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Publisher: John Wiley and Sons   (Total: 1592 journals)

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Showing 1 - 200 of 1592 Journals sorted alphabetically
Abacus     Hybrid Journal   (Followers: 13, SJR: 0.48, h-index: 22)
About Campus     Hybrid Journal   (Followers: 5)
Academic Emergency Medicine     Hybrid Journal   (Followers: 66, 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: 54, SJR: 1.02, h-index: 88)
Acta Archaeologica     Hybrid Journal   (Followers: 171, 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: 14, 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: 37, SJR: 2.518, h-index: 113)
Acta Zoologica     Hybrid Journal   (Followers: 7, SJR: 0.459, h-index: 29)
Acute Medicine & Surgery     Hybrid Journal   (Followers: 5)
Addiction     Hybrid Journal   (Followers: 36, SJR: 2.086, h-index: 143)
Addiction Biology     Hybrid Journal   (Followers: 15, SJR: 2.091, h-index: 57)
Adultspan J.     Hybrid Journal   (SJR: 0.127, h-index: 4)
Advanced Energy Materials     Hybrid Journal   (Followers: 26, 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: 279, 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: 18, 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: 11)
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: 16, 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: 34, 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: 152, 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: 93, 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: 35, SJR: 1.761, h-index: 77)
American J. of Human Biology     Hybrid Journal   (Followers: 13, 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: 17, 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: 38, SJR: 1.41, h-index: 88)
American J. of Political Science     Hybrid Journal   (Followers: 296, 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: 4, SJR: 1.347, h-index: 75)
American J. of Transplantation     Hybrid Journal   (Followers: 18, SJR: 2.792, h-index: 140)
American J. on Addictions     Hybrid Journal   (Followers: 10, SJR: 0.843, h-index: 57)
Anaesthesia     Hybrid Journal   (Followers: 141, SJR: 1.404, h-index: 88)
Analyses of Social Issues and Public Policy     Hybrid Journal   (Followers: 10, SJR: 0.397, h-index: 18)
Analytic Philosophy     Hybrid Journal   (Followers: 20)
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: 166)
Angewandte Chemie Intl. Edition     Hybrid Journal   (Followers: 234, 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: 49, 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: 12)
Annual Review of Information Science and Technology     Hybrid Journal   (Followers: 14)
Anthropology & Education Quarterly     Hybrid Journal   (Followers: 26, SJR: 0.72, h-index: 31)
Anthropology & Humanism     Hybrid Journal   (Followers: 18, 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: 93, SJR: 0.545, h-index: 15)
Antipode     Hybrid Journal   (Followers: 52, 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: 73, SJR: 0.754, h-index: 69)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 7, SJR: 0.632, h-index: 58)
Applied Psychology     Hybrid Journal   (Followers: 181, SJR: 1.023, h-index: 64)
Applied Psychology: Health and Well-Being     Hybrid Journal   (Followers: 51, 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: 32, 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: 30, 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: 27, 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: 13, SJR: 0.938, h-index: 57)
Art History     Hybrid Journal   (Followers: 267, SJR: 0.153, h-index: 13)
Arthritis & Rheumatology     Hybrid Journal   (Followers: 55, 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: 326, 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   (Followers: 1, 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: 3, 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: 13, SJR: 0.82, h-index: 62)
Australian Dental J.     Hybrid Journal   (Followers: 6, SJR: 0.482, h-index: 46)
Australian Economic History Review     Hybrid Journal   (Followers: 6, 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: 15, 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: 429, SJR: 0.418, h-index: 29)
Australian J. of Rural Health     Hybrid Journal   (Followers: 6, SJR: 0.43, h-index: 34)
Australian Occupational Therapy J.     Hybrid Journal   (Followers: 74, SJR: 0.59, h-index: 29)
Australian Psychologist     Hybrid Journal   (Followers: 12, SJR: 0.331, h-index: 31)
Australian Veterinary J.     Hybrid Journal   (Followers: 23, SJR: 0.459, h-index: 45)
Autism Research     Hybrid Journal   (Followers: 37, 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: 23, 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: 18, SJR: 1.172, h-index: 90)
Biological Reviews     Hybrid Journal   (Followers: 5, 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: 157, 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: 7, 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: 248, SJR: 2.083, h-index: 125)

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Journal Cover Angewandte Chemie
  [166 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0044-8249 - ISSN (Online) 1521-3757
   Published by John Wiley and Sons Homepage  [1592 journals]
  • Lewis Acid Catalyzed Stereoselective Dearomative Coupling of Indolylboron
           Ate Complexes with D-A Cyclopropanes and Alkyl Halides
    • Authors: Saikat Das; Constantin Gabriel Daniliuc, Armido Studer
      Abstract: Indolylboron ate complexes readily generated from 2-lithio indoles and boronic esters undergo multicomponent dearomative coupling with D-A cyclopropanes and alkyl halides in the presence of Sc(OTf)3 as a catalyst. Reactions proceed with complete diastereoselectivity and excellent stereospecificity to provide indolines bearing three contiguous stereocenters. The valuable boronic ester moiety remains in the product and allows for subsequent functionalization.
      PubDate: 2018-02-17T04:40:34.367473-05:
      DOI: 10.1002/ange.201711923
       
  • N-Heterocyclic Carbene-Treated Gold Surfaces in Pentacene Organic
           
    • Authors: Aifeng Lv; Matthias Freitag, Kathryn M. Chepiga, Andreas H. Schäfer, Frank Glorius, Lifeng Chi
      Abstract: N-Heterocyclic carbene (NHC) molecules, which reacted with the surface of Au electrodes, have been successfully applied in the pentacene transistors. With the application of NHCs, the charge carrier mobility of pentacene transistors increased by five times, while the contact resistance at the pentacene-Au interface reduced down to 85%. Even after annealing the NHC-Au electrodes at 200 oC for two hours before pentacene deposition, the charge carrier mobility of the pentacene transistors did not decrease. The distinguished performance renders the NHCs as excellent alternatives to thiols as metal modifiers for the application in organic field-effect transistors (OFETs).
      PubDate: 2018-02-16T21:40:26.077642-05:
      DOI: 10.1002/ange.201713415
       
  • Nucleopeptide Assemblies Selectively Sequester ATP in Cells
    • Authors: Huaimin Wang; Zhaoqianqi Feng, Yanan Qin, Jiaqing Wang, Bing Xu
      Abstract: Here we report that assemblies of nucleopeptides selectively sequestrate ATP in complex conditions (e.g., serum and cytosol). We develop assemblies of nucleopeptides that selectively sequester ATP over ADP. Counteracting enzymes interconvert ATP and ADP to modulate the nanostructures formed by the nucleopeptides and the nucleotides. The nucleopeptides, sequestering ATP effectively in cells, slow down efflux pumps in multidrug resistance cancer cells, thus boosting the efficacy of an anticancer drug. Examining additional 11 nucleopeptides (including D- and L-enantiomers) yields five more nucleopeptides that differentiate ATP and ADP via either precipitation or gelation. As the first example of using assemblies of nucleopeptides for interacting with ATP and disrupting intracellular ATP dynamics, this work illustrates the use of supramolecular assemblies to interact with small and essential biological molecules for controlling cell behaviors
      PubDate: 2018-02-16T15:40:28.700099-05:
      DOI: 10.1002/ange.201712834
       
  • One-Step Synthesis of Hybrid Core-Shell Metal-Organic Frameworks
    • Authors: Xinyu Yang; Shuai Yuan, Lanfang Zou, Hannah Drake, Yingmu Zhang, Junsheng Qin, Ali Alsalme, Hongcai Zhou
      Abstract: Epitaxial growth of MOF-on-MOF composite is an evolving research topic. In current methods, the core-shell MOFs are synthesized via a stepwise strategy which involves growing the shell-MOFs on top of the preformed core-MOFs with matched lattice parameters. However, the inconvenient stepwise synthesis and the strict lattice-matching requirement have limited the development of core-shell MOFs. Herein, we demonstrate that hybrid core-shell MOFs with mismatching lattices can be synthesized under the guidance of nucleation kinetics. A series of MOF composites with mesoporous core and microporous shell were constructed and characterized by optical microscopy, powder X-ray diffraction, gas sorption measurement, and scanning electron microscopy. Isoreticular expansion of microporous shells and orthogonal modification of the core was realized to produce multifunctional MOF composites, which acted as size selective catalysts for olefin epoxidation with high activity and selectivity.
      PubDate: 2018-02-16T15:10:24.744237-05:
      DOI: 10.1002/ange.201710019
       
  • Rational tuning of fluorobenzene probes for cysteine-selective protein
           modification
    • Authors: Ahmed M. Embaby; Sanne Schoffelen, Christian Kofoed, Meldal Morten, Frederik Diness
      Abstract: Fluorobenzene probes for protein profiling through selective cysteine labeling have been developed by rational reactivity tuning. Tuning was achieved by selecting an electron-withdrawing para-substituent combined with variation of the number of fluorine substituents. Optimized probes chemo-selectively arylated cysteine residues in proteins under aqueous conditions. Probes linked to azide, biotin or a fluorophore were applicable to labeling of eGFP and albumin. Selective inhibition of cysteine proteases was also demonstrated with the probes. Additionally, probes were tuned for site selective labeling among cysteine residues and for activity based protein profiling in cell lysates.
      PubDate: 2018-02-16T13:40:48.628007-05:
      DOI: 10.1002/ange.201712589
       
  • Direct Measurement of Charge Regulation in Metalloprotein Electron
           Transfer
    • Authors: Collin T. Zahler; Hongyu Zhou, Alireza Abdolvahabi, Rebecca L. Holden, Sanaz Rasouli, Peng Tao, Bryan Shaw
      Abstract: Quantifying how a protein regulates its net electrostatic charge during electron transfer (ET) is a means of directly measuring factors that contribute to either redox potential and/or reorganization energy. Charge regulation by proteins during ET has never been measured because few tools exist to measure the net charge of a folded protein in solution at different oxidation states. Here, by using protein charge ladders and capillary electrophoresis, we determined that the net charge of myoglobin, cytochrome c, and azurin changed by 0.62 ± 0.06, 1.19 ± 0.02, and 0.51 ± 0.04 units upon single ET. Computational analysis predicts that these fluctuations in charge arise from changes in the pKa of multiple non-coordinating residues (predominantly histidine) and require between 0.42-0.90 eV. These results suggest that ionizable residues can tune the reactivity of redox centers via charge regulation.
      PubDate: 2018-02-16T13:40:30.435301-05:
      DOI: 10.1002/ange.201712306
       
  • Enhanced Photodynamic Therapy by Reduced Intracellular Glutathione Levels
           Employing Nano-MOF with Cu (II) as Active Center
    • Authors: Wei Zhang; Jun Lu, Xiaonan Gao, Ping Li, Wen Zhang, Yu Ma, Hui Wang, Bo Tang
      Abstract: In photodynamic therapy (PDT), the level of reactive oxygen species (ROS) produced in the cell directly determines therapeutic effect. Therefore, the development of photosensitizers combining the ability of reducing GSH levels through synergisticallyimproving ROS concentration to strengthen the efficacy of PDT for tumor is important. We report a nano-metal-organic framework based on Cu (II) as active center for PDT. This MOF-2 is readily uptaken by breast cancer cells, and high-level ROS is generated under light irradiation. Meanwhile, intracellular GSH is considerably decreased owing to absorption on MOF-2, synergistically increasing ROS concentration and accelerating apoptosis, thereby enhancing the effect of PDT. Notably, through the direct adsorption of GSH, MOF-2 showed comparable effect with commercial antitumor drug camptothecin in mouse breast cancer treatment. This work provides strong evidence for MOF-2 as a promising new PDT candidate and anti-cancer drug.
      PubDate: 2018-02-16T10:40:27.005198-05:
      DOI: 10.1002/ange.201710800
       
  • Selective sp3 C-H Aerobic Oxidation enabled by Deca-tungstate
           Photocatalysis in Flow
    • Authors: Gabriele Laudadio; Sebastian Govaerts, Ying Wang, Davide Ravelli, Hannes Koolman, Maurizio Fagnoni, Stevan Djuric, Timothy Noel
      Abstract: A mild and selective sp3 C-H aerobic oxidation enabled by deca-tungstate photocatalysis has been developed. The reaction can be significantly improved in a microflow reactor enabling the safe use of oxygen and the enhanced irradiation of the reaction mixture. Our method allows for the oxidation of both activated and unactivated C-H bonds (30 examples). The ability to selectively oxidize natural scaffolds, such as (-)-ambroxide, pregnenolone acetate, (+)-sclareolide and artemisinin exemplifies the utility of this new method.
      PubDate: 2018-02-16T10:05:41.409409-05:
      DOI: 10.1002/ange.201800818
       
  • Phosphinic Acid Based Linkers: New Building Block in MOF Chemistry
    • Authors: Jan Hynek; Petr Brázda, Jan Rohlíček, Michael G.S. Londesborough, Jan Demel
      Abstract: Metal-organic frameworks (MOFs) are a chemically and topologically diverse family of materials composed of inorganic nodes and organic linkers bound together by coordination bonds. In this contribution we present two significant innovations in this field. The first is the use of a new coordination group in phenylene-1,4-bis(methylphosphinic acid) (PBPA), a phosphinic acid analogue of commonly-used terephtalic acid. We show that the use of this new linker group leads to the formation of a hydrothermally stable permanently porous MOF structure. The second innovation is the application of electron diffraction tomography (EDT), coupled with dynamical refinement of the EDT data, to the elucidation of the structure of the new material including the localization of hydrogen atoms.
      PubDate: 2018-02-16T09:10:25.351856-05:
      DOI: 10.1002/ange.201800884
       
  • Polyvalent Display of Biomolecules on Live Cells
    • Authors: Peng Shi; Nan Zhao, Jinping Lai, James Coyne, Erin R. Gaddes, Yong Wang
      Abstract: Surface display of biomolecules on live cells offers new opportunities to treat human diseases and perform basic studies. Existing methods are primarily focused on monovalent functionalization, that is, the display of single biomolecules across the cell surface. Here we show that the surface of live cells can be functionalized to display polyvalent biomolecular structures through two-step reactions under physiological conditions. This polyvalent functionalization enables the cell surface to recognize the microenvironment one order of magnitude more effectively than with monovalent functionalization. Thus, polyvalent display of biomolecules on live cells holds great potential for various biological and biomedical applications.Viel hilft viel: Biomoleküle auf lebenden Zellen bestimmen, wie die Zellen ihre Umgebung erkennen. Die Oberfläche lebender Zellen kann mit polyvalenten biomolekularen Strukturen funktionalisiert werden, um eine bessere molekulare Erkennung zu gewährleisten als mit monovalenter Funktionalisierung.
      PubDate: 2018-02-16T07:01:06.922382-05:
      DOI: 10.1002/ange.201712596
       
  • Kallol Ray
    • PubDate: 2018-02-16T06:47:19.114163-05:
      DOI: 10.1002/ange.201801205
       
  • Dynamic Covalent Chemistry. Principles, Reactions, and Applications
           Herausgegeben von Wei Zhang und Yinghua Jin.
    • Authors: Stefan Kubik
      Abstract: John Wiley and Sons, Hoboken 2018. 464 S., geb., 182.00 €.—ISBN 978-1119075639
      PubDate: 2018-02-16T06:47:17.163799-05:
      DOI: 10.1002/ange.201801152
       
  • Phosphine-Catalyzed anti-Carboboration of Alkynoates with 9-BBN-Based
           1,1-Diborylalkanes: Synthesis and Use of Multisubstituted
           γ-Borylallylboranes
    • Authors: Ayaka Yamazaki; Kazunori Nagao, Tomohiro Iwai, Hirohisa Ohmiya, Masaya Sawamura
      Abstract: Trialkylphosphine organocatalysis has enabled the regioselective anti-carboboration of alkynoates with 9-BBN-based 1,1-diborylalkanes to produce secondary allylboranes with β-alkoxycarbonyl and γ-boryl substituents. The utility of the densely functionalized allylboranes was demonstrated by the highly diastereoselective allylation of N-(trimethylsilyl)aldimines to produce homoallylamines containing tertiary allylborane and acrylate moieties.Organokatalyse mit einem Trialkylphosphin ermöglichte die regioselektive anti-Carboborierung von Alkinoaten mit 1,1-Diborylalkanen zu sekundären Allylboranen mit β-Alkoxycarbonyl- und γ-Borylsubstituenten (siehe Schema). Die dicht funktionalisierten Allylborane bewirken eine hoch diastereoselektive Allylierung von N-(Trimethylsilyl)aldiminen, die Homoallylamine mit tertiären Allylboran- und Acrylateinheiten liefert.
      PubDate: 2018-02-16T06:47:03.793491-05:
      DOI: 10.1002/ange.201712351
       
  • Supramolecular Modulation of Structural Polymorphism in Pathogenic
           α-Synuclein Fibrils Using Copper(II) Coordination
    • Authors: Tae Su Choi; Jeeyoung Lee, Jong Yoon Han, Byung Chul Jung, Piriya Wongkongkathep, Joseph A. Loo, Min Jae Lee, Hugh I. Kim
      Abstract: Structural variation of α-synuclein (αSyn) fibrils has been linked to the diverse etiologies of synucleinopathies. However, little is known about what specific mechanism provides αSyn fibrils with pathologic features. Herein, we demonstrate Cu(II)-based supramolecular approach for unraveling the formation process of pathogenic αSyn fibrils and its application in a neurotoxic mechanism study. The conformation of αSyn monomer was strained by macrochelation with Cu(II), thereby disrupting the fibril elongation while promoting its nucleation. This non-canonical process formed shortened, β-sheet enriched αSyn fibrils (
      PubDate: 2018-02-16T06:46:55.367394-05:
      DOI: 10.1002/ange.201712286
       
  • Unsymmetrical, Cyclic Diborenes and Thermal Rearrangement to a
           Borylborylene
    • Authors: Tom Stennett; James Mattock, Ivonne Vollert, Alfredo Vargas, Holger Braunschweig
      Abstract: Cyclic diboranes(4) based on a chelating monoanionic benzylphosphine linker were prepared by boron-silicon exchange between arylsilanes and B2Br4. Coordination of Lewis bases to the remaining sp2 boron atom yielded unsymmetrical sp3-sp3 diboranes, which were reduced with KC8 to their corresponding trans-diborenes. These compounds were studied by a combination of spectroscopic methods, X-ray diffraction and DFT calculations. PMe3-stabilized diborene 6 was found to undergo thermal rearrangement to gem-diborene 8. DFT calculations on 8 reveal a polar boron-boron bond, and indicate that the compound is best described as a borylborylene.
      PubDate: 2018-02-16T06:42:30.835248-05:
      DOI: 10.1002/ange.201800671
       
  • Synthesis of Biaryls via Hypervalent Iodine-Tethered Sigmatropic
           Rearrangement
    • Authors: Mitsuki Hori; Jing-Dong Guo, Tomoyuki Yanagi, Keisuke Nogi, Takahiro Sasamori, Hideki Yorimitsu
      Abstract: Metal-free dehydrogenative coupling of aryliodanes with phenols to afford 2-hydroxy-2'-iodobiaryls has been developed. This reaction proceeds via ligand exchange on the hypervalent iodine atom, followed by [3,3] sigmatropic rearrangement, to realize exclusive regioselectivity. This coupling, in combination with in situ oxidation by mCPBA, facilitates the convenient conversion of iodoarenes into the desired biaryls. The obtained biaryls have convertible iodo and hydroxy groups in close proximity, and are thus synthetically useful, as exemplified by the controlled syntheses of π-expanded furans and a substituted [5] helicene. DFT calculations clearly revealed that the rearrangement is sigmatropic and involves C-C bond formation and I-O bond cleavage in a concerted manner. Acetic acid, which was found to be the best solvent for this protocol, would make the iodine atom more cationic and thus accelerate the sigmatropic rearrangement.
      PubDate: 2018-02-16T06:41:38.075016-05:
      DOI: 10.1002/ange.201801132
       
  • Helicenophyrins - expanded carbaporphyrins incorporating aza[5]helicene
           and heptacyclic S-shaped aza[5]helicene motifs
    • Authors: Bartosz Szyszko; Monika Przewoznik, Michal J. Bialek, Agata Bialonska, Piotr J. Chmielewski, Jakub Cichos, Lechoslaw Latos-Grazynski
      Abstract: Incorporation of phenanthrene into a hexaphyrin(1.1.1.1.1.0) frame resulted in the intramolecular fusion giving rise to chiral helicenophyrins, i.e. molecules which convolute helicene and porphyrin features incorporating aza[5]helicene or heptacyclic S-shaped aza[5]helicene.
      PubDate: 2018-02-16T05:40:34.641269-05:
      DOI: 10.1002/ange.201800879
       
  • N-Functionalized Ferrocenes. Subvalent Group XIV Element Chlorides and an
           tButyl Lithium-Induced C─C Bond Cleavage Under Mild Conditions
    • Authors: Bastian Nayyar; Hazem Alnasr, Wolf Hiller, Klaus Jurkschat
      Abstract: The ferrocene derivative η5-CpFeη5-C5H3-1-(ArNCH)-2-(CH2NMe2) (1, Ar = 2,6-iPr2C6H3)) reacts diastereoselectively with LiR under carbolithiation and subsequent hydrolysis to give η5-CpFeη5-C5H3-1-(ArHNCHR)-2-(CH2NMe2) (3, R = tBu; 4, R = Ph; 5, R = Me) in high yields. For R = tBu the organolithium derivative η5-CpFeη5-C5H3-1-(ArLiNCHR)-2-(CH2NMe2) (2) was isolated. Compound 2 reacts with GeCl2∙dioxane and SnCl2, respectively, giving the metallylene amide chlorides η5-CpFeη5-C5H3-1-(ArMNCHtBu)-2-(CH2NMe2) (6, M = GeCl; 7, M = SnCl) containing each three stereogenic centres. The potential of 7 as ligand in transition metal chemistry is demonstrated by formation of its complex η5-CpFeη5-C5H3-1-(ArMNCHtBu)-2-(CH2NMe2) [9, M = Sn(Cl)W(CO)5]. Treatment at room temperature of 3 with tert-butyllithium causes an unprecedented carbon-carbon bond cleavage while under kinetic control lithiation at the Cp-3 position takes place allowing the isolation of η5-CpFeη5-C5H3-1-(ArHNCHtBu)-2-(CH2NMe2)-3-SiMe3 (10).
      PubDate: 2018-02-16T04:40:39.623891-05:
      DOI: 10.1002/ange.201800128
       
  • ADUC-Preise / Carl-Duisberg-Gedächtnispreis für Bill Morandi / Neue
           Mitglieder der Académie des Sciences / Max-Delbrück-Nachwuchspreis für
           Sabrina Disch / Novartis Early Career Award
    • PubDate: 2018-02-16T04:03:08.905872-05:
      DOI: 10.1002/ange.201801006
       
  • Organometallic-Mediated Radical Polymerization of Vinylidene Fluoride
    • Authors: Sanjib Banerjee; Vincent Ladmiral, Antoine Debuigne, Christophe Detrembleur, Rinaldo Poli, Bruno Améduri
      Abstract: An unprecedented level of control for the radical polymerization of vinylidene fluoride (VDF), yielding well-defined PVDF (at least up to 14 500 g mol−1) with low dispersity (≤1.32), was achieved using organometallic-mediated radical polymerization (OMRP) with an organocobalt compound as initiator. The high chain-end fidelity was demonstrated by the synthesis of PVDF- and PVAc-containing di-and triblock copolymers. DFT calculations rationalize the efficient reactivation of both head and tail chain end dormant species.Kein Ende absehbar: Eine Organocobaltverbindung vermittelt die metallorganische radikalische Polymerisation (OMRP) von Vinylidenfluorid (VDF) zu definiertem PVDF (bis 14 500 g mol−1 und darüber) mit niedriger Dispersität (≤1.32). Dichtefunktionalrechnungen belegen, dass so erhaltenes PVDF an beiden Enden reaktiviert werden kann.
      PubDate: 2018-02-16T04:02:53.006454-05:
      DOI: 10.1002/ange.201712347
       
  • Bildgebung von Nano-Bio-Interaktionen in der Niere: Für ein besseres
           Verständnis der Nanopartikel-Clearance
    • Authors: Junqing Wang; Gang Liu
      Abstract: Alles klar! Jüngste Studien haben zu einem besseren Verständnis der Wechselwirkungen zwischen biologischen Strukturen und Nanopartikeln geführt und zum rationalen Design renal eliminierbarer Nanopartikel in erkrankten Nieren beigetragen. Die renale Clearance von Goldnanopartikeln (AuNPs) hängt nicht nur von den Choi-Kriterien ab, sondern wird auch von der Mikrostruktur der glomerulären Barriere sowie von pathophysiologischen Veränderungen im Nephron beeinflusst.
      PubDate: 2018-02-16T04:02:30.416759-05:
      DOI: 10.1002/ange.201711705
       
