step Closer to Metal-Free Dinitrogen Activation: A New Chapter in the
           Chemistry of Frustrated Lewis Pairs
    • Authors: Rebecca L. Melen
      Abstract: The end of the metal age: Recent developments in small-molecule activation and chemical transformations of main-group species pose the question as to whether metal catalysts could be avoided altogether in the activation of dinitrogen. A ground-breaking study by Stephan and co-workers clearly implies that the metal-free activation of N2 with frustrated Lewis pairs may be achievable in the not-too-distant future.
      PubDate: 2017-12-08T05:23:43.871741-05:
      DOI: 10.1002/anie.201711945
       
  • Rhodium-Catalyzed Cyclization of O,ω-Unsaturated Alkoxyamines: Formation
           of Oxygen-Containing Heterocycles
    • Authors: Julien Escudero; Véronique Bellosta, Janine Cossy
      Abstract: O,ω-Unsaturated N-tosyl alkoxyamines undergo unexpected RhIII-catalyzed intramolecular cyclization by oxyamination to produce oxygen-containing heterocycles. Mechanistic studies show that an aziridine intermediate seems to be responsible for the formation of the heterocycles, possibly via a RhV species.Unexpected reactivity: Functionalized tetrahydrofurans were unexpectedly obtained instead of the intended isoxazolidines. The reaction proceeds from N-tosyl O,ω-unsaturated alkoxyamines and a known rhodium(III)-catalyzed allylic C−H activation protocol. The scope and limitations of this surprising reaction are described. A mechanism, involving a rhodium(V) nitrenoid and an aziridination step, is discussed.
      PubDate: 2017-12-08T05:23:37.236992-05:
      DOI: 10.1002/anie.201710895
       
  • Nickel(0)-Catalyzed Hydroarylation of Styrenes and 1,3-Dienes with
           Organoboron Compounds
    • Authors: Li-Jun Xiao; Lei Cheng, Wei-Min Feng, Mao-Lin Li, Jian-Hua Xie, Qi-Lin Zhou
      Abstract: A Ni-catalyzed hydroarylation of styrenes and 1,3-dienes with organoboron compounds has been developed. The reaction offers a highly selective approach to diarylalkanes and allylarenes under redox-neutral conditions. In this hydroarylation reaction, a new strategy that uses the proton of methanol to generate the active catalyst species Ni−H was developed. The Ni-catalyzed hydroarylation, combined with a Ir-catalyzed C−H borylation, affords a very efficient and straightforward access to a retinoic acid receptor agonist.OH yeah: A nickel(0)-catalyzed hydroarylation of alkenes with organoboron reagents using an alcohol OH group as the H-atom source is reported. The reaction offers a highly selective approach to diarylalkanes and allylarenes under redox-neutral conditions.
      PubDate: 2017-12-08T05:22:58.73158-05:0
      DOI: 10.1002/anie.201710735
       
  • Purely Physisorption-Based CO-Selective Gate-Opening in Microporous
           Organically Pillared Layered Silicates
    • Authors: Markus M. Herling; Martin Rieß, Hiroshi Sato, Liangchun Li, Thomas Martin, Hussein Kalo, Ryotaro Matsuda, Susumu Kitagawa, Josef Breu
      Abstract: Separation of gas molecules with similar physical and chemical properties is challenging but nevertheless highly relevant for chemical processing. By introducing the elliptically shaped molecule, 1,4-dimethyl-1,4-diazabicyclo[2.2.2]octane, into the interlayer space of a layered silicate, a two-dimensional microporous network with narrow pore size distribution is generated (MOPS-5). The regular arrangement of the pillar molecules in MOPS-5 was confirmed by the occurrence of a 10 band related to a long-range pseudo-hexagonal superstructure of pillar molecules in the interlayer space. Whereas with MOPS-5 for CO2 adsorption, gate-opening occurs at constant volume by freezing pillar rotation, for CO the interlayer space is expanded at gate-opening and a classical interdigitated layer type of gate-opening is observed. The selective nature of the gate-opening might be used for separation of CO and N2 by pressure swing adsorption.MOPS (microporous organically pillared layered silicates) are capable of discriminating two, physically very similar gases (CO/N2) by a simple selective gate-opening process. More importantly, gate-opening seems to be a general feature of MOPS, and selectivity may be easily tuned by the highly modular design of MOPS.
      PubDate: 2017-12-08T05:22:52.378415-05:
      DOI: 10.1002/anie.201710717
       
  • Thermally Activated Delayed Fluorescence in a Y3N@C80 Endohedral
           Fullerene: Time-Resolved Luminescence and EPR Studies
    • Authors: Michal Zalibera; Denis S. Krylov, Dimitrios Karagiannis, Paul-Anton Will, Frank Ziegs, Sandra Schiemenz, Wolfgang Lubitz, Sebastian Reineke, Anton Savitsky, Alexey A. Popov
      Abstract: The endohedral fullerene Y3N@C80 exhibits luminescence with reasonable quantum yield and extraordinary long lifetime. By variable-temperature steady-state and time-resolved luminescence spectroscopy, it is demonstrated that above 60 K the Y3N@C80 exhibits thermally activated delayed fluorescence with maximum emission at 120 K and a negligible prompt fluorescence. Below 60 K, a phosphorescence with a lifetime of 192±1 ms is observed. Spin distribution and dynamics in the triplet excited state is investigated with X- and W-band EPR and ENDOR spectroscopies and DFT computations. Finally, electroluminescence of the Y3N@C80/PFO film is demonstrated opening the possibility for red-emitting fullerene-based organic light-emitting diodes (OLEDs).Delayed on the cage: Efficient thermally activated delayed fluorescence is found in the endohedral fullerene Y3N@C80. Predominant localization of the exciton on the carbon cage is confirmed by ENDOR spectroscopy.
      PubDate: 2017-12-08T05:22:43.892446-05:
      DOI: 10.1002/anie.201710637
       
  • Controlled Sol–Gel Transitions of a Thermoresponsive Polymer in a
           Photoswitchable Azobenzene Ionic Liquid as a Molecular Trigger
    • Authors: Caihong Wang; Kei Hashimoto, Ryota Tamate, Hisashi Kokubo, Masayoshi Watanabe
      Abstract: Producing ionic liquids (ILs) that function as molecular trigger for macroscopic change is a challenging issue. Photoisomerization of an azobenzene IL at the molecular level evokes a macroscopic response (light-controlled mechanical sol–gel transitions) for ABA triblock copolymer solutions. The A endblocks, poly(2-phenylethyl methacrylate), show a lower critical solution temperature in the IL mixture containing azobenzene, while the B midblock, poly(methyl methacrylate), is compatible with the mixture. In a concentrated polymer solution, different gelation temperatures were observed in it under dark and UV conditions. Light-controlled sol–gel transitions were achieved by a photoresponsive solubility change of the A endblocks upon photoisomerization of the azobenzene IL. Therefore, an azobenzene IL as a molecular switch can tune the self-assembly of a thermoresponsive polymer, leading to macroscopic light-controlled sol–gel transitions.Photoswitchable sol–gel transitions: An ABA triblock copolymer with thermoresponsive A endblocks was dissolved in a mixture of conventional and photoresponsive ionic liquid (IL). The azobenzene IL can tune the affinities between the A blocks and the solvent: the polymer is soluble in the trans-IL and insoluble in the cis-IL. Thus, a molecular-level switch evokes a reversible macroscopic sol–gel transition.
      PubDate: 2017-12-08T05:22:36.645365-05:
      DOI: 10.1002/anie.201710288
       
  • Crochelins: Siderophores with an Iron-Chelating Moiety from the
           Nitrogen-Fixing Bacterium Azotobacter chroococcum
    • Authors: Oliver Baars; Xinning Zhang, Marcus I. Gibson, Alan T. Stone, François M. M. Morel, Mohammad R. Seyedsayamdost
      Abstract: Microbes use siderophores to access essential iron resources in the environment. Over 500 siderophores are known, but they utilize a small set of common moieties to bind iron. Azotobacter chroococcum expresses iron-rich nitrogenases, with which it reduces N2. Though an important agricultural inoculant, the structures of its iron-binding molecules remain unknown. Here, the “chelome” of A. chroococcum is examined using small molecule discovery and bioinformatics. The bacterium produces vibrioferrin and amphibactins as well as a novel family of siderophores, the crochelins. Detailed characterization shows that the most abundant member, crochelin A, binds iron in a hexadentate fashion using a new iron-chelating γ-amino acid. Insights into the biosynthesis of crochelins and the mechanism by which iron may be removed upon import of the holo-siderophore are presented. This work expands the repertoire of iron-chelating moieties in microbial siderophores.New ways to bind iron: Crochelin A, the founding member of a family of siderophores with an unprecedented iron-ligating substructure, has been discovered from the agricultural inoculant Azotobacter chroococcum. It binds iron with an unusual γ-amino acid (see picture, red). Insights into its iron-binding capability and biosynthesis are obtained from experimental and bioinformatic studies.
      PubDate: 2017-12-08T05:22:20.722952-05:
      DOI: 10.1002/anie.201709720
       
  • Manganese Complexes for (De)Hydrogenation Catalysis: A Comparison to
           Cobalt and Iron Catalysts
    • Authors: Fabian Kallmeier; Rhett Kempe
      Abstract: The sustainable use of the resources on our planet is essential. Noble metals are very rare and are diversely used in key technologies, such as catalysis. Manganese is the third most abundant transition metal of the Earth's crust and based on the recently discovered impressive reactivity in hydrogenation and dehydrogenation reactions, is a potentially useful noble-metal “replacement”. The hope of novel selectivity profiles, not possible with noble metals, is also an aim of such a “replacement”. The reactivity of manganese complexes in (de)hydrogenation reactions was demonstrated for the first time in 2016. Herein, we summarize the work that has been published since then and especially discuss the importance of homogeneous manganese catalysts in comparison to cobalt and iron catalysts.A latecomer worth waiting for: In the last two years manganese complexes have been identified as highly active catalysts for diverse hydrogenation and dehydrogenation reactions. The results in this field are summarized and discussed and compared to iron and cobalt catalysts.
      PubDate: 2017-12-08T05:21:59.283103-05:
      DOI: 10.1002/anie.201709010
       
  • Quantum Refinement Does Not Support Dinuclear Copper Sites in Crystal
           Structures of Particulate Methane Monooxygenase
    • Authors: Lili Cao; Octav Caldararu, Amy C. Rosenzweig, Ulf Ryde
      Abstract: Particulate methane monooxygenase (pMMO) is one of the few enzymes that can activate methane. The metal content of this enzyme has been highly controversial, with suggestions of a dinuclear Fe site or mono-, di-, or trinuclear Cu sites. Crystal structures have shown a mono- or dinuclear Cu site, but the resolution was low and the geometry of the dinuclear site unusual. We have employed quantum refinement (crystallographic refinement enhanced with quantum-mechanical calculations) to improve the structure of the active site. We compared a number of different mono- and dinuclear geometries, in some cases enhanced with more protein ligands or one or two water molecules, to determine which structure fits two sets of crystallographic raw data best. In all cases, the best results were obtained with mononuclear Cu sites, occasionally with an extra water molecule. Thus, we conclude that there is no crystallographic support for a dinuclear Cu site in pMMO.Two crystal structures of particulate methane monooxygenase (pMMO) were studied with quantum refinement. For the putative active site, several different mono- and dinuclear geometries, in some cases with more protein ligands or one or two water molecules, were compared to determine which structure fits the crystallographic raw data best. The results indicate that there is no crystallographic support for a dinuclear Cu site in pMMO.
      PubDate: 2017-12-08T05:21:45.44718-05:0
      DOI: 10.1002/anie.201708977
       
  • Temperature-Directed Biocatalysis for the Sustainable Production of
           Aromatic Aldehydes or Alcohols
    • Authors: Jun Ni; Yan-Yan Gao, Fei Tao, Hong-Yu Liu, Ping Xu
      Abstract: The biosynthesis of aromatic aldehydes and alcohols from renewable resources is currently receiving considerable attention because of an increase in demand, finite fossil resources, and growing environmental concerns. Here, a temperature-directed whole-cell catalyst was developed by using two novel enzymes from a thermophilic actinomycete. Ferulic acid, a model lignin derivative, was efficiently converted into vanillyl alcohol at a reaction temperature at 30 °C. However, when the temperature was increased to 50 °C, ferulic acid was mainly converted into vanillin with a productivity of 1.1 g L−1 h−1. This is due to the fact that the redundant endogenous alcohol dehydrogenases (ADHs) are not active at this temperature while the functional enzymes from the thermophilic strain remain active. As the biocatalyst could convert many other renewable cinnamic acid derivatives into their corresponding aromatic aldehydes/alcohols, this novel strategy may be extended to generate a vast array of valuable aldehydes or alcohols.By using two novel enzymes from a thermophilic actinomycete, a whole-cell catalyst was constructed for the sustainable production of aromatic aldehydes or alcohols from renewable cinnamic acid derivatives. Ferulic acid was converted into vanillyl alcohol at 30 °C whereas the same reaction mainly gave vanillin at 50 °C because the endogenous alcohol dehydrogenases are not active at this temperature.
      PubDate: 2017-12-08T05:21:00.56683-05:0
      DOI: 10.1002/anie.201710793
       
  • Palladium-Catalyzed Intramolecular Trost-Oppolzer-Type Alder-Ene Reaction
           of Dienyl Acetates to Cyclopentadienes
    • Authors: Siddheshwar K. Bankar; Bara Singh, Pinku Tung, S. S. V. Ramasastry
      Abstract: A new approach for the synthesis of highly substituted cyclopentadienes, indenes and cyclopentene-fused heteroarenes via the Pd-catalyzed Trost-Oppolzer-type intramolecular Alder-ene reaction of 2,4-pentadienyl acetates is described. This unprecedented transformation combines the electrophilic features of the Tsuji-Trost reaction with the nucleophilic features of the Alder-ene reaction. The overall outcome can be perceived as a hitherto unknown 'acid-free' iso-Nazarov-type cyclization. The versatility of this strategy was further demonstrated via the formal synthesis of paucifloral F, a resveratrol-based natural product.
      PubDate: 2017-12-08T05:11:28.729821-05:
      DOI: 10.1002/anie.201711797
       
  • Solar hydrogen generation from lignocellulose
    • Authors: Moritz Kuehnel; Erwin Reisner
      Abstract: Photocatalytic reforming of lignocellulosic biomass is an emerging approach to produce renewable H2. This process combines photo-oxidation of aqueous biomass with photocatalytic hydrogen evolution at ambient temperature and pressure. Biomass conversion is less energy demanding than water splitting and generates high-purity H2 without O2 production. Direct photoreforming of raw, unprocessed biomass has the potential to provide affordable, clean energy across the globe from locally sourced materials.
      PubDate: 2017-12-08T02:41:45.631797-05:
      DOI: 10.1002/anie.201710133
       