  • A Versatile Ligand Platform for Palladium- and Nickel-Catalyzed Ethylene
           Copolymerization with Polar Monomers
    • Authors: Min Chen; Changle Chen
      Abstract: The ability to carry out transition-metal-catalyzed copolymerizations of olefins with polar monomers is a great challenge in the field of olefin polymerization. Palladium has been the dominant player in this field, while its low-cost nickel counterpart has only achieved very limited success. We report the synthesis and evaluation of a highly versatile platform based on diphosphazane monoxide ligands. Both palladium and nickel catalysts bearing these ligands mediate the copolymerization of ethylene with a number of fundamental polar monomers.Polymerisationsplattform: Eine vielseitige Plattform auf Basis von Diphosphazanmonoxid-Liganden wurde entworfen und untersucht. Palladium- und Nickelkatalysatoren mit diesen Liganden vermitteln die Copolymerisation von Ethylen mit einer Reihe von polaren Monomeren.
      PubDate: 2018-02-16T04:01:40.003188-05:
      DOI: 10.1002/ange.201711753
       
  • Two Chiral Events in a Single C-H Activation Step: a route towards
           terphenyl ligands with two atropisomeric axes.
    • Authors: Françoise Colobert; Quentin Dherbassy, Jean-Pierre Djukic, Joanna Wencel-Delord
      Abstract: Herein we disclose the synthesis of original chiral scaffolds - ortho-orientated terphenyls presenting two atropisomeric Ar-Ar axes. These unusual structures are built up using the C-H activation approach and remarkably both chiral axes are controlled with excellent stereoselectivities in a single transformation. During the reaction, not only atroposelective functionalization of the biaryl precursor occurs imposing one chiral axis, but also an unprecedented atropo-stereoselective C-H arylation takes place generating the second chiral element. These functionalized enantiopure ortho-terphenyls present an original tridimensional structure and thus constitute a unique ground to build-up rapidly and efficiently a library of enantiopure mono- and bicoordinating ligands such as new S/N-Biax and diphosphine Biax-Phos ligands.
      PubDate: 2018-02-16T03:10:59.787586-05:
      DOI: 10.1002/ange.201801130
       
  • An Organic Mixed-Valence Ligand for Multistate Redox-Active Coordination
           Networks
    • Authors: Joo yeon Ha; Jin young Koo, Hiroyoshi Ohtsu, Yumi Yakiyama, Kimoon Kim, Daisuke Hashizume, Masaki Kawano
      Abstract: The multi-redox-active/multi-interactive ligand 5,5',8,8'-tetra(4-pyridyl)-2,2'-(1,4-phenylene)bis-1H-perimidine (H2TPP) was designed and synthesized. H2TPP exhibits four one-electron oxidation steps, and was subsequently used for the preparation of a multi-redox-active coordination network via a solid-liquid interface reaction using molten Cd2+ cations. The multiple redox states of H2TPP were confirmed spectroscopically by a stepwise four-electron oxidation. The spectroscopic analysis indicated that the mixed-valence states of the ligand are Class II on the UV-vis-NIR time scale and borderline Class II/Class III on the ESR time scale.
      PubDate: 2018-02-16T01:10:28.521374-05:
      DOI: 10.1002/ange.201713035
       
  • Synthesis of a Helical Bilayer Nanographene
    • Authors: Paul Jameson Evans; Jiangkun Ouyang, Ludovic Favereau, Jeanne Crassous, Israel Fernández, Josefina Perles Hernáez, Nazario Martin
      Abstract: A rigid, inherently chiral bilayer nanographene has been synthesized as both the racemate and enantioenriched M isomer (with an ee of 93%) in three steps from precedented helicenes. This folded nanographene is comprised of two hexa-peri-hexabenzocoronene layers fused to a [10]helicene, with an interlayer distance of 3.6Å as determined by X-ray crystallography. The rigidity of the helicene linker forces the layers to adopt a nearly-aligned AA-stacked conformation rarely observed in few-layer graphene. By combining the advantages of nanographenes and helicenes, we have constructed a bilayer system of 30 fused benzene rings that is also chiral, rigid, and remains soluble in common organic solvents. We present this as a molecular model system of bilayer graphene, with properties of interest in a variety of potential applications.
      PubDate: 2018-02-15T13:10:52.69762-05:0
      DOI: 10.1002/ange.201800798
       
  • Ni-catalyzed Umpolung Arylation of Ambiphilic a-Bromo Boronic Esters
    • Authors: Ruben Martin; Shang-Zheng Sun
      Abstract: A Ni-catalyzed reductive arylation of ambiphilic a-bromo boronic esters with aryl halides is described. This platform provides an unrecognized opportunity to promote catalytic umpolung reactivity of ambiphilic reagents with aryl halides, thus unlocking a new cross-coupling strategy that complements existing technologies for the preparation of densely functionalized alkyl organometallic reagents from simple and accessible precursors
      PubDate: 2018-02-15T11:40:57.955535-05:
      DOI: 10.1002/ange.201712428
       
  • The Amyloid Polymorphism in the Protein Folding and Aggregation Energy
           Landscape
    • Authors: Raffaele Mezzenga; Jozef Adamcik
      Abstract: Protein folding (and misfolding) is of paramount importance to an extraordinary vast class of fields, spanning from biochemistry to biology, medicine, biophysics and statistical thermodynamics. The folding process involves a large number of steps and conformations in which the folding protein samples different thermodynamic states characterized by local minima and activation energies in between. The kinetically trapped on- or off-pathway intermediates identifying the relative minima are metastable folding intermediates towards the lowest absolute energy minima, which have been postulated to be the natively folded state for the regime in which the intramolecular interactions dominate, and the amyloid status for the regime where intermolecular interactions rule. This view, however, has largely neglected the rich polymorphism characterizing the various amyloid species. In this article, we review the protein folding energy landscape in view of recent findings identifying specific transition routes among different amyloid polymorphs. Observed transitions such as twisted ribboncrystal or helical ribbonnanotube or forbidden transitions such helical ribbon crystal, are discussed and precisely positioned within the protein folding and aggregation energy landscape. In particular, because these transitions occur without an unfolding/refolding process, the various energetic states can be navigated by relying on continuous mechanic concepts, which concur, together with experimental evidence, to identify amyloid crystals as the ground state of the protein folding and aggregation energy landscape.
      PubDate: 2018-02-15T11:26:35.179117-05:
      DOI: 10.1002/ange.201713416
       
  • Confinement effects on the benzene orientational structure
    • Authors: Marta Falkowska; Daniel T. Bowron, Haresh Manyar, Tristan G. A. Youngs, Christopher Hardacre
      Abstract: Liquids under confinement exhibit different properties compared with their corresponding bulk phases, for example miscibility, phase transitions, and diffusion. The underlying cause is the local ordering of molecules which is usually only studied using pure simulation methods. Herein, we derive experimentally the structure of benzene confined in MCM-41 using total neutron scattering measurements. The study reveals a layering of molecules across a pore, and four concentric cylindrical shells can be distinguished for a pore with the radius of 18 Å. The nanoscale confinement of the liquid has a major effect on the spatial and orientational correlations observed between the molecules, when compared with the structure of the bulk liquid. These differences are most marked for the molecules in the parallel configurations, and this suggests differences in chemical reactivity between the confined and bulk liquids.
      PubDate: 2018-02-15T09:40:26.962274-05:
      DOI: 10.1002/ange.201713115
       
  • Epoxides as Alkylating Reagents for the Catellani Reaction
    • Authors: Hong-Gang Cheng; Chenggui Wu, Han Chen, Ruiming Chen, Guangyin Qian, Zhi Geng, Qiang Wei, Yuanyuan Xia, Jingyang Zhang, Yuming Zhang, Qianghui Zhou
      Abstract: We report a cooperative catalytic system comprising a PdII complex, XPhos, and the potassium salt of 5-norbornene-2-carboxylic acid that enables the use of epoxides as alkylating reagents in the Catellani reaction, thereby expanding the existing paradigm of this powerful transformation. The potassium salt of inexpensive 5-norbornene-2-carboxylic acid acts as both mediator and base in the process. This mild, chemoselective, scalable, and atom-economical protocol is compatible with a wide variety of readily available functionalized aryl iodides and epoxides, as well as terminating olefins. The resulting products undergo facile oxa-Michael addition to furnish ubiquitous isochroman scaffolds.Ein kooperatives katalytisches System aus einem PdII/XPhos-Komplex und dem Kaliumsalz von 5-Norbornen-2-carbonsäure, das als Reaktionsvermittler und Base zugleich fungiert, ermöglichte die Verwendung von Epoxiden als Alkylierungsreagentien in der Catellani-Reaktion (siehe Schema). Die Produkte können durch Oxa-Michael-Addition in Isochroman-Gerüste umgewandelt werden.
      PubDate: 2018-02-15T09:15:33.519167-05:
      DOI: 10.1002/ange.201800573
       
  • Formation of NiCo2V2O8 Yolk–Double Shell Spheres with Enhanced
           Lithium Storage Properties
    • Authors: Yan Lu; Jianwei Nai, Xiong Wen (David) Lou
      Abstract: Complex nanostructures with multi-components and intricate architectures hold great potential in developing high-performance electrode materials for lithium-ion batteries (LIBs). Herein, we demonstrate a facile self-templating strategy for the synthesis of metal vanadate nanomaterials with complex chemical composition of NiCo2V2O8 and a unique yolk–double shell structure. Starting with the Ni-Co glycerate spheres, NiCo2V2O8 yolk–double shell spheres are synthesized through an anion-exchange reaction of Ni-Co glycerate templates with VO3− ions, followed by an annealing treatment. By virtue of compositional and structural advantages, these NiCo2V2O8 yolk–double shell spheres manifest outstanding lithium storage properties when evaluated as anodes for LIBs. Impressively, an extra-high reversible capacity of 1228 mAh g−1 can be retained after 500 cycles at a high current density of 1.0 Ag−1.NiCo2V2O8-Kugeln mit einer Dotter-Zweischalen-Struktur wurden mit einer einfachen Templat-Technik unter Verwendung einer Ionenaustauschreaktion zwischen Ni-Co-Glycerat-Kugeln und NH4VO3 unter Rückflussbedingungen synthetisiert, gefolgt von einer Wärmebehandlung an Luft. Die synthetisierten NiCo2V2O8-Verbindungen zeigen hervorragende elektrochemische Eigenschaften, wenn sie als Anodenmaterial in Lithiumionenbatterien verwendet werden.
      PubDate: 2018-02-15T09:10:42.724171-05:
      DOI: 10.1002/ange.201800363
       
  • Bioorthogonal Catalytic Activation of Platinum and Ruthenium Anticancer
           Complexes by FAD and Flavoproteins
    • Authors: Silvia Alonso-de Castro; Aitziber L. Cortajarena, Fernando López-Gallego, Luca Salassa
      Abstract: Recent advances in bioorthogonal catalysis promise to deliver new chemical tools for performing chemoselective transformations in complex biological environments. Herein, we report how FAD (flavin adenine dinucleotide), FMN (flavin mononucleotide), and four flavoproteins act as unconventional photocatalysts capable of converting PtIV and RuII complexes into potentially toxic PtII or RuII−OH2 species. In the presence of electron donors and low doses of visible light, the flavoproteins mini singlet oxygen generator (miniSOG) and NADH oxidase (NOX) catalytically activate PtIV prodrugs with bioorthogonal selectivity. In the presence of NADH, NOX catalyzes PtIV activation in the dark as well, indicating for the first time that flavoenzymes may contribute to initiating the activity of PtIV chemotherapeutic agents.Substrat statt Katalysator: Flavine agieren als selektive Photokatalysatoren für die Aktivierung Metall-basierter Prodrugs in biologischer Umgebung. Anders als in der gewöhnlichen Katalyse sind Metallkomplexe die Substrate, und nicht die Katalysatoren dieser Reaktionen.
      PubDate: 2018-02-15T09:05:59.744289-05:
      DOI: 10.1002/ange.201800288
       
  • Kinetic Resolution of sec-Thiols by Enantioselective Oxidation with
           Rationally Engineered 5-(Hydroxymethyl)furfural Oxidase
    • Authors: Mathias Pickl; Alexander Swoboda, Elvira Romero, Christoph K. Winkler, Claudia Binda, Andrea Mattevi, Kurt Faber, Marco W. Fraaije
      Abstract: Various flavoprotein oxidases were recently shown to oxidize primary thiols. Herein, this reactivity is extended to sec-thiols by using structure-guided engineering of 5-(hydroxymethyl)furfural oxidase (HMFO). The variants obtained were employed for the oxidative kinetic resolution of racemic sec-thiols, thus yielding the corresponding thioketones and nonreacted R-configured thiols with excellent enantioselectivities (E≥200). The engineering strategy applied went beyond the classic approach of replacing bulky amino acid residues with smaller ones, as the active site was additionally enlarged by a newly introduced Thr residue. This residue established a hydrogen-bonding interaction with the substrates, as verified in the crystal structure of the variant. These strategies unlocked HMFO variants for the enantioselective oxidation of a range of sec-thiols.Passend gemacht: Gezielt entworfene Varianten der 5-(Hydroxymethyl)furfural(HMF)-Oxidase katalysieren die enantioselektive Oxidation von 1-Phenylethanthiolen und erreichen dabei eine kinetische Racematspaltung mit besipiellosen Selektivitäten. Dieses Ergebnis wird anhand der Kristallstruktur einer solchen Variante erklärt.
      PubDate: 2018-02-15T09:01:17.966651-05:
      DOI: 10.1002/ange.201713189
       
  • Base-Free Generation of Organic Electron Donors from Air-Stable Precursors
    • Authors: Guillaume Tintori; Pierre Nabokoff, Ruqaya Buhaibeh, David Bergé-Lefranc, Sébastien Redon, Julie Broggi, Patrice Vanelle
      Abstract: Organic electron donors (OEDs) are powerful reducing agents recognized for their potential in the reduction of challenging substrates and in original applications. Nonetheless, their low stability in atmospheric oxygen or over time complicates their manipulation and storage. To overcome these constraints and enhance OED practicality, new air- and moisture-stable aminopyridinium carboxylate and carbonate precursors were synthesized and thermally activated to generate the potent electron donor in situ. Carboxylate adducts proved to be excellent latent OED systems, enabling the facile and efficient reduction of challenging substrates. Their reduction properties were correlated to their structural characteristics by thermogravimetric and spectroscopic analysis.Um die Praktikabilität organischer Elektronendonoren (OEDs) zu verbessern, wurden neue luft- und feuchtigkeitsstabile Carboxylat- und Carbonat-Vorstufen synthetisiert. Diese wurden in situ durch thermische Aktivierung in potente Elektronendonoren überführt und ermöglichen so die effiziente Reduktion anspruchsvoller Substrate (ET=Elektronentransfer).
      PubDate: 2018-02-15T09:01:12.17506-05:0
      DOI: 10.1002/ange.201713079
       
  • Total Synthesis of Astellatol
    • Authors: Nan Zhao; Shuqiang Yin, Shengling Xie, Hao Yan, Pan Ren, Gui Chen, Fang Chen, Jing Xu
      Abstract: A nearly-30-year-old unanswered synthetic puzzle, astellatol, has been solved in an enantiospecific manner. The highly congested pentacyclic skeleton of this rare sesterterpenoid, which possesses a unique bicyclo[4.1.1]octane motif, ten stereocenters, a cyclobutane that contains two quaternary centers, an exo-methylene group, and a sterically encumbered isopropyl trans-hydrindane motif, makes astellatol arguably one of the most challenging targets for sesterterpenoid synthesis. An intramolecular Pauson–Khand reaction was exploited to construct the right-hand side scaffold of this sesterterpenoid. An unprecedented reductive radical 1,6-addition, mediated by SmI2, forged the cyclobutane motif. Last, a strategic oxidation/reduction step provided not only the decisive solution for the remarkably challenging late-stage transformations, but also a highly valuable unravelling of the notorious issue of trans-hydrindane synthesis. Importantly, the synthesis of astellatol showcases a rapid, scalable strategy to access diverse complex isopropyl trans-hydrindane sesterterpenoids.Ein pentacyclisches Sesterterpenoid – Astellatol – wurde enantiospezifisch synthetisiert. Eine Pauson-Khand-Reaktion erzeugte die rechte Seite des Produkts, und eine reduktive radikalische 1,6-Addition unter Verwendung von SmI2 lieferte die Bicyclo[4.1.1]octan-Einheit. Durch strategische Oxidation/Reduktion gegen Ende der Syntheseroute wurde das hoch substituierte trans-Hydrindan fertiggestellt.
      PubDate: 2018-02-15T09:01:04.368077-05:
      DOI: 10.1002/ange.201800167
       
  • Catalytic Gas-Phase Production of Lactide from Renewable Alkyl Lactates
    • Authors: Rik De Clercq; Michiel Dusselier, Ekaterina Makshina, Bert F. Sels
      Abstract: A new route to lactide, which is a key building block of the bioplastic polylactic acid, is proposed involving a continuous catalytic gas-phase transesterification of renewable alkyl lactates in a scalable fixed-bed setup. Supported TiO2/SiO2 catalysts are highly selective to lactide, with only minimal lactide racemization. The solvent-free process allows for easy product separation and recycling of unconverted alkyl lactates and recyclable lactyl intermediates. The catalytic activity of TiO2/SiO2 catalysts was strongly correlated to their optical properties by DR UV/Vis spectroscopy. Catalysts with high band-gap energy of the supported TiO2 phase, indicative of a high surface spreading of isolated Ti centers, show the highest turnover frequency per Ti site.Ein effizientes Herstellungsverfahren für Lactid – einen cyclischen Baustein für Biokunststoffe – beruht auf der Umesterung von Alkyllactaten in der Gasphase. TiO2/SiO2-Trägerkatalysatoren erzielen dabei hohe Lactid-Selektivitäten. Die Aktivität der Katalysatoren korreliert mit ihrer Bandlücke und nimmt bei Reduktion des Ti-Polymerisationsgrads stark zu.
      PubDate: 2018-02-15T09:00:35.671495-05:
      DOI: 10.1002/ange.201711446
       
  • Ge14Br8(PEt3)4: A Subhalide Cluster of Germanium - First Step into a Novel
           Field in Germanium Chemistry
    • Authors: Andreas Bernd Schnepf; Claudio Schrenk, Tanja Kunz
      Abstract: Heating a metastable solution of Ge(I)Br to room temperature leads to the first structurally characterized metalloid subhalide cluster Ge14Br8(PEt3)4 (1). Furthermore 1 can be seen as the first isolated binary halide cluster on the way from Ge(I)Br to elemental germanium, giving insight into the complex reaction mechanism of its disproportionation reaction. Quantum chemical calculations further indicate that within 1 a classical bonding situation is realized and that the last step of the formation of 1 might include the trapping of GeBr2 units.
      PubDate: 2018-02-15T07:41:09.561008-05:
      DOI: 10.1002/ange.201712247
       
  • Coumarin Photocages Modified with an Electron-Rich Styryl Moiety at the
           3-Position: Long Wavelength Excitation, Rapid Photolysis and
           Photobleaching
    • Authors: Linyong Zhu; Qiuning Lin, Lipeng Yang, Zhiqiang Wang, Yujie Hua, Dasheng Zhang, Bingkun Bao, Chunyan Bao, Xueqing Gong
      Abstract: A new class of coumarin photocages modified with an electron-rich styryl moiety at the 3-position was constructed. The large π-conjugated structure and stabilization of the carbocation intermediates by electron-donors endowed the new photocages excellent long wavelength absorption, large two-photon absorption cross-sections and high uncaging quantum yields. Moreover, the new photocages displayed unique photobleaching property after photocleavage as a result of the intramolecular cyclization rearrangement of carbocation intermediate to form five-membered ring byproducts and block the styryl conjugation at the 3-position. These superior properties of the new photocages are extremely beneficial for high concentration samples and thick specimens, thus extending the application of photocages in many fields.
      PubDate: 2018-02-15T06:11:12.85484-05:0
      DOI: 10.1002/ange.201800713
       
  • Co-assembly of Polyoxometalates and Zwitterionic Amphiphiles into
           Supramolecular Hydrogels: From Crystalline Fibrillar to Amorphous Micellar
           Networks
    • Authors: Aoli Wu; Xinpei Gao, Panpan Sun, Fei Lu, Liqiang Zheng
      Abstract: Gelation mechanism is of utmost importance to the rational design of supramolecular hydrogelators. Although both kinetic and thermodynamic controlling self-assembly processes have been widely studied in hydrogels, the evolution relationship between crystalline and amorphous gel networks still remains ambiguous. Herein, a gelation transformation from kinetic to thermodynamic process was achieved by balancing the rigidity and flexibility of the inorganic-organic co-assemblies. And for the first time, the transition morphologies between crystalline and amorphous hydrogel networks were evidenced as ordered wormlike micelles. Given the versatile applications of hydrogels in biological systems and material science, we expect our findings may highlight the potential of inorganic-organic binary supramolecular hydrogelators and fill in the blank between kinetic and thermodynamic controlling gelation processes.
      PubDate: 2018-02-15T05:35:28.975243-05:
      DOI: 10.1002/ange.201800939
       
  • Ein auf Sulfoxid basierendes, isobares Derivatisierungsreagens für die
           präzise quantitative Massenspektrometrie
    • Authors: Michael Stadlmeier; Jana Bogena, Miriam Wallner, Martin Wühr, Thomas Carell
      Abstract: Die moderne Proteomik erfordert Reagentien für eine akkurate Quantifizierung von Peptiden in komplexen Proben. Peptide werden üblicherweise mit isobaren Markierungen versehen, die aus einem Massenausgleicher und einem Reporter bestehen, die in der Gasphase gespalten werden. Eine geschickte Verteilung der stabilen Isotope liefert mehrere Reagentien mit identischem Molekulargewicht, jedoch mit einer abweichenden Masse der Reportergruppen, was die relative Quantifizierung mehrerer Proben in einer einzigen Messung ermöglicht. Hier wird ein neues isobares Derivatisierungsreagens vorgestellt, in dem der Massenausgleicher und der Reporter über eine Sulfoxidgruppe verbunden sind, was auf Basis einer Sulfoxidpyrolyse zu einer einfachen und asymmetrischen Spaltung bei niedriger Energie führt. Das neue Reagensdesign zeigt eine signifikante Verbesserung der Spaltung, was zu intensiveren Signalen der komplementären Ionen führt und somit auch die Analyse der Komplementärionen-Cluster ermöglicht.Ein neuer Tag bricht an: Ein neues Reagens (SulfOxide Tag) für die quantitative Proteomik wurde entwickelt, das einfacher fragmentiert wird und dadurch zu höheren Reporter- und Komplementärionen-Intensitäten führt.
      PubDate: 2018-02-15T05:00:56.045293-05:
      DOI: 10.1002/ange.201708867
       
  • Synergistic Photoredox and Organocatalysis for Inverse Hydroboration of
           Imines
    • Authors: Jin Xie
      Abstract: The first catalytic inverse hydroboration of imines with N-heterocyclic carbene boranes has been realized by means of cooperative organocatalysis and photocatalysis. This catalytic combination brings a promising platform to promote NHC-boryl radical chemistry under sustainable and radical initiator free conditions. The highly important functional group compatibility and possible application in late-stage hydroboration represent an important step-forward to an enhanced -amino organoboron lead library.
      PubDate: 2018-02-15T04:35:40.122291-05:
      DOI: 10.1002/ange.201800421
       
  • Stereodivergent Evolution of Artificial Enzymes for the Michael Reaction
    • Authors: Xavier Garrabou Pi; Duncan Stuart Macdonald, Basile I. M. Wicky, Donald Hilvert
      Abstract: Enzymes are valuable biocatalysts for asymmetric synthesis due to their exacting stereocontrol. Changing the selectivity of an existing catalyst for new applications is, however, challenging. Here we show that, in contrast, the stereoselectivity of an artificial enzyme created by design and directed evolution is readily tunable. We engineered a promiscuous artificial retro-aldolase into four stereocomplementary catalysts for the Michael addition of a tertiary carbanion to an unsaturated ketone. Notably, this selectivity is also preserved with alternative Michael nucleophiles. Complete stereodiversification of other designer enzymes should similarly be possible by extension of these approaches.
      PubDate: 2018-02-15T03:35:22.965779-05:
      DOI: 10.1002/ange.201712554
       
  • Stabilizing and Organizing Bi3Cu4 and Bi7Cu12 Nanoclusters in
           Two-Dimensional Metal-Organic Networks
    • Authors: Linghao Yan; Bowen Xia, Qiushi Zhang, Guowen Kuang, Hu Xu, Jun Liu, Pei Nian Liu, Nian Lin
      Abstract: Multinuclear heterometallic nanoclusters with controllable stoichiometry and structure are anticipated to possess promising catalytic, magnetic, and optical properties. Here we demonstrate that heterometallic nanoclusters with precise stoichiometry of Bi3Cu4 and Bi7Cu12 can be stabilized in the scaffold of two-dimensional metal-organic networks on a Cu(111) surface through on-surface metallosupramolecular self-assembly processes. The atomic structures of the nanoclusters were resolved using scanning tunnelling microscopy and density functional theory calculations. The nanoclusters feature highly symmetric planar hexagonal shapes and core-shell charge modulation. The clusters are arranged as triangular lattices with a periodicity that can be tuned by choosing molecules of different size. This work shows that on-surface metallosupramolecular self-assembly creates unique possibilities for the design and synthesis of multinuclear heterometallic nanoclusters.
      PubDate: 2018-02-15T03:11:10.490842-05:
      DOI: 10.1002/ange.201800906
       
  • Rh-Catalyzed Arylation of Cyclopropenes Based on Asymmetric Directed
           Functionalization of Three-Membered Carbocycles
    • Authors: Ilan Marek; Longyang Dian
      Abstract: A large variety of highly diastereo- and enantiomerically enriched arylcyclopropanes is obtained through the asymmetric Rh-catalyzed arylation reaction of achiral non-functionalized cyclopropene derivatives with commercially available aryl boronic acids and (R,S)-Josiphos
      PubDate: 2018-02-15T03:10:45.846289-05:
      DOI: 10.1002/ange.201713324
       
  • Entropy-Driven Diastereoselectivity Improvement in the Paternò-Büchi
           Reaction of 1-Naphthylarylethenes with Chiral Cyanobenzoate through Remote
           Alkylation
    • Authors: Keisuke Nagasaki; Yoshihisa Inoue, Tadashi Mori
      Abstract: Precisely stereocontrolling photocycloaddition is still a significant challenge, due to mechanistic complexity and highly reactive and short-lived nature of intermediates. Attempts have hitherto been made through structural modifications, mostly by introducing steric conflicts, to increase difference in enthalpic barrier. Here, we show that entropy plays a crucial role in manipulating diastereoselectivity of Paternò-Büchi reaction. A remote meta-alkylation of donor caused nominal changes in photophysical properties as well as exciplexes derived therefrom. Nevertheless, diastereomeric excess of oxetane produced was greatly improved by ca. 40%. This enhancement without accompanying any significant photophysical property changes is difficult to rationalize by conventional enthalpic control concept based on repulsive steric and/or attractive intermolecular interactions as well as electronic perturbations. Differential activation parameters and compensatory enthalpy-entropy relationship revealed that the diastereoselectivity enhancement is not simply enthalpic but also entropic in origin.
      PubDate: 2018-02-14T21:41:17.186672-05:
      DOI: 10.1002/ange.201801330
       
  • The Solution of the Puzzle of Smectic-Q: The Phase Structure and the
           Origin of Spontaneous Chirality
    • Authors: Huanjun Lu; Xiangbing Zeng, Goran Ungar, Christian Dressel, Carsten Tschierske
      Abstract: Flüssigkristalle existieren in diversen Strukturen, die viele Möglichkeiten für nanotechnologische Anwendungen bieten. Die Struktur einer bestimmten flüssigkristallinen Phase, der Smektisch-Q-Phase, konnte allerdings über 35 Jahre nicht aufgeklärt werden. Jetzt ist es soweit: X. B. Zeng, G. Ungar, C. Tschierske et al. beschreiben in ihrer Zuschrift (
      DOI : 10.1002/ange.201712812) die verwirrende Anordnung orthogonaler helikaler Säulen, die nicht aus chiralen Molekülen aufgebaut ist und doch homochiral.
      PubDate: 2018-02-14T08:45:47.758373-05:
       
  • Identification of Tumor Initiating Cells with a Small-Molecule Fluorescent
           Probe by Using Vimentin as a Biomarker
    • Authors: Yong-An Lee; Jong-Jin Kim, Jungyeol Lee, Jia Hui Jane Lee, Srikanta Sahu, Haw-Young Kwon, Sung-Jin Park, Se-Young Jang, Jun-Seok Lee, Zhenxun Wang, Wai Leong Tam, Bing Lim, Nam-Young Kang, Young-Tae Chang
      Abstract: Tumor initiating cells (TICs) have been implicated in clinical relapse and metastasis of a variety of epithelial cancers, including lung cancer. While efforts toward the development of specific probes for TIC detection and targeting are ongoing, a universal TIC probe has yet to be developed. We report the first TIC-specific fluorescent chemical probe, TiY, with identification of the molecular target as vimentin, a marker for epithelial-to-mesenchymal transition (EMT). TiY selectively stains TICs over differentiated tumor cells or normal cells, and facilitates the visualization and enrichment of functionally active TICs from patient tumors. At high concentration, TiY also shows anti-TIC activity with low toxicity to non-TICs. With the unexplored target vimentin, TiY shows potential as a first universal probe for TIC detection in different cancers.Eine selektive Sonde für Tumor-initiierende Zellen (TICs) – TiY – nutzt Vimentin als Zielmolekül. TiY erleichtert die Verfolgung und Anreicherung funktionsfähiger TICs aus Tumoren von Patienten und allen anderen untersuchten Krebszelllinien. In hohen Konzentrationen war TiY auch gegen TICs wirksam.
      PubDate: 2018-02-14T08:21:17.6794-05:00
      DOI: 10.1002/ange.201712920
       
  • CO2-ausgelöste schaltbare Hydrophilie von heterogen konjugierten
           Polymerphotokatalysatoren für verbesserte katalytische Aktivität in
           Wasser
    • Authors: Jeehye Byun; Wei Huang, Di Wang, Run Li, Kai A. I. Zhang
      Abstract: Zahlreiche aktuelle Studien befassen sich mit wasserlöslichen, heterogenen Photokatalysatoren für Energie- und Umweltanwendungen. Ein Problem dieser Systeme ist jedoch, dass normalerweise ein Kompromiss zwischen der Hydrophilie und der Wiederverwendbarkeit der Photokatalysatoren eingegangen werden muss. In dieser Studie stellen wir konjugierte Polymerphotokatalysatoren mit tertiären terminalen Aminen vor, die reversibel CO2 binden und somit eine veränderbare Hydrophilie aufweisen können. Die durch die CO2-Bindung ausgelöste Hydrophilie verstärkt die photokatalytische Effizienz des Polymerphotokatalysators in wässrigen Lösungen. Wird CO2 desorbiert, kann der Photokatalysator unter einfachsten Bedingungen aus dem Reaktionsmedium regeneriert werden, wodurch der Katalysator wiederverwendbar wird. Die Kontrolle über die hydrophilen/hydrophoben Eigenschaften des Katalysators wurde anhand verschiedener organischer Photoredox-Reaktionen, die durch Bestrahlung mit sichtbarem Licht ausgelöst werden, in wässrigem Medium demonstriert.An/Aus-Hydrophilie des Photokatalysators: Die Hydrophilie eines konjugierten Polymerphotokatalysators mit tertiären Aminseitengruppen kann durch einfachen CO2/N2-Austausch geschaltet werden. Diese Hydrophilieumschaltung ermöglicht eine Verbesserung der katalytischen Effizienz und Wiederverwendbarkeit des heterogenen Polymerphotokatalysators in organischen Photoredox-Reaktionen in Wasser.
      PubDate: 2018-02-14T08:16:18.548389-05:
      DOI: 10.1002/ange.201711773
       
  • Nucleophile Promiscuity of Engineered Class II Pyruvate Aldolase
           YfaU from E. Coli
    • Authors: Karel Hernández; Jesús Joglar, Jordi Bujons, Teodor Parella, Pere Clapés
      Abstract: Pyruvate-dependent aldolases exhibit a stringent selectivity for pyruvate, limiting application of their synthetic potential, which is a drawback shared with other existing aldolases. Structure-guided rational protein engineering rendered a 2-keto-3-deoxy-l-rhamnonate aldolase variant, fused with a maltose-binding protein (MBP-YfaU W23V/L216A), capable of efficiently converting larger pyruvate analogues, for example, those with linear and branched aliphatic chains, in aldol addition reactions. Combination of these nucleophiles with N-Cbz-alaninal (Cbz=benzyloxycarbonyl) and N-Cbz-prolinal electrophiles gave access to chiral building blocks, for example, derivatives of (2S,3S,4R)-4-amino-3-hydroxy-2-methylpentanoic acid (68 %, d.r. 90:10) and the enantiomer of dolaproine (33 %, d.r. 94:6) as well as a collection of unprecedented α-amino acid derivatives of the proline and pyrrolizidine type. Conversions varied between 6–93 % and diastereomeric ratios from 50:50 to 95:5 depending on the nucleophilic and electrophilic components.Leichte Vielfalt: Strukturgeleitete rationale Proteinveränderungen resultierten in einer Fusion aus 2-Keto-3-deoxy-l-rhamnonat-Aldolase-Variante und Maltose-bindendem Protein (MBP-YfaU W23V/L216A), die chirale Bausteine sowie eine Reihe beispielloser Prolin- und Pyrrolizidin-α-Aminosäurederivate liefern kann.
      PubDate: 2018-02-14T08:15:39.746438-05:
      DOI: 10.1002/ange.201711289
       
  • Übergangsmetall-katalysierte selektive Funktionalisierung von
           C(sp3)-H-Bindungen in Naturstoffen
    • Authors: Rashad R. Karimov; John F. Hartwig
      Abstract: Die direkte Funktionalisierung von Naturstoffen ist wichtig für die Untersuchung von Struktur-Aktivitäts- und Struktur-Eigenschafts-Beziehungen dieser Moleküle. Jüngste Fortschritte bei Übergangsmetall-katalysierten Funktionalisierungen von C(sp3)-H-Bindungen, den zwar häufigsten, aber inerten Bindungen in Naturstoffen, haben gezeigt, dass selektiv Derivate dieser Naturstoffe hergestellt werden können. Strategien, um eine solche Transformation zu realisieren, werden diskutiert.Direkt derivatisiert: Die direkte Funktionalisierung von Naturstoffen ist wichtig zum Studium ihrer Struktur-Aktivitäts- und Struktur-Eigenschafts-Beziehungen. Aktuelle Fortschritte bei Übergangsmetall-katalysierten Funktionalisierungen von C(sp3)-H-Bindungen haben gezeigt, dass sich selektiv Derivate dieser Naturstoffe synthetisieren lassen. Dieser Kurzaufsatz erörtert Strategien für die Realisierung einer solchen Transformation.
      PubDate: 2018-02-14T08:10:31.210878-05:
      DOI: 10.1002/ange.201710330
       
  • Me3Si−SiMe2[o-CON(i-Pr)2-C6H4]: A New Unsymmetrical Disilane Reagent for
           Regio- and Stereoselective Bis-silylation of Alkynes
    • Authors: Zhen Lei Song; Peihong Xiao, Yanjun Cao, Yingying Gui, Lu Gao
      Abstract: The air-stable unsymmetrical disilane Me3Si−SiMe2[o-CON(i-Pr)2C6H4] has been developed for bis-silylation of alkynes. This reagent tolerates a range of functional groups, providing Z-vinyl disilanes in high yields. The phenyl ring-tethered amide group is proposed to direct oxidative addition of Pd(0) into the Si-Si bond, that might facilitate formation of a six-membered Pd cycle, leading to the observed good to excellent regioselectivity.
      PubDate: 2018-02-14T07:41:21.683102-05:
      DOI: 10.1002/ange.201800513
       
  • Synthesis of Sub-2 nm Fe-Doped NiSe2 Nanowires and Their Surface Confined
           Oxidation for Oxygen Evolution Catalysis
    • Authors: Shu-Hong Yu; Chao Gu, Shaojin Hu, Xusheng Zheng, Min-Rui Gao, Ya-Rong Zheng, Lei Shi, Qiang Gao, Xiao Zheng, Wangsheng Chu, Hong-Bin Yao, Junfa Zhu
      Abstract: Ultrathin nanostructures are attractive for diverse applications owing to their unique properties compared to their bulks. Transition metal chalcogenides are promising electrocatalysts, yet there remains difficult to make ultrathin structures (sub-2 nm), and the realization of their chemical doping is even more challenging. Here we describe a soft template mediated colloidal synthesis of Fe-doped NiSe2 ultrathin nanowires (UNWs) with diameter down to 1.7 nm. The synergistic interplay between oleylamine and 1-dodecanethiol is crucial to yield these UNWs. The in-situ formed amorphous hydroxide layers that confined on the surface of the ultrathin scaffolds enable efficient oxygen evolution electrocatalysis. The resultant UNW derivatives exhibit a very low overpotential of 268 mV at 10 mA cm-2 in 0.1 M KOH, as well as remarkable long-term stability, representing one of the most efficient noble-metal-free catalysts.
      PubDate: 2018-02-14T07:41:01.694552-05:
      DOI: 10.1002/ange.201800883
       
  • Electrolyte additives for lithium metal anodes and rechargeable lithium
           metal batteries: progresses and perspectives
    • Authors: Heng Zhang; Gebrekidan Gebresilassie Eshetu, Xabier Judez, Chunmei Li, Lide M. Rodriguez-Martínez, Michel Armand
      Abstract: Lithium metal (Li°) - based rechargeable batteries (LMBs), such as Li° anode vs. intercalation and/or conversion type cathode batteries, lithium-sulphur (Li-S), and lithium-oxygen (O2)/air (Li-O2/air) are becoming increasingly important for electrifying the modern transportation system, enabling sustainable mobility in the near future. Though some rechargeable LMBs batteries (e.g., Li°/LiFePO4 batteries from Bolloré Bluecar®, Li-S batteries from OXIS Energy and Sion Power) are already commercially viable in niche applications, their large-scale deployment is still hampered due to the existence of a number of formidable challenges, including lithium dendrite growth, electrolyte instability towards high voltage intercalation type cathode, poor electronic and ionic conductivities of sulphur (S8) and O2, as well as their corresponding reduction products (e.g., Li2S and Li2O), dissolution and shuttling of polysulphide (PS) intermediates etc. This ultimately results in short cycle life, low coulombic/energy efficiency, poor safety, and a high self-discharge rate. Among other mitigating strategies, the use of electrolyte additives is considered as one of the most economical, and effective approach for circumventing these dilemmas. Set out to offer an in-depth insight into the rapidly growing research on the account of electrolyte additives for rechargeable LMBs, this review presents an overview of the various functional additives, that are being applied in Li-anode/intercalation cathode-based, Li-S and Li-O2 batteries. This review is believed to assess the status quo of the research and thereby arouse new thoughts and opportunities, opening new avenues for the practical realization of these appealing devices.
      PubDate: 2018-02-14T07:12:16.976516-05:
      DOI: 10.1002/ange.201712702
       
  • A Benzene-1,3,5-Triaminyl Radical Fused with Zn(II)-Porphyrins: Remarkable
           Stability and High Spin Quartet Ground State
    • Authors: Atsuhiro Osuka; Daiki Shimizu
      Abstract: A benzene-1,3,5-triaminyl radical fused with three Zn(II)-porphyrins was synthesized via a three-fold oxidative fusion reaction of 1,3,5-tris(Zn(II)-porphyrinylamino)benzene followed by oxidation with PbO2 as key steps. This triaminyl radical has been proved to possess a quartet ground state with a doublet-quartet energy gap of 3.1 kJ/mol by SQUID studies. Despite the high-spin nature, this triradical is remarkably stable, allowing for its separation and recrystallization under ambient conditions. Moreover, this triradical can be stored as solids more than one year without serious deterioration. The high stability of the triradical has been attributed to effective spin delocalization over the porphyrin segments and steric protection at the nitrogen centers and the porphyrin meso-positions.
      PubDate: 2018-02-14T07:11:36.690978-05:
      DOI: 10.1002/ange.201801080
       
  • Rhodium(I)-Catalyzed Cycloisomerization of Homopropargylallene-Alkynes
           through C(sp3)−C(sp) Bond Activation
    • Authors: Yasuaki Kawaguchi; Kenya Yabushita, Chisato Mukai
      Abstract: Upon exposure to a catalytic amount of [RhCl(CO)2]2 in 1,4-dioxane, homopropargylallene-alkynes underwent a novel cycloisomerization accompanied by the migration of the alkyne moiety of the homopropargyl functional group to produce six/five/five tricyclic compounds in good yields. A plausible mechanism was proposed on the basis of an experiment with 13C-labeled substrate. The resulting tricyclic derivatives were further converted into the corresponding bicyclo[3.3.0] skeletons with vicinal cis dihydroxy groups.In Gegenwart von [RhCl(CO)2]2 reagieren Homopropargylallen-substituierte Alkine über C(sp3)-C(sp)-Bindungsspaltung und Migration zu tricyclischen Gerüsten mit einer Trien-Einheit. Deren Oxidation ergibt benachbarte cis-Diole in einer stereo- und regioselektiven Reaktion.
      PubDate: 2018-02-14T05:56:46.935013-05:
      DOI: 10.1002/ange.201713096
       
  • Densely Packed, Ultra Small SnO Nanoparticles for Enhanced Activity and
           Selectivity in Electrochemical CO2 Reduction
    • Authors: Jun Gu; Florent Héroguel, Jeremy Luterbacher, Xile Hu
      Abstract: Controlling the selectivity in electrochemical CO2 reduction is an unsolved challenge. While tin (Sn) has emerged as a promising non-precious catalyst for CO2 electroreduction, most Sn-based catalysts produce formate as the major product, which is less desirable than CO in terms of separation and further use. Tin monoxide (SnO) nanoparticles supported on carbon black were synthesized and assembled and their application in CO2 reduction was studied. Remarkably high selectivity and partial current densities for CO formation were obtained using these SnO nanoparticles compared to other Sn catalysts. The high activity is attributed to the ultra-small size of the nanoparticles (2.6 nm), while the high selectivity is attributed to a local pH effect arising from the dense packing of nanoparticles in the conductive carbon black matrix.Zinnmonoxid-Nanopartikel (SnO-NPs) auf einem Kohlenstoffträger wurden zur Reduktion von CO2 verwendet, wo sie im Vergleich zu anderen Zinnkatalysatoren hohe Partialstromdichten für die CO-Bildung ergaben. Die hohe Aktivität wird mit der geringen Größe der Nanopartikel (2.6 nm) erklärt, die hohe Selektivität mit einem pH-Effekt der dichten NP-Packung auf dem leitfähigen Kohlenstoffsubstrat.
      PubDate: 2018-02-14T05:41:43.436893-05:
      DOI: 10.1002/ange.201713003
       
  • Dynamic Interconversion between Boroxine Cages Based on Pyridine Ligation
    • Authors: Kosuke Ono; Shunsuke Shimo, Kohei Takahashi, Nobuhiro Yasuda, Hidehiro Uekusa, Nobuharu Iwasawa
      Abstract: Dynamic interconversion between large covalent organic cages was achieved simply by heating or acid/base treatment. A mixture of the boroxine cages 12-mer and 15-mer was cleanly converted into a pyridine adduct of the 9-mer boroxine cage upon treatment with pyridine, and the geometry of N-coordinated boron atoms changed from trigonal to tetrahedral. The reverse reaction was achieved by heating or acid treatment. In this process, the larger boroxine cages 12-mer and 15-mer were found to be entropically favored owing to the release of free pyridine molecules from 9-mer⋅6 Py.Eine Mischung aus den Boroxin-Käfigverbindungen 12-mer und 15-mer wurde mit Pyridin sauber in ein Pyridin-Addukt des Boroxin-Käfigs 9-mer überführt. Die Rückreaktion gelang durch Erwärmen oder Behandlung mit Säure. Die Bildung der größeren Boroxin-Käfige 12-mer und 15-mer ist aufgrund der Freisetzung von Pyridin-Molekülen aus 9-mer⋅6 Py entropisch begünstigt.
      PubDate: 2018-02-14T05:41:26.712195-05:
      DOI: 10.1002/ange.201713221
       
  • The [U2F12]2− Anion of Sr[U2F12]
    • Authors: Benjamin Scheibe; Clemens Pietzonka, Otto Mustonen, Maarit Karppinen, Antti J. Karttunen, Mihail Atanasov, Frank Neese, Matthias Conrad, Florian Kraus
      Abstract: The D2h-symmetric dinuclear complex anion [U2F12]2− of pastel green Sr[U2F12] shows a hitherto unknown structural feature: The coordination polyhedra around the U atoms are edge-linked monocapped trigonal prisms, the UV atoms are therefore seven-coordinated. This leads to a U–U distance of 3.8913(6) Å. A weak UV–UV interaction is observed for the dinuclear [U2F12]2− complex and described by the antiferromagnetic exchange Jexp of circa −29.9 cm−1. The crystalline compound can be easily prepared from SrF2 and β-UF5 in anhydrous hydrogen fluoride (aHF) at room temperature. It was studied by means of single crystal X-ray diffraction, IR, Raman and UV/VIS spectroscopy, magnetic measurements, and by molecular as well as by solid-state quantum chemical calculations.Ein zweikerniges Fluoridouranat(V) – das D2h-symmetrische [U2F12]2−-Anion – ist ein beispielloses Merkmal des neu synthetisierten Sr[U2F12]. Die spektroskopischen und magnetischen Eigenschaften des Produkts wurden in quantenchemischen Rechnungen reproduziert. Eine antiferromagnetische Kopplung der UV-Atome wird beobachtet.
      PubDate: 2018-02-14T05:40:43.431915-05:
      DOI: 10.1002/ange.201800743
       
  • Monitoring Dissociation Kinetics during Electrophoretic Focusing to Enable
           High-Specificity Nucleic Acid Detection
    • Authors: Tal Zeidman Kalman; Rebecca Khalandovsky, Elena Tenenbaum Gonikman, Moran Bercovici
      Abstract: A wide range of medical conditions can be diagnosed through sequence-specific analysis of nucleic acids. However, a major challenge remains in detecting a specific target in samples containing a high concentration of mismatching sequences. A single-step kinetic homogenous (free solution) assay is presented in which free sequence-specific probes are continuously separated from probe–target hybrids during electrophoretic sample focusing, allowing monitoring of dissociation kinetics. Under these conditions, the different kinetics of targets versus mismatches result in distinct patterns of the signal (for example, linear increase for target versus exponential decay for mismatch), allowing the detection of desired sequences even in the presence of high background nucleic acid content. Additionally, an analytical model provides insight into the underlying dynamics, and allows design of assays based on this mechanism.In einem Schritt und in homogener Lösung arbeitet ein Assay, das im Zuge einer elektrophoretischen Probenfokussierung freie sequenzspezifische Sonden kontinuierlich von Sonde-Analyt-Hybriden trennt. Die Methode kann gewünschte Sequenzen auch in Proben mit einem hohen Gehalt an anderen Nukleinsäuren nachweisen.
      PubDate: 2018-02-14T05:36:20.856479-05:
      DOI: 10.1002/ange.201711673
       
  • Cocrystals Strategy towards Novel Materials for Near-infrared Photothermal
           Conversion and Imaging
    • Authors: Wenping Hu; Yu Wang, Weigang Zhu, Wenna Du, Xinfeng Liu, Xiaotao Zhang, Huanli Dong
      Abstract: Herein, a cocrystal strategy with simple preparation process is developed to fabricate novel materials for Near-infrared photothermal (PT) conversion and imaging. Dibenzotetrathiafulvalene (DBTTF) and tetracyanobenzene (TCNB) are selected as electron-donor and electron-acceptor, which self-assemble into new cocrystals through non-covalent interactions. The strong interaction between the donors and acceptors leads to a narrow bandgap with near-infrared (NIR) absorption and that both the ground state and lowest-lying excited state are CT state. Remarkably, under the illumination of 808 nm laser (0.7 W/cm2), the temperature of cocrystal is sharply increased and reaches as high as 66.1 °C within 5 minutes. As a contrast, without cocrystals the sample rises only 3 °C, hence, the cocrystal demonstrates high performance PT conversion efficiency (η = 18.8%).
      PubDate: 2018-02-14T05:35:34.282185-05:
      DOI: 10.1002/ange.201712949
       
  • Shape-Tunable Colloids from Structured Liquid Droplet Templates
    • Authors: Bing Liu; Zhang Luo
      Abstract: Shaping colloidal building units is paramount important for their self-assembly to complex objects. Continuous tuning of colloidal shapes is highly desired for understanding self-assembly, but it still remains a challenge. Here we report a new templated strategy for shape-tunable synthesis of anisotropic colloids with shapes continuously tuned from discoids (oblate spheroids) to spheres to theta shapes to dumbbells. This is realized by creating structured shape-tunable droplets with patchy colloidal discs and followed by using the droplets as templates. In particular, we find a controlled dumbbell-to-eyeball droplet transformation that can be used for the synthesis of eyeball-shaped colloids. We demonstrate the droplets transformation pathways and extend the method to synthesize colloidal molecules. These colloids provide possibilities for exploring their ordered packing structures and the method based on structured droplets can be adapted for the synthesis of other functional colloidal particles.
      PubDate: 2018-02-14T05:35:31.023221-05:
      DOI: 10.1002/ange.201800587
       
  • Precisely Tailoring Upconversion Dynamics via Energy Migration in
           Core–Shell Nanostructures
    • Authors: Jing Zuo; Dapeng Sun, Langping Tu, Yanni Wu, Yinghui Cao, Bin Xue, Youlin Zhang, Yulei Chang, Xiaomin Liu, Xianggui Kong, Wybren Jan Buma, Evert Jan Meijer, Hong Zhang
      Abstract: Upconversion emission dynamics have long been believed to be determined by the activator and its interaction with neighboring sensitizers. Herein this assumption is, however, shown to be invalid for nanostructures. We demonstrate that excitation energy migration greatly affects upconversion emission dynamics. “Dopant ions’ spatial separation” nanostructures are designed as model systems and the intimate link between the random nature of energy migration and upconversion emission time behavior is unraveled by theoretical modelling and confirmed spectroscopically. Based on this new fundamental insight, we have successfully realized fine control of upconversion emission time behavior (either rise or decay process) by tuning the energy migration paths in various specifically designed nanostructures. This result is significant for applications of this type of materials in super resolution spectroscopy, high-density data storage, anti-counterfeiting, and biological imaging.Der Weg nach oben: Eine aufwärtskonvertierte Emission mit maßgeschneiderter Dynamik beruht auf der Kontrolle über die Energieverlagerungspfade in Kern-Schale-Nanostrukturen. Dies setzt Strukturen voraus, in denen die dotierenden Ionen räumlich voneinander getrennt sind.
      PubDate: 2018-02-14T05:32:14.996018-05:
      DOI: 10.1002/ange.201711606
       