  • Reversing Conventional Reactivity of Mixed Oxo/Alkyl Rare Earth Complexes:
           Non-Redox Oxygen Atom Transfer
    • Authors: Xigeng Zhou; Jianquan Hong, Haiwen Tian, Lixin Zhang, Linhong Weng, Iker del Rosal, Laurent Maron
      Abstract: The preferential substitution of oxo ligands over alkyl ones of rare earth complexes is commonly considered as "impossible" due to the high oxophilicity of metal centers. Now, it has been shown that simply assembling mixed methyl/oxo rare earth complexes to a rigid trinuclear cluster framework can not only enhance the activity of the Ln-oxo bond, but also protect the highly reactive Ln-alkyl bond, thus providing a previously unrecognized opportunity to selectively manipulate the oxo ligand in the presence of numerous reactive functionalities. Such trimetallic cluster has proved to be a suitable platform for developing the unprecedented non-redox rare earth-mediated oxygen atom transfer from ketones to CS2 and PhNCS. Controlled experiments and computational studies shed light on the driving force for these reactions, emphasizing the importance of the sterical accessibility and multimetallic effect of the cluster framework in promoting reversal of reactivity of rare earth oxo complexes.
      PubDate: 2017-12-08T02:41:28.833812-05:
      DOI: 10.1002/anie.201711305
       
  • Single-cell Mass Spectrometry Approaches to Explore Cellular Heterogeneity
    • Authors: Linwen Zhang; Akos Vertes
      Abstract: Compositional diversity is a fundamental property in cell populations that is responsible for evolutionary adaptation and resilience. Single-cell analysis promises new insights into this cellular heterogeneity and the corresponding subpopulations on the genomic, transcriptomic, proteomic, and metabolomic levels. Mass spectrometry (MS) is a label-free technique that enables the multiplexed analysis of proteins, peptides, lipids, and metabolites in individual cells. The abundances of these molecular classes are correlated with the physiological states and environmental responses of the cells. In this Minireview, we discuss recent advances in single-cell MS techniques with an emphasis on sampling and ionization methods developed for volume-limited samples. Strategies for sample treatment, separation methods, and data analysis require special considerations for single cells. Ongoing analytical challenges include the need for high-throughput, high molecular coverage, minimal perturbation, subcellular heterogeneity, and non-normal statistical distributions of cellular properties. The insights obtained by single-cell MS techniques inform fundamental cell biology, immunology, and individualized medicine.
      PubDate: 2017-12-07T23:06:33.664429-05:
      DOI: 10.1002/anie.201709719
       
  • Quantum machine learning in chemical compound space
    • Authors: Anatole von Lilienfeld
      Abstract: Rather than numerically solving the computationally demanding equationsof quantum or statistical mechanics, machine learning methods caninfer approximate solutions, interpolating previously acquired propertydata sets of molecules and materials. The case is made for quantum machine learning: An inductive molecular modeling approach which can beapplied to quantum chemistry problems.
      PubDate: 2017-12-07T14:05:56.397895-05:
      DOI: 10.1002/anie.201709686
       
  • A Cesium Rare-Earth Silicate Cs3RESi6O15 (RE = Dy-Lu, Y, In): The "Parent"
           of an Unusual Structural Class Featuring a Remarkable 57 Å Unit Cell Axis
           
    • Authors: Rylan Terry; Daniel Vinton, Colin McMillen, Joseph Kolis
      Abstract: A new structural member of the broad class of A3RESi6O15 compounds has been discovered for the formula Cs3RESi6O15, where RE = Dy-Lu,Y,In. The structure is unusual in that it contains octahedrally coordinated rare earth ions whose relative orientation dictates the structure as they rotate about the c-axis supported by the cyclic Si6O15 framework. The repeat unit of the rotation is eight units generating a very long, ~57 Å, unit cell axis. This unusual repeat unit is created by the structural flexibility of the hexasilicate ring, which is in turn affected by the size of the rare earth ion as well as the size of alkali ion residing within the silicate layers. The products described here are prepared as large, high quality single crystals using a high temperature (650˚C) hydrothermal method with CsOH and F- mineralizers. The presence of fluoride is essential to the formation of the product, as reactions without fluoride do not form these products.
      PubDate: 2017-12-07T14:05:41.208255-05:
      DOI: 10.1002/anie.201708798
       
  • New views of head-to-middle and cis- head-to-tail prenyltransferases:
           Structure of isosesquilavandulyl diphosphate synthase
    • Authors: Jian Gao; Tzu-Ping Ko, Lu Chen, Satish R. Malwal, Jianan Zhang, Xiangying Hu, Fiona Qu, Weidong Liu, Jian-Wen Huang, Ya-Shan Cheng, Chun-Chi Chen, Yunyun Yang, Yonghui Zhang, Eric Oldfield, Rey-Ting Guo
      Abstract: We report the first X-ray crystallographic structure of the "head-to-middle" prenyltransferase, isosesquilavandulyl diphosphate synthase, involved in biosynthesis of the merochlorin class of antibiotics. The protein adopts the ζ or cis-prenyl transferase fold but remarkably, unlike tuberculosinol adenosine synthase and other cis-prenyl transferases (e.g. cis-farnesyl, decaprenyl, undecaprenyl diphosphate synthases), the large, hydrophobic side-chain does not occupy a central hydrophobic tunnel. Instead, it occupies a surface pocket oriented at ~90º to the hydrophobic tunnel. Product chain-length control is achieved by squeezing out the ligand from the conventional allylic S1 binding site, with proton abstraction being achieved via a diphosphate-Asn-Ser relay. The structures revise and unify our thinking as to the mechanism of action of many other prenyl transferases and may also be of use in engineering new merochlorin-class antibiotics.
      PubDate: 2017-12-07T11:46:18.776702-05:
      DOI: 10.1002/anie.201710185
       
  • A Zero-Dimensional Organic Seesaw-Shaped Tin Bromide with Highly Efficient
           Strongly Stokes-Shifted Deep-Red Emission
    • Authors: Chenkun Zhou; Haoran Lin, Hongliang Shi, Yu Tian, Chongin Pak, Michael Shatruk, Yan Zhou, Peter Djurovich, Maohua Du, Biwu Ma
      Abstract: We report the synthesis and characterization of (C9NH20)2SnBr4, a novel organic metal halide hybrid with a zero-dimensional (0D) structure, in which individual seesaw-shaped tin (II) bromide anions (SnBr42-) are co-crystallized with 1-butyl-1-methylpyrrolidinium cations (C9NH20+). Upon photoexcitation, the bulk crystals exhibit a highly efficient broadband deep-red emission peaked at 695 nm, with a large Stokes shift of 332 nm and a high quantum efficiency of around 46%. The unique photophysical properties of this hybrid material are attributed to two major factors, (i) the 0D structure allowing the bulk crystals to exhibit the intrinsic properties of individual SnBr42- species, and (ii) the seesaw structure enabling a pronounced excited state structural deformation as confirmed by density functional theory (DFT) calculations.
      PubDate: 2017-12-07T11:40:32.172848-05:
      DOI: 10.1002/anie.201710383
       
  • Deuterated Molecular Ruby with Record Luminescence Quantum Yield
    • Authors: Cui Wang; Sven Otto, Matthhias Dorn, Elisabeth Kreidt, Jakob Lebon, Laura Sran, Patrick Di Martino-Fumo, Markus Gerhards, Ute Resch-Genger, Michael Seitz, Katja Heinze
      Abstract: The recently reported luminescent chromium(III) complex [Cr(ddpd)2]3+ shows exceptionally strong near-IR emission in water under ambient conditions (QY 11 %) with a microsecond lifetime. In the absence of energy acceptors such as dioxygen, the remaining decay pathways are energy transfer to high energy solvent and ligand oscillators, namely OH and CH stretching vibrations. Selective deuteration of the solvents and theddpd ligands probes the efficiency of these oscillators in the excitedstate deactivation. Addressing these energy transfer pathways in thefirst and second coordination sphere furnishes a record 30 % quantumyield and a 2.3 millisecond lifetime for a metal complex with an earth abundant metal ion in solution at room temperature. The combinedfundamental insights will pave the way for selective design strategiesin the field of luminescent complexes with earth-abundant metal ions.
      PubDate: 2017-12-07T11:05:44.710486-05:
      DOI: 10.1002/anie.201711350
       
  • Polymer film dewetting by water/surfactant/good solvent mixtures: a
           mechanistic insight and its implications for the conservation of Cultural
           Heritage
    • Authors: Michele Baglioni; Costanza Montis, David Chelazzi, Rodorico Giorgi, Debora Berti, Piero Baglioni
      Abstract: Aqueous nanostructured fluids (NSFs) have been proposed in the recent past to remove polymer coatings from the surfaces of works of art; this process usually involves film dewetting. Here we report on a major advancement in the study of NSFs cleaning mechanisms using several complementary techniques that are employed to get a mechanistic insight on the interaction of a methacrylic/acrylic copolymer (Paraloid B72®) film laid on glass surfaces and several NSFs, based on two different solvents, i.e. propylene carbonate (PC) and 2-butanone (MEK), and two different surfactants, i.e. a nonionic alcohol ethoxylate (C9-11E6) and sodium dodecylsulfate (SDS). The experimental results provide a detailed picture of the dewetting process, where the role of each component is elucidated. These findings open new perspectives in the formulation of cleaning systems in the field of cultural heritage conservation, as well as coatings and detergency.
      PubDate: 2017-12-07T10:20:18.070499-05:
      DOI: 10.1002/anie.201710930
       
  • Triplet Tellurophene-based Acceptors for Organic Solar Cells
    • Authors: Lei Yang; Wenxing Gu, Lei Lv, Yusheng Chen, Yufei Yang, Pan Ye, Jianfei Wu, Ling Hong, Aidong Peng, Hui Huang
      Abstract: Triplet materials have been employed to achieve high performing OSCs, while the triplet nonfullerene acceptor materials have never been reported for bulk heterojunction OSCs. Herein, for the first time, three triplet molecular acceptors based on tellurophene with different extent of ring fusing were designed and synthesized for OSCs. Significantly, these molecules possess long exciton lifetime and diffusion length, leading to efficient power conversion efficiency (7.52%), which is the highest values for tellurophene based OSCs. Moreover, the influence of the extent of ring fusing on molecular geometry and OSCs performance was investigated to show the PCEs continuously increased along with increasing the extent of ring fusing. This contribution demonstrated a novel method to design high performing nonfullerene acceptors for OSCs and provided new insights for understanding the relationship between molecular geometry and OSCs performances.
      PubDate: 2017-12-07T10:15:39.339725-05:
      DOI: 10.1002/anie.201712011
       
  • Photochemical Creation of Fluorescent Quantum Defects in Semiconducting
           Carbon Nanotube Hosts
    • Authors: Xiaojian Wu; Mijin Kim, Hyejin Kwon, YuHuang Wang
      Abstract: Quantum defects are an emerging class of synthetic single photon emitters that hold potential for near-infrared imaging, chemical sensing, materials engineering, and quantum information processing. Herein, we show it is possible to optically direct the synthetic creation of molecularly tunable fluorescent quantum defects in semiconducting single-walled carbon nanotube hosts through photochemical reactions. By exciting the host semiconductor with light that resonates with its electronic transition, we find that halide-containing aryl groups can covalently bond to the sp2 carbon lattice. The reaction is independent of temperature but correlates strongly with the photon energy used to drive the reaction, suggesting a photochemical mechanism rather than photothermal effects. This type of photochemical reactions opens the possibility to control the synthesis of quantum defects using light and may enable lithographic patterning of quantum emitters with electronic and molecular precision.
      PubDate: 2017-12-07T09:35:41.894099-05:
      DOI: 10.1002/anie.201709626
       
  • A Vinyl Sulfone-Based Fluorogenic Probe Capable of Selective Labeling of
           PHGDH in Live Mammalian Cells
    • Authors: Sijun Pan; Se-Young Jang, Si Si Liew, Jiaqi Fu, Danyang Wang, Jun-Seok Lee, Shao Q. Yao
      Abstract: Chemical probes are powerful tools for interrogating small molecule-target interactions. With additional fluorescence Turn-ON functionality, such probes might enable direct measurements of target engagement in live mammalian cells. DNS-pE (and its terminal alkyne-containing version DNS-pE2) is the first small molecule that can selectively label endogenous 3-phosphoglycerate dehydrogenase (PHGDH) from various mammalian cells. Endowed with an electrophilic vinyl sulfone moiety that possesses fluorescence-quenching properties, DNS-pE/DNS-pE2 became highly fluorescent only upon irreversible covalent modification of PHGDH. With an inhibitory property (in vitro Ki=7.4 μm) comparable to that of known PHGDH inhibitors, our probes thus offer a promising approach to simultaneously image endogenous PHGDH activities and study its target engagement in live-cell settings.Turn-ON the label: A fluorogenic probe that selectively and covalently labels endogenous PHGDH from various live mammalian cells was developed based on a vinyl sulfone-containing dansyl fluorophore. This enables simultaneous live-cell imaging of PHGDH activities and studies of its active-site engagement.
      PubDate: 2017-12-07T08:42:05.351099-05:
      DOI: 10.1002/anie.201710856
       
  • Engineering of a DNA Polymerase for Direct m6A Sequencing
    • Authors: Joos Aschenbrenner; Stephan Werner, Virginie Marchand, Martina Adam, Yuri Motorin, Mark Helm, Andreas Marx
      Abstract: Methods for the detection of RNA modifications are of fundamental importance for advancing epitranscriptomics. N6-methyladenosine (m6A) is the most abundant RNA modification in mammalian mRNA and is involved in the regulation of gene expression. Current detection techniques are laborious and rely on antibody-based enrichment of m6A-containing RNA prior to sequencing, since m6A modifications are generally “erased” during reverse transcription (RT). To overcome the drawbacks associated with indirect detection, we aimed to generate novel DNA polymerase variants for direct m6A sequencing. Therefore, we developed a screen to evolve an RT-active KlenTaq DNA polymerase variant that sets a mark for N6-methylation. We identified a mutant that exhibits increased misincorporation opposite m6A compared to unmodified A. Application of the generated DNA polymerase in next-generation sequencing allowed the identification of m6A sites directly from the sequencing data of untreated RNA samples.Deliberate error: A KlenTaq DNA polymerase variant with elevated error rates opposite m6A but not unmodified A in an RNA template was evolved by using a primer-extension-based screening assay. The identified mutant was applied in a next-generation sequencing (NGS) library preparation method and m6A sites could be directly identified in the sequencing data as mutational hotspots.
      PubDate: 2017-12-07T08:41:48.575505-05:
      DOI: 10.1002/anie.201710209
       