  • Functional Hydride Transfer by a Thiolate-Containing Model of Mono-Iron
           Hydrogenase featuring an Anthracene Scaffold
    • Authors: Spencer A. Kerns; Anne-Clarisse Magtaan, Pisey R. Vong, Michael J. Rose
      Abstract: We report the synthesis, X-ray structure and functional biomimetic activity of a model complex of mono-iron hydrogenase (Hmd). To achieve the desired biomimetic fac-CNS(thiolate) ligation motif, an anthracene framework is used to provide the requisite donors in a single chelate. A bulky aryl thiolate (ortho dimethylphenyl) is included to achieve mononuclearity. In addition to exhibiting structural (X-ray) and spectroscopic (NMR, IR) similarity to the enzyme, the complex is competent for H2 activation (heterolysis) and hydride transfer to a model substrate—mimicking the functional behavior of the enzyme in a biomimetic CNS coordination sphere for the first time.Spiegelbildliche Aktivität: Ein synthetisches Modell des Enzyms Monoeisenhydrogenase mit „Anthracen-Gerüst” katalysiert die biomimetische H2-Aktivierung und den Hydridtransfer auf ein Modellsubstrat. Der Modellkomplex imitiert dabei eine Enzymfunktion in einer biomimetischen CNS-Koordinationssphäre.
      PubDate: 2018-02-14T05:25:56.017171-05:
      DOI: 10.1002/ange.201712948
       
  • Rapid and Efficient Generation of Stable Antibody–Drug Conjugates via an
           Encoded Cyclopropene and an Inverse-Electron-Demand Diels–Alder Reaction
           
    • Authors: Benjamí Oller-Salvia; Gene Kym, Jason W. Chin
      Abstract: Homogeneous antibody–drug conjugates (ADCs), generated by site-specific toxin linkage, show improved therapeutic indices with respect to traditional ADCs. However, current methods to produce site-specific conjugates suffer from low protein expression, slow reaction kinetics, and low yields, or are limited to particular conjugation sites. Here we describe high yielding expression systems that efficiently incorporate a cyclopropene derivative of lysine (CypK) into antibodies through genetic-code expansion. We express trastuzumab bearing CypK and conjugate tetrazine derivatives to the antibody. We show that the dihydropyridazine linkage resulting from the conjugation reaction is stable in serum, and generate an ADC bearing monomethyl auristatin E that selectively kills cells expressing a high level of HER2. Our results demonstrate that CypK is a minimal bioorthogonal handle for the rapid production of stable therapeutic protein conjugates.Ein Cyclopropen-Derivat von Lysin, CypK, kann durch Erweiterung des genetischen Codes effizient in Antikörper eingebaut werden. Konjugation von CypK an Moleküle mit Tetrazin-Motiv ergibt eine in Serum stabile Vernetzung. Monomethyl-Auristatin E kann mit diesem Verfahren an Trastuzumab gebunden werden, um ein Antikörper-Wirkstoff-Konjugat aufzubauen, das selektiv gegen Zellen mit hohem HER2-Spiegel wirkt.
      PubDate: 2018-02-14T05:25:34.724287-05:
      DOI: 10.1002/ange.201712370
       
  • A Diazido Mannose Analogue as a Chemoenzymatic Synthon for Synthesizing
           Di-N-acetyllegionaminic Acid-Containing Glycosides
    • Authors: Abhishek Santra; An Xiao, Hai Yu, Wanqing Li, Yanhong Li, Linh Ngo, John B. McArthur, Xi Chen
      Abstract: A chemoenzymatic synthon was designed to expand the scope of the chemoenzymatic synthesis of carbohydrates. The synthon was enzymatically converted into carbohydrate analogues, which were readily derivatized chemically to produce the desired targets. The strategy is demonstrated for the synthesis of glycosides containing 7,9-di-N-acetyllegionaminic acid (Leg5,7Ac2), a bacterial nonulosonic acid (NulO) analogue of sialic acid. A versatile library of α2-3/6-linked Leg5,7Ac2-glycosides was built by using chemically synthesized 2,4-diazido-2,4,6-trideoxymannose as a chemoenzymatic synthon for highly efficient one-pot multienzyme (OPME) sialylation followed by downstream chemical conversion of the azido groups into acetamido groups. The syntheses required 10 steps from commercially available d-fucose and had an overall yield of 34–52 %, thus representing a significant improvement over previous methods. Free Leg5,7Ac2 monosaccharide was also synthesized by a sialic acid aldolase-catalyzed reaction.Eine Bibliothek biologisch wichtiger α2-3/6-verknüpfter Leg5,7NAc2-haltiger Glykoside wurde ausgehend von chemisch synthetisiertem 6deoxyMan2,4diN3 als chemoenzymatischem Synthon mithilfe von Eintopf-Multienzym-Sialylierungssystemen und anschließender chemischer Umwandlung der Azido- in Acetamidogruppen aufgebaut (siehe Schema). In diesem hoch effizienten chemoenzymatischen Prozess sind kommerziell erhältliche Enzyme einsetzbar.
      PubDate: 2018-02-14T05:25:27.769875-05:
      DOI: 10.1002/ange.201712022
       
  • Ice Melting to Release Reactants in Solution Syntheses
    • Authors: Hehe Wei; Kai Huang, Le Zhang, Binghui Ge, Dong Wang, Jialiang Lang, Jingyuan Ma, Da Wang, Shuai Zhang, Qunyang Li, Ruoyu Zhang, Naveed Hussain, Ming Lei, Li-Min Liu, Hui Wu
      Abstract: Aqueous solution syntheses are mostly based on mixing two solutions with different reactants. It is shown that freezing one solution and melting it in another solution provides a new interesting strategy to mix chemicals and to significantly change the reaction kinetics and thermodynamics. For example, a precursor solution containing a certain concentration of AgNO3 was frozen and dropped into a reductive NaBH4 solution at about 0 °C. The ultra-slow release of reactants was successfully achieved. An ice-melting process can be used to synthesize atomically dispersed metals, including cobalt, nickel, copper, rhodium, ruthenium, palladium, silver, osmium, iridium, platinum, and gold, which can be easily extended to other solution syntheses (such as precipitation, hydrolysis, and displacement reactions) and provide a generalized method to redesign the interphase reaction kinetics and ion diffusion in wet chemistry.Eine Lösung einfrieren und in einer anderen wieder auftauen bildet eine Strategie zur Mischung von Chemikalien, wodurch kinetische und thermodynamische Reaktionseigenschaften modifiziert werden können. Einfrieren einer AgNO3-Lösung und Zugabe zu einer NaBH4-Lösung bei ungefähr 0 °C lieferte beispielsweise dispergierte Metallatome. Die Methode kann aber auch auf Fällungsvorgänge, Hydrolysen und Austauschreaktionen angewendet werden.
      PubDate: 2018-02-14T05:21:01.939182-05:
      DOI: 10.1002/ange.201711128
       
  • Total Synthesis and Conformational Study of Callyaerin A:
           Anti-Tubercular Cyclic Peptide Bearing a Rare Rigidifying (Z)-2,3-
           Diaminoacrylamide Moiety
    • Authors: Shengping Zhang; Luis M. De Leon Rodriguez, Ivanhoe K. H. Leung, Gregory M. Cook, Paul W. R. Harris, Margaret A. Brimble
      Abstract: The first synthesis of the anti-TB cyclic peptide callyaerin A (1), containing a rare (Z)-2,3-diaminoacrylamide bridging motif, is reported. Fmoc-formylglycine-diethylacetal was used as a masked equivalent of formylglycine in the synthesis of the linear precursor to 1. Intramolecular cyclization between the formylglycine residue and the N-terminal amine in the linear peptide precursor afforded the macrocyclic natural product 1. Synthetic 1 possessed potent anti-TB activity (MIC100=32 μm) while its all-amide congener was inactive. Variable-temperature NMR studies of both the natural product and its all-amide analogue revealed the extraordinary rigidity imposed by this diaminoacrylamide unit on peptide conformation. The work reported herein pinpoints the intrinsic role that the (Z)-2,3-diaminoacrylamide moiety confers on peptide bioactivity.Starre Struktur: Callyaerin A, ein makrocyclisches Anti-Tuberkulose-Peptid mit seltener (Z)-2,3-Diaminoacrylamid-Einheit, wurde in hoher Ausbeute aus einem ungewöhnlichen Baustein – Fmoc-Formylglycindiethylacetal – synthetisiert. VT-NMR-Studien zufolge überträgt das (Z)-2,3-Diaminoacrylamid eine hohe konformative Rigidität auf die Peptidstruktur; es zeigt damit großes Potenzial als neuartiges Strukturelement zur konformativen Einschränkung.
      PubDate: 2018-02-14T05:20:33.770399-05:
      DOI: 10.1002/ange.201712792
       
  • A Reconfigurable DNA Accordion Rack
    • Authors: Yeongjae Choi; Hansol Choi, Amos C. Lee, Hyunung Lee, Sunghoon Kwon
      Abstract: DNA nanostructure-based mechanical systems that control the distance between elements of interest have demonstrated great potential for various applications, including nanoplasmonic systems, molecular reactors, and other nanotechnology platforms. However, previously reported systems could not collectively manipulate a 2D or 3D nanoscale network of elements to various forms in multiple stages. A reconfigurable DNA accordion rack structure is introduced that is a DNA beam lattice that changes its conformation with a small amount of short-length DNA locks as the controlling input. The lattice shape of the 2D DNA accordion rack and the diameter and the height of the 3D DNA nanotubular structure made of the DNA accordion rack could be controlled. Furthermore, by sequentially repeating the detachment and the attachment of the different DNA locks using strand displacement, the shape reconfiguration was repeatedly carried out.Ein feststellbares DNA-Scherengitter mit beweglichen Kreuzungspunkten ändert seine Konformation bei Zugabe kleiner Mengen an kurzen DNA-Knebelsequenzen. Die Gitterform sowie der Durchmesser und die Höhe von DNA-Nanoröhren, die aus den Gittern aufgebaut werden, ließen sich auf diese Weise vorgeben.
      PubDate: 2018-02-14T05:16:10.238397-05:
      DOI: 10.1002/ange.201709362
       
  • Light-Activated Control of Translation by Enzymatic Covalent mRNA Labeling
    • Authors: Dongyang Zhang; Cun Yu Zhou, Kayla N. Busby, Seth C. Alexander, Neal K. Devaraj
      Abstract: Activation of cellular protein expression upon visible-light photocleavage of small-molecule caging groups covalently attached to the 5′ untranslated region (5′ UTR) of an mRNA was achieved. These photocleavable caging groups are conjugated to in vitro transcribed mRNA (IVT-mRNA) through RNA transglycosylation, an enzymatic process in which a bacterial tRNA guanine transglycosylase (TGT) exchanges a guanine nucleobase in a specific 17-nucleotide motif (Tag) for synthetic pre-queuosine1 (preQ1) derivatives. The caging groups severely reduce mRNA translation efficiency when strategically placed in the 5′ UTR. Using this method, we demonstrate the successful spatiotemporal photoregulation of gene expression with single-cell precision. Our method can be applied to therapeutically relevant chemically modified mRNA (mod-mRNA) transcripts. This strategy provides a modular and efficient approach for developing synthetic gene regulatory circuits, biotechnological applications, and therapeutic discovery.Freie Fahrt für die Translation: Die Gentranslation kann durch Abspaltung hemmender Gruppen (rot) vom untranslatierten 5′-Ende von mRNA unter Bestrahlung mit sichtbarem Licht aktiviert werden. Die hemmenden Gruppen werden durch RNA-Transglykosylierung angebracht und reduzieren die mRNA-Translationseffizienz erheblich. Mit dieser Methode wird die räumliche und zeitliche Steuerung der Genexpression mithilfe von Licht auf der Ebene einzelner Zellen möglich.
      PubDate: 2018-02-14T05:15:32.586042-05:
      DOI: 10.1002/ange.201710917
       
  • Effect of Cation-π Interaction on the Macroionic Self-Assembly
    • Authors: JIANCHENG LUO; Kun Chen, Panchao Yin, Tao Li, Gang Wan, Jin Zhang, Songtao Ye, Xiaoman Bi, Yi Pang, Yongge Wei, Tianbo Liu
      Abstract: A series of rod-shaped polyoxometalates (POMs) were chosen to study the effects of cation-π interaction on the macroionic self-assembly. Diffusion Ordered Spectroscopy (DOSY) and Isothermal Titration Calorimetry (ITC) techniques show that the binding affinity between the POMs and Zn2+ ions is enhanced significantly after grafting aromatic groups onto the clusters, leading to the effective replacement of TBAs upon the addition of ZnCl₂. The incorporation of aromatic groups results in the significant contribution of cation-π interaction to the self-assembly, as confirmed by the opposite trend of assembly size vs. ionic strength when compared with those without aromatic groups. The small difference between two aromatic groups toward the Zn2+ ions is amplified after combining with the clusters, which consequently triggers the self-recognition behavior between these two highly similar macroanions.
      PubDate: 2018-02-13T22:35:32.136736-05:
      DOI: 10.1002/ange.201800409
       
  • Towards Sequence-Controlled Antimicrobial Polymers: Effect of Polymer
           Block Order on Antimicrobial Activity
    • Authors: Peter R Judzewitsch; Thuy-Khanh Nguyen, Sivaprakash Shanmugam, Edgar H. H. Wong, Cyrille Andre Jean Marie Boyer
      Abstract: The biological effects of sequence control in synthetic antimicrobial polymers are currently not well understood. As such, we investigate the antimicrobial effects of monomer distribution within linear high-order multiblock copolymers which were made in a one-pot synthesis approach via photoinduced electron transfer-reversible addition-fragmentation chain transfer polymerisation (PET-RAFT). Through different combinations of monomer/polymer block order, the antimicrobial and haemolytic activities are tuneable in a manner comparable to antimicrobial peptides. Specifically, the partitioning of cationic functional groups from amphiphilic domains results in bacterial genus specificity that has yet to be observed in antimicrobial polymers. This study indicates that the design of new antimicrobial polymers should focus on manipulating localised functional group composition for specific biological outcomes, rather than solely on global compositional manipulations.
      PubDate: 2018-02-13T22:06:29.744183-05:
      DOI: 10.1002/ange.201713036
       
  • Chemoselective Z-Olefin Synthesis via Rh-Catalyzed, Formate Mediated
           1,6-Reduction
    • Authors: Raphael Dada; Zhongyu Wei, Ruohua Gui, Rylan J. Lundgren
      Abstract: Z-olefins are important functional units in synthetic chemistry; thus their preparation has received considerable attention. Many prevailing methods for cis-olefination are complicated by the presence of multiple unsaturated units or electrophilic functional groups. In this study, Z-olefin products are delivered via selective reduction of activated dienes using formic acid. The reaction proceeds with high regio- and stereoselectivity (typically>90:10 and>95:5 respectively) and preserves other alkenyl, alkynyl, protic and electrophilic groups.
      PubDate: 2018-02-13T22:06:22.205336-05:
      DOI: 10.1002/ange.201800361
       
  • Heteroleptic Copper(I)-Based Complexes for Photocatalysis: Combinatorial
           Assembly, Discovery, and Optimization
    • Authors: Shawn Collins; Clémentine Minozzi, Antoine Caron, Jeffrey Santandrea, Jean-Christophe Grenier-Petel
      Abstract: A library of 50 copper-based complexes derived from bisphosphines and diamines was prepared and evaluated in three mechanistically distinct photocatalytic reactions. In all cases, a copper-based catalyst was identified to afford high yields, where new heteroleptic complexes derived from the bisphosphine BINAP displayed high efficiency across all reaction types. Importantly, the evaluation of the library of copper-complexes revealed that even when photophysical data is available, it is not always possible to predict which catalyst structure will be efficient or inefficient in a given process, emphasizing the advantages for catalyst structures with high modularity and structural variability.
      PubDate: 2018-02-13T09:05:56.305402-05:
      DOI: 10.1002/ange.201800144
       
  • Nucleophilic Activation of Sulfur Hexafluoride: Metal-free, Selective
           Degradation by Phosphines
    • Authors: Fabian Dielmann; Florenz Buß, Christian Mück-Lichtenfeld, Paul Mehlmann
      Abstract: The development of new methods for the chemical activation of the extremely inert greenhouse gas sulfur hexafluoride (SF6) not only is of current environmental interest, but also offers new opportunities for applications of SF6 as a reagent in organic synthesis. We herein report the first nucleophilic activation of SF6 by Lewis bases, namely by phosphines, which results either in its complete degradation to phosphine sulfides and difluorophosphoranes or in the selective conversion of SF6 into a bench-stable, crystalline salt containing the SF5− anion. Quantum chemical calculations reveal a nucleophilic substitution mechanism (SN2) for the initial fluorine abstraction from SF6 by the phosphine. Furthermore, a scalable one-pot procedure for the complete decomposition of SF6 into solid, nonvolatile products is presented based on cheap and commercially available starting materials.
      PubDate: 2018-02-13T09:05:44.14283-05:0
      DOI: 10.1002/ange.201713206
       
  • Hybrid Indicators for Fast and Sensitive Voltage Imaging
    • Authors: Yongxian Xu; Luxin Peng, Sicong Wang, Anqi Wang, Ruirui Ma, Ying Zhou, Jiahe Yang, De-en Sun, Wei Lin, Xing Chen, Peng Zou
      Abstract: Membrane voltage is an important biophysical signal that underlies intercellular electrical communications. In this study, we present a novel fluorescent voltage indicator that enables the investigation of electrical signaling at high spatial resolution. Our method is built upon the site-specific modification of microbial rhodopsin proteins with organic fluorophores, resulting in a hybrid indicator scaffold that represents one of the most sensitive and fastest orange-colored voltage indicators developed to date. We applied this technique to optically map electrical connectivity in cultured cells, which revealed gap junction-mediated long-range coupling that spanned over hundreds of micrometers.
      PubDate: 2018-02-13T08:36:10.418974-05:
      DOI: 10.1002/ange.201712614
       
  • Dynamic Kinetic Resolution of Heterobiaryl Ketones via Zn-catalyzed
           Asymmetric Hydrosilylation
    • Authors: José M. Lassaletta; Valentín Hornillos, Jose Alberto Carmona, Abel Ros, Javier Iglesias-Sigüenza, Rosario Fernández, Joaquín López-Serrano
      Abstract: A diastereo and highly enantioselective dynamic kinetic resolution (DKR) of configurationally labile heterobiaryl ketones is described. The DKR proceeds by zinc-catalyzed hydrosilylation of the carbonyl group, leading to secondary alcohols bearing axial and central chirality. The strategy relies on the labilization of the stereogenic axis that takes place thanks to a Lewis acid-base interaction between a nitrogen atom in the heterocycle and the ketone carbonyl. The synthetic utility of the methodology is demonstrated through racemization-free, stereospecific transformations into N,N-ligands or appealing axially chiral, bifunctional thiourea organocatalysts.
      PubDate: 2018-02-13T08:35:52.513562-05:
      DOI: 10.1002/ange.201713200
       
  • Catalytic Enantioselective Aza-Benzoin Reactions of Aldehydes with
           2H-Azirines
    • Authors: Jian Wang; qiupeng peng, Donghui Guo, Jianbo Bie
      Abstract: The unprecedented enantioselective aza-benzoin reaction of aldehydes with 2H-azirines has been developed. In the presence of a L-phenylalanine-derived N-heterocyclic carbene catalyst, reactions promoted smoothly and yielded corresponding products in good yield with high enantioselectivity. The obtained optically active aziridines as useful synthons could further transfer to other valuable molecules.
      PubDate: 2018-02-13T07:05:45.921621-05:
      DOI: 10.1002/ange.201712785
       
  • Reversible Hydrogen Activation by a Pyridonate Borane Complex: Combining
           Frustrated Lewis Pair Reactivity with Boron-Ligand Cooperation
    • Authors: Urs Gellrich
      Abstract: A pyridone borane complex that liberates dihydrogen under mild conditions is described. The reverse reaction, dihydrogen activation by the formed pyridonate borane complex, is achieved under moderate H2 pressure (2 bar) at room temperature. DFT and DLPNO CCSD(T) computations reveal that the active form of the pyridonate borane complex is a boroxypyridine that can be described as single component Frustrated Lewis Pair (FLP). Significantly, the boroxypyridine undergoes a chemical transformation to a neutral pyridone donor ligand in the course of the hydrogen activation. This unprecedented mode of action may thus, in analogy to metal-ligand cooperation, be regarded as an example of boron-ligand cooperation.
      PubDate: 2018-02-13T06:35:43.749984-05:
      DOI: 10.1002/ange.201713119
       
  • A Manganese Nanosheet: New Cluster Topology and Catalysis
    • Authors: Axel Jacobi von Wangelin; Uttam Chakraborty, Efrain Reyes-Rodriguez, Serhiy Demeshko, Franc Meyer
      Abstract: While the coordination chemistry of monometallic complexes and the surface characteristics of larger metal particles are well understood, preparations of molecular metallic nanoclusters remain a great challenge. Discrete planar metal clusters constitute nanoscale snapshots of cluster growth but are especially rare due to the strong preference for three-dimensional structures and rapid aggregation or decomposition. A simple ligand exchange protocol has led to the formation of a novel heteroleptic Mn6 nanocluster that crystallized in an unprecedented flat chair topology and exhibited unique magnetic and catalytic properties. Magnetic susceptibility studies documented strong electronic communication between the Mn ions. Reductive activation of the molecular Mn6 cluster enabled catalytic hydrogenations of alkenes, alkynes, and imines.
      PubDate: 2018-02-13T06:05:47.975941-05:
      DOI: 10.1002/ange.201800079
       
  • Frontispiz: Folding DNA into a Lipid-Conjugated Nanobarrel for Controlled
           Reconstitution of Membrane Proteins
    • Authors: Yuanchen Dong; Shuobing Chen, Shijian Zhang, Joseph Sodroski, Zhongqiang Yang, Dongsheng Liu, Youdong Mao
      Abstract: DNA-Nanotechnologie In der Zuschrift auf S. 2094 berichten Y. Mao et al. über die Rekonstitution von Membranproteinen zu einem selbstorganisierten DNA-Nanofass. Das Potenzial der DNA-Nanofässer für die Strukturanalyse von Membranproteinen mit Kryo-EM wird demonstriert.
      PubDate: 2018-02-13T05:12:37.630652-05:
      DOI: 10.1002/ange.201880861
       
  • Solid-Solution Alloy Nanoparticles of the Immiscible Ir-Cu System with a
           Wide Composition Range for Enhanced Electrocatalytic Applications
    • Authors: Fenglong Wang; Kohei Kusada, Dongshuang Wu, Tomokazu Yamamoto, Takaaki Toriyama, Syo Matsumura, Yusuke Nanba, Michihisa Koyama, Hiroshi Kitagawa
      Abstract: For the first time, we have synthesized solid-solution alloy nanoparticles between Ir and Cu with a size of ~2 nm, despite Ir and Cu being immiscible in the bulk up to their melting over the whole composition range. We performed a systematic characterization on the nature of the IrxCu1-x solid-solution alloys using powder X-ray diffraction, scanning transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. The results showed that the obtained IrxCu1-x alloys had a face-centered-cubic structure; charge transfer from Cu to Ir occurred in the alloy nanoparticles, as the core-level Ir 4f peaks shifted to lower energy region with the increase in Cu content. The electron transfer from Cu to Ir observed in the alloy nanoparticles matched the theoretical results well. Furthermore, we observed that the alloying of Ir with Cu enhanced both the electrocatalytic oxygen evolution and oxygen reduction reactions. The enhanced activities could be attributed to the electronic interaction between Ir and Cu arising from the alloying effect at atomic-level.
      PubDate: 2018-02-13T03:30:38.340371-05:
      DOI: 10.1002/ange.201800650
       
  • Glycosyl-Substituted Dicarboxylates as Detergents for the Extraction,
           Overstabilization, and Crystallization of Membrane Proteins
    • Authors: Kim-Anh Nguyen; Marine Peuchmaur, Sandrine Magnard, Romain Haudecoeur, Cédric Boyère, Saravanan Mounien, Ikram Benammar, Veronica Zampieri, Sébastien Igonet, Vincent Chaptal, Anass Jawhari, Ahcène Boumendjel, Pierre Falson
      Abstract: To tackle the problems associated with membrane protein (MP) instability in detergent solutions, we designed a series of glycosyl-substituted dicarboxylate detergents (DCODs) in which we optimized the polar head to clamp the membrane domain by including, on one side, two carboxyl groups that form salt bridges with basic residues abundant at the membrane–cytoplasm interface of MPs and, on the other side, a sugar to form hydrogen bonds. Upon extraction, the DCODs 8 b, 8 c, and 9 b preserved the ATPase function of BmrA, an ATP-binding cassette pump, much more efficiently than reference or recently designed detergents. The DCODs 8 a, 8 b, 8 f, 9 a, and 9 b induced thermal shifts of 20 to 29 °C for BmrA and of 13 to 21 °C for the native version of the G-protein-coupled adenosine receptor A2AR. Compounds 8 f and 8 g improved the diffraction resolution of BmrA crystals from 6 to 4 Å. DCODs are therefore considered to be promising and powerful tools for the structural biology of MPs.Tenside, die für das Extrahieren von Membranproteinen (MPs) in wässrige Lösung verwendet werden, destabilisieren diese oftmals. Neue Derivate auf der Basis von Glykosyl-substituierten Dicarboxylaten umklammern die Membrandomäne und bilden Salzbrücken zu basischen Resten in den MPs. Sie erhalten die ATPase-Funktion von BmrA nach dem Extrahieren und verbessern die Stabilität und Kristallisation.
      PubDate: 2018-02-13T02:35:50.881707-05:
      DOI: 10.1002/ange.201713395
       
  • Catalyst-Enabled Site-divergent Stereoselective Michael Reactions:
           Overriding Intrinsic Reactivity of Enynyl Carbonyl Acceptors
    • Authors: Daisuke Uraguchi; Ryo Shibazaki, Naoya Tanaka, Kohei Yamada, Ken Yoshioka, Takashi Ooi
      Abstract: A site-divergent stereoselective Michael reaction system is developed based on the identification of two distinct catalysts. Cinchonidine-derived thiourea catalyzes the 1,4-addition of prochiral azlactone enolates to enynyl N-acyl pyrazoles in a highly diastereo- and enantioselective manner to give stereochemically defined alkynes, while P-spiro chiral triaminoiminophosphorane catalytically controls the stereoselective 1,6-addition and the consecutive γ-protonation of the vinylogous enolate intermediate to afford Z,E-configured conjugated dienes. This 1,6-adduct serves as a valuable precursor for the synthesis of a 2-amino-2-deoxy sugar.
      PubDate: 2018-02-13T01:31:11.757338-05:
      DOI: 10.1002/ange.201800057
       
  • Thermally Rearranged Polymer Membranes Containing Tröger's Base Units
           with Exceptional Performance for Air Separations
    • Authors: Stephen M. Meckler; Jonathan E. Bachman, Benjamin P. Robertson, Chenhui Zhu, Jeffrey R. Long, Brett A. Helms
      Abstract: The influence of backbone rigidity on the gas separation performance of thermally rearranged (TR) polymer membranes is established for TR polybenzoxazoles featuring Tröger's base (TB) monomer subunits as exceptionally rigid sites of contortion along the polymer backbone. These TR polymers are accessed from solution-processable ortho-acetate functionalized polyimides, which are readily synthesized with sufficiently high molecular weight for membrane casting. We find that thermal rearrangement leads to a small increase in d-spacing between polymer chains, and a dramatic pore-network reconfiguration that increases both membrane permeability and selectivity for air separations, putting its performance above the 2015 upper bound.
      PubDate: 2018-02-12T22:06:22.769193-05:
      DOI: 10.1002/ange.201800556
       
  • Mitigation of Inflammatory Immune Responses with Hydrophilic Nanoparticles
    • Authors: Bowen Li; Shaoyi Jiang, Jingyi Xie, Zhefan Yuan, Priyesh Jain, Xiaojie Lin, Kan Wu
      Abstract: While hydrophobic nanoparticles (NPs) have been long recognized to boost the immune activation, whether hydrophilic NPs modulate an immune system challenged by immune stimulators and how their hydrophilic properties may affect the immune response is still unclear. To answer this question, three polymers, poly(ethylene glycol)(PEG), poly(sulfobetaine)(PSB) and poly(carboxybetaine)(PCB) are studied. For fair comparison, nanogels with uniform size and pure surface functionalities were made from these polymers. Peripheral blood mononuclear cells stimulated by lipopolysaccharide (LPS), and LPS-induced lung inflammation murine model were used to investigate the influence of nanogels on the immune system. Results show that hydrophilic NPs attenuated the immune responses both in vitro and in vivo. Moreover, PCB NPs with the strongest hydration and the lowest non-specific protein binding manifested the best performance in alleviating the immune activation, followed by PSB and PEG NPs.
      PubDate: 2018-02-12T22:06:12.626441-05:
      DOI: 10.1002/ange.201710068
       
  • Direct Cyclization of Tertiary Arylamines with Iodonium Ylides
    • Authors: Zhiguo Zhao; Yongrui Luo, Shuya Liu, Liang Zhang, Lei Feng, Yao Wang
      Abstract: Described herein is a direct cyclization of simple tertiary arylamines with iodonium ylides leading to a broad range of N-heterocycles. Completely different from known reactivity of iodonium ylides, an exceptional finding reported herein is that iodonium ylide is capable of cleaving a C(sp3)-H bond and accepting two hydrogen atoms of tertiary arylamine, thus inducing a novel cyclization process. This transformation can proceed without assistance of a transition metal catalyst while eliminating the need for premodification of amines or using additional initiator/oxidant.
      PubDate: 2018-02-12T22:05:54.189755-05:
      DOI: 10.1002/ange.201800389
       
  • Highly Stable Aqueous Zinc-ion Storage Using Layered Calcium Vanadium
           Oxide Bronze Cathode
    • Authors: Chuan Xia; Jing Guo, Peng Li, Xixiang Zhang, Husam N. Alshareef
      Abstract: Cost-effective aqueous rechargeable batteries are attractive alternatives to non-aqueous cells for stationary grid energy storage. Among different aqueous cells, zinc-ion batteries (ZIBs), based on Zn2+ intercalation chemistry, stand out as they can employ high-capacity Zn metal as anode material. Herein, we report a layered calcium vanadium oxide bronze as cathode material for aqueous Zn batteries. For the storage of Zn2+ ions in aqueous electrolyte, we demonstrate that calcium based bronze structure can deliver a high capacity of 340 mAh g-1 at 0.2 C, good rate capability and very long cycling life (96% retention after 3000 cycles at 80 C). Further, we investigate the Zn2+ storage mechanism, and the corresponding electrochemical kinetics in this bronze cathode. Finally, we show that our Zn cell delivers an energy density of 267 Wh kg-1 at a power density of 53.4 W kg-1.
      PubDate: 2018-02-12T14:00:29.362486-05:
      DOI: 10.1002/ange.201713291
       
  • Barium as honorary transition metal in action: Experimental and
           theoretical study of [Ba(CO)]+ and [Ba(CO)]−
    • Authors: Gernot Frenking; Lili Zhao, Israel Fernandez, Robert Berger, Mingfei Zhou, Dandan Jiang
      Abstract: BaCO+ and BaCO− were and isolated in a low-temperature neon matrix. The observed C-O stretching wavenumber for BaCO+ of 1911.2 cm−1 is the most red-shifted value measured for any metal carbonyl cations, indicating strong π backdonation of electron density from Ba+ to CO. Quantum chemical calculations indicate that BaCO+ has a 2 ground state, which correlates with the 2D(5d1) excited state of Ba+ that comprises significant Ba+(5dπ1)CO(* LUMO) backbonding, letting the BaCO+ complex behave like a conventional transition-metal carbonyl. A bonding analysis shows that the  backdonation in BaCO+ is much stronger than the Ba+(5dσ/6s)CO(HOMO)  donation interaction. The Ba+ cation in the 2D(5d1) excited state is a donor rather than an acceptor. Covalent bonding in the radical anion Ba(CO)− takes place mainly through Ba(5dπ)CO-(π* SOMO) π donation and Ba(5dσ/6s)CO-(HOMO) σ donation. The most important valence functions at barium in BaCO+ cation and BaCO− anion are the 5d orbitals.
      PubDate: 2018-02-12T11:00:24.158132-05:
      DOI: 10.1002/ange.201713002
       
  • Ion-selective electrodes based on hydrophilic ionophore-modified nanopores
    • Authors: Soma Papp; Gyula Jágerszki, Róbert Ervin Gyurcsanyi
      Abstract: We report the synthesis and analytical application of the first Cu(II)-selective synthetic ion channel based on peptide-modified gold nanopores. A Cu(II) binding peptide motif (Gly-Gly-His) along with two additional functional thiol derivatives inferring cation-permselectivity and hydrophobicity was self-assembled on the surface of gold nanoporous membranes comprising of ca. 5 nm diameter pores. These membranes were used to construct Cu(II) ion-selective electrodes (ISEs) with extraordinary Cu(II) selectivities, approaching 6 orders of magnitude over certain ions. Since all constituents are immobilized to a supporting nanoporous membrane, their leaching, that is a ubiquitous problem of conventional ionophore-based ISEs was effectively suppressed.
      PubDate: 2018-02-12T10:06:02.919-05:00
      DOI: 10.1002/ange.201800954
       
  • Sample Ripening through Nanophase Separation Impacts the Performance of
           Dynamic Nuclear Polarization
    • Authors: Emmanuelle Weber; Giuseppe Sicoli, Hervé Vezin, Ghislaine Frébourg, Daniel Abergel, Geoffrey Bodenhausen, Dennis Kurzbach
      Abstract: Mixtures of water and glycerol provide popular matrices for low-temperature spectroscopy of vitrified samples. However, they involve counterintuitive physicochemical properties, such as spontaneous nanoscopic phase separations (NPS) in solutions that appear macroscopically homogeneous. We demonstrate that such phenomena can substantially impact the efficiency of dynamic nuclear polarization (DNP) by factors up to 20% by causing fluctuations in local concentrations of polarization agents (radicals). Thus, a spontaneous NPS of water/glycerol mixtures that takes place on time scales on the order of 30-60 min results in a confinement of polarization agents in nanoscopic water-rich vesicles, which in return affects the DNP. Such effects were found for three common polarization agents, TEMPOL, AMUPol and Trityl.
      PubDate: 2018-02-12T10:05:51.299259-05:
      DOI: 10.1002/ange.201800493
       
  • Counterion-Induced Asymmetric Control on Azetidiniums: A Facile Access to
           Chiral Amines
    • Authors: Deyun Qian; Min Chen, Alex C. Bissember, Jianwei Sun
      Abstract: Counterion-induced stereocontrol is a powerful tool in organic synthesis. However, such enantiocontrol on tetrahedral ammonium cations remains challenging. Herein we demonstrate the first example of using chiral anion phase-transfer catalysis to achieve intermolecular ring-opening of azetidiniums with excellent enantioselectivity (up to 97% ee). Precise control over the formation and reaction of the chiral ion pair as well as inhibition of the background reaction by the biphasic system is key to success.
      PubDate: 2018-02-12T10:05:38.41216-05:0
      DOI: 10.1002/ange.201712395
       
  • Does Charge Matter' Formation of Highly Reactive Cobalt Nanocluster
           Crystal within Highly Negative Porous Coordination Cage
    • Authors: Yu Fang; Zhifeng Xiao, Jialuo Li, Christina Lollar, Lujia Liu, Xizhen Lian, Shuai Yuan, Sayan Banerjee, Peng Zhang, Hongcai Zhou
      Abstract: Earth abundant first-row transition-metal nanoclusters (NCs) have been extensively investigated as catalysts. However, their catalytic activity is relatively low compared with noble metal NCs. In this work we show that enhanced catalytic activity of cobalt NCs can be achieved by encapsulating Co NCs in soluble porous coordination cages. Two cages, PCC-2a and 2b, possess almost identical cavity in shape and size, while PCC-2a has five times more net charges than PCC-2b. Co2+ cations were accumulated in PCC-2a and reduced to Co NCs in situ, while for PCC-2b, only bulky Co particles were formed. As a result, Co NCs@PCC-2a accomplished the highest catalytic activity in the hydrolysis of ammonium borane among all the first-row transition-metals NPs. Based on these results we envision that confining in the charged porous coordination cage can be a novel route for the synthesis of ultrasmall NCs with extraordinary properties.
      PubDate: 2018-02-12T09:00:43.054411-05:
      DOI: 10.1002/ange.201712372
       
  • Rhodium(I)-Catalyzed Carboacylation/Aromatization Cascade Initiated by
           Regioselective C−C Activation of Benzocyclobutenones
    • Authors: Tianwen Sun; Yuna Zhang, Bo Qiu, Yafei Wang, Yuting Qin, Guangbin Dong, Tao Xu
      Abstract: Described here is the first example of a rhodium-catalyzed carboacylation/aromatization cascade of a C=O bond by C−C activation. In this transformation, a reactive rhodaindanone complex is regioselectively generated and adds across a C=O bond with subsequent elimination, thus providing a unique strategy to access a multisubstituted benzofuran scaffold. A diverse range of benzofuran analogues were obtained in good yields. Mechanistic studies show a tricyclic lactone was a viable intermediate. Application of this methodology to the total synthesis of C13-deOH-viniferifuran and C13-deOH-diptoindonesin G was achieved.Ein reaktiver Rhodaindanon-Komplex wird bei der Titelreaktion regioselektiv erzeugt. Addition an eine C=O-Bindung mit anschließender Eliminierung führt in guten Ausbeuten zu mehrfach substituierten Benzofuranen. Die Methode wurde in Totalsynthesen von C13-deOH-Viniferifuran und C13-deOH-Diptoindonesin G eingesetzt.
      PubDate: 2018-02-12T07:21:03.083799-05:
      DOI: 10.1002/ange.201713179
       
  • Preise der Académie des Sciences 2017/Horst-Dietrich-Hardt-Preis für
           Lutz H. Gade/Yamada-Koga-Preis für Jan-E. Bäckvall/
    • PubDate: 2018-02-12T07:15:56.976792-05:
      DOI: 10.1002/ange.201801303
       
  • Four-fold Channel-Nicked Human Ferritin Nanocages for Active Drug Loading
           and pH-Responsive Drug Release
    • Authors: Byungjun Ahn; Seong-Gyu Lee, Hye Ryeon Yoon, Jeong Min Lee, Hyeok Jin Oh, Ho Min Kim, Yongwon Jung
      Abstract: Human ferritins are emerging platforms for non-toxic protein-based drug delivery, owing to their intrinsic or acquirable targeting abilities to cancer cells and hollow cage structures for drug loading. However, reliable strategies for high-level drug encapsulation within ferritin cavities and prompt cellular drug release are still lacking. Ferritin nanocages were developed with partially opened hydrophobic channels, which provide stable routes for spontaneous and highly accumulated loading of FeII-conjugated drugs as well as pH-responsive rapid drug release at endoplasmic pH. Multiple cancer-related compounds, such as doxorubicin, curcumin, and quercetin, were actively and heavily loaded onto the prepared nicked ferritin. Drugs on these minimally modified ferritins were effectively delivered inside cancer cells with high toxicity.Spontan und hochkonzentriert können diverse Wirkstoffe durch einen Ferritin-Nanokäfig aufgenommen werden, wenn die hydrophoben Kanäle von Ferritin etwas geöffnet werden. Wirkstoff-FeII-Komplexe wurden in diesem modifizierten Ferritin akkumuliert, in Zellen transportiert und dort durch einen pH-responsiven Prozess freigesetzt.
      PubDate: 2018-02-12T07:15:33.75461-05:0
      DOI: 10.1002/ange.201800516
       
  • Ralf I. Kaiser
    • PubDate: 2018-02-12T07:15:21.120421-05:
      DOI: 10.1002/ange.201800440
       
  • Single-Molecule Determination of the Isomers of d-Glucose and d-Fructose
           that Bind to Boronic Acids
    • Authors: William J. Ramsay; Hagan Bayley
      Abstract: Monosaccharides, such as d-glucose and d-fructose, exist in aqueous solution as an equilibrium mixture of cyclic isomers and can be detected with boronic acids by the reversible formation of boronate esters. The engineering of accurate, discriminating and continuous monitoring devices relies on knowledge of which cyclic isomer of a sugar binds to a boronic acid receptor. Herein, by monitoring fluctuations in ionic current, we show that an engineered α-hemolysin (αHL) nanopore modified with a boronic acid reacts reversibly with d-glucose as the pyranose isomer (α-d-glucopyranose) and d-fructose as either the furanose (β-d-fructofuranose) or the pyranose (β-d-fructopyranose). Both of these binding modes contradict current binding models. With this knowledge, we distinguished the individual sugars in a mixture of d-maltose, d-glucose, and d-fructose.Süß und sauer: Die reversible kovalente Verknüpfung von Boronsäuren mit Diolen lässt sich im Inneren eines Protein-Nanoreaktors verfolgen. Der Ansatz kann diejenigen cyclischen Isomere von d-Glucose und d-Fructose identifizieren, die in wässriger Lösung an eine Boronsäure binden. Beide Bindungsmodi sind in gängigen Bindungsmodellen nicht vorgesehen.
      PubDate: 2018-02-12T07:10:51.249819-05:
      DOI: 10.1002/ange.201712740
       
  • Stimuli-Responsive Dual-Color Photon Upconversion: A Singlet-to-Triplet
           Absorption Sensitizer in a Soft Luminescent Cyclophane
    • Authors: Kazuma Mase; Yoichi Sasaki, Yoshimitsu Sagara, Nobuyuki Tamaoki, Christoph Weder, Nobuhiro Yanai, Nobuo Kimizuka
      Abstract: Reversible emission color switching of triplet–triplet annihilation-based photon upconversion (TTA-UC) is achieved by employing an Os complex sensitizer with singlet-to-triplet (S-T) absorption and an asymmetric luminescent cyclophane with switchable emission characteristics. The cyclophane contains the 9,10-bis(phenylethynyl)anthracene unit as an emitter and can assemble into two different structures, a stable crystalline phase and a metastable supercooled nematic phase. The two structures exhibit green and yellow fluorescence, respectively, and can be accessed by distinct heating/cooling sequences. The hybridization of the cyclophane with the Os complex allows near-infrared-to-visible TTA-UC. The large anti-Stokes shift is possible by the direct S-T excitation, which dispenses with the use of a conventional sequence of singlet–singlet absorption and intersystem crossing. The TTA-UC emission color is successfully switched between green and yellow by thermal stimulation.Gelb oder Grün' Bei einer Photonenaufwärtskonversion auf Basis von Triplett-Triplett-Annihilierung (TTA-UC) kann die Farbe reversibel geschaltet werden. Dazu wird ein unsymmetrisches Cyclophan, das infolge einer Strukturpolymorphie verschiedenfarbig fluoreszieren kann, mit einem Singulett-Triplett(S-T)-Absorptionssensibilisator für den Nah-IR-Bereich kombiniert, der Energieverluste bei der Besetzung des Triplettzustands minimiert.
      PubDate: 2018-02-12T07:10:44.33382-05:0
      DOI: 10.1002/ange.201712644
       
  • (Radio)fluoroclick Reaction Enabled by a Hydrogen-Bonding Cluster
    • Authors: Xiaojun Zeng; Junling Li, Chin K. Ng, Gerald B. Hammond, Bo Xu
      Abstract: We have developed a widely applicable nucleophilic (radio)fluoroclick reaction of ynamides with readily available and easy-to-handle KF(18F). The reactions exhibited high functional-group tolerance and needed only an ambient atmosphere. This 18F addition to C−C unsaturated bonds proceeded with extraordinarily high radiochemical yields.Bereit und in der Lage: α-Fluorenamide werden in einer nukleophilen Fluorierung von Inamiden mit leicht verfügbarem KF(18F) in Hexafluor-2-propanol (HFIP), das als Protonenquelle fungiert, gebildet (siehe Schema). Die Reaktionen sind gut verträglich mit funktionellen Gruppen und lassen sich an der Luft ausführen. Die Methode ermöglicht die Addition von 18F an ungesättigte C-C-Bindungen mit hoher radiochemischer Ausbeute (RCY).
      PubDate: 2018-02-12T07:10:31.263423-05:
      DOI: 10.1002/ange.201711341
       
  • DNA Origami Directed Assembly of Gold Bowtie Nanoantennas for
           Single-Molecule Surface-Enhanced Raman Scattering
    • Authors: Pengfei Zhan; Te Wen, Zhen-gang Wang, Yingbo He, Jia Shi, Ting Wang, Xinfeng Liu, Guowei Lu, Baoquan Ding
      Abstract: Metallic bowtie nanoarchitectures can produce dramatic electric field enhancement, which is advantageous in single-molecule analysis and optical information processing. Plasmonic bowtie nanostructures were successfully constructed using a DNA origami-based bottom-up assembly strategy, which enables precise control over the geometrical configuration of the bowtie with an approximate 5 nm gap. A single Raman probe was accurately positioned at the gap of the bowtie. Single-molecule surface-enhanced Raman scattering (SM-SERS) of individual nanostructures, including ones containing an alkyne group, was observed. The design achieved repeatable local field enhancement of several orders of magnitude. This method opens the door on a novel strategy for the fabrication of metal bowtie structures and SM-SERS, which can be utilized in the design of highly-sensitive photonic devices.Plasmonische Nanostrukturen in Doppeldreieck-Form wurden selbstorganisiert nach einem DNA-Origami-Ansatz aufgebaut. Eine einzelne Raman-Sonde wurde genau an dem Berührungspunkt der beiden Dreiecke positioniert, und Einzelmolekül-SERS der Nanostrukturen wurde beobachtet.
      PubDate: 2018-02-12T07:05:40.472338-05:
      DOI: 10.1002/ange.201712749
       
  • From Aniline to Aryl Ether: A Facile, Efficient and Versatile Synthetic
           Protocol Employing Mild Conditions
    • Authors: Dong-Yu Wang; Ze-Kun Yang, Chao Wang, Ao Zhang, Masanobu Uchiyama
      Abstract: We have developed a simple and direct protocol for synthesis of aryl ethers by reaction of alcohols/phenols (ROH) with aryl ammonium salts (ArNMe3+), which are readily prepared from anilines (ArNR´2, R' = H or Me). This reaction proceeds smoothly and rapidly (within a few hours) at room temperature in the presence of a commercially available base, such as KOtBu or KHMDS, and has a broad substrate scope for both ROH and ArNR´2. It is scalable, and compatible with a wide range of functional groups. We show that various functional molecules, including natural products, pharmaceuticals, dyes, etc., can be directly transformed to ethereal derivatives in high yield with excellent chemo-selectivity.
      PubDate: 2018-02-12T07:00:44.879814-05:
      DOI: 10.1002/ange.201712618
       
  • Lewis Base-Promoted Ring-Opening 1,3-Dioxygenation of Unactivated
           Cyclopropanes using Hypervalent Iodine Reagent
    • Authors: Matthew H. Gieuw; Zhihai Ke, Ying-Yeung Yeung
      Abstract: A facile and effective system has been developed for the regio- and chemoselective ring-opening/electrophilic functionalization of cyclopropanes via C-C bond activation by [bis(trifluoroacetoxy)iodo]benzene with the aid of the Lewis basic promoter p-toluenesulfonamide. Notably, the p-toluenesulfonamide-promoted system works well for a wide range of cyclopropanes, resulting in the formation of 1,3-diol products in good yields and regioselectivity.
      PubDate: 2018-02-12T06:00:28.878597-05:
      DOI: 10.1002/ange.201713422
       
  • Spectroscopic Evidence for Aminomethylene (H-C̈-NH2) - The Simplest
           Amino Carbene
    • Authors: André Kristopher Eckhardt; Peter Richard Schreiner
      Abstract: Although N-heterocyclic carbenes have been well-studied, the simplest aminocarbene, aminomethylene H-C̈-NH2, has not been spectroscopically identified yet. Here we report the gas phase prep-aration of aminomethylene by high-vacuum flash pyrolysis of cyclo-propylamine and subsequent trapping of the pyrolysate in an inert argon matrix at 12 K. Aminomethylene was characterized by matching matrix IR and UV/Vis spectroscopic data with ab initio coupled cluster computations. After UV irradiation of the matrix aminomethylene re-arranges to its isomer methanimine (formaldimine) H2C=NH. Based on our experimental results and computations aminomethylene has a singlet ground state with a reaction barrier of almost 46 kcal mol-1 to methanimine so that H-tunneling to formaldimine is excluded.
      PubDate: 2018-02-12T05:36:19.793399-05:
      DOI: 10.1002/ange.201800679
       
  • Amipurimycin: Total Synthesis of the Proposed Structures and
           Diastereoisomers
    • Authors: Shengyang Wang; Jiansong Sun, Qingju Zhang, Xin Cao, Yachen Zhao, Gongli Tang, Biao Yu
      Abstract: The proposed diastereoisomers (1 a–d) together with their C8′-epimers (1 e–h) of amipurimycin, a unique antifungal peptidyl nucleoside antibiotic, have been synthesized for the first time. The synthetic approach is efficient and stereodivergent, and features a stereoselective aldol condensation to build the branched C9 sugar amino acid skeleton and a regio- and stereocontrolled gold(I)-catalyzed N-glycosylation to furnish the purine nucleoside. Analysis of the NMR data suggests that the previously assigned configuration of the tertiary C3′ in amipurimycin should be of opposite configuration.Umkonfiguriert: Die vorgeschlagenen Diastereomere und die entsprechenden C8′-Epimere des Peptidylnukleosid-Antibiotikums Amipurimycin wurden synthetisiert. Eine Analyse der NMR-Daten deutet darauf hin, dass das tertiäre C3′ in Amipurimycin die entgegengesetzte Konfiguration haben sollte als früher postuliert.
      PubDate: 2018-02-12T03:12:00.780082-05:
      DOI: 10.1002/ange.201800169
       