  • Maximizing the Catalytic Activity of Nanoparticles through Monolayer
           Assembly on Nitrogen-Doped Graphene
    • Authors: Chao Yu; Xuefeng Guo, Mengqi Shen, Bo Shen, Michelle Muzzio, Zhouyang Yin, Qing Li, Zheng Xi, Junrui Li, Christopher T. Seto, Shouheng Sun
      Abstract: We report a facile method for assembly of a monolayer array of nitrogen-doped graphene (NG) and nanoparticles (NPs) and the subsequent transfer of two layers onto a solid substrate (S). Using 3 nm NiPd NPs as an example, we demonstrate that NiPd-NG-Si (Si=silicon wafer) can function as a catalyst and show maximum NiPd catalysis for the hydrolysis of ammonia borane (H3NBH3, AB) with a turnover frequency (TOF) of 4896.8 h−1 and an activation energy (Ea) of 18.8 kJ mol−1. The NiPd-NG-S catalyst is also highly active for catalyzing the transfer hydrogenation from AB to nitro compounds, leading to the green synthesis of quinazolines in water. Our assembly method can be extended to other graphene and NP catalyst materials, providing a new 2D NP catalyst platform for catalyzing multiple reactions in one pot with maximum efficiency.A versatile catalyst: A simple method was developed for the assembly of nanoparticles and nitrogen-doped graphene (NG) monolayers onto a solid substrate. The as-prepared NiPd-NG-Si material (Si=silicon wafer) serves as a robust and highly efficient catalyst for the hydrolysis of ammonia borane and for the following tandem reactions that lead to the high-yield synthesis of quinazolines in water.
      PubDate: 2017-12-07T08:41:33.881055-05:
      DOI: 10.1002/anie.201709815
       
  • Ruthenium(II)-catalyzed C-H Difluoromethylation of Ketoxime: Tuning the
           Regioselectivity from meta to para Position
    • Authors: Chunchen Yuan; Lei Zhu, Runsheng Zeng, Yu Lan, Yingsheng Zhao
      Abstract: A highly para-selective CAr-H difluoromethylation of ketoxime ether using a ruthenium catalyst has been developed. A wide variety of ketoxime ethers are compatible in the reaction, leading to the corresponding para-selective difluorometylated products in moderate to good yield. A mechanistic study clearly shows that chelation-assisted cycloruthenation is the key factor in achieving the para-selective difluoromethylation of ketoxime ethers. The density functional theory (DFT) method was used to gain a theoretical understanding of the para-selectivity.
      PubDate: 2017-12-07T08:14:04.583001-05:
      DOI: 10.1002/anie.201711221
       
  • Integration of Plasmonic Effect and Schottky Junction into Metal-Organic
           Framework Composites: Steering Charge Flow for Enhanced Visible-Light
           Photocatalysis
    • Authors: Hai-Long Jiang; Juan-Ding Xiao, Lili Han, Jun Luo, Shu-Hong Yu
      Abstract: A wide range of light absorption and rapid electron-hole separation are desired for efficient photocatalysis. Herein, on the basis of a semiconductor-like metal-organic framework (MOF), the rationally designed Pt@MOF/Au catalyst with two types of metal-MOF interfaces integrates the surface plasmon resonance excitation of Au nanorods with Pt-MOF Schottky junction, which not only extends the light absorption of the MOF from UV to visible region but also greatly accelerates charge transfer. The spatial separation of Pt and Au particles by the MOF further steers the formation of charge flow and expedites the charge migration. As a result, the Pt@MOF/Au presents an exceptionally high photocatalytic H2 production rate by water splitting under visible light irradiation, far superior to Pt/MOF/Au, MOF/Au and other counterparts with similar Pt or Au contents, highlighting the important role of each component and the Pt location in the catalyst.
      PubDate: 2017-12-07T08:13:30.170999-05:
      DOI: 10.1002/anie.201711725
       
  • A General Approach Towards Triazole-linked Adenosine Diphosphate
           Ribosylated Peptides and Proteins
    • Authors: Qiang Liu; Hans A. V. Kistemaker, Sagar Bhogaraju, Ivan Dikic, Herman S. Overkleeft, Gijsbert A. van der Marel, Huib Ovaa, Gerbrand van der Heden van Noort, Dmitri V. Filippov
      Abstract: Current chemistries to prepare Adenosine Diphosphate ribosylated (ADPr) peptides are not generally applicable due to the labile nature of this post-translational modification and its incompatibility with strong acidic conditions used in standard solid phase peptide synthesis protocols. We present a general strategy to prepare ADPr peptide analogues based on a copper catalysed click reaction between an azide modified peptide and an alkyne modified ADPr counterpart. We expand the scope of this approach to proteins by preparing two ADPr Ubiquitin analogues carrying the biological relevant α-glycosidic linkage. Biochemical validation using Legionella effector enzyme SdeA shows that clicked Ub-ADPr is well tolerated and highlights the potential of this strategy to prepare ADPr proteins.
      PubDate: 2017-12-07T05:36:15.957751-05:
      DOI: 10.1002/anie.201710527
       
  • Microemulsions, Micelles and Functional Gels. How Colloid and Soft Matter
           Preserve Works of Art
    • Authors: David Chelazzi; Rodorico Giorgi, Piero Baglioni
      Abstract: Colloid Science provides fundamental knowledge to fields such as pharmaceutical, detergency, paint and food industry. An exciting application is art conservation, which poses a challenge owing to the complex range of interfacial interactions involved in restoring artefacts. Currently, the majority of the most performing and environmentally safe cleaning and consolidation agents for artworks belong to soft matter and colloids. We report here on the development and application of increasingly complex systems, from microemulsions to semi-interpenetrating hydrogels containing such fluids. These systems have been used on diverse artefacts, from Renaissance frescos to works by Picasso and Pollock. Chemical design can be implemented to meet the requirements of curators, and knowledge of the colloids structure and dynamics can overcome serendipitous approaches of traditional conservation practice. Finally, we summarize future perspectives that soft matter and colloid science can disclose in the field of cultural heritage preservation.
      PubDate: 2017-12-07T04:36:51.197361-05:
      DOI: 10.1002/anie.201710711
       
  • Visible Light-Driven Iminyl Radical-Mediated C-C Single Bond
           Cleavage/Radical Addition Cascade of Oxime Esters
    • Authors: Wen-Jing Xiao; Xiao-Ye Yu, Jia-Rong Chen, Peng-Zi Wang, Meng-Nan Yang, Dong Liang
      Abstract: A room temperature, visible light-driven N-centered iminyl radical-mediated and redox-neutral C-C single bond cleavage/radical addition cascade reaction of oxime esters and unsaturated systems has been accomplished. The strategy tolerates a wide range of O-acyl oximes and unsaturated systems such as alkenes, silyl enol ethers, alkynes, and isonitrile, enabling highly selective formation of various chemical bonds. This protocol thus provides an efficient approach to various diversely substituted cyano-containing alkenes, ketones, carbocycles and heterocycles.
      PubDate: 2017-12-07T03:36:56.356414-05:
      DOI: 10.1002/anie.201710618
       
  • Incorporation of 2,6-Connected Azulene Units into the Backbone of
           Conjugated Polymers towards High-Performance Organic Optoelectronic
           Materials
    • Authors: Xike Gao; Hanshen Xin, Congwu Ge, Xuechen Jiao, Xiaodi Yang, Kira Rundel, Chris McNeill
      Abstract: Azulene is considered to be a promising candidate for constructing optoelectronic materials. We present herein an effective strategy to obtain high performance conjugated polymers by incorporating 2,6-connected azulene units into the polymeric backbone, and two conjugated copolymers P(TBAzDI-TPD) and P(TBAzDI-TFB) are designed and synthesized based on this strategy. They are the first two examples for 2,6-connected azulene-based conjugated polymers and exhibit unipolar n-type transistor performance with an electron mobility of up to 0.42 cm2 V-1 s-1, which is among the highest values for n-type polymeric semiconductors in bottom-gate top-contact organic field effect transistors. Besides, preliminary all-polymer solar cell devices with P(TBAzDI-TPD) as the electron acceptor and PTB7-Th as the electron donor display a power conversion efficiency of 1.82%.
      PubDate: 2017-12-07T03:35:55.88971-05:0
      DOI: 10.1002/anie.201711802
       
  • Boosting Electrochemical Water Oxidation with Metal Hydroxide Carbonate
           Templated Prussian Blue Analogues
    • Authors: Arindam Indra; Ungyu Paik, Taeseup Song
      Abstract: Development of efficient and stable catalyst systems with low cost, abundant and non-toxic materials is the primary demand for the electrochemical water oxidation. Here, we report a unique method for the syntheses of metal hydroxide carbonate templated Prussian blue analogues (PBAs) on carbon cloth and their outstanding water oxidation activities in alkaline medium. The best water oxidation activity is obtained with cobalt hydroxide carbonate templated t-CoII-CoIII with overpotential as low as 240 mV to reach the current density 10 mA cm-2 and produces constant current over 48 h in chronoamperometric measurements. Moreover, the catalysts outperform the activities of the PBAs prepared without any template and even the noble metal catalyst RuO2. Spectroscopic and microscopic studies clearly prove that the PBAs are transformed into layered hydroxide-oxyhydroxide structures during electrochemical process and provide the active sites for the water oxidation.
      PubDate: 2017-12-07T01:37:14.655438-05:
      DOI: 10.1002/anie.201710809
       
  • Chemicals on demand: Photo-induced release from nano- and microparticle
           containers
    • Authors: Ulrich S. Schubert; Christoph Englert, Ivo Nischang, Cornelia Bader, Philipp Borchers, Julien Alex, Michael Proehl, Martin Hentschel, Matthias Hartlieb, Anja Traeger, Georg Pohnert, Stephanie Schubert, Michael Gottschaldt
      Abstract: A benzoin-derived diol linker was synthesized and used to create biocompatible polyesters, which can be fully decomposed on demand triggered by UV light. Extensive structural optimization of the linker unit was performed to enable a defined encapsulation of structurally diverse organic compounds in polymeric structures and a well-controllable polymer cleavage process. Selective tracking of release kinetics of encapsulated model compounds from the polymeric nano- and microparticle containers was enabled by confocal laser scanning microscopy as a proof-of-principle for desired applications. The model compounds comprised physico-chemical properties from fully hydrophilic to fully hydrophobic. Demonstrated biocompatibility of the utilized polyesters and degradation products enables advanced applications, e.g. for smart packaging of UV sensitive pharmaceuticals or nutrition components, or even in the area of spatially-selective self-healing processes.
      PubDate: 2017-12-06T22:11:23.873569-05:
      DOI: 10.1002/anie.201710756
       
  • Breaking Unstrained C-C Bond in Acenes by Boron and Light: Transformation
           of Naphthalene to Benzoborepin
    • Authors: Suning Wang; Kang Yuan, Ming-feng Hu, Xiang Wang, Tai Peng, nan wang, Quansong Li
      Abstract: Naphthalene and acenaphthene with peri 2-py and BMes2 (Mes = mesityl) substituents have been found to undergo facile phototransformation, cleaving a C-C bond of naphthalene and forming 2-py-bound benzoborepins as the major products. Mechanistic pathways of this new photoreaction are established by examining both excited and ground states using CASSCF and CASPT2 methods with DFT and TD-DFT. The Mes to py-naphthyl charge transfer transition and the Mes migration from boron to naphthyl drive this unprecedented C-C bond cleavage and boron insertion reaction.
      PubDate: 2017-12-06T15:05:48.169069-05:
      DOI: 10.1002/anie.201711658
       
  • Cover Picture: Efficient Encapsulation of Fluorinated Drugs in the
           Confined Space of Water-Dispersible Fluorous Supraparticles (Angew. Chem.
           Int. Ed. 51/2017)
    • Authors: Claudia Pigliacelli; Daniele Maiolo, Nonappa, Johannes S. Haataja, Heinz Amenitsch, Claire Michelet, Paola Sánchez Moreno, Ilaria Tirotta, Pierangelo Metrangolo, Francesca Baldelli Bombelli
      Pages: 16093 - 16093
      Abstract: A Passion for Fluorine transport of fluorinated drugs in aqueous environments requires stable, water-dispersible carriers. In their Communication on page 16186 ff., P. Metrangolo and F. Baldelli Bombelli et al. describe a passionfruit-like supraparticle filled with fluorinated gold nanoparticles, which is coated by the vegetable protein hydrophobin II. The fluorous confined space of the supraparticle permits encapsulation of millions of fluorinated drug molecules.
      PubDate: 2017-12-05T07:30:34.614439-05:
      DOI: 10.1002/anie.201712048
       
  • Inside Cover: Sorting of C4 Olefins with Interpenetrated Hybrid
           Ultramicroporous Materials by Combining Molecular Recognition and
           Size-Sieving (Angew. Chem. Int. Ed. 51/2017)
    • Authors: Zhaoqiang Zhang; Qiwei Yang, Xili Cui, Lifeng Yang, Zongbi Bao, Qilong Ren, Huabin Xing
      Pages: 16094 - 16094
      Abstract: The sorting of C4 olefins is possible with a combination of molecular recognition and size-sieving effects. In their Communication on page 16282 ff. H. B. Xing and co-workers report anion-pillared hybrid interpenetrated porous materials with finely tuned cavities (the bridge tunnel) and functional sites (flowers) arranged at 0.2 Å increments. These materials exhibit outstanding performance for the separation of C4 olefins.
      PubDate: 2017-11-29T02:26:36.609246-05:
      DOI: 10.1002/anie.201711715
       
  • Graphical Abstract: Angew. Chem. Int. Ed. 51/2017
    • Pages: 16097 - 16111
      PubDate: 2017-12-13T03:08:45.672646-05:
      DOI: 10.1002/anie.201785111
       
  • Corrigendum: Copper-Catalyzed Synthesis of γ-Amino Acids Featuring
           Quaternary Stereocenters
    • Authors: José Enrique Gómez; Wusheng Guo, Silvia Gaspa, Arjan W. Kleij
      Pages: 16111 - 16111
      PubDate: 2017-12-13T03:08:45.223301-05:
      DOI: 10.1002/anie.201711781
       
  • Corrigendum: Trace H2O2-Assisted High-Capacity Tungsten Oxide
           Electrochromic Batteries with Ultrafast Charging in Seconds
    • Authors: Jinxiong Zhao; Yuyu Tian, Zhen Wang, Shan Cong, Di Zhou, Qingzhu Zhang, Mei Yang, Weikun Zhang, Fengxia Geng, Zhigang Zhao
      Pages: 16111 - 16111
      PubDate: 2017-12-13T03:08:38.246409-05:
      DOI: 10.1002/anie.201711618
       