  • Die enantioselektive Totalsynthese von Bischinolizidin-Alkaloiden: Ein
           modularer “Inside-Out”-Zugang
    • Authors: Dagmar Scharnagel; Jessica Goller, Nicklas Deibl, Wolfgang Milius, Matthias Breuning
      Abstract: Charakteristisch für Bischinolizidin-Alkaloide ist ein chirales Bispidin-Kerngerüst (3,7-Diazabicylo[3.3.1]nonan), an das Kombinationen aus einem α,N-anellierten 2-Pyridon, endo- oder exo-α,N-anellierten Piperidin(on)en und einem exo-Allylsubstituenten angebracht sind. Wir entwickelten eine modulare “Inside-Out”-Strategie, die einen Zugang zu den meisten Vertretern dieser Naturstoffklasse erlaubt. Ihr Anwendungspotential wurde anhand der asymmetrischen Synthese von 21 Bischinolizidin-Naturstoffen demonstriert, darunter mehr als zehn enantioselektive Erstsynthesen. Schlüsselschritte sind die erste erfolgreiche Herstellung beider Enantiomere von C2-symmetrischem 2,6-Dioxobispidin durch Desymmetrisierung einer 2,4,6,8-Tetraoxo-Vorstufe, der Aufbau des α,N-anellierten 2-Pyridons über eine Enamin-Bromacrylsäure-Strategie und die Einführung von endo- oder, wahlweise, exo-anellierten Piperidin(on)en.Alle auf einen Streich: Ein diversitätsorientierter, modularer „Inside-Out”-Zugang zu Bischinolizidin-Naturstoffen wurde entwickelt und seine Flexibilität anhand der enantioselektiven Totalsynthese von 21 Alkaloiden demonstriert. Schlüsselschritte sind eine Desymmetrisierung, die Zugang zu beiden Enantiomeren eines C2-symmetrischen 2,6-Dioxobispidins erlaubt, und die Anellierung eines 2-Pyridons und von endo- oder exo-Piperidin(on)en an diesen chiralen Kernbaustein.
      PubDate: 2018-02-12T03:11:32.743185-05:
      DOI: 10.1002/ange.201712852
       
  • Konfigurationsisomerie in Polyoxovanadaten
    • Authors: Lisa K. Mahnke; Aleksandar Kondinski, Ulrike Warzok, Christian Näther, Jan van Leusen, Christoph A. Schalley, Kirill Yu. Monakhov, Paul Kögerler, Wolfgang Bensch
      Abstract: Ein wasserlöslicher Abkömmling des Polyoxovanadat-Archetyps {V15E6O42} (E=Halbmetall) ermöglicht die Untersuchung supramolekular induzierter Clusterschalen-Umwandlungen. Eine für E=Sb spezifische Reaktion, die durch einen Ligandenaustausch in [Ni(ethylendiamin)3]2+-Gegenionen eingeleitet wird, resultiert in der Bildung des metastabilen α1*-Konfigurationsisomers des {V14Sb8O42}-Clustertyps. Im Unterschied zu allen bisher bekannten Polyoxovanadat-Schalenarchitekturen weist dieses Isomer eine nach innen ausgerichtete Vanadylgruppe auf und ist ca. 50 bzw. 12 kJ mol−1 energiereicher als die zuvor isolierten α- und β-Isomere. Diese unerwartete Reaktion wird im Hinblick auf supramolekulare Sb-O⋅⋅⋅V- und Sb-O⋅⋅⋅Sb-Bindungen diskutiert, die sich in {V14Sb8O42}2-Dimeren im Festkörper manifestieren. ESI-MS-Experimente untermauern die Stabilität dieser Dimere auch in Lösung und in der Gasphase. DFT-Rechnungen zufolge sollten so auch weitere, bislang noch nicht gefundene {V14Sb8}-Isomere zugänglich sein.Supramolekulare Wechselwirkungen innerhalb von und zwischen Clustern begünstigen die energetisch aufwändige Bildung eines Konfigurationsisomers (α1*) aus der {V14Sb8}-Familie der Antimonatopolyoxovanadate.
      PubDate: 2018-02-12T03:11:09.983083-05:
      DOI: 10.1002/ange.201712417
       
  • Smart superwetting surface with responsivity in both surface chemistry and
           microstructure
    • Authors: Dongjie Zhang; Zhongjun Cheng, Hongjun Kang, Jianxin Yu, Yuyan Liu, Lei Jiang
      Abstract: Recently, smart surfaces with switchable wettability have aroused much attention. However, only single surface chemistry or microstructure can be changed on these surfaces, which significantly limits their wetting performances, controllability and applications. Herein, a new surface with both tunable surface microstructure and chemistry is prepared by grafting poly(N-isopropylacrylamide) onto the pillar-structured shape memory polymer, on which, multiple wetting states from the superhydrophilicity to superhydrophobicity can be reversibly and precisely controlled by synergistically regulating the surface microstructure and chemistry. Meanwhile, based on the excellent controllability, we also showed the application of the surface as a rewritable platform, and various gradient wettings can be obtained. This work first time reports a surface with controllability in both surface chemistry and microstructure, which starts some new ideas for the design of novel superwetting materials.
      PubDate: 2018-02-11T22:06:39.203815-05:
      DOI: 10.1002/ange.201800416
       
  • Blending Non-Group-IIIB Transition Metal and Rare Earth Metal into a C80
           Fullerene Cage with D5h Symmetry: which Metal is Decisive'
    • Authors: Shangfeng Yang; Tao Wei, Fei Jin, Runnan Guan, Jing Huang, Muqing Chen, Qunxiang Li
      Abstract: Rare earth metals have been mostly entrapped into fullerene cage to form endohedral clusterfullerenes, whereas the reported non-Group-IIIB transition metals which can form clusterfullerenes are quite limited to titanium (Ti) and vanadium (V), and both are exclusively entrapped within an Ih-C80 cage. Herein, we report the first non-Group-IIIB transition metal-containing endohedral fullerenes based on a C80 cage with D5h symmetry — VxSc3-xN@D5h-C80 (x=1, 2), which exhibit two variable cluster compositions. The molecular structure of VSc2N@D5h-C80 was unambiguously determined by X-ray crystallography. According to a comparative study with the reported Ti- and V-containing clusterfullerenes based on Ih-C80 cage as well as the analogous D5h-C80-based metal nitride clusterfullerenes containing rare earth metals only, the decisive role of the non-Group-IIIB transition metal on the formation of the corresponding D5h-C80-based clusterfullerenes is unraveled.
      PubDate: 2018-02-11T22:06:33.759078-05:
      DOI: 10.1002/ange.201800630
       
  • Reversible Phase Transfer of Carbon Dots between Organics and Aqueous
           Solution Triggered by CO2
    • Authors: Xiaoyan Pei; Dazhen Xiong, Huiyong Wang, Shuaiqi Gao, Xinying Zhang, Suojiang Zhang, Jian Ji Wang
      Abstract: Carbon dots (CDs) have attracted increasing attention in applications such as bio-imaging, sensors, catalysis, and drug delivery. However, unlike metallic and semiconductor nanoparticles, the transfer of CDs between polar and non-polar phases is little understood. In this work, a novel class of amine-terminated CDs is developed and their phase transfer behaviour has been investigated. It is found that these CDs can reversibly transfer between aqueous and organic solvents by alternatively bubbling and removal of CO2 at atmospheric pressure. The mechanism of such CO2-switched phase transfer involves reversible acid-base reaction of amine-terminated CDs with CO2 and the reversible formation of hydrophilic ammonium salts. By using the CDs as catalysts, the phase transfer protocol is applied in Knoevenagel reaction for efficient homogeneous reaction, heterogeneous separation, and recycling of the catalysts.
      PubDate: 2018-02-11T22:06:27.580614-05:
      DOI: 10.1002/ange.201800037
       
  • Tuning the High-Temperature Wetting Behavior of Metals toward Ultrafine
           Nanoparticles
    • Authors: Yubing Zhou; Bharath Natarajan, Yanchen Fan, Hua Xie, Chunpeng Yang, Shaomao Xu, Yonggang Yao, Feng Jiang, Qianfan Zhang, Jeffrey W. Gilman, Liangbing Hu
      Abstract: The interaction between metal nanoparticles (NPs) and their substrate plays a critical role in determining the particle morphology, distribution, and properties. The pronounced impact of a thin oxide coating on the dispersion of metal NPs on a carbon substrate is presented. Al2O3-supported Pt NPs are compared to the direct synthesis of Pt NPs on bare carbon surfaces. Pt NPs with an average size of about 2 nm and a size distribution ranging between 0.5 nm and 4.0 nm are synthesized on the Al2O3 coated carbon nanofiber, a significant improvement compared to those directly synthesized on a bare carbon surface. First-principles modeling verifies the stronger adsorption of Pt clusters on Al2O3 than on carbon, which attributes the formation of ultrafine Pt NPs. This strategy paves the way towards the rational design of NPs with enhanced dispersion and controlled particle size, which are promising in energy storage and electrocatalysis.Eine dünne Oxidschicht hat starke Auswirkungen auf die Dispersion metallischer Nanopartikel (NPs) auf einem Kohlenstoffsubstrat. Direkt auf Kohlenstoffoberflächen synthetisierte Pt-NPs wurden mit Pt-NPs auf einer Al2O3-beschichteten Kohlenstoffnanofaser verglichen. Letztere wiesen eine durchschnittliche Größe von 2 nm und eine Größenverteilung von 0.5 bis 4.0 nm auf – ein deutlicher Vorteil gegenüber den direkt auf Kohlenstoff synthetisierten Pt-NPs.
      PubDate: 2018-02-09T05:35:36.566474-05:
      DOI: 10.1002/ange.201712202
       
  • Katalytische, positions- und enantioselektive C-H-Oxygenierung durch einen
           chiralen Mangan-Porphyrin-Komplex mit einer entfernten Bindungsstelle
    • Authors: Finn Burg; Maxime Gicquel, Stefan Breitenlechner, Alexander Pöthig, Thorsten Bach
      Abstract: Ein chiraler Mangan-Porphyrin-Komplex mit einem Wasserstoffbrückenmotiv wurde synthetisiert und anschließend in der katalytischen C-H-Oxygenierung von 3,4-Dihydrochinolonen erprobt. Die gewünschte Oxygenierung fand mit perfekter Positionsselektivität an der C4-Methylengruppe und mit hoher Enantioselektivität zugunsten des entsprechenden (4S)-konfigurierten sekundären Alkohols statt (12 Beispiele, 29–97 % Umsatz, 19–68 % Ausbeute, 87–99 % ee). Mechanistische Studien unterstützen einen geschwindigkeits- und selektivitätsbestimmenden Angriff des reaktiven Mangan-Oxo-Komplexes am Wasserstoffbrücken-gebundenen Substrat sowie eine Sauerstoffübertragung durch einen Rebound-Mechanismus.Schau mir ins aktive Zentrum, Kleines: Ein chiraler Mangan-Porphyrin-Komplex katalysiert die Oxygenierung von 3,4-Dihydrochinolonen zur entsprechenden (4S)-Hydroxyverbindung (12 Beispiele, 87–99 % ee). Die Enantio- und Positionsselektivität wird durch Wasserstoffbrücken zum Katalysator bewirkt: Methylengruppen am C3 oder C7 Kohlenstoff werden nicht angegriffen.
      PubDate: 2018-02-09T04:01:21.799308-05:
      DOI: 10.1002/ange.201712340
       
  • A Three-Component Organometallic Tyrosine Bioconjugation
    • Authors: Jun Ohata; Mary K. Miller, Courtney M. Mountain, Farrukh Vohidov, Zachary T. Ball
      Abstract: Metal-based bioconjugation linkages represent a little-studied approach to protein functionalization that provides novel reactivity, stability, and function. Described is an organometallic bioconjugation, employing rhodium(III) salts, to link boronic acids with tyrosine residues by an arene complex. Both peptides and proteins are amenable to the mild bioconjugation in aqueous media, allowing incorporation of useful functionalities, such as affinity handles or fluorophores. Because of the metastability of the inorganic linkage, the conjugates are susceptible to cleavage by nucleophilic redox mediators but are stable toward typical biological conditions.In Gegenwart von Boronsäuren bilden Rhodium(III)-Salze metallorganische Arenkomplexe an Tyrosinresten. Die Verknüpfung mit Rhodium stellt eine unter biologischen Bedingungen stabile Proteinfunktionalisierung dar. DTT=Dithiothreitol.
      PubDate: 2018-02-09T04:01:01.58088-05:0
      DOI: 10.1002/ange.201711868
       
  • Accelerating Membrane-based CO2 Separation by Soluble Nanoporous Polymer
           Networks Produced by Mechanochemical Oxidative Coupling
    • Authors: Xiang Zhu; Yinying Hua, Chengcheng Tian, Carter W. Abney, Peng Zhang, Tian Jin, Gongping Liu, Katie L. Browning, Robert L. Sacci, Gabriel M. Veith, Hong-Cai Zhou, Wanqin Jin, Sheng Dai
      Abstract: Achieving homogeneous dispersion of nanoporous fillers within membrane architectures remains a great challenge for mixed-matrix membrane (MMMs) technology. Imparting solution processability of nanoporous materials would help advance the development of MMMs for membrane-based gas separations. A mechanochemically assisted oxidative coupling polymerization strategy was used to create a new family of soluble nanoporous polymer networks. The solid-state ball-milling method affords inherent molecular weight control over polymer growth and therefore provides unexpected solubility for the resulting nanoporous frameworks. MMM-based CO2/CH4 separation performance was significantly accelerated by these new soluble fillers. We anticipate this facile method will facilitate new possibilities for the rational design and synthesis of soluble nanoporous polymer networks and promote their applications in membrane-based gas separations.Mechanochemie hilft bei der Bildung nanoporöser Polymergerüste durch oxidative Kupplung. In der Kugelmühle lässt sich das Molekulargewicht des wachsenden Polymers kontrollieren, und es werden nanoporöse Gerüste mit ungewöhnlicher Löslichkeit erhalten. Der Einsatz dieser löslichen Füllstoffe in Mischmembranen beschleunigt die Trennung von CO2 und CH4 deutlich.
      PubDate: 2018-02-09T04:00:55.102404-05:
      DOI: 10.1002/ange.201710420
       
  • Herkunftsbezogene Nomenklatur für einstrangige Homo- und Copolymere
           (IUPAC-Empfehlungen 2016)
    • Authors: Karl-Heinz Hellwich; Kathrin-M. Roy
      Abstract: IUPAC-Empfehlungen zur herkunftsbezogenen Nomenklatur für einstrangige Polymere wurden bisher hauptsächlich im Hinblick auf Copolymere, nichtlineare Polymere und Polymerassoziate sowie im Zusammenhang mit der generischen herkunftsbezogenen Polymernomenklatur formuliert. Im Folgenden werden möglichst klare und präzise Regeln zur Entwicklung eines geeigneten herkunftsbezogenen Namens für ein Polymer, ob Homopolymer oder Copolymer, formuliert. Somit wird das herkunftsbezogene System zur Benennung von Polymeren in einer Gesamtheit vorgelegt, die als nutzerfreundliche Alternative zum strukturbezogenen System der Polymernomenklatur dient. Zudem wurden Empfehlungen für die Verwendung traditioneller Polymernamen ausgearbeitet, da deren Gebrauch weit verbreitet und etabliert ist.Möglichst klare und präzise Regeln zur Entwicklung eines geeigneten herkunftsbezogenen Namens für ein Polymer, ob Homopolymer oder Copolymer, zu entwickeln, war das Ziel der Verfasser der hier in deutscher Übersetzung vorliegenden IUPAC-Empfehlung.
      PubDate: 2018-02-09T04:00:34.323303-05:
      DOI: 10.1002/ange.201706791
       
  • Decoupling Hydrogen and Oxygen Production in Acidic Water Electrolysis
           Using a Polytriphenylamine-Based Battery Electrode
    • Authors: Yuanyuan Ma; Xiaoli Dong, Yonggang Wang, Yongyao Xia
      Abstract: Hydrogen production through water splitting is considered a promising approach for solar energy harvesting. However, the variable and intermittent nature of solar energy and the co-production of H2 and O2 significantly reduce the flexibility of this approach, increasing the costs of its use in practical applications. Herein, using the reversible n-type doping/de-doping reaction of the solid-state polytriphenylamine-based battery electrode, we decouple the H2 and O2 production in acid water electrolysis. In this architecture, the H2 and O2 production occur at different times, which eliminates the issue of gas mixing and adapts to the variable and intermittent nature of solar energy, facilitating the conversion of solar energy to hydrogen (STH). Furthermore, for the first time, we demonstrate a membrane-free solar water splitting through commercial photovoltaics and the decoupled acid water electrolysis, which potentially paves the way for a new approach for solar water splitting.Entkoppelte Wasserelektrolyse: Eine organische Polytriphenylamin-basierte Batterieelektrode wird vorgestellt, mit der die Wasser- und Sauerstoffproduktion in der sauren Wasserelektrolyse entkoppelt werden kann, wodurch die membranlose Umwandlung von Sonnenenergie in Wasserstoff möglich wird. Die Trennung von Wasser- und Sauerstoffproduktion könnte zur flexiblen Nutzung von Sonnenenergie führen.
      PubDate: 2018-02-09T03:57:24.551146-05:
      DOI: 10.1002/ange.201800436
       
  • Reversible Redox Chemistry of Azo Compounds for Sodium-Ion Batteries
    • Authors: Chao Luo; Gui-Liang Xu, Xiao Ji, Singyuk Hou, Long Chen, Fei Wang, Jianjun Jiang, Zonghai Chen, Yang Ren, Khalil Amine, Chunsheng Wang
      Abstract: Sustainable sodium-ion batteries (SSIBs) using renewable organic electrodes are promising alternatives to lithium-ion batteries for the large-scale renewable energy storage. However, the lack of high-performance anode material impedes the development of SSIBs. Herein, we report a new type of organic anode material based on azo group for SSIBs. Azobenzene-4,4′-dicarboxylic acid sodium salt is used as a model to investigate the electrochemical behaviors and reaction mechanism of azo compound. It exhibits a reversible capacity of 170 mAh g−1 at 0.2C. When current density is increased to 20C, the reversible capacities of 98 mAh g−1 can be retained for 2000 cycles, demonstrating excellent cycling stability and high rate capability. The detailed characterizations reveal that azo group acts as an electrochemical active site to reversibly bond with Na+. The reversible redox chemistry between azo compound and Na ions offer opportunities for developing long-cycle-life and high-rate SSIBs.Azoverbindungen wurden als leistungsfähiges organisches Elektrodenmaterial für Natriumionenbatterien (SIBs) vorgestellt. Das ausgedehnte konjugierte π-System aromatischer Azoverbindungen und die starke Anlagerung der Na+-Ionen an den Stickstoffatomen der Azogruppe bilden die Grundlage für eine lange Lebensdauer und gutes Ratenverhalten.
      PubDate: 2018-02-09T03:56:17.906766-05:
      DOI: 10.1002/ange.201713417
       
  • (NHC)NiH-Catalyzed Regiodivergent Cross-Hydroalkenylation of Vinyl Ethers
           with α-Olefins: Syntheses of 1,2- and 1,3-Disubstituted Allyl Ethers
    • Authors: Weihao Chen; Yang Li, Yang Chen, Chun-Yu Ho
      Abstract: Cross-hydroalkenylation of a vinyl ether (1) with an α-olefin (2) was first achieved by a set of [NHC-Ni(allyl)]BArF (NHC=N-heterocyclic carbene) catalysts. Both 1,2- and 1,3-disubstituted allyl ethers were obtained, highly selectively, by using NHCs of different sizes. In contrast, the chemoselectivity (i.e., 1 as acceptor and 2 as donor) was controlled mostly by electronic effects through the catalyst–substrate interaction. Sterically bulkier alkenes (2) were used as preferred donors compared to smaller alkenes. This electronic effect also served as a basis for the first tail-to-head cross-hydroalkenylations of 1 with either a vinyl silane or boronic ester.Elektronisches: Allylether wurden regiodivergent durch katalytisch gekreuzte Hydroalkenylierung synthetisiert, wobei Substrat-Katalysator-Wechselwirkungen die Chemoselektivität vorgeben. Sperrige Alkene und Vinylsilane/Boronsäureester sind geeignete Olefindonoren für kleine Vinylether. Diese bislang kinetisch unvorteilhafte Kombination eröffnet Möglichkeiten für die Kreuzdimerisierung neuer Substratklassen.
      PubDate: 2018-02-09T03:56:04.158533-05:
      DOI: 10.1002/ange.201712693
       
  • Synergistic N-Heterocyclic Carbene/Palladium-Catalyzed Reactions of
           Aldehyde Acyl Anions with either Diarylmethyl or Allylic Carbonates
    • Authors: Shigeo Yasuda; Takuya Ishii, Shunsuke Takemoto, Hiroki Haruki, Hirohisa Ohmiya
      Abstract: Benzylation and allylation of aldehyde acyl anions were enabled by the merger of a thiazolium N-heterocyclic carbene (NHC) catalyst and a palladium/bisphosphine catalyst in a synergistic manner. Owing to the mildness of the reaction conditions, various functional groups were tolerated in the substrates.In synergistischer Weise vermittelt eine Katalysatorkombination aus Thiazolium-basiertem N-heterocyclischem Carben (NHC) und Palladium-Disphosphan-Komplex die Benzylierung und Allylierung von Aldehyd-Acylanionen. Unter milden Reaktionsbedingungen werden Substrate mit verschiedenen funktionellen Gruppen erfolgreich umgesetzt.
      PubDate: 2018-02-09T03:55:55.508682-05:
      DOI: 10.1002/ange.201712811
       
  • Formation of Acetylene in the Reaction of Methane with Iron Carbide
           Cluster Anions FeC3− under High-Temperature Conditions
    • Authors: Hai-Fang Li; Li-Xue Jiang, Yan-Xia Zhao, Qing-Yu Liu, Ting Zhang, Sheng-Gui He
      Abstract: The underlying mechanism for non-oxidative methane aromatization remains controversial owing to the lack of experimental evidence for the formation of the first C−C bond. For the first time, the elementary reaction of methane with atomic clusters (FeC3−) under high-temperature conditions to produce C−C coupling products has been characterized by mass spectrometry. With the elevation of temperature from 300 K to 610 K, the production of acetylene, the important intermediate proposed in a monofunctional mechanism of methane aromatization, was significantly enhanced, which can be well-rationalized by quantum chemistry calculations. This study narrows the gap between gas-phase and condensed-phase studies on methane conversion and suggests that the monofunctional mechanism probably operates in non-oxidative methane aromatization.Acetylen wurde als C-C-Kupplungsprodukt in Reaktionen von Methan mit FeC3−-Clustern bei hoher Temperatur identifiziert. Dieses Ergebnis trägt auf molekularer Ebene zur Aufklärung des monofunktionellen Mechanismus der nichtoxidativen Methan-Aromatisierung bei, der für kondensierte Systeme vorgeschlagen wurde.
      PubDate: 2018-02-09T03:55:49.852485-05:
      DOI: 10.1002/ange.201712463
       
  • IR Spectrum and Structure of Protonated Monosilanol: Dative Bonding
           between Water and the Silylium Ion
    • Authors: Martin Andreas Robert George; Nguyen Xuan Truong, Marco Savoca, Otto Dopfer
      Abstract: We report the spectroscopic characterization of protonated monosilanol (SiH3OH2+) isolated in the gas phase, thus providing the first experimental determination of the structure and bonding of a member of the elusive silanol family. The SiH3OH2+ ion is generated in a silane/water plasma expansion, and its structure is derived from the IR photodissociation (IRPD) spectrum of its Ar cluster measured in a tandem mass spectrometer. The chemical bonding in SiH3OH2+ is analyzed by density functional theory (DFT) calculations, providing detailed insight into the nature of the dative H3Si+-OH2 bond. Comparison with protonated methanol illustrates the differences in bonding between carbon and silicon, which are mainly related to their different electronegativity and the different energy of the vacant valence pz orbital of SiH3+ and CH3+.Nachweis von protoniertem Monosilanol: Das IR-Spektrum von protoniertem Silanol, SiH3OH2+, wurde aus der resonanten IR-Photodissoziation schwach gebundener SiH3OH2+⋅Ar-Cluster abgeleitet. Seine Analyse ermöglicht die spektroskopische Charakterisierung dieses kleinsten Silanol-Kations. Das Ergebnis deutet auf eine dative Bindung von H2O an SiH3+ hin.
      PubDate: 2018-02-09T03:55:40.170183-05:
      DOI: 10.1002/ange.201712999
       