  • Spotlights on our sister journals: Angew. Chem. Int. Ed. 51/2017
    • Pages: 16114 - 16117
      PubDate: 2017-12-13T03:08:51.249048-05:
      DOI: 10.1002/anie.201785113
       
  • Sensuke Ogoshi
    • Pages: 16118 - 16118
      Abstract: “My favorite place on earth is Parker Ridge Trail in the Rocky Mountains. If I were not a scientist, I would be a lawyer ...” This and more about Sensuke Ogoshi can be found on page 16118.
      PubDate: 2017-09-18T11:37:17.130585-05:
      DOI: 10.1002/anie.201708270
       
  • Fellows of the Electrochemical Society: C. Amatore, K. Amine, P.
           Atanassov, C. P. Grey, Y. Shao-Horn, and N. Wu / Priestley Medal: G.
           Richmond / Förderungspreis der Stadt Wien: N. Maulide
    • Pages: 16119 - 16120
      PubDate: 2017-11-28T09:35:42.30449-05:0
      DOI: 10.1002/anie.201711427
       
  • Chiral Imprinting in the Gas Phase
    • Authors: David W. Pratt; Brooks H. Pate
      Pages: 16122 - 16124
      Abstract: Undoing the twist: Recent successful attempts to change the relative populations of two otherwise identical enantiomers of a large gas-phase molecule using resonant microwave fields are highlighted. Specifically, the population of a specific enantiomer of a chiral terpene could be enhanced relative to the other enantiomer by the application of a sequence of microwave pulses in a phase- and polarization-controlled manner.
      PubDate: 2017-11-08T10:26:42.845582-05:
      DOI: 10.1002/anie.201709438
       
  • The Quest for Mononuclear Gold(II) and Its Potential Role in
           Photocatalysis and Drug Action
    • Authors: Katja Heinze
      Pages: 16126 - 16134
      Abstract: The chemistry of gold strongly focuses on the ubiquitous oxidation states +I and +III. The intermediate oxidation state +II is generally avoided in mononuclear gold species. In recent years, gold(II) has been increasingly suggested as a key intermediate in artificial photosynthesis systems, with gold(III) moieties acting as electron acceptors, as well as in gold-catalyzed photoredox catalysis and radical chemistry. This Minireview provides a concise summary of confirmed and characterized mononuclear open-shell gold(II) complexes. Recent findings on structural motifs and reactivity patterns will be discussed. Exciting developments in the fields of photosynthesis, photocatalysis, and potential roles in medicinal chemistry will be outlined.Gold(II) plays a key role in artificial photosynthesis systems, with gold(III) moieties acting as electron acceptors, as well as in gold photoredox catalysis and radical chemistry. This Minireview provides a concise summary of unambiguously characterized mononuclear gold(II) complexes along with evolving structural motifs and reactivity patterns. Developments in the fields of photosynthesis, photocatalysis, and potential modes of action of anticancer drugs are outlined.
      PubDate: 2017-11-22T03:48:29.419828-05:
      DOI: 10.1002/anie.201708349
       
  • Selected Copper-Based Reactions for C−N, C−O, C−S, and
           C−C Bond Formation
    • Authors: Subhajit Bhunia; Govind Goroba Pawar, S. Vijay Kumar, Yongwen Jiang, Dawei Ma
      Pages: 16136 - 16179
      Abstract: Metal-catalyzed cross-coupling reactions belong to the most important transformations in organic synthesis. Copper catalysis has received great attention owing to the low toxicity and low cost of copper. However, traditional Ullmann-type couplings suffer from limited substrate scopes and harsh reaction conditions. The introduction of several bidentate ligands, such as amino acids, diamines, 1,3-diketones, and oxalic diamides, over the past two decades has totally changed this situation as these ligands enable the copper-catalyzed coupling of aryl halides and nucleophiles at both low reaction temperatures and catalyst loadings. The reaction scope has also been greatly expanded, rendering this copper-based cross-coupling attractive for both academia and industry. In this Review, we have summarized the latest progress in the development of useful reaction conditions for the coupling of (hetero)aryl halides with different nucleophiles. Additionally, recent advances in copper-catalyzed coupling reactions with aryl boronates and the copper-based trifluoromethylation of aromatic electrophiles will be discussed.Recent advances in copper/ligand-catalyzed cross-couplings of (hetero)aryl halides and nucleophiles, copper-catalyzed coupling reactions with aryl boronates, and copper-enabled trifluoromethylations of aromatic electrophiles are discussed in this Review.
      PubDate: 2017-11-15T05:33:20.034978-05:
      DOI: 10.1002/anie.201701690
       
  • Facile Supramolecular Processing of Carbon Nanotubes and Polymers for
           Electromechanical Sensors
    • Authors: Chae Bin Kim; Ki Beom Jeong, Beom Joo Yang, Jong-Won Song, Bon-Cheol Ku, Seunghyun Lee, Seoung-Ki Lee, Chiyoung Park
      Pages: 16180 - 16185
      Abstract: We herein report a facile, cost-competitive, and scalable method for producing viscoelastic conductors via one-pot melt-blending using polymers and supramolecular gels composed of carbon nanotubes (CNTs), diphenylamine (DP), and benzophenone (BP). When mixed, a non-volatile eutectic liquid (EL) produced by simply blending DP with BP (1:1 molar ratio) enabled not only the gelation of CNTs (EL-CNTs) but also the dissolution of a number of commodity polymers. To make use of these advantages, viscoelastic conductors were produced via one-pot melt-blending the EL and CNTs with a model thermoplastic elastomer, poly(styrene-b-butadiene-b-styrene) (SBS, styrene 30 wt %). The resulting composites displayed an excellent electromechanical sensory along with re-mendable properties. This simple method using cost-competitive EL components is expected to provide an alternative to the use of expensive ionic liquids as well as to facilitate the fabrication of novel composites for various purposes.Sense of gel: A supramolecular, non-volatile eutectic liquid (EL), consisting of diphenylamine and benzophenone, can not only dissolve many commodity polymers but also form bucky gels with CNTs upon grinding. A viscoelastic conductor composed of the EL, CNTs, and polymers was prepared by one-pot melt-blending. The resulting viscoelastic conductor behaves as a highly sensitive, self-healing electromechanical sensor.
      PubDate: 2017-11-09T12:20:31.408802-05:
      DOI: 10.1002/anie.201708111
       
  • Efficient Encapsulation of Fluorinated Drugs in the Confined Space of
           Water-Dispersible Fluorous Supraparticles
    • Authors: Claudia Pigliacelli; Daniele Maiolo, Nonappa, Johannes S. Haataja, Heinz Amenitsch, Claire Michelet, Paola Sánchez Moreno, Ilaria Tirotta, Pierangelo Metrangolo, Francesca Baldelli Bombelli
      Pages: 16186 - 16190
      Abstract: Fluorophobic-driven assemblies of gold nanomaterials were stabilized into water-dispersible fluorous supraparticles by the film-forming protein hydrophobin II. The strategy makes use of fluorous nanomaterials of different dimensions to engineer size and inner functionalization of the resulting confined space. The inner fluorous compartments allow efficient encapsulation and transport of high loadings of partially fluorinated drug molecules in water.Fluorous supraparticles: The film-forming protein hydrophobin II stabilizes fluorophobic-driven assemblies of gold nanomaterials in water. Using nanomaterials of different dimensions, the size and inner functionalization of the resulting confined space can be engineered. Partially fluorinated drug molecules are encapsulated efficiently and can be transported in water.
      PubDate: 2017-11-23T09:16:52.500507-05:
      DOI: 10.1002/anie.201710230
       
  • Transition-Metal-Free Catalytic Hydrodefluorination of Polyfluoroarenes by
           Concerted Nucleophilic Aromatic Substitution with a Hydrosilicate
    • Authors: Kotaro Kikushima; Mary Grellier, Masato Ohashi, Sensuke Ogoshi
      Pages: 16191 - 16196
      Abstract: A transition-metal-free catalytic hydrodefluorination (HDF) reaction of polyfluoroarenes is described. The reaction involves direct hydride transfer from a hydrosilicate as the key intermediate, which is generated from a hydrosilane and a fluoride salt. The eliminated fluoride regenerates the hydrosilicate to complete the catalytic cycle. Dispersion-corrected DFT calculations indicated that the HDF reaction proceeds through a concerted nucleophilic aromatic substitution (CSNAr) process.A simple but artful combination: Transition-metal-free catalytic hydrodefluorination (HDF) of polyfluoroarenes was enabled by a hydrosilicate catalyst formed in situ from a hydrosilane and a fluoride ion. The reaction involves direct hydride transfer from the hydrosilicate through concerted nucleophilic aromatic substitution (CSNAr; see scheme).
      PubDate: 2017-11-22T03:48:21.403626-05:
      DOI: 10.1002/anie.201708003
       
  • One-Pot Synthesis of Cyclopropane-Fused Cyclic Amidines: An Oxidative
           Carbanion Cyclization
    • Authors: Kirana Devarahosahalli Veeranna; Kanak Kanti Das, Sundarababu Baskaran
      Pages: 16197 - 16201
      Abstract: A novel and efficient one-pot method has been developed for the synthesis of cyclopropane-fused bicyclic amidines on the basis of a CuBr2-mediated oxidative cyclization of carbanions. The usefulness of this unique multicomponent strategy has been demonstrated by the use of a wide variety of substrates to furnish novel cyclopropane-containing amidines with a quaternary center in very good yields. This ketenimine-based approach provides straightforward access to biologically active and pharmaceutically important 3-azabicyclo[n.1.0]alkane frameworks under mild conditions. The synthetic power of this methodology is exemplified in the concise synthesis of the pharmaceutically important antidepressant drug candidate GSK1360707 and key intermediates for the synthesis of amitifadine, bicifadine, and narlaprevir.No stopping! An efficient one-pot multistep process enabled the synthesis of novel cyclopropane-fused cyclic amidines with a quaternary center in good yields (see scheme). This method provides ready access to the 3-azabicyclo[n.1.0]alkane framework. The synthetic utility of the CuBr2-mediated oxidative cyclization was demonstrated by a short (four-step) synthesis of the antidepressant drug candidate GSK1360707.
      PubDate: 2017-11-27T08:06:43.276981-05:
      DOI: 10.1002/anie.201708138
       
  • Room-Temperature-Phosphorescence-Based Dissolved Oxygen Detection by
           Core-Shell Polymer Nanoparticles Containing Metal-Free Organic Phosphors
    • Authors: Youngchang Yu; Min Sang Kwon, Jaehun Jung, Yingying Zeng, Mounggon Kim, Kyeongwoon Chung, Johannes Gierschner, Ji Ho Youk, Sergey M. Borisov, Jinsang Kim
      Pages: 16207 - 16211
      Abstract: The highly sensitive optical detection of oxygen including dissolved oxygen (DO) is of great interest in various applications. We devised a novel room-temperature-phosphorescence (RTP)-based oxygen detection platform by constructing core–shell nanoparticles with water-soluble polymethyloxazoline shells and oxygen-permeable polystyrene cores crosslinked with metal-free purely organic phosphors. The resulting nanoparticles show a very high sensitivity for DO with a limit of detection (LOD) of 60 nm and can be readily used for oxygen quantification in aqueous environments as well as the gaseous phase.Gl-O2-w!: A dissolved oxygen (DO)-detection platform based on core–shell nanoparticles with a water-soluble polymethyloxazoline shell and oxygen-permeable polystyrene core crosslinked with metal-free purely organic phosphors is reported. The resulting nanoparticles show a very high sensitivity and can be used for oxygen quantification in a variety of environments.
      PubDate: 2017-11-22T04:05:24.648843-05:
      DOI: 10.1002/anie.201708606
       
  • Breaking Bonds and Forming Nanographene Diradicals with Pressure
    • Authors: Maude Desroches; Paula Mayorga Burrezo, Joël Boismenu-Lavoie, Miriam Peña Álvarez, Carlos J. Gómez-García, Jon M. Matxain, David Casanova, Jean-François Morin, Juan Casado
      Pages: 16212 - 16217
      Abstract: New anthanthrone-based polycyclic scaffolds possessing peripheral crowded quinodimethanes have been prepared. While the compounds adopt a closed-shell butterfly-shaped structure in the ground state, a curved-to-planar fluxional inversion is accessible with a low energy barrier through a biradicaloid transition state. Inversion is primarily driven by the release of strain associated with steric hindrance at the peri position of the anthanthrone core; a low-lying diradical state is accessible through planarization of the core, which is attained in solution at moderate temperatures. The most significant aspect of this transformation is that planarization is also achieved by application of mild pressure in the solid state, wherein the diradical remains kinetically trapped. Complementary information from quantum chemistry, 1H NMR, and Raman spectroscopies, together with magnetic experiments, is consistent with the formation of a nanographene-like structure that possesses radical centers localized at the exo-anthanthrone carbons bearing phenyl substituents.Breaking a π bond with your bare hands: Quinodimethane nanographenes with a closed-shell structure display a curve-to-planar fluxional inversion, which passes through a diradical intermediate. The diradical can be trapped kinetically and is characterized by a low-energy lying triplet. Key: pressure (P), solvent (S).
      PubDate: 2017-11-28T08:01:05.184414-05:
      DOI: 10.1002/anie.201708740
       
  • Liver-Targeted Small-Molecule Inhibitors of Proprotein Convertase
           Subtilisin/Kexin Type 9 Synthesis
    • Authors: Kim F. McClure; David W. Piotrowski, Donna Petersen, Liuqing Wei, Jun Xiao, Allyn T. Londregan, Adam S. Kamlet, Anne-Marie Dechert-Schmitt, Brian Raymer, Roger B. Ruggeri, Daniel Canterbury, Chris Limberakis, Spiros Liras, Paul DaSilva-Jardine, Robert G. Dullea, Paula M. Loria, Benjamin Reidich, Christopher T. Salatto, Heather Eng, Emi Kimoto, Karen Atkinson, Amanda King-Ahmad, Dennis Scott, Kevin Beaumont, Jeffrey R. Chabot, Michael W. Bolt, Kevin Maresca, Kenneth Dahl, Ryosuke Arakawa, Akihiro Takano, Christer Halldin
      Pages: 16218 - 16222
      Abstract: Targeting of the human ribosome is an unprecedented therapeutic modality with a genome-wide selectivity challenge. A liver-targeted drug candidate is described that inhibits ribosomal synthesis of PCSK9, a lipid regulator considered undruggable by small molecules. Key to the concept was the identification of pharmacologically active zwitterions designed to be retained in the liver. Oral delivery of the poorly permeable zwitterions was achieved by prodrugs susceptible to cleavage by carboxylesterase 1. The synthesis of select tetrazole prodrugs was crucial. A cell-free in vitro translation assay containing human cell lysate and purified target mRNA fused to a reporter was used to identify active zwitterions. In vivo PCSK9 lowering by oral dosing of the candidate prodrug and quantification of the drug fraction delivered to the liver utilizing an oral positron emission tomography 18F-isotopologue validated our liver-targeting approach.A liver-targeting strategy was developed for a small-molecule drug candidate that inhibits PCSK9 synthesis at the human ribosome. Chemistry enabling the synthesis of N1 tetrazole prodrugs and a companion PET tracer were essential to validating the approach.
      PubDate: 2017-11-24T05:55:37.902789-05:
      DOI: 10.1002/anie.201708744
       
  • A Supramolecular Capsule for Reversible Polysulfide Storage/Delivery in
           Lithium-Sulfur Batteries
    • Authors: Jin Xie; Hong-Jie Peng, Jia-Qi Huang, Wen-Tao Xu, Xiang Chen, Qiang Zhang
      Pages: 16223 - 16227
      Abstract: Supramolecular materials, in which small organic molecules are assembled into regular structures by non-covalent interactions, attract tremendous interests because of their highly tunable functional groups and porous structure. Supramolecular adsorbents are expected to fully expose their abundant adsorptive sites in a dynamic framework. In this contribution, we introduced cucurbit[6]uril as a supramolecular capsule for reversible storage/delivery of mobile polysulfides in lithium-sulfur (Li-S) batteries to control undesirable polysulfide shuttle. The Li-S battery equipped with the supramolecular capsules retains a high Coulombic efficiency and shows a large increase in capacity from 300 to 900 mAh g−1 at a sulfur loading of 4.2 mg cm−2. The implementation of supramolecular capsules offers insights into intricate multi-electron-conversion reactions and manifests as an effective and efficient strategy to enhance Li-S batteries and analogous applications that involve complex transport phenomena and intermediate manipulation.Smart energy storage: Solutions for effectively managing the transport of polysulfides in Li-S batteries address the shuttle. A supramolecular capsule with the ability to reversibly store/deliver polysulfides was introduced to Li-S batteries.
      PubDate: 2017-11-20T05:45:31.481938-05:
      DOI: 10.1002/anie.201710025
       
  • Temperature-Mediated Template Release: Facile Growth of Copper(I) Mixed
           Ethynediide/Isopropylethynide Nanoclusters
    • Authors: Leon Li-Min Zhang; Thomas C. W. Mak
      Pages: 16228 - 16232
      Abstract: In the comproportionation reaction of CuIIX2 and Cu0 with isopropylacetylene (iPr−C≡C−H), the ethynediide species C22− is generated via concomitant C−H/C−C bond cleavage of the iPr−C≡C−H precursor under moderate temperature to direct the formation of CuI mixed ethynediide/isopropylethynide nanoclusters (potentially explosive). The active ethynediide dianion C22− exhibits chameleon-like templating behavior to form C2@Cum (m=6 (3, 4), 7 (2, 4), 8 (1)) central structural units for successive formation of {C22−⊂Cu24} (1, 2), {6 C22−⊂Cu48} (3), and {18 C22−⊂Cu92} (4) complexes. Bearing the highest C22− content, complex 4 features an unprecedented nanoscale Cu2C2 kernel. Furthermore, 1–3 exhibit structure-controlled photoluminescence in the solid state.Template release: Temperature variation triggers the release of ethynediide C22− from isopropylacetylene through concomitant C−H/C−C bond cleavage, leading to formation of CuI mixed ethynediide/alkynide nanoclusters. Synthesis of {C22−⊂Cu24}, {6 C22−⊂Cu48}, and {18 C22−⊂Cu92} establishes a class of tunable nanostructures where the increasing number of ethynediide bestows nuclearity expansion and structural diversity.
      PubDate: 2017-11-22T04:18:08.525239-05:
      DOI: 10.1002/anie.201708760
       
  • Functional Cellular Mimics for the Spatiotemporal Control of Multiple
           Enzymatic Cascade Reactions
    • Authors: Xiaoling Liu; Petr Formanek, Brigitte Voit, Dietmar Appelhans
      Pages: 16233 - 16238
      Abstract: Next-generation therapeutic approaches are expected to rely on the engineering of biomimetic cellular systems that can mimic specific cellular functions. Herein, we demonstrate a highly effective route for constructing structural and functional eukaryotic cell mimics by loading pH-sensitive polymersomes as membrane-associated and free-floating organelle mimics inside the multifunctional cell membrane. Metabolism mimicry has been validated by performing successive enzymatic cascade reactions spatially separated at specific sites of cell mimics in the presence and absence of extracellular organelle mimics. These enzymatic reactions take place in a highly controllable, reproducible, efficient, and successive manner. Our biomimetic approach to material design for establishing functional principles brings considerable enrichment to the fields of biomedicine, biocatalysis, biotechnology, and systems biology.Metabolism mimicry in cell mimics: Multicompartmentalized systems containing pH-responsive Ada-polymersomes as organelle mimics were developed. These systems were employed as cell mimics to mimic metabolism by incorporating various stimuli for regulating enzymatic cascade reactions and for controlling the simultaneous and/or subsequent release of the encapsulated (therapeutic) molecules.
      PubDate: 2017-11-22T04:06:02.892555-05:
      DOI: 10.1002/anie.201708826
       
  • Supramolecular Radical Anions Triggered by Bacteria In Situ for
           Selective Photothermal Therapy
    • Authors: Yuchong Yang; Ping He, Yunxia Wang, Haotian Bai, Shu Wang, Jiang-Fei Xu, Xi Zhang
      Pages: 16239 - 16242
      Abstract: A supramolecular complex that can be selectively reduced to radical anions in situ by facultative anaerobic bacteria is reported. To this end, a water-soluble bifunctional monomer bearing perylene diimide was synthesized, and its supramolecular complex with cucurbit[7]uril was fabricated on the basis of host–guest complexation, which could be reduced to forming radical anions in the presence of E. coli. It was found that this supramolecular complex could display different ability of generating radical anions by facultative anaerobic and aerobic bacteria in terms of their various reductive abilities. The selective antibacterial activity of the supramolecular complex could be realized by the photothermal performance of the radical anions under near-infrared irradiation. It is anticipated that this method may lead to a novel bacteria-responsive photothermal therapy to regulate balance of bacterial flora.Photothermal therapy: A supramolecular complex of a perylene diimide derivative and cucurbit[7]uril shows different possibilities of generating radical anions by facultative anaerobic and aerobic bacteria. The selective antibacterial activity of the supramolecular complex is based on the photothermal effect of the radical anions that convert optical energy into heat under near-infrared illumination.
      PubDate: 2017-11-28T09:40:39.838355-05:
      DOI: 10.1002/anie.201708971
       
  • Adsorption-Induced Structural Phase Transformation in Nanopores
    • Authors: Bogdan Kuchta; Ege Dundar, Filip Formalik, Philip L. Llewellyn, Lucyna Firlej
      Pages: 16243 - 16246
      Abstract: We report a new type of structural transformation occurring in methane adsorbed in micropores. The observed methane structures are defined by probability distributions of molecular positions. The mechanism of the transformation has been modeled using Monte Carlo method. The transformation is totally determined by a reconstruction of the probability distribution functions of adsorbed molecules. The methane molecules have some freedom to move in the pore but most of the time they are confined to the positions around the high probability adsorption sites. The observed high-probability structures evolve as a function of temperature and pressure. The transformation is strongly discontinuous at low temperature and becomes continuous at high temperature. The mechanism of the transformation is influenced by a competition between different components of the interaction and the thermal energy. The methane structure represents a new state of matter, intermediate between solid and liquid.Between solid and liquid: New type of structural transformation has been observed in a model of methane molecules adsorbed in micropores of the IRMOF-1 metal–organic framework (MOF). The mechanism of the transformation is defined by a probability distribution function. The methane structure in the pore is characterized by limited mobility, and represents a new state of matter, intermediate between solid and liquid.
      PubDate: 2017-11-20T05:40:32.703848-05:
      DOI: 10.1002/anie.201708993
       
  • Synthesis of a Phlorin from a Meso-Fused Anthriporphyrin by a
           Diels–Alder Strategy
    • Authors: Adil S. Aslam; Jung-Ho Hong, June-Ho Shin, Dong-Gyu Cho
      Pages: 16247 - 16251
      Abstract: An anthracene-containing meso-fused carbaporphyrin, which has extended π-conjugation pathways as compared to the corresponding naphthalene-containing carbaporphyrin, has been synthesized. The weak global aromaticity of the anthriporphyrin also allowed its use as the diene for a Diels–Alder reaction with dimethyl acetylenedicarboxylate (DMAD). The resulting phlorin contains an interesting bicyclic structure. Moreover, to the best of our knowledge, this phlorin is the first Diels–Alder adduct of a diene forming part of the global π-conjugation pathway of an aromatic porphyrinoid.Expanding horizons: An anthracene-containing meso-fused carbaporphyrin with weak aromaticity was synthesized as a diene for a Diels–Alder reaction and thus further expanded into a meso-fused phlorin (see scheme). The metal-coordination chemistry of the anthriporphyrin and the novel phlorin was investigated by the synthesis of palladium(II) complexes.
      PubDate: 2017-11-27T03:51:38.342768-05:
      DOI: 10.1002/anie.201709026
       
  • Microporous Cyclic Titanium-Oxo Clusters with Labile Surface Ligands
    • Authors: Chaowei Zhao; Ying-Zi Han, Shuqi Dai, Xumao Chen, Juanzhu Yan, Weijie Zhang, Haifeng Su, Shuichao Lin, Zichao Tang, Boon K. Teo, Nanfeng Zheng
      Pages: 16252 - 16256
      Abstract: By using ethylene glycol and monocarboxylic acid as surface ligands, a series of cyclic Ti-oxo clusters (CTOC) with permanent microporosity are successfully synthesized. With a cyclic {Ti32O16} backbone made of eight connected Ti4 tetrahedral cages that are arranged in a zigzag fashion, the clusters have a “donut” shape with an inner diameter of 8.3 Å, outer diameter of 26.9 Å and height of 10.4 Å. While both inner and outer walls of the “donut” clusters are modified by double-deprotonated ethylene glycolates, their upper and lower surfaces are bound by carboxylates and mono-deprotonated ethylene glycolates. The clusters are readily packed into one-dimensional tubes which are further arranged in two different modes into crystalline microporous solids with surface areas over 660 m2 g−1, depending on the surface carboxylates. The solid with olefin-bearing carboxylates exhibits a superior CO2 adsorption capacity of 40 cm3 g−1 at 273 K under 1 atm. Moreover, the mono-deprotonated ethylene glycolates on the clusters are demonstrated to be highly exchangeable by other alcohols, providing a nice platform for creating microporous solids or films with a wide variety of surface functionalities.Microporous materials: A strategy based on the surface ligands ethylene glycol and monocarboxylic acid has been successfully implemented to prepare macrocyclic Ti-oxo clusters (TOCs). The donut TOCs interlock with each other into one-dimensional nanotubes which form microporous solids. The labile surface ligands also make it possible to generate microporous TOCs with a wide variety of surface functionalities.
      PubDate: 2017-11-28T09:40:47.537668-05:
      DOI: 10.1002/anie.201709096
       
  • On the Non-Metallicity of 2.2 nm Au246(SR)80 Nanoclusters
    • Authors: Meng Zhou; Chenjie Zeng, Yongbo Song, Jonathan W. Padelford, Gangli Wang, Matthew Y. Sfeir, Tatsuya Higaki, Rongchao Jin
      Pages: 16257 - 16261
      Abstract: The transition from molecular to plasmonic behaviour in metal nanoparticles with increasing size remains a central question in nanoscience. We report that the giant 246-gold-atom nanocluster (2.2 nm in gold core diameter) protected by 80 thiolate ligands is surprisingly non-metallic based on UV/Vis and femtosecond transient absorption spectroscopy as well as electrochemical measurements. Specifically, the Au246 nanocluster exhibits multiple excitonic peaks in transient absorption spectra and electron dynamics independent of the pump power, which are in contrast to the behaviour of metallic gold nanoparticles. Moreover, a prominent oscillatory feature with frequency of 0.5 THz can be observed in almost all the probe wavelengths. The phase and amplitude analysis of the oscillation suggests that it arises from the wavepacket motion on the ground state potential energy surface, which also indicates the presence of a small band-gap and thus non-metallic or molecular-like behaviour.When is a metal not a metal' The ultrafast electron and phonon dynamics of Au246(SR)80 nanoclusters reveal that Au246 is still non-metallic despite its large size (2.2 nm in diameter). A prominent oscillatory feature with frequency of 0.5 THz is observed indicating the presence of a small band-gap and thus non-metallic or molecular-like behaviour.
      PubDate: 2017-11-22T10:25:31.969333-05:
      DOI: 10.1002/anie.201709095
       
  • Ligand-controlled Regiodivergent C−H Alkenylation of Pyrazoles and its
           Application to the Synthesis of Indazoles
    • Authors: Hyun Tae Kim; Hyeri Ha, Geunhee Kang, Og Soon Kim, Ho Ryu, Abul Kalam Biswas, Sang Min Lim, Mu-Hyun Baik, Jung Min Joo
      Pages: 16262 - 16266
      Abstract: Regioselective C4-, C5-, and di-alkenylations of pyrazoles were achieved. An electrophilic Pd catalyst generated by trifluoroacetic acid (TFA) and 4,5-diazafluoren-9-one (DAF) leads to C4-alkenylation, whereas KOAc and mono-protected amino acid (MPAA) ligand Ac-Val-OH give C5-alkenylation. A combination of palladium acetate, silver carbonate, and pivalic acid affords dialkenylation products. Annulation through sequential alkenylation, thermal 6π-electrocyclization, and oxidation gives functionalized indazoles. This comprehensive strategy greatly expands the range of readily accessible pyrazole and indazole derivatives, enabling useful regiodivergent C−H functionalization of pyrazoles and other heteroaromatic systems.A regioselective C−H functionalization of pyrazoles was developed to provide C4-, C5-, and di-alkenyl pyrazoles using three distinctive Pd catalytic systems. The systematic preparation of alkenyl pyrazoles enabled the synthesis of multifunctionalized indazoles and π-extended pyrazoles from readily available, inexpensive pyrazoles and olefins.
      PubDate: 2017-11-27T03:51:55.166785-05:
      DOI: 10.1002/anie.201709162
       