  • Kohlenhydratresponsive Oberflächenhaftung basierend auf dynamisch
           
    • Authors: Sebastian Lamping; Tobias Otremba, Bart Jan Ravoo
      Abstract: Ein Kleber, dessen starke Haftfähigkeit (2.38 kg) auf dynamisch kovalenter Chemie beruht, welche zudem wasserbeständig und durch Kohlenhydrateinfluss schaltbar ist, wird vorgestellt. Zu diesem Zweck wurden Glas- und Siliciumoberflächen mithilfe der oberflächeninitiierten radikalischen Atomtransferpolymerisation (surface-induced atom transfer radical polymerization, SI-ATRP) mit Copolymeren, die zum einen Phenylboronsäuren und zum anderen Catechole enthielten, funktionalisiert. Nach Strukturierung mit Mikrokontaktdruck (microcontact printing, μCP) wird aus den Polymerbürsten ein kohlenhydratresponsiver supramolekularer “Klettverschluss” erhalten.Verklebt und gelöst: Die Kombination von oberflächeninitiierter radikalischer Atomtransferpolymerisation und dynamischer kovalenter Chemie von Phenylboronsäuren und Catecholen führt zu einer supramolekularen Oberflächenhaftung. Die Oberflächenhaftung ist robust (2.38 kg cm−2), wasserbeständig und wiederverwendbar, aber löst sich nach Zugabe eines Kohlenhydrates.
      PubDate: 2018-02-09T02:28:07.975157-05:
      DOI: 10.1002/ange.201711529
       
  • Eine pericyclische Reaktionskaskade in der Leporin-Biosynthese
    • Authors: Anna Glöckle; Tobias A. M. Gulder
      Abstract: Alle Wege führen nach Rom: Die Biosynthese der Leporine in Aspergillus sp. enthält eine neue pericyclische Reaktionskaskade. Das Enzym LepI steuert die Periselektivität einer [4+2]-Cycloaddition in Richtung einer hetero-Diels-Alder-Reaktion zum Leporin-Gerüst. Das Diels-Alder-Nebenprodukt wird zudem durch eine LepI-katalysierte retro-Claisen-Umlagerung in das Leprin-Gerüst umgewandelt. Daraus ergibt sich eine effiziente, kinetische Produktrezyklierung.
      PubDate: 2018-02-08T05:12:13.608213-05:
      DOI: 10.1002/ange.201800629
       
  • Titelbild: A 3D Nanostructured Hydrogel-Framework-Derived High-Performance
           Composite Polymer Lithium-Ion Electrolyte (Angew. Chem. 8/2018)
    • Authors: Jiwoong Bae; Yutao Li, Jun Zhang, Xingyi Zhou, Fei Zhao, Ye Shi, John B. Goodenough, Guihua Yu
      Pages: 2025 - 2025
      Abstract: Keramische Gerüste …. … mit dreidimensionaler Nanostruktur steigern die Leistung von Kompositpolymer-Elektrolyten in Lithiumbatterien. In ihrer Zuschrift auf S. 2118 leiten G. Yu et al. ein keramisches Gerüst mit 3D-Nanostruktur von einem Hydrogel ab und vereinen es mit einem Polymer zu einer flexiblen Elektrolytmembran mit perkoliertem Netzwerk. Die kontinuierliche Interphase verbessert die Lithiumionenleitfähigkeit, und der hohe Keramikanteil wirkt stabilisierend bei elektrochemischer und thermischer Belastung.
      PubDate: 2018-02-02T02:53:09.972465-05:
      DOI: 10.1002/ange.201800929
       
  • Innentitelbild: Z-Scheme Photocatalytic Water Splitting on a 2D
           Heterostructure of Black Phosphorus/Bismuth Vanadate Using Visible Light
           (Angew. Chem. 8/2018)
    • Authors: Mingshan Zhu; Zhichao Sun, Mamoru Fujitsuka, Tetsuro Majima
      Pages: 2026 - 2026
      Abstract: Die spontane solarbetriebene Spaltung von Wasser in H2 und O2, also die Umwandlung von Sonnenenergie in chemische Energie, ist Gegenstand intensiver Forschungen. M. Fujitsuka, T. Majima et al. präsentieren in ihrer Zuschrift auf S. 2182 eine zweidimensionale Heterostruktur aus schwarzem Phosphor und Bismutvanadat für die photokatalytische Wasserspaltung mit sichtbarem Licht ohne Opferreagentien. Die Bandstrukturen im Z-Schema tragen zur effektiven Ladungstrennung bei.
      PubDate: 2018-01-31T03:09:42.714119-05:
      DOI: 10.1002/ange.201800579
       
  • Graphisches Inhaltsverzeichnis: Angew. Chem. 8/2018
    • Pages: 2029 - 2040
      PubDate: 2018-02-13T05:12:37.140719-05:
      DOI: 10.1002/ange.201880811
       
  • Top-Beiträge aus unseren Schwesterzeitschriften: Angew. Chem. 8/2018
    • Pages: 2042 - 2045
      PubDate: 2018-02-13T05:12:36.45588-05:0
      DOI: 10.1002/ange.201880813
       
  • Preise der Chemical Research Society of India 2018
    • Pages: 2047 - 2048
      PubDate: 2018-01-26T07:31:12.95183-05:0
      DOI: 10.1002/ange.201800332
       
  • Antikörpergerichtete Therapien: Quo vadis'
    • Authors: Tiago Rodrigues; Gonçalo J. L. Bernardes
      Pages: 2050 - 2052
      Abstract: Weniger ist mehr: Die Wirksamkeit von Antikörper-Wirkstoff-Konjugaten (ADCs) für die Krebstherapie wird für gewöhnlich mit spaltbaren Linkern für die Wirkstofffreisetzung in Verbindung gebracht. Hinweise sprechen nun dafür, dass einfachere Konstrukte ohne spaltbare Gruppen stabilere und wirksamere ADCs darstellen können.
      PubDate: 2018-01-17T08:45:49.854341-05:
      DOI: 10.1002/ange.201712185
       
  • Wellenlängengesteuerte dynamische kovalente Chemie
    • Authors: Hendrik Frisch; David E. Marschner, Anja S. Goldmann, Christopher Barner-Kowollik
      Pages: 2054 - 2064
      Abstract: Chemische Reaktionen werden klassisch über die Auswahl funktioneller Gruppen und die Kontrolle externer Faktoren wie Temperatur oder Katalysatoren gesteuert. Die Nutzung von lichtgesteuerten Reaktionen ermöglicht darüber hinaus nicht nur eine sehr präzise zeitliche und ortsaufgelöste Kontrolle, sondern auch das Ansteuern hoch spezifischer Reaktionskanäle durch die Verwendung geeigneter Wellenlängen und Intensitäten, sodass kovalente Bindungen gezielt geknüpft und gebrochen werden können. Dieses Potenzial lässt sich anhand photoreversibler Cycloadditionen, bestehend aus reversiblen Cyclisierungen und Cycloreversionen, verdeutlichen. Dieser Aufsatz stellt die Herausforderungen bei der Anwendung von photochemischen Cycloadditionen vor, sowie die notwendigen Schritte, um ihr volles Potenzial in den Bereichen der Molekularbiologie, biomimetischer Systeme, der 3D-Stereolithographie und weicher Materie mit reprogrammierbaren und selbstheilenden Eigenschaften zu nutzen.Perfekt ferngesteuerte, selektive chemische Reaktionen unter der Einwirkung von Licht mit bestimmter Wellenlänge und Intensität sind bisher ein noch unerfüllter Traum. Hier werden die Herausforderungen bei der Anwendung des Konzepts auf reversible Photocycloadditionen erläutert, und es wird diskutiert, wie dieser Traum realisiert werden kann.
      PubDate: 2018-01-16T02:50:38.697627-05:
      DOI: 10.1002/ange.201709991
       
  • Von der Präzisionssynthese von Blockcopolymeren zu Eigenschaften und
           Anwendungen von funktionellen Nanopartikeln
    • Authors: Xiao Li; James Iocozzia, Yihuang Chen, Shiqiang Zhao, Xun Cui, Wei Wang, Haifeng Yu, Shaoliang Lin, Zhiqun Lin
      Pages: 2066 - 2093
      Abstract: Anorganische Nanopartikel haben sich aufgrund ihrer besonderen Eigenschaften auf zahlreichen Gebieten zu einem Forschungsschwerpunkt entwickelt. Die Steuerung der Größe und Form von Nanopartikeln ist ein wesentlicher Aspekt ihrer Synthese. Die Herstellung von anorganischen Nanopartikeln mithilfe von Blockcopolymer-Templaten ist einer der sichersten Wege zur Einstellung der Größe und Form von Nanopartikeln mit hoher Präzision. In diesem Aufsatz erörtern wir die neuesten Fortschritte bei der Entwicklung von Blockcopolymer-Templaten für die Herstellung von sphärischen anorganischen Nanopartikeln, die kompakte, hohle und Kern-Schale-Nanopartikel umfassen. Als Template dienen zum einen Micellen, die durch Selbstorganisation von linearen Blockcopolymeren gebildet werden, und zum anderen unimolekulare sternförmige Blockcopolymere. Neben der präzisen Steuerung der Größe und Morphologie werden auch nützliche Eigenschaften und Anwendungen solcher anorganischer Nanopartikel angesprochen.Stabilität und eine präzise einstellbare Größe sind entscheidend, um die vorteilhaften Eigenschaften von anorganischen Nanopartikeln auszuschöpfen. Die Synthese sphärischer Nanopartikel mit kompakter, hohler und Kern-Schale-Struktur mithilfe linearer und unimolekularer sternförmiger Blockcopolymer-Template wird erörtert. Es wird aufgezeigt, wie ihre Größe und Form gesteuert werden können und welche Eigenschaften und Anwendungen sich ergeben.
      PubDate: 2018-01-15T04:31:35.282368-05:
      DOI: 10.1002/ange.201705019
       
  • Folding DNA into a Lipid-Conjugated Nanobarrel for Controlled
           Reconstitution of Membrane Proteins
    • Authors: Yuanchen Dong; Shuobing Chen, Shijian Zhang, Joseph Sodroski, Zhongqiang Yang, Dongsheng Liu, Youdong Mao
      Pages: 2094 - 2098
      Abstract: Building upon DNA origami technology, we introduce a method to reconstitute a single membrane protein into a self-assembled DNA nanobarrel that scaffolds a nanodisc-like lipid environment. Compared with the membrane-scaffolding-protein nanodisc technique, our approach gives rise to defined stoichiometry, controlled sizes, as well as enhanced stability and homogeneity in membrane protein reconstitution. We further demonstrate potential applications of the DNA nanobarrels in the structural analysis of membrane proteins.Origami-Zylinder: Eine Methode zur Rekonstitution einzelner Membranproteine zu einem selbstorganisierten DNA-Nanofass mit Lipidumgebung wurde entwickelt. Das Potenzial der DNA-Nanofässer für die Strukturanalyse von Membranproteinen wird am Beispiel einer Einzelpartikelanalyse mit kryoelektronenmikoskopischer Bildgebung demonstriert.
      PubDate: 2018-01-09T07:40:52.088833-05:
      DOI: 10.1002/ange.201710147
       
  • 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 D. McMillen, Joseph W. Kolis
      Pages: 2099 - 2102
      Abstract: The structure of Cs3RESi6O15, where RE=Dy–Lu, Y, In, is unusual in that it contains octahedrally coordinated rare-earth ions; their 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 (ca. 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. Previous work showed for the smaller Sc3+ ion, the rotation of the octahedra is not sufficient to achieve closure at an integral repeat unit and an incommensurate structure results. The products 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.Caesium-Seltenerdmetall-Silicate der Zusammensetzung Cs3RE(Si6O15) (RE=Dy–Lu, Y, In) wurden synthetisiert und charakterisiert. Ihre Strukturen enthalten eine lange c-Achse (ca. 57 Å) und liefern ein vollständig geordnetes Modell für andere Alkalimetall-Seltenerdmetall-Silicate mit modulierten oder fehlgeordneten Strukturen.
      PubDate: 2018-02-01T05:32:54.334861-05:
      DOI: 10.1002/ange.201708798
       
  • C8N26H4: An Environmentally Friendly Primary Explosive with High Heat of
           Formation
    • Authors: Dan Chen; Hongwei Yang, Zhenxin Yi, Hualin Xiong, Lin Zhang, Shunguan Zhu, Guangbin Cheng
      Pages: 2103 - 2106
      Abstract: The synthesis and characterization of the metal-free polyazido compounds 3,6-bis-(2-(4,6-diazido-1,3,5-triazin-2-yl)-hydrazinyl)-1,2,4,5-tetrazine (2) and 3,6-bis-(2-(4,6-diazido-1,3,5-triazin-2-yl)-diazenyl)-1,2,4,5-tetrazine (4) are presented. Two compounds were characterized by NMR spectra, IR spectroscopy, mass spectrometry, and differential scanning calorimetry (DSC). Additionally, the structure of 2 was confirmed by single-crystal X-ray diffraction. Compounds 2 and 4 exhibit measured densities (1.755 g cm−3 and 1.763 g cm−3), good thermal stabilities (194 °C and 189 °C), high heat of formation (2114 kJ mol−1 and 2820 kJ mol−1), and excellent detonation performance (D, 8365 m s−1 and 8602 m s−1; P, 26.8 GPa and 29.4 GPa). Furthermore, compounds 2 and 4 have been tested for their priming ability to detonate RDX. The results indicate that the title compound 2 is a potential environmentally friendly alternative candidate to lead-based primary explosives.Energiereiche Polyazidoverbindungen wurden durch die N3-Funktionalisierung von Stickstoffheterocyclen hergestellt. Diese metallfreien Zündstoffe für den Explosivstoff RDX könnten Anwendungen als umweltverträgliche Primärsprengstoffe finden.
      PubDate: 2018-02-01T05:10:40.652441-05:
      DOI: 10.1002/ange.201711220
       
  • Design and Assembly of a Chiral Metallosalen-Based Octahedral Coordination
           Cage for Supramolecular Asymmetric Catalysis
    • Authors: Chunxia Tan; Jingjing Jiao, Zijian Li, Yan Liu, Xing Han, Yong Cui
      Pages: 2107 - 2112
      Abstract: Supramolecular containers featuring both high catalytic activity and high enantioselectivity represent a design challenge of practical importance. Herein, it is demonstrated that a chiral octahedral coordination cage can be constructed by using twelve enantiopure Mn(salen)-derived dicarboxylic acids as linear linkers and six Zn4-p-tert-butylsulfonylcalix[4]arene clusters as tetravalent four-connected vertices. The porous cage features a large hydrophobic cavity (≈3944 Å3) decorated with catalytically active metallosalen species and is shown to be an efficient and recyclable asymmetric catalyst for the oxidative kinetic resolution of racemic secondary alcohols and the epoxidation of olefins with up to>99 % enantiomeric excess. The cage architecture not only prevents intermolecular deactivation and stabilizes the Mn(salen) catalysts but also encapsulates substrates and concentrates reactants in the cavity, resulting in enhanced reactivity and enantioselectivity relative to the free metallosalen catalyst.Ein chiraler poröser Koordinationskäfig mit Oktaederform, bestehend aus zwölf enantiomerenreinen Mn(salen)-Dicarbonsäure-Einheiten als Kanten und sechs Zn4-p-tert-Butylsulfonylcalix[4]aren-Clustern als vierfach verknüpfte Ecken, ist ein mehrfach verwendbarer, effizienter Katalysator für die oxidative kinetische Racematspaltung sekundärer Alkohole und für die Olefin-Epoxidierung.
      PubDate: 2018-01-25T08:05:39.79118-05:0
      DOI: 10.1002/ange.201711310
       
  • Ion Specificity on Electric Energy Generated by Flowing Water Droplets
    • Authors: Junwoo Park; Suhwan Song, ChaeHo Shin, YoungJun Yang, Stefan A. L. Weber, Eunji Sim, Youn Sang Kim
      Pages: 2113 - 2117
      Abstract: The development of energy-conversion devices using water movement has actively progressed. Ionovoltaic devices, which are driven by ion dynamics, show ion specificity by which different ions with identical charges show different output performance. However, the ion specificity remains poorly understood because the influence of the ion species on generated electric signals is not elucidated. The ion specificity in electric signals induced by flowing water droplet was investigated in terms of its relationship with the potential profile across the solid–liquid interface.Spezifische Ausgabesignale liefert eine ionovoltaische Funktionseinheit, die durch einen Tröpfchenfluss angetrieben wird, für verschiedene Ionen mit identischer Ladung. Die Gründe für die Ionenspezifität an der Fest-flüssig-Grenzfläche wurden untersucht.
      PubDate: 2018-01-18T05:45:42.177248-05:
      DOI: 10.1002/ange.201711505
       
  • A 3D Nanostructured Hydrogel-Framework-Derived High-Performance Composite
           Polymer Lithium-Ion Electrolyte
    • Authors: Jiwoong Bae; Yutao Li, Jun Zhang, Xingyi Zhou, Fei Zhao, Ye Shi, John B. Goodenough, Guihua Yu
      Pages: 2118 - 2122
      Abstract: Solid-state electrolytes have emerged as a promising alternative to existing liquid electrolytes for next generation Li-ion batteries for better safety and stability. Of various types of solid electrolytes, composite polymer electrolytes exhibit acceptable Li-ion conductivity due to the interaction between nanofillers and polymer. Nevertheless, the agglomeration of nanofillers at high concentration has been a major obstacle for improving Li-ion conductivity. In this study, we designed a three-dimensional (3D) nanostructured hydrogel-derived Li0.35La0.55TiO3 (LLTO) framework, which was used as a 3D nanofiller for high-performance composite polymer Li-ion electrolyte. The systematic percolation study revealed that the pre-percolating structure of LLTO framework improved Li-ion conductivity to 8.8×10−5 S cm−1 at room temperature.Pfadfinder: Der Effekt der Perkolation auf die Leitfähigkeit von Polymerkompositelektrolyten wurde untersucht. Typische Nanopartikelagglomerate als Füllstoffe führen in hohen Konzentrationen zu diskontinuierlichen Lithiumionenpfaden. Ein Elektrolyt mit nanostrukturiertem Hydrogelnetzwerk ist deutlich leitfähiger, da er eine kontinuierliche Interphase bildet.
      PubDate: 2018-01-16T09:50:53.829767-05:
      DOI: 10.1002/ange.201710841
       
  • Total Synthesis of Aurofusarin: Studies on the Atropisomeric Stability of
           Bis-Naphthoquinones
    • Authors: Chao Qi; Wenyu Wang, Kyle D. Reichl, James McNeely, John A. Porco
      Pages: 2123 - 2126
      Abstract: An efficient annulation involving pyrone addition to a quinone and Dieckmann condensation was developed for rapid assembly of a γ-naphthopyrone monomeric precursor to the bis-naphthoquinone natural product aurofusarin. Dimerization was achieved through PdII-catalyzed dehydrogenative coupling. Further studies employing asymmetric nucleophilic epoxidation indicate that the atropisomers of aurofusarin and derivatives are not configurationally stable at ambient temperature.Schnell synthetisiert wurde eine γ-Naphthopyron-Vorstufe des Naturstoffs Aurofusarin über eine Sequenz aus Michael-Addition und Dieckmann-Reaktion. Eine PdII-katalysierte dehydrierende Kupplung mit anschließender selektiver Demethylierung führte zu dem Bis(naphthochinon) Aurofusarin. In weiteren Studien zeigte sich, dass die Atropisomere von Bis(methoxynaphthochinonen) wie Aurofusarin und dessen Derivate nicht konfigurationsstabil sind.
      PubDate: 2018-01-29T08:35:27.802767-05:
      DOI: 10.1002/ange.201711535
       
  • Easy-to-Attach/Detach Solubilizing-Tag-Aided Chemical Synthesis of an
           Aggregative Capsid Protein
    • Authors: Shugo Tsuda; Masayoshi Mochizuki, Hiroyuki Ishiba, Kumiko Yoshizawa-Kumagaye, Hideki Nishio, Shinya Oishi, Taku Yoshiya
      Pages: 2127 - 2131
      Abstract: A solubilizing Trt-K10 tag was developed for the effective chemical preparation of peptides/proteins with low solubility. The Trt-K10 tag comprises a hydrophilic oligo-Lys sequence and a trityl anchor, and can be selectively introduced to a side chain thiol of Cys of deprotected peptides/proteins with a trityl alcohol-type introducing reagent Trt(OH)-K10 under acidic conditions. Significantly, the ligation product in the reaction mixture of a thiol-additive-free native chemical ligation can be modified directly in a one-pot manner to facilitate the isolation of the product by high-performance liquid chromatography. Finally, the Trt-K10 tag can be readily removed with a standard trifluoroacetic acid cocktail. Using this easy-to-attach/detach tag-aided method, a hepatitis B virus capsid protein that is usually difficult to handle was synthesized successfully.Eine löslichkeitssteigernde Trt-K10-Markierung für die effektive Herstellung schlecht löslicher Peptide/Proteine durch native chemische Ligation (NCL) wurde entwickelt. Trt(OH)-K10 wurde selektiv mit der Thiolgruppe eines Cys-Restes umgesetzt. Mithilfe dieser leicht einführbaren und abspaltbaren Markierung wurde ein Capsid-Protein des Hepatitis-B-Virus synthetisiert, das auf anderem Wege schwer zugänglich ist.
      PubDate: 2018-01-25T08:06:44.740169-05:
      DOI: 10.1002/ange.201711546
       
  • Using a Multi-Shelled Hollow Metal–Organic Framework as a Host to Switch
           the Guest-to-Host and Guest-to-Guest Interactions
    • Authors: Xiao-Yuan Liu; Furui Zhang, Tian-Wei Goh, Yang Li, Yu-Cai Shao, Lianshun Luo, Wenyu Huang, Yi-Tao Long, Lien-Yang Chou, Chia-Kuang Tsung
      Pages: 2132 - 2136
      Abstract: A bio-inspired design of using metal–organic framework (MOF) microcrystals with well-defined multi-shelled hollow structures was used as a matrix to host multiple guests including molecules and nanoparticles at separated locations to form a hierarchical material, mimicking biological structures. The interactions such as energy transfer (ET) between different guests are regulated by precisely fixing them in the MOF shells or encapsulating them in the cavities between the MOF shells. The proof-of-concept design is demonstrated by hosting chromophore molecules including rhodamine 6G (R6G) and 7-amino-4-(trifluoromethyl)coumarin (C-151), as well as metal nanoparticles (Pd NPs) into the multi-shelled hollow zeolitic imidazolate framework-8 (ZIF-8). We could selectively establish or diminish the guest-to-framework and guest-to-guest ET. This work provides a platform to construct complex multifunctional materials, especially those need precise separation control of multi-components.Mikrokristalle aus Metall-organischen Gerüsten (MOF) mit mehrschaliger hohler Struktur sind ideale Matrices für die räumlich getrennte Aufnahme mehrere molekularer Gastspezies (z. B. der Farbstoffe R6G und C-151) und Nanopartikel. Über eine kontrollierte Lokalisierung konnte zwischen Gast-zu-Gitter- und Gast-zu-Gast-Energietransfer geschaltet werden.
      PubDate: 2018-01-26T03:35:31.804251-05:
      DOI: 10.1002/ange.201711600
       
  • Enantioselective Polyene Cyclization Catalyzed by a Chiral Brønsted
           Acid
    • Authors: Liwen Fan; Chunyu Han, Xuerong Li, Jiasheng Yao, Zhengning Wang, Chaochao Yao, Weihao Chen, Tao Wang, Junfeng Zhao
      Pages: 2137 - 2141
      Abstract: The first enantioselective polyene cyclization initiated by a BINOL-derived chiral N-phosphoramide (NPA) catalyzed protonation of an imine is described. The ion-pair formed between the iminium ion and chiral counter anion of the NPA plays an important role for controlling the stereochemistry of the overall transformation. This strategy offers a highly efficient approach to fused tricyclic frameworks containing three contiguous stereocenters, which are widely found in natural products. In addition, the first catalytic asymmetric total synthesis of (−)-ferruginol was accomplished with an NPA catalyzed enantioselective polyene cyclization, as the key step for the construction of the tricyclic core, with excellent yield and enantioselectivity.Ein zielstrebiges Paar: Die erste enantioselektive Polyencyclisierung, die durch eine BINOL-N-Phosphoramid(NPA)-katalysierte Protonierung eines Imins ausgelöst wird, wird beschrieben. Das Ionenpaar, das zwischen dem Iminiumion und chiralen Gegenion des NPA gebildet wird, spielt eine wichtige Rolle für die Stereochemie der Gesamtumwandlung. Die Methode wurde zur ersten katalytischen Totalsynthese von (−)-Ferruginol verwendet.
      PubDate: 2018-02-02T02:51:33.353409-05:
      DOI: 10.1002/ange.201711603
       
  • Autophagy Caught in the Act: A Supramolecular FRET Pair Based on an
           Ultrastable Synthetic Host–Guest Complex Visualizes
           Autophagosome–Lysosome Fusion
    • Authors: Meng Li; Ara Lee, Kyung Lock Kim, James Murray, Annadka Shrinidhi, Gihyun Sung, Kyeng Min Park, Kimoon Kim
      Pages: 2142 - 2147
      Abstract: A supramolecular FRET pair based on the ultrahigh binding affinity between cyanine 3 conjugated cucurbit[7]uril (CB[7]-Cy3) and cyanine 5 conjugated adamantylamine (AdA-Cy5) was exploited as a new synthetic tool for imaging cellular processes in live cells. Confocal laser scanning microscopy revealed that CB[7]-Cy3 and AdA-Cy5 were intracellularly translocated and accumulated in lysosomes and mitochondria, respectively. CB[7]-Cy3 and AdA-Cy5 then formed a host–guest complex, reported by a FRET signal, as a result of the fusion of lysosomes and mitochondria. This observation not only indicated that CB[7] forms a stable complex with AdA in a live cell, but also suggested that this FRET pair can visualize dynamic organelle fusion processes, such as those involved in the degradation of mitochondria through autophagy (mitophagy), by virtue of its small size, chemical stability, and ease of use.Auf frischer Tat: Ein stabiles synthetisches Bindungspaar wurde entwickelt und als supramolekularer FRET-Marker eingesetzt. Die einzelnen FRET-Komponenten werden in unterschiedliche Organellen transloziert, deren Zusammentreffen dann über ein FRET-Signal als Schritt im Autophagieprozess beobachtet werden kann (siehe Bild).
      PubDate: 2018-02-01T07:01:32.279401-05:
      DOI: 10.1002/ange.201711629
       