  • Controlled and Reversible Stepwise Growth of Linear Copper(I) Chains
           Enabled by Dynamic Ligand Scaffolds
    • Authors: Orestes Rivada-Wheelaghan; Sandra L. Aristizábal, Joaquín López-Serrano, Robert R. Fayzullin, Julia R. Khusnutdinova
      Pages: 16267 - 16271
      Abstract: Reversible stepwise chain growth in linear CuI assemblies can be achieved by using the dynamic, unsymmetric naphthyridinone-based ligand scaffolds L1 and L2. With the same ligand scaffolds, the length of the linear copper chain can be varied from two to three and four copper atoms, and the nuclearity of the complex is easily controlled by the stepwise addition of a CuI precursor to gradually increase the chain length, or by the reductive removal of Cu atoms to decrease the chain length. This represents a rare example of a stepwise controlled chain growth in extended metal atom chains (EMACs). All complexes are formed with excellent selectivity, and the mutual transformations of the complexes of different nuclearity were found to be fast and reversible. These unusual rearrangements of metal chains of different nuclearities were achieved by a stepwise “sliding” movement of the naphthyridinone bridging fragment along the metal chain.Copper chain traffic control: The stepwise growth of copper(I) linear chain complexes was achieved with dynamic ligand scaffolds. Complexes containing the same ligand and one, two, three, or four CuI atoms interconvert reversibly in a process that is controlled by the stoichiometry, solvent polarity, and redox transformations.
      PubDate: 2017-11-23T09:18:09.276513-05:
      DOI: 10.1002/anie.201709167
       
  • Controlling the Host–Guest Interaction Mode through a Redox Stimulus
    • Authors: György Szalóki; Vincent Croué, Vincent Carré, Frédéric Aubriet, Olivier Alévêque, Eric Levillain, Magali Allain, Juan Aragó, Enrique Ortí, Sébastien Goeb, Marc Sallé
      Pages: 16272 - 16276
      Abstract: A proof-of-concept related to the redox-control of the binding/releasing process in a host–guest system is achieved by designing a neutral and robust Pt-based redox-active metallacage involving two extended-tetrathiafulvalene (exTTF) ligands. When neutral, the cage is able to bind a planar polyaromatic guest (coronene). Remarkably, the chemical or electrochemical oxidation of the host–guest complex leads to the reversible expulsion of the guest outside the cavity, which is assigned to a drastic change of the host–guest interaction mode, illustrating the key role of counteranions along the exchange process. The reversible process is supported by various experimental data (1H NMR spectroscopy, ESI-FTICR, and spectroelectrochemistry) as well as by in-depth theoretical calculations performed at the density functional theory (DFT) level.Stimuli-responsive metallacages: A self-assembled, redox-active platinum cage constructed from an extended-tetrathiafulvalene ligand can be reversibly oxidized to its stable tetracationic state. The reversible control of the cavity charge from 0 to 4+ makes it possible to tune the binding and releasing of a polyaromatic.
      PubDate: 2017-11-23T04:52:29.440883-05:
      DOI: 10.1002/anie.201709483
       
  • Aqueous Bismuth Titanium–Oxo Sulfate Cluster Speciation and
           Crystallization
    • Authors: Pedro I. Molina; Karoly Kozma, Melissa Santala, Clément Falaise, May Nyman
      Pages: 16277 - 16281
      Abstract: Inorganic aqueous metal–oxo clusters are both functional “molecular metal oxides” and intermediates to understand metal oxide growth from water. There has been a recent surge in discovery of aqueous Ti-oxo clusters but without extensive solution characterization. We use small-angle and total X-ray scattering, dynamic light scattering, transmission electron microscopy, and a single-crystal X-ray structure to show that heterometals such as bismuth stabilize labile Ti–oxo sulfate clusters in aqueous solution.[Ti22Bi7O41(OH)(OH2)30(SO4)12]2+ features edge-sharing between the Ti and Bi polyhedra, in contrast to the dominant corner-linking of Ti-oxo clusters. Bi stabilizes the Ti-polyhedra, which are synergistically stabilized by the bidentate sulfates. Gained stability and potential functionality from heterometals is an incentive to develop more broadly the landscape of heterometallic Ti–oxo clusters.Disassembly, re-assembly: Titanium oxysulfate immediately self-assembles into monodisperse polynuclear clusters upon dissolution in water. According to X-ray scattering, these clusters are highly labile without distinct internal order. They are disassembled stepwise by adding nitric acid and BiIII; a solution that yields a heterometallic Ti–oxo cluster.
      PubDate: 2017-11-24T04:55:37.60307-05:0
      DOI: 10.1002/anie.201709539
       
  • Sorting of C4 Olefins with Interpenetrated Hybrid Ultramicroporous
           Materials by Combining Molecular Recognition and Size-Sieving
    • Authors: Zhaoqiang Zhang; Qiwei Yang, Xili Cui, Lifeng Yang, Zongbi Bao, Qilong Ren, Huabin Xing
      Pages: 16282 - 16287
      Abstract: C4 olefin separations present one of the great challenges in hydrocarbon purifications owing to their similar structures, thus a single separation mechanism often met with limited success. Herein we report a series of anion-pillared interpenetrated copper coordination for which the cavity and functional site disposition can be varied in 0.2 Å scale increments by altering the anion pillars and organic linkers (GeFSIX-2-Cu-i (ZU-32), NbFSIX-2-Cu-i (ZU-52), GeFSIX-14-Cu-i (ZU-33)), which enable selective recognition of different C4 olefins. In these materials the rotation of the organic linkers is controlled to create a contracted flexible pore window that enables the size-exclusion of specific C4 olefins, while still adsorbing significant amounts of 1,3-butadiene (C4H6) or 1-butene (n-C4H8). Combining the molecular recognition and size-sieving effect, these materials unexpectedly realized the sieving of C4H6/n-C4H8, C4H6/iso-C4H8, and n-C4H8/iso-C4H8 with high capacity.Separate ways: Three anion-pillared interpenetrated copper coordination networks were prepared for the highly efficient separation of C4 olefins by combining targeted molecular recognition and size-sieving effects. These dual-functional materials are varied by altering the anions and organic linkers to change the shape and functionality, and are able to distinguish the multiple differences between hydrocarbon isomers therefore maximize the separation efficiency.
      PubDate: 2017-10-24T11:42:47.790808-05:
      DOI: 10.1002/anie.201708769
       
  • Record High-Nuclearity Polyoxoniobates: Discrete Nanoclusters {Nb114},
           {Nb81}, and {Nb52}, and Extended Frameworks Based on {Cu3Nb78} and
           {Cu4Nb78}
    • Authors: Lu Jin; Zeng-Kui Zhu, Yan-Lan Wu, Yan-Jie Qi, Xin-Xiong Li, Shou-Tian Zheng
      Pages: 16288 - 16292
      Abstract: A series containing the highest nuclearity polyoxoniobate (PONb) nanoclusters, ranging from dimers to tetramers, has been obtained. They include one 114-nuclear {Li8⊂Nb114O316}, one 81-nuclear {Li3K⊂Nb81O225}, and one 52-nuclear {H4Nb52O150}. The Nb nuclearity of these PONbs is remarkably larger than those of all known high-nuclearity PONbs (≤32). Furthermore, the introduction of 3d Cu2+ ions can lead to the generation of extended inorganic–organic hybrid frameworks built from novel, high-nuclearity, nanoscale heterometallic PONb building blocks {H3Cu3Nb78O222} or {H3Cu4(en)Nb78O222}. These building blocks also contain the largest number of Nb centers of any heterometallic PONbs reported to date. The synthesis of new-type PONbs has long been a challenging subject in PONb chemistry.Big, bigger, biggest: A series of record high-nuclearity PONbs, ranging from 52-nuclear {Nb52}, 81-nuclear {Nb81} to 114-nuclear {Nb114}, is made. The introduction of 3d Cu2+ ions allows the construction of extended inorganic–organic hybrid PONb frameworks based on giant heterometallic nanoclusters {Cu3Nb78} and {Cu4Nb78}.
      PubDate: 2017-11-22T03:20:52.328221-05:
      DOI: 10.1002/anie.201709565
       
  • Asymmetric Synthesis of Less Accessible α-Tertiary Amines from
           Alkynyl Z-Ketimines
    • Authors: Taichi Kano; Yusuke Aota, Keiji Maruoka
      Pages: 16293 - 16296
      Abstract: A highly stereoselective synthesis of hitherto less accessible chiral α-tertiary amines with multiple structurally similar linear carbon chains was achieved through chiral auxiliary mediated addition of organolithium reagents to the geometrically well-controlled alkynyl Z-ketimines. This stereoselective nucleophilic addition offers a general approach to the asymmetric synthesis of nitrogen-containing chiral materials.One-sided: Geometrically well-controlled alkynyl Z-ketimines were prepared and successfully employed in the asymmetric synthesis of less accessible α-tertiary amines bearing multiple linear carbon chains through chiral auxiliary mediated nucleophilic addition of organolithium reagents.
      PubDate: 2017-11-27T03:44:41.865638-05:
      DOI: 10.1002/anie.201710084
       
  • An in situ Dynamic Continuum of Supramolecular Phosphoglycopeptides
           Enables Formation of 3D Cell Spheroids
    • Authors: Huaimin Wang; Junfeng Shi, Zhaoqianqi Feng, Rong Zhou, Shiyu Wang, Avital A. Rodal, Bing Xu
      Pages: 16297 - 16301
      Abstract: Higher-order assemblies of proteins, with a structural and dynamic continuum, is an important concept in biology, but these insights have yet to be applied in designing biomaterials. Dynamic assemblies of supramolecular phosphoglycopeptides (sPGPs) transform a 2D cell sheet into 3D cell spheroids. A ligand–receptor interaction between a glycopeptide and a phosphopeptide produces sPGPs that form nanoparticles, which transform into nanofibrils upon partial enzymatic dephosphorylation. The assemblies form dynamically and hierarchically in situ on the cell surface, and interact with the extracellular matrix molecules and effectively abolish contact inhibition of locomotion (CIL) of the cells. Integrating molecular recognition, catalysis, and assembly, these active assemblies act as a dynamic continuum to disrupt CIL, thus illustrating a new kind of biomaterial for regulating cell behavior.Sphere we go: Enzymatically formed dynamic biomaterials in the cell milieu modulate intercellular interactions to generate three-dimensional cell spheroids.
      PubDate: 2017-11-22T03:21:42.213674-05:
      DOI: 10.1002/anie.201710269
       
  • Cyclic Triimidazole Derivatives: Intriguing Examples of Multiple Emissions
           and Ultralong Phosphorescence at Room Temperature
    • Authors: Elena Lucenti; Alessandra Forni, Chiara Botta, Lucia Carlucci, Clelia Giannini, Daniele Marinotto, Alessandro Pavanello, Andrea Previtali, Stefania Righetto, Elena Cariati
      Pages: 16302 - 16307
      Abstract: The performance of solid luminogens depends on both their inherent electronic properties and their packing status. Intermolecular interactions have been exploited to achieve persistent room-temperature phosphorescence (RTP) from organic molecules. However, the design of organic materials with bright RTP and the rationalization of the role of interchromophoric electronic coupling remain challenging tasks. Cyclic triimidazole has been shown to be a promising scaffold for such purposes owing to its crystallization-induced room-temperature ultralong phosphorescence (RTUP), which has been associated with H-aggregation. Herein, we report three triimidazole derivatives as significant examples of multifaceted emission. In particular, dual fluorescence, RTUP, and phosphorescence from the molecular and supramolecular units were observed. H-aggregation is responsible for the red RTUP, and Br substituents favor yellow molecular phosphorescence while halogen-bonded Br⋅⋅⋅Br tetrameric units are involved in the blue-green phosphorescence.Three triimidazole derivatives were synthesized that display multiple emissions covering dual fluorescence, room-temperature ultralong phosphorescence (RTUP), and phosphorescence from the molecular and supramolecular units. H-aggregation is responsible for the red RTUP, Br substituents favor yellow molecular phosphorescence, and halogen-bonded Br⋅⋅⋅Br tetrameric units are involved in the blue-green phosphorescence.
      PubDate: 2017-11-30T04:16:21.912196-05:
      DOI: 10.1002/anie.201710279
       
  • Organocatalytic Atroposelective Arylation of 2-Naphthylamines as a
           Practical Approach to Axially Chiral Biaryl Amino Alcohols
    • Authors: Ye-Hui Chen; Liang-Wen Qi, Fang Fang, Bin Tan
      Pages: 16308 - 16312
      Abstract: The first phosphoric acid catalyzed direct arylation of 2-naphthylamines with iminoquinones for the atroposelective synthesis of axially chiral biaryl amino alcohols has been developed. This reaction constitutes a highly functional-group-tolerant route for the rapid construction of enantioenriched axially chiral biaryl amino alcohols, and is a rare example of 2-naphthylamines acting as nucleophiles in an organocatalytic enantioselective transformation. Furthermore, the products, which feature various halogen atoms, provide access to structurally diverse axially chiral amino alcohols through further transformations.The phosphoric acid catalyzed direct arylation of 2-naphthylamines with iminoquinones enables the atroposelective synthesis of axially chiral biaryl amino alcohols. Many functional groups are tolerated in this reaction, and it is a rare example of 2-naphthylamines acting as nucleophiles in an organocatalytic enantioselective transformation.
      PubDate: 2017-11-23T04:52:54.561417-05:
      DOI: 10.1002/anie.201710537
       
  • Three-Dimensional Anionic Cyclodextrin-Based Covalent Organic Frameworks
    • Authors: Yuanyuan Zhang; Jiyun Duan, Dou Ma, Pengfei Li, Siwu Li, Haiwei Li, Junwen Zhou, Xiaojie Ma, Xiao Feng, Bo Wang
      Pages: 16313 - 16317
      Abstract: Three-dimensional covalent organic frameworks (3D COFs) are promising crystalline materials with well-defined structures, high porosity, and low density; however, the limited choice of building blocks and synthetic difficulties have hampered their development. Herein, we used a flexible and aliphatic macrocycle, namely γ-cyclodextrin (γ-CD), as the soft struts for the construction of a polymeric and periodic 3D extended network, with the units joined via tetrakis(spiroborate) tetrahedra with various counterions. The inclusion of pliable moieties in the robust open framework endows these CD-COFs with dynamic features, leading to a prominent Li ion conductivity of up to 2.7 mS cm−1 at 30 °C and excellent long-term Li ion stripping/plating stability. Exchanging the counterions within the pores can effectively modulate the interactions between the CD-COF and CO2 molecules.Three-dimensional anionic covalent organic frameworks (COFs) were constructed from aliphatic and flexible macrocyclic γ-cyclodextrin (γ-CD) units joined via spiroborate linkages with various counterions. The CD-COF with Li+ is a good Li ion conductor, and different counterions within the framework lead to different interactions with CO2.
      PubDate: 2017-11-22T04:05:46.934467-05:
      DOI: 10.1002/anie.201710633
       