  • Utilization of Donor–Acceptor Interactions for the Catalytic
           Acceleration of Nucleophilic Additions to Aromatic Carbonyl Compounds
    • Authors: Tatsuhiro Uchikura; Kosuke Ono, Kohei Takahashi, Nobuharu Iwasawa
      Pages: 2152 - 2155
      Abstract: A conceptually new method for the catalytic electrophilic activation of aromatic carbonyl substrates, by utilizing donor–acceptor interactions between an electron-deficient macrocyclic boronic ester host ([2+2]BTH-F) and an aromatic carbonyl guest substrate, was realized. In the presence of a catalytic amount of [2+2]BTH-F, dramatic acceleration of the nucleophilic addition of a ketene silyl acetal towards either electron-rich aromatic aldehydes or ketones was achieved. Several control experiments confirmed that inclusion of the aromatic substrates within [2+2]BTH-F, through efficient donor–acceptor interactions, is essential for the acceleration of the reaction.Hilfreicher Wirt: Ein neues Konzept zur katalytischen elektrophilen Aktivierung aromatischer Carbonylsubstrate beruht auf Donor-Akzeptor-Wechselwirkungen mit einem elektronenarmen makrocyclischen Boronsäureester, der als Wirt auftritt.
      PubDate: 2018-01-26T03:30:56.494459-05:
      DOI: 10.1002/ange.201711726
       
  • Stereodivergent Synthesis of Tetrahydrofuroindoles through Pd-Catalyzed
           Asymmetric Dearomative Formal [3+2] Cycloaddition
    • Authors: Qiang Cheng; Fang Zhang, Yue Cai, Yin-Long Guo, Shu-Li You
      Pages: 2156 - 2160
      Abstract: A stereodivergent synthesis of tetrahydrofuroindoles through palladium-catalyzed asymmetric dearomative formal [3+2] cycloaddition of nitroindoles with epoxybutenes was developed. The polarity of the solvent was found to play a key role in the diastereoselectivity. In toluene, good to excellent yields (70–99 %), diastereoselectivity (87/13->95/5 d.r.), and enantioselectivity (85/15–94/6 e.r.) were obtained, regardless of the properties of the substituents on nitroindoles. In acetonitrile, tetrahydrofuroindoles of a different diastereoisomer were produced with good to excellent yields (75–98 %) and stereoselectivity (78/22–93/7 d.r., 93/7–99/1 e.r.). Mechanistic studies were conducted to illustrate the origin of the diastereodivergency. The kinetic experiments indicate that the rate-determining step of this reaction is different in different solvents. ESI-MS experiments also support the existence of key palladium complex intermediates and the catalytic cycle of the reaction.Am Scheideweg: Eine stereodivergente Synthese von Tetrahydrofuroindolen über die palladiumkatalysierte asymmetrische desaromatisierende formale [3+2]-Cycloaddition von Nitroindolen mit Epoxybutenen wurde entwickelt. Die Polarität des Lösungsmittels beeinflusst die Diastereoselektivität: Toluol ergibt ein Diastereomer, Acetonitril ein anderes.
      PubDate: 2018-01-26T07:35:39.348055-05:
      DOI: 10.1002/ange.201711873
       
  • Light-Driven Shape-Memory Porous Films with Precisely Controlled
           Dimensions
    • Authors: Wei Wang; Dingfeng Shen, Xiao Li, Yuan Yao, Jiaping Lin, Aurelia Wang, Jiwoo Yu, Zhong Lin Wang, Suck Won Hong, Zhiqun Lin, Shaoliang Lin
      Pages: 2161 - 2165
      Abstract: Shape-memory polymers (SMPs) are an intriguing class of smart materials possessing reversible shape change and recovery capabilities. Effective routes to shape-memory porous films (SMPFs) are few and limited in scope owing to the difficulty in manipulating the shape change of pores by conventional methods. Herein we report an unconventional strategy for crafting light-driven SMPFs by judiciously constructing highly ordered porous films via a facile “breath figure” approach, followed by sequential vapor crosslinking and nondestructive directional light manipulation. Micropores can thus be transformed into other shapes including rectangle, rhombus and size-reduced micropores at room temperature. The transformed micropores can be reverted to their original shapes by either thermal annealing or UV irradiation. As such, this strategy expands the rich diversity of SMPs accessible.Ein unkonventioneller Ansatz liefert durch Licht steuerbare poröse Filme mit Formgedächtnis. Hoch geordnete poröse Filme werden dabei über ein Kondensationsmuster aufgebaut, gefolgt von einer Dampfvernetzung und zerstörungsfreier Ausrichtung mit linear polarisiertem Licht (LPL).
      PubDate: 2018-01-29T08:46:42.000479-05:
      DOI: 10.1002/ange.201712100
       
  • From Intramolecular (Circular) in an Isolated Molecule to Intermolecular
           Hole Delocalization in a Two-Dimensional Solid-State Assembly: The Case of
           Pillarene
    • Authors: Maxim V. Ivanov; Denan Wang, Tushar S. Navale, Sergey V. Lindeman, Rajendra Rathore
      Pages: 2166 - 2171
      Abstract: To achieve long-range charge transport/separation and, in turn, bolster the efficiency of modern photovoltaic devices, new molecular scaffolds are needed that can self-assemble in two-dimensional (2D) arrays while maintaining both intra- and intermolecular electronic coupling. In an isolated molecule of pillarene, a single hole delocalizes intramolecularly via hopping amongst the circularly arrayed hydroquinone ether rings. The crystallization of pillarene cation radical produces a 2D self-assembly with three intermolecular dimeric (sandwich-like) contacts. Surprisingly, each pillarene in the crystal lattice bears a fractional formal charge of +1.5. This unusual stoichiometry of oxidized pillarene in crystals arises from effective charge distribution within the 2D array via an interplay of intra- and intermolecular electronic couplings. This important finding is expected to help advance the rational design of efficient solid-state materials for long-range charge transfer.Nichtganzzahlige Ladungen im Festkörper: Das Pillar[5]aren-Radikalkation bildet Kristalle mit einer zweidimensionalen Anordnung, in der die Moleküle jeweils drei Sandwich-artige intermolekulare Kontakte eingehen. Jedes Pillaren im Kristallgitter trägt formal eine Ladung von +1.5.
      PubDate: 2018-02-01T05:11:51.898043-05:
      DOI: 10.1002/ange.201712159
       
  • Cation-Tuned Synthesis of Fluorooxoborates: Towards Optimal
           Deep-Ultraviolet Nonlinear Optical Materials
    • Authors: Ying Wang; Bingbing Zhang, Zhihua Yang, Shilie Pan
      Pages: 2172 - 2176
      Abstract: The development of new nonlinear optical (NLO) materials for deep-ultraviolet (DUV) applications is in great demand. However, the synthesis of an ideal DUV NLO crystal is a serious challenge. Herein, three new alkali-metal fluorooxoborates, AB4O6F (A=K, Rb, and Cs, and a mixed cation between two of them), were successfully synthesized by cation regulation. It is found that all reported compounds exhibit short UV absorption edges (
      PubDate: 2018-01-18T05:45:33.091896-05:
      DOI: 10.1002/ange.201712168
       
  • Visible-Light-Mediated Decarboxylative Radical Additions to Vinyl Boronic
           Esters: Rapid Access to γ-Amino Boronic Esters
    • Authors: Adam Noble; Riccardo S. Mega, Daniel Pflästerer, Eddie L. Myers, Varinder K. Aggarwal
      Pages: 2177 - 2181
      Abstract: The synthesis of alkyl boronic esters by direct decarboxylative radical addition of carboxylic acids to vinyl boronic esters is described. The reaction proceeds under mild photoredox catalysis and involves an unprecedented single-electron reduction of an α-boryl radical intermediate to the corresponding anion. The reaction is amenable to a diverse range of substrates, including α-amino, α-oxy, and alkyl carboxylic acids, thus providing a novel method to rapidly access boron-containing molecules of potential biological importance.Mild und direkt: Die Synthese von Alkylboronsäureestern durch direkte decarboxylierende Radikaladdition von Carbonsäuren an Vinylboronsäureester verläuft unter milder Photoredoxkatalyse und ist auf vielfältige Substrate anwendbar, darunter α-Amino-, α-Oxy- und Alkylcarbonsäuren.
      PubDate: 2018-01-26T04:20:33.570348-05:
      DOI: 10.1002/ange.201712186
       
  • Z-Scheme Photocatalytic Water Splitting on a 2D Heterostructure of Black
           Phosphorus/Bismuth Vanadate Using Visible Light
    • Authors: Mingshan Zhu; Zhichao Sun, Mamoru Fujitsuka, Tetsuro Majima
      Pages: 2182 - 2186
      Abstract: Spontaneously solar-driven water splitting to produce H2 and O2, that is, the conversion of solar energy to chemical energy is a dream of mankind. However, it is difficult to make overall water splitting feasible without using any sacrificial agents and external bias. Drawing inspiration from nature, a new artificial Z-scheme photocatalytic system has been designed herein based on the two-dimensional (2D) heterostructure of black phosphorus (BP)/bismuth vanadate (BiVO4). An effective charge separation makes possible the reduction and oxidation of water on BP and BiVO4, respectively. The optimum H2 and O2 production rates on BP/BiVO4 were approximately 160 and 102 μmol g−1 h−1 under irradiation of light with a wavelength longer than 420 nm, without using any sacrificial agents or external bias.Grenzflächen-Elektronentransfer: Die photokatalytische Spaltung von Wasser ohne Opferagens wurde unter Einstrahlung von sichtbarem Licht an einer zweidimensionalen Heterostruktur aus schwarzem Phosphor (BP) und Bismutvanadat (BiVO4) beobachtet. Die Z-Schema-Bandstruktur trägt zur effektiven Ladungstrennung bei, sodass Reduktion und Oxidation von Wasser an BP und BiVO4 möglich sind.
      PubDate: 2018-01-09T07:35:35.710781-05:
      DOI: 10.1002/ange.201711357
       
  • Evaluation of the Stability of DNA i-Motifs in the Nuclei of Living
           Mammalian Cells
    • Authors: Simon Dzatko; Michaela Krafcikova, Robert Hänsel-Hertsch, Tomas Fessl, Radovan Fiala, Tomas Loja, Daniel Krafcik, Jean-Louis Mergny, Silvie Foldynova-Trantirkova, Lukas Trantirek
      Pages: 2187 - 2191
      Abstract: C-rich DNA has the capacity to form a tetra-stranded structure known as an i-motif. The i-motifs within genomic DNA have been proposed to contribute to the regulation of DNA transcription. However, direct experimental evidence for the existence of these structures in vivo has been missing. Whether i-motif structures form in complex environment of living cells is not currently known. Herein, using state-of-the-art in-cell NMR spectroscopy, we evaluate the stabilities of i-motif structures in the complex cellular environment. We show that i-motifs formed from naturally occurring C-rich sequences in the human genome are stable and persist in the nuclei of living human cells. Our data show that i-motif stabilities in vivo are generally distinct from those in vitro. Our results are the first to interlink the stability of DNA i-motifs in vitro with their stability in vivo and provide essential information for the design and development of i-motif-based DNA biosensors for intracellular applications.DNA-Live-Übertragung: Die Stabilität von DNA-i-Motiven, gebildet aus natürlichen C-reichen Sequenzen im Humangenom, wurde in den Zellkernen lebender menschlicher Zellen studiert. Ein reversibler Faltungs-Entfaltungs-Zyklus wurde nachgewiesen, und die (thermodynamische) Stabilität der DNA-i-Motive in vitro und in vivo wurde in Zusammenhang gesetzt.
      PubDate: 2018-01-29T08:40:44.278973-05:
      DOI: 10.1002/ange.201712284
       
  • An Efficient Method for the Conjugation of Hydrophilic and Hydrophobic
           Components by Solid-Phase-Assisted Disulfide Ligation
    • Authors: Kyohei Muguruma; Takuya Shirasaka, Daichi Akiyama, Kentarou Fukumoto, Akihiro Taguchi, Kentaro Takayama, Atsuhiko Taniguchi, Yoshio Hayashi
      Pages: 2192 - 2195
      Abstract: Chemical conjugation between hydrophilic and hydrophobic components is difficult because of their extremely different solubility. Herein, we report a new versatile method with a solid-phase-assisted disulfide ligation to overcome the difficulty of conjugation attributed to solubility. The method involves two steps in a one-pot process: 1) loading of a hydrophobic molecule onto a resin in an organic solvent, and 2) release of the solid-supported hydrophobic molecule as a conjugate with a hydrophilic molecule into an aqueous solvent. This strategy allows the use of a suitable solvent system for the substrates in each step. Conjugates of a water-insoluble drug, plinabulin, with hydrophilic carriers that could not be prepared by solution-phase reactions were obtained in moderate yields (29–45 %). This strategy is widely applicable to the conjugation of compounds with solubility problems.Disulfidligation an der Festphase umgeht löslichkeitsbedingte Schwierigkeiten bei der Konjugation hydrophiler mit hydrophoben Komponenten. Konjugate des schlecht wasserlöslichen Modellwirkstoffs Plinabulin mit verschiedenen hydrophilen Trägern wurden auf diese Weise in mäßigen Ausbeuten erhalten.
      PubDate: 2018-01-19T04:35:27.407599-05:
      DOI: 10.1002/ange.201712324
       
  • Direct Synthesis of Polysubstituted Aldehydes via Visible-Light Catalysis
    • Authors: Fengjin Wu; Leifeng Wang, Jiean Chen, David A. Nicewicz, Yong Huang
      Pages: 2196 - 2200
      Abstract: Aldehydes are among the most versatile functional groups for synthetic chemistry. However, access to polysubstituted alkyl aldehydes is very limited and requires lengthy synthetic routes that involve multiple-step functional-group conversion. This paper reports a one-step synthesis of polysubstituted aldehydes from readily available olefin substrates using visible-light photoredox catalysis. Despite a number of competing reaction pathways, commercial styrenes react with vinyl ethers selectively in the presence of an acridinium salt photooxidant and a disulfide hydrogen-atom-transfer catalyst under blue LED irradiation. Alkyl aldehydes with different substitution patterns are prepared in good yields. This strategy can be applied to structurally sophisticated substrates.Kommerzielle Styrole reagieren mit Vinylethern in Gegenwart eines Acridiniumsalzes als Photooxidationsmittel und eines Disulfids als H-Atomtransfer-Katalysator unter Bestrahlung mit blauem LED-Licht in einer Stufe selektiv zu polysubstituierten Aldehyden. Diese Strategie lässt sich auf strukturell anspruchsvolle Substrate anwenden.
      PubDate: 2018-01-24T04:05:46.836238-05:
      DOI: 10.1002/ange.201712384
       
  • N-Substituted Hydrazones by Manganese-Catalyzed Coupling of Alcohols with
           Hydrazine: Borrowing Hydrogen and Acceptorless Dehydrogenation in One
           System
    • Authors: Uttam Kumar Das; Yehoshoa Ben-David, Yael Diskin-Posner, David Milstein
      Pages: 2201 - 2204
      Abstract: An unprecedented one-step synthesis of N-substituted hydrazones by coupling of alcohols with hydrazine is reported. This partial hydrogen-borrowing reaction is catalyzed by a new manganese pincer complex under mild reaction conditions, thus liberating water and dihydrogen as the only byproducts. Mechanistic insight, based on the observation of intermediates, is provided.In einer Stufe werden N-substituierte Hydrazone durch Kupplung von Alkoholen mit Hydrazin synthetisiert. Diese Kombination von Wasserstoff-Autotransfer und akzeptorfreier Dehydrierung wird durch einen Mangan-Pincer-Komplex katalysiert. Die Reaktion läuft unter milden Bedingungen ab und liefert nur Wasser und Diwasserstoff als Koppelprodukte.
      PubDate: 2018-01-29T08:40:28.730482-05:
      DOI: 10.1002/ange.201712593
       
  • p–π Conjugated Polymers Based on Stable Triarylborane with n-Type
           Behavior in Optoelectronic Devices
    • Authors: Bin Meng; Yi Ren, Jun Liu, Frieder Jäkle, Lixiang Wang
      Pages: 2205 - 2209
      Abstract: p–π conjugation with embedded heteroatoms offers unique opportunities to tune the electronic structure of conjugated polymers. An approach is presented to form highly electron-deficient p–π conjugated polymers based on triarylboranes, demonstrate their n-type behavior, and explore device applications. By combining alternating [2,4,6-tris(trifluoromethyl)phenyl]di(thien-2-yl)borane (FBDT) and electron-deficient isoindigo (IID)/pyridine-flanked diketopyrrolopyrrole (DPPPy) units, we achieve low-lying lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) energy levels, high electron mobilities, and broad absorptions in the visible region. All-polymer solar cells with these polymers as electron acceptors exhibit encouraging photovoltaic performance with power conversion efficiencies of up to 2.83 %. These results unambiguously prove the n-type behavior and demonstrate the photovoltaic applications of p–π conjugated polymers based on triarylborane.Plastiksolarzellen: Eine Route zu p-π-konjugierten Organoboranpolymeren mit stark erhöhtem Akzeptorcharakter wurde entwickelt. Sehr niedrige LUMO/HOMO-Niveaus und hohe Elektronenbeweglichkeiten werden erreicht, was Anwendungen als effiziente Elektronenakzeptoren in Polymersolarzellen nahelegt.
      PubDate: 2018-02-01T05:06:00.236376-05:
      DOI: 10.1002/ange.201712598
       
  • An Isolable Phosphaethynolatoborane and Its Reactivity
    • Authors: Daniel W. N. Wilson; Alexander Hinz, Jose M. Goicoechea
      Pages: 2210 - 2215
      Abstract: The synthesis and characterization of a stable phosphaethynolatoborane, [B]OCP (1, [B]=N,N′-bis(2,6-diisopropylphenyl)-2,3-dihydro-1H-1,3,2-diazaboryl), is described. The increased triple bond character of the P−C bond in 1 relative to the free ion (PCO−) is probed in a series of reactivity studies. Compound 1 readily dimerises in donor solvents to afford a cyclic five-membered 6π-aromatic compound, cyclo-P2{C[B]}O{CO[B]} (2), which decarbonylates on UV irradiation. By contrast the nickel-mediated dimerisation of 1 affords the isomeric diphosphacyclobutene [P(CO[B])]2. When 1 is reacted with organolithium reagents such as MesLi (Mes=2,4,6-trimethylphenyl), the boryl moiety shifts and the formation of the lithoxy-boryl-phosphaalkene [LiOC[B]P(Mes)]2 was observed. The reactivity of this species towards electrophiles is also described.BOCParty: Die Synthese, Charakterisierung und Reaktivität des beständigen Phosphaethinolatoborans [B]OCP (1) werden beschrieben. [B]=N,N′-Bis(2,6-diisopropylphenyl)-2,3-dihydro-1H-1,3,2-diazaboryl.
      PubDate: 2018-01-25T08:10:54.675611-05:
      DOI: 10.1002/ange.201712624
       
  • Reversible Phase Transition of Robust Luminescent Hybrid Hydrogels
    • Authors: Zhiqiang Li; Guannan Wang, Yige Wang, Huanrong Li
      Pages: 2216 - 2220
      Abstract: We report herein on remote control over a reversible phase transition of robust luminescent hybrid hydrogels as enabled by the rational selection and incorporation of photoswitches. Azobenzene units functionalized with a guanidinium group were utilized as the photoswitches and incorporated through a host–guest inclusion method involving α-cyclodextrins functionalized with 2,6-pyridinedicarboxylic acid (PDA) groups. While the guanidinium functional groups bind to the negatively charged Laponite matrix surface to connect organic and inorganic components, the PDA groups enable simultaneous coordination with different lanthanide metal ions, thus rendering the hydrogel broadly luminescent. Owing to its conformation-dependent binding behavior with α-cyclodextrin, the isomerization of azobenzene induced association or dissociation of the inclusion complexes and thus lead to a reversible photocontrolled solgel phase transition of the luminescent hybrid hydrogels.Die Fernsteuerung eines reversiblen Sol-Gel-Phasenübergangs eines robusten lumineszierenden Hybridhydrogels (siehe Bild) wurde durch den Einbau einer photoschaltbaren Wirt-Gast-Einschlussverbindung in das Hydrogelsystem ermöglicht. Guanidiniumgruppen an den Azobenzol-Gästen binden an eine Laponitmatrix, während Pyridindicarbonsäuregruppen am α-Cyclodextrin-Wirt an Lanthanoidionen koordinieren, wodurch das Hydrogel in einem breiten Bereich lumineszierend wird.
      PubDate: 2018-01-18T08:01:49.906346-05:
      DOI: 10.1002/ange.201712670
       
  • A Zeolite Family Nonjointly Built from the 1,3-Stellated Cubic Building
           Unit
    • Authors: Donghui Jo; Gi Tae Park, Jiho Shin, Suk Bong Hong
      Pages: 2221 - 2225
      Abstract: From a technological point of view, the synthesis of new high-silica zeolites is of prime importance owing to their high potential as industrial catalysts and catalyst supports. Two such materials have been synthesized which are made up of the 1,3-stellated cubic unit (hexahedral ([4254]) bre unit) as a secondary building unit, with the aid of existing imidazolium-based structure-directing agents under “excess fluoride” conditions. One of them, denoted PST-21, is the first aluminosilicate zeolite consisting of 9-ring apertures solely; it displays exceptional activity towards steering the skeletal isomerization of 1-butene to isobutene and bridges the gap between small- and medium-pore structures. A series of hypothetical structures are also described that are nonjointly built from the bre unit; all of these structures are chemically feasible and will thus be helpful in designing the synthesis of novel zeolites containing 9-ring and/or 10-ring channels.Alles neu macht die Neun: PST-21, ein Alumosilikat-Zeolith, der ausschließlich 9-Ring-Kanäle enthält, und PST-22, mit sowohl 10- als auch 8-Ring-Poren, wurden mithilfe von methylsubstituierten Imidazolium-Kationen in Gegenwart eines Fluoridüberschusses synthetisiert. PST-21 ist außergewöhnlich reaktiv und selektiv in der Isomerisierung von 1-Buten.
      PubDate: 2018-01-29T04:02:37.634927-05:
      DOI: 10.1002/ange.201712885
       
  • Tetrablock Metallopolymer Electrochromes
    • Authors: Haibin Gu; Roberto Ciganda, Patricia Castel, Sergio Moya, Ricardo Hernandez, Jaime Ruiz, Didier Astruc
      Pages: 2226 - 2230
      Abstract: Multi-block polymers are highly desirable for their addressable functions that are both unique and complementary among the blocks. With metal-containing polymers, the goal is even more challenging insofar as the metal properties may considerably extend the materials functions to sensing, catalysis, interaction with metal nanoparticles, and electro- or photochrome switching. Ring-opening metathesis polymerization (ROMP) has become available for the formation of living polymers using highly efficient initiators such as the 3rd generation Grubbs catalyst [RuCl2(NHC)(=CHPh)(3-Br-C5H4N)2], 1. Among the 24 possibilities to introduce 4 blocks of metallopolymers into a tetrablock metallocopolymer by ROMP using the catalyst 1, two viable pathways are disclosed. The synthesis, characterization, electrochemistry, electron-transfer chemistry, and remarkable electrochromic properties of these new nanomaterials are presented.Zwei Vierblockmetallocopolymere aus polymeren Norbornen-Derivaten mit vier verschiedenen robusten Metallocen-Redoxzentren in den Seitenketten wurden mithilfe von ROMP aufgebaut. Beim Einsatz geeigneter Redoxreagentien zeigten die Polymere ausgedehnte Redoxkaskaden und multielektrochromes Verhalten.
      PubDate: 2018-01-24T04:32:42.876185-05:
      DOI: 10.1002/ange.201712945
       
  • Benzonorcorrole NiII Complexes: Enhancement of Paratropic Ring Current and
           Singlet Diradical Character by Benzo-Fusion
    • Authors: Takuya Yoshida; Kohtaro Takahashi, Yuki Ide, Ryohei Kishi, Jun-ya Fujiyoshi, Sangsu Lee, Yuya Hiraoka, Dongho Kim, Masayoshi Nakano, Takahisa Ikeue, Hiroko Yamada, Hiroshi Shinokubo
      Pages: 2231 - 2235
      Abstract: Fused benzene rings to antiaromatic compounds generally improve their stability but attenuate their antiaromaticity. The opposite case is now reported. NiII benzonorcorroles were synthesized