  • Enantiospecific sp2–sp3 Coupling of ortho- and para-Phenols with
           Secondary and Tertiary Boronic Esters
    • Authors: Claire M. Wilson; Venkataraman Ganesh, Adam Noble, Varinder K. Aggarwal
      Pages: 16318 - 16322
      Abstract: The coupling of ortho- and para-phenols with secondary and tertiary boronic esters has been explored. In the case of para-substituted phenols, after reaction of a dilithio phenolate species with a boronic ester, treatment with Ph3BiF2 or Martin's sulfurane gave the coupled product with complete enantiospecificity. The methodology was applied to the synthesis of the broad spectrum antibacterial natural product (−)-4-(1,5-dimethylhex-4-enyl)-2-methyl phenol. For ortho-substituted phenols, initial incorporation of a benzotriazole on the phenol oxygen atom was required. Subsequent ortho-lithiation and borylation gave the coupled product, again with complete stereospecificity.The coupling of ortho- and para-phenols with boronic esters has been explored. In the case of para-bromophenols, after reaction of the dilithio aryl species with the boronic ester, treatment with Ph3BiF2 or Martin's sulfurane gave the coupled product with complete enantiospecificity. For ortho-phenols, initial incorporation of a benzotriazole on the phenol oxygen atom was required.
      PubDate: 2017-11-28T08:01:33.67493-05:0
      DOI: 10.1002/anie.201710777
       
  • Enantioselective and Collective Total Syntheses of Xanthanolides
    • Authors: Juan Feng; Xiaoqiang Lei, Ruiyang Bao, Yuanhe Li, Chengqian Xiao, Lihong Hu, Yefeng Tang
      Pages: 16323 - 16327
      Abstract: An enantioselective synthesis of (+)-8-epi-xanthatin hinging on a chiral phosphoric acid catalyzed tandem allylboration/lactonization reaction is reported. With (+)-8-epi-xanthatin as the precursor, the collective synthesis of a series of synthetically challenging xanthanolides was also accomplished. Among them, xanthipungolide, one of the most complex xanthanolide monomers, was accessed through a bioinspired tandem double-bond isomerization/6π electronic cyclization/intramolecular Diels–Alder reaction, and pungiolides A, B, D, E, and L–N, a group of xanthanolide dimers, were assembled through a bioinspired Diels–Alder dimerization followed by late-stage diversification.The more the merrier: The enantioselective synthesis of (+)-8-epi-xanthatin from readily available fragments was completed in seven steps (longest linear sequence) and 15 % overall yield. A further 1–3 steps were required for the collective total synthesis of various synthetically challenging xanthanolide monomers and dimers (see scheme) on the basis of a series of intriguing bioinspired transformations.
      PubDate: 2017-11-27T03:44:50.214777-05:
      DOI: 10.1002/anie.201710846
       
  • Development of an Efficient Biosensor for the In Vivo Monitoring of Cu+
           and pH in the Brain: Rational Design and Synthesis of Recognition
           Molecules
    • Authors: Wei Liu; Hui Dong, Limin Zhang, Yang Tian
      Pages: 16328 - 16332
      Abstract: An efficient biosensor was created for the ratiometric monitoring of Cu+ and pH in the brain using both current and potential outputs. A series of N,N-bis(2-[2-(ethylthio)ethyl])-based (NS4s) derivatives was designed for the specific recognition of Cu+. After systematically evaluating the electrochemical parameters of Cu+ oxidation by tuning alkyl chain length, polyaromatic structure, and substitute group site of NS4, N,N-bis(2-[2-(ethylthio)ethyl])-2-naphthamide (NS4-C1) was finally optimized for Cu+ detection as it showed the most negative potential and the largest current density. At the same time, 9,10-anthraquinone was used as a selective pH sensor with 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) as an internal reference. This single biosensor with both current and potential signal outputs can simultaneously determine Cu+ concentrations from 0.5 to 9.5 μm and pH values ranging from 6.0 to 8.0. The efficient biosensor was applied to the simultaneous detection of Cu+ and pH in the live brain. The average levels of Cu+ were reported for the first time in the cortex, hippocampus, and striatum in a mouse model of Alzheimer's disease.The cuprous ion (Cu+) and pH play vital roles in the physiological and pathological events of brain. An efficient biosensor, using two types of electrical signal outputs, was created for the ratiometric monitoring of Cu+ and pH in a mouse model of Alzheimer's disease (AD). The average levels of Cu+ were reported in the cortex, hippocampus, and striatum in the mouse model of AD.
      PubDate: 2017-11-30T04:30:49.415425-05:
      DOI: 10.1002/anie.201710863
       
  • In-Situ Microfluidic Study of Biphasic Nanocrystal Ligand-Exchange
           Reactions Using an Oscillatory Flow Reactor
    • Authors: Yi Shen; Milad Abolhasani, Yue Chen, Lisi Xie, Lu Yang, Connor W. Coley, Moungi G. Bawendi, Klavs F. Jensen
      Pages: 16333 - 16337
      Abstract: Oscillatory flow reactors provide a surface energy-driven approach for automatically screening reaction conditions and studying reaction mechanisms of biphasic nanocrystal ligand-exchange reactions. Sulfide and cysteine ligand-exchange reactions with as-synthesized CdSe quantum dots (QDs) are chosen as two model reactions. Different reaction variables including the new-ligand-to-QD ratio, the size of the particles, and the original ligand type are examined systematically. Based on the in situ-obtained UV/Vis absorption spectra during the reaction, we propose two different exchange pathways for the sulfide exchange reaction.Oscillatory flow reactors were used to automatically screen reaction kinetics and study the reaction mechanisms of biphasic nanocrystal ligand-exchange reactions with CdSe quantum dots (QDs). Based on the UV/Vis absorption spectra obtained in situ during the reaction, two different reaction pathways are proposed.
      PubDate: 2017-11-21T03:37:11.05544-05:0
      DOI: 10.1002/anie.201710899
       
  • Consecutive Transformations of Tetrafluoropropenes: Hydrogermylation and
           Catalytic C−F Activation Steps at a Lewis Acidic Aluminum Fluoride
    • Authors: Gisa Meißner; Konrad Kretschmar, Thomas Braun, Erhard Kemnitz
      Pages: 16338 - 16341
      Abstract: Functionalization reactions of the refrigerants HFO-1234yf (2,3,3,3-tetrafluoropropene) and HFO-1234ze (1,3,3,3-tetrafluoropropene) were developed. The selectivity and reactivity towards CF3 groups of C−F activation reactions can be controlled by employing either a germane or a silane as the hydrogen source. Unique transformations were designed to accomplish consecutive hydrogermylation and C−F activation steps. This allowed for an unprecedented transformation of an olefinic C−F bond into a C−H bond by heterogeneous catalysis. These reactions are catalyzed by nanoscopic aluminum chlorofluoride (ACF) under very mild conditions.Functionalizations of tetrafluoropropenes such as HFO-1234yf were developed. The transformation of the CF3 group into an olefinic CF2 group was achieved at nanoscopic aluminum chlorofluoride (ACF) with silane. Consecutive hydrogermylation and C−F activation steps enabled the transformation of an olefinic C−F into a C−H bond.
      PubDate: 2017-11-23T09:15:36.602024-05:
      DOI: 10.1002/anie.201707759
       
  • Nucleophilic Arylation of N,O-Ketene Acetals with Triaryl Aluminum
           Reagents: Access to α-Aryl Amides through an Umpolung Process
    • Authors: Norihiko Takeda; Erika Futaki, Yukiko Kobori, Masafumi Ueda, Okiko Miyata
      Pages: 16342 - 16346
      Abstract: A novel approach for the umpolung α-arylation of amides is presented. By the nucleophilic phenylation of O-silyl N,O-ketene acetals, generated in situ from N-alkoxy amides, a phenyl group can be introduced onto the α-carbon atom of amides through N−O bond cleavage in a two-step, one-pot process. The asymmetric synthesis of α-aryl amides through the diastereoselective arylation of a chiral N,O-ketene acetal is also described.Changing the rules to win the game: By means of an umpolung strategy involving the generation of O-silyl N,O-ketene acetals in situ from N-alkoxyamides, a phenyl group could be introduced onto the α-carbon center of amides through N−O bond cleavage in a two-step, one-pot process (see scheme). The asymmetric synthesis of α-aryl amides through the diastereoselective arylation of a chiral N,O-ketene acetal is also described.
      PubDate: 2017-11-27T03:51:21.4679-05:00
      DOI: 10.1002/anie.201708665
       
  • Supramolecular Recognition Allows Remote, Site-Selective C−H Oxidation
           of Methylenic Sites in Linear Amines
    • Authors: Giorgio Olivo; Giulio Farinelli, Alessia Barbieri, Osvaldo Lanzalunga, Stefano Di Stefano, Miquel Costas
      Pages: 16347 - 16351
      Abstract: Site-selective C−H functionalization of aliphatic alkyl chains is a longstanding challenge in oxidation catalysis, given the comparable relative reactivity of the different methylenes. A supramolecular, bioinspired approach is described to address this challenge. A Mn complex able to catalyze C(sp3)-H hydroxylation with H2O2 is equipped with 18-benzocrown-6 ether receptors that bind ammonium substrates via hydrogen bonding. Reversible pre-association of protonated primary aliphatic amines with the crown ether selectively exposes remote positions (C8 and C9) to the oxidizing unit, resulting in a site-selective oxidation. Remarkably, such control of selectivity retains its efficiency for a whole series of linear amines, overriding the intrinsic reactivity of C−H bonds, no matter the chain length.Remote control: Supramolecular recognition of protonated primary amines on 18-crown-6 receptors exposes specific, remote methylenes to the Mn active site. Linear alkyl chains can thus be selectively oxidized on C8 and C9 positions with H2O2, overriding the intrinsic reactivity of C−H bonds.
      PubDate: 2017-11-27T03:44:08.31287-05:0
      DOI: 10.1002/anie.201709280
       
  • Enantioselective Rhodium-Catalyzed Coupling of Arylboronic Acids,
           1,3-Enynes, and Imines by Alkenyl-to-Allyl 1,4-Rhodium(I) Migration
    • Authors: Michael Callingham; Benjamin M. Partridge, William Lewis, Hon Wai Lam
      Pages: 16352 - 16356
      Abstract: A chiral rhodium complex catalyzes the highly enantioselective coupling of arylboronic acids, 1,3-enynes, and imines to give homoallylic sulfamates. The key step is the generation of allylrhodium(I) species by alkenyl-to-allyl 1,4-rhodium(I) migration.A chiral rhodium complex catalyzes the highly enantioselective coupling of arylboronic acids, 1,3-enynes, and imines to give homoallylic sulfamates. The key step is the generation of allylrhodium(I) species by alkenyl-to-allyl 1,4-rhodium(I) migration. tAm=tert-amyl.
      PubDate: 2017-11-24T05:56:29.913808-05:
      DOI: 10.1002/anie.201709334
       
  • Formation of Polymeric Nanocubes by Self-Assembly and Crystallization of
           Dithiolane-Containing Triblock Copolymers
    • Authors: Katherine Margulis; Xiangyi Zhang, Lydia-Marie Joubert, Karsten Bruening, Christopher J. Tassone, Richard N. Zare, Robert M. Waymouth
      Pages: 16357 - 16362
      Abstract: Template-free fabrication of non-spherical polymeric nanoparticles is desirable for various applications, but has had limited success owing to thermodynamic favorability of sphere formation. Herein we present a simple way to prepare cubic nanoparticles of block copolymers by self-assembly from aqueous solutions at room temperature. Nanocubes with edges of 40–200 nm are formed spontaneously on different surfaces upon water evaporation from micellar solutions of triblock copolymers containing a central poly(ethylene oxide) block and terminal trimethylene carbonate/dithiolane blocks. These polymers self-assemble into 28±5 nm micelles in water. Upon drying, micelle aggregation and a kinetically controlled crystallization of central blocks evidently induce solid cubic particle formation. An approach for preserving the structures of these cubes in water by thiol- or photo-induced crosslinking was developed. The ability to solubilize a model hydrophobic drug, curcumin, was also explored.Polymers cubed: Cubic polymeric nanoparticles are prepared simply by self-assembly from aqueous solutions at room temperature. Cubes with edges of 40–200 nm are formed spontaneously upon drying from micellar solutions of triblock copolymers containing a central poly(ethylene oxide) block and terminal trimethylene carbonate/dithiolane blocks. An approach for preserving the cube structure by dithiolane crosslinking is developed.
      PubDate: 2017-11-24T05:56:15.947126-05:
      DOI: 10.1002/anie.201709564
       
  • Magnesium Boryl Reactivity with 9-BBN and Ph3B: Rational B−B′ Bond
           Formation and Diborane Isomerization
    • Authors: Anne-Frédérique Pécharman; Michael S. Hill, Claire L. McMullin, Mary F. Mahon
      Pages: 16363 - 16366
      Abstract: Reactions of a magnesium-based pinacolatoboryl nucleophile with the electrophilic organoboranes, 9-BBN and Ph3B, provide facile B−B′ single bond formation. Although the Ph3B derivative is thermally stable, when heated, the unsymmetrical diborane(5) anion derived from 9-BBN is found to isomerize to two regioisomeric species via a proposed mechanism involving dehydroboration of the borabicyclo[3.3.1]nonane and syn-diboration of the resultant alkenyl carbocycle.B-B King: Reactions of a magnesium-based pinacolatoboryl nucleophile with electrophilic organoboranes, 9-BBN or Ph3B, provide facile B−B′ single bond formation.
      PubDate: 2017-11-27T03:43:49.58636-05:0
      DOI: 10.1002/anie.201709902
       
  • Cobalt-Catalyzed Suzuki Biaryl Coupling of Aryl Halides
    • Authors: Soneela Asghar; Sanita B. Tailor, David Elorriaga, Robin B. Bedford
      Pages: 16367 - 16370
      Abstract: Readily accessed cobalt pre-catalysts with N-heterocyclic carbene ligands catalyze the Suzuki cross-coupling of aryl chlorides and bromides with alkyllithium-activated arylboronic pinacolate esters. Preliminary mechanistic studies indicate that the cobalt species is reduced to Co0 during the reaction.Co-ming of age: Simple cobalt N-heterocyclic-carbene-based catalysts allow facile Suzuki cross-coupling of aryl chloride and bromide substrates.
      PubDate: 2017-11-28T09:40:55.856393-05:
      DOI: 10.1002/anie.201710053
       
  • Cooperative Multifunctional Catalysts for Nitrone Synthesis: Platinum
           Nanoclusters in Amine-Functionalized Metal–Organic Frameworks
    • Authors: Xinle Li; Biying Zhang, Linlin Tang, Tian Wei Goh, Shuyan Qi, Alexander Volkov, Yuchen Pei, Zhiyuan Qi, Chia-Kuang Tsung, Levi Stanley, Wenyu Huang
      Pages: 16371 - 16375
      Abstract: Nitrones are key intermediates in organic synthesis and the pharmaceutical industry. The heterogeneous synthesis of nitrones with multifunctional catalysts is extremely attractive but rarely explored. Herein, we report ultrasmall platinum nanoclusters (PtNCs) encapsulated in amine-functionalized Zr metal–organic framework (MOF), UiO-66-NH2 (Pt@UiO-66-NH2) as a multifunctional catalyst in the one-pot tandem synthesis of nitrones. By virtue of the cooperative interplay among the selective hydrogenation activity provided by the ultrasmall PtNCs and Lewis acidity/basicity/nanoconfinement endowed by UiO-66-NH2, Pt@UiO-66-NH2 exhibits remarkable activity and selectivity, in comparison to Pt/carbon, Pt@UiO-66, and Pd@UiO-66-NH2. Pt@UiO-66-NH2 also outperforms Pt nanoparticles supported on the external surface of the same MOF (Pt/UiO-66-NH2). To our knowledge, this work demonstrates the first examples of one-pot synthesis of nitrones using recyclable multifunctional heterogeneous catalysts.In tandem: Platinum nanoclusters (PtNCs) encapsulated in amine-functionalized UiO-66-NH2 (Pt@UiO-66-NH2) act as a multifunctional catalyst in the one-pot tandem synthesis of nitrones. By the cooperative interplay between the selective hydrogenation activity provided by PtNCs and Lewis acidity/basicity/nanoconfinement provided by the MOF, Pt@UiO-66-NH2 exhibits remarkable activity and selectivity.
      PubDate: 2017-11-22T11:05:54.956741-05:
      DOI: 10.1002/anie.201710164
       
  • The MOF+ Technique: A Significant Synergic Effect Enables High Performance
           Chromate Removal
    • Authors: Ming Biao Luo; Yang Yang Xiong, Hui Qiong Wu, Xue Feng Feng, Jian Qiang Li, Feng Luo
      Pages: 16376 - 16379
      Abstract: A significant synergic effect between a metal–organic framework (MOF) and Fe2SO4, the so-called MOF+ technique, is exploited for the first time to remove toxic chromate from aqueous solutions. The results show that relative to the pristine MOF samples (no detectable chromate removal), the MOF+ method enables super performance, giving a 796 Cr mg g−1 adsorption capacity. The value is almost eight-fold higher than the best value of established MOF adsorbents, and the highest value of all reported porous adsorbents for such use. The adsorption mechanism, unlike the anion-exchange process that dominates chromate removal in all other MOF adsorbents, as unveiled by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), is due to the surface formation of Fe0.75Cr0.25(OH)3 nanospheres on the MOF samples.A pause from pores: Relying on the surface rather than the pores of metal–organic frameworks (MOFs), the MOF+ method enables an ultrahigh chromate removal in aqueous solution of up to 796 Cr mg g−1, exceeding any porous material for this kind use. The hexavalent chromate is reduced by FeSO4 to generate FeIII and CrIII ions, the MOF surface then induces the formation of Fe0.75Cr0.25(OH)3 nanospheres.
      PubDate: 2017-11-20T03:15:35.960114-05:
      DOI: 10.1002/anie.201709197
       
  • Solid-State Structure of Protonated Ketones and Aldehydes
    • Authors: Daniel Stuart; Stacey D. Wetmore, Michael Gerken
      Pages: 16380 - 16384
      Abstract: Protonated carbonyl compounds have been invoked as intermediates in many acid-catalyzed organic reactions. To gain key structural and electronic data about such intermediates, oxonium salts derived from five representative examples of ketones and aldehydes are synthesized in the solid state, and characterized by X-ray crystallography and Raman spectroscopy for the first time. DFT calculations were carried out on the cations in the gas phase. Whereas an equimolar reaction of the carbonyl compounds, acetone, cyclopentanone, adamantanone, and acetaldehyde, with SbF5 in anhydrous HF yielded mononuclear oxonium cations, the same stoichiometry in a reaction with benzaldehyde resulted in formation of a hemiprotonated, hydrogen-bridged dimeric cation. Hemiprotonated acetaldehyde was obtained when a 2:1 ratio of aldehyde and SbF5 was used. Experimental and NBO analyses quantify the significant increase in electrophilicity of the oxonium cations compared to that of the parent ketones/aldehydes.Reactive intermediates: Solid-state structures of protonated carbonyl compounds are presented. Whereas protonation of ketones (acetone, cyclopentanone and adamantanone) in superacidic solution yielded the mononuclear oxonium ions, hemiprotonated hydrogen-bridged dinculear structures were observed in the crystal structure obtained from reactions of benzaldehyde or acetaldehyde with HF/SbF5.
      PubDate: 2017-11-29T08:32:11.770404-05:
      DOI: 10.1002/anie.201710263
       
  • Spata-13,17-diene Synthase—An Enzyme with Sesqui-, Di-, and
           Sesterterpene Synthase Activity from Streptomyces xinghaiensis
    • Authors: Jan Rinkel; Lukas Lauterbach, Jeroen S. Dickschat
      Pages: 16385 - 16389
      Abstract: A terpene synthase from the marine bacterium Streptomyces xinghaiensis has been characterised, including a full structure elucidation of its products from various substrates and an in-depth investigation of the enzyme mechanism by isotope labelling experiments, metal cofactor variations, and mutation experiments. The results revealed an interesting dependency of Mn2+ catalysis on the presence of Asp-217, a residue that is occupied by a highly conserved Glu in most other bacterial terpene synthases.On active duty: A terpene synthase from Streptomyces xinghaiensis with sesqui-, di-, and sesterterpene synthase activity has been identified. The enzyme mechanism was investigated by isotope labelling experiments. Site-directed mutagenesis uncovered several previously unrecognised highly conserved residues that are important for catalysis. One of these residues was linked to the requirement of a Mg2+ or Mn2+ cofactor.
      PubDate: 2017-11-23T04:53:17.353132-05:
      DOI: 10.1002/anie.201711142
       
  • Preparation of Functionalized Diaryl- and Diheteroaryllanthanum Reagents
           by Fast Halogen–Lanthanum Exchange
    • Authors: Andreas D. Benischke; Lucile Anthore-Dalion, Guillaume Berionni, Paul Knochel
      Pages: 16390 - 16394
      Abstract: Aryl and heteroaryl halides (X=Br, I) undergo a fast and convenient halogen–lanthanum exchange with nBu2LaMe, which leads to functionalized diaryl- and diheteroaryllanthanum derivatives. Subsequent trapping reactions with selected electrophiles, such as ketones, aldehydes, or amides, proceeded smoothly at −50 °C in THF, affording polyfunctionalized alcohols and carbonyl derivatives. Kinetic competition experiments revealed a similar reactivity trend as for Br/Mg exchange, but 106-times higher rates, making it comparable to Br/Li exchange.Lanthanum as a lithium alternative: Aryl and heteroaryl halides (X=Br, I) undergo a fast and convenient halogen–lanthanum exchange with nBu2LaMe, which leads to functionalized diaryl- and diheteroaryllanthanum derivatives. Trapping reactions with ketones, aldehydes, or amides proceeded smoothly at −50 °C, affording polyfunctionalized alcohols and carbonyl derivatives.
      PubDate: 2017-11-22T11:06:37.451069-05:
      DOI: 10.1002/anie.201709553
       
  • Are There Carbenes in N-Heterocyclic Carbene Organocatalysis'
    • Authors: Sascha Gehrke; Oldamur Hollóczki
      Pages: 16395 - 16398
      Abstract: Azolium cations are widely employed in organocatalysis to catalyse highly valuable synthetic processes in the presence of a base. These reactions are called “N-heterocyclic carbene catalysis”, based on the assumption that they are initiated by the formation of a free carbene through deprotonation, which can then react with the substrates and thereby affect their reactivity to obtain the desired products. However, we herein provide evidence that an electrophilic aromatic substitution mechanism is energetically more favourable, in which the azolium cation reacts directly with the substrate, avoiding the formation of the free carbene in solution.Another alternative: A novel reaction pathway for N-heterocyclic carbene organocatalysis has been identified. In this process, proton transfer and the binding of the substrate to the catalyst occur simultaneously in a single elementary reaction step, without the formation of a free carbene molecule in the reaction mixture.
      PubDate: 2017-11-22T11:06:44.163778-05:
      DOI: 10.1002/anie.201708305
       
  • O2 Activation on Ceria Catalysts—The Importance of Substrate
           Crystallographic Orientation
    • Authors: Chengwu Yang; Xiaojuan Yu, Stefan Heißler, Peter G. Weidler, Alexei Nefedov, Yuemin Wang, Christof Wöll, Thomas Kropp, Joachim Paier, Joachim Sauer
      Pages: 16399 - 16404
      Abstract: An atomic-level understanding of dioxygen activation on metal oxides remains one of the major challenges in heterogeneous catalysis. By performing a thorough surface-science study of all three low-index single-crystal surfaces of ceria, probably the most important redox catalysts, we provide a direct spectroscopic characterization of reactive dioxygen species at defect sites on the reduced ceria (110) and (100) surfaces. Surprisingly, neither of these superoxo and peroxo species was found on ceria (111), the thermodynamically most stable surface of this oxide. Applying density functional theory, we could relate these apparently inconsistent findings to a sub-surface diffusion of O vacancies on (111) substrates, but not on the less-closely packed surfaces. These observations resolve a long standing debate concerning the location of O vacancies on ceria surfaces and the activation of O2 on ceria powders.A puzzle is solved: The first infrared reflection–absorption spectroscopy (IRRAS) data of dioxygen activation on an oxide single-crystal surface show, in conjunction with theory, the formation of various superoxo and peroxo species on reduced CeO2(110) and (100) surfaces, but not on CeO2(111). This inconsistency originates from a subsurface diffusion of O vacancies.
      PubDate: 2017-11-23T04:51:24.096579-05:
      DOI: 10.1002/anie.201709199
       
  • Overcoming the Lack of Oral Availability of Cyclic Hexapeptides: Design of
           a Selective and Orally Available Ligand for the Integrin αvβ3
    • Authors: Michael Weinmüller; Florian Rechenmacher, Udaya Kiran Marelli, Florian Reichart, Tobias G. Kapp, Andreas F. B. Räder, Francesco Saverio Di Leva, Luciana Marinelli, Ettore Novellino, José M. Muñoz-Félix, Kairbaan Hodivala-Dilke, Adi Schumacher, Joseph Fanous, Chaim Gilon, Amnon Hoffman, Horst Kessler
      Pages: 16405 - 16409
      Abstract: A highly systematic approach for the development of both orally bioavailable and bioactive cyclic N-methylated hexapeptides as high affinity ligands for the integrin αvβ3 is based on two concepts: a) screening of systematically designed libraries with spatial diversity and b) masking of the peptide charge with a lipophilic protecting group. The key steps of the method are 1) initial design of a combinatorial library of N-methylated analogues of the stem peptide cyclo(d-Ala-Ala5); 2) selection of cyclic peptides with the highest intestinal permeability; 3) design of sublibraries with the bioactive RGD sequence in all possible positions; 4) selection of the best ligands for RGD-recognizing integrin subtypes; 5) fine-tuning of the affinity and selectivity by additional Ala to Xaa substitutions; 6) protection of the charged functional groups according to the prodrug concept to regain intestinal and oral permeability; 7) proof of biological effects in mice after oral administration.The oral bioavailability of peptides is mainly limited by their transport through epithelial cells into the blood stream. The development of both orally bioavailable and bioactive cyclic N-methylated hexapeptides by a systematic approach involving screening permeable peptide libraries with spatial diversity and masking the peptides with lipophilic protecting groups led to orally active ligands for the integrin subtype αvβ3.
      PubDate: 2017-11-23T09:16:02.729754-05:
      DOI: 10.1002/anie.201709709
       
  • Oxidation of Organic Molecules with a Redox-Active Guanidine Catalyst
    • Authors: Ute Wild; Florian Schön, Hans-Jörg Himmel
      Pages: 16410 - 16413
      Abstract: Herein, we report the first examples of the use of redox-active guanidines as catalysts in the green oxidation of organic molecules with dioxygen. In one half-reaction, the oxidized form of the redox-active guanidine is converted into the reduced, protonated state, thereby enabling dehydrogenative oxidation of the substrate (3,5-di-tert-butylcatecholortho-benzoquinone, benzoinbenzil, and 2,4-di-tert-butylphenolbiphenol). In the other half-reaction, efficient re-oxidation of the guanidine to the oxidized state is achieved with dioxygen in the presence of a copper catalyst. These results pave the way for the broader use of redox-active guanidines as oxidation catalysts.Green and organic: Owing to the combination of high Brønsted basicity and electron-donor properties, redox-active guanidines are superior organic redox catalysts, as herein shown for the first catalytic oxidation reactions of 3,5-di-tert-butylcatechol, benzoin, and 2,4-di-tert-butylphenol with dioxygen.
      PubDate: 2017-11-22T03:20:35.471556-05:
      DOI: 10.1002/anie.201709809
       
  • Inside Back Cover: A Supramolecular Capsule for Reversible Polysulfide
           Storage/Delivery in Lithium-Sulfur Batteries (Angew. Chem. Int. Ed.
           51/2017)
    • Authors: Jin Xie; Hong-Jie Peng, Jia-Qi Huang, Wen-Tao Xu, Xiang Chen, Qiang Zhang
      Pages: 16415 - 16415
      Abstract: A supramolecular capsule that is similar to an octopus in the ocean makes possible reversible polysulfide storage and delivery in a working battery. In their Communication on page 16223 ff., Q. Zhang et al. report the introduction of cucurbit[6]uril capsules that confer high stability and high efficiency to lithium–sulfur batteries and enable high sulfur loading.
      PubDate: 2017-12-05T07:31:45.028522-05:
      DOI: 10.1002/anie.201712175
       
  • Back Cover: The MOF+ Technique: A Significant Synergic Effect Enables High
           Performance Chromate Removal (Angew. Chem. Int. Ed. 51/2017)
    • Authors: Ming Biao Luo; Yang Yang Xiong, Hui Qiong Wu, Xue Feng Feng, Jian Qiang Li, Feng Luo
      Pages: 16416 - 16416
      Abstract: Metal–organic frameworks (MOFs) used as chromium(VI) adsorbent are mainly restricted by their low adsorption capacity. F. Luo et al. show in their Communication on page 16376 ff. that the so-called MOF+ method, which relies on the surface rather than the pores of MOFs, enables ultrahigh CrVI removal of up to 796 Cr mg g−1, which is mainly due to a significant synergic effect between MOF and FeSO4.
      PubDate: 2017-12-05T07:30:32.215051-05:
      DOI: 10.1002/anie.201712176
       
 
 
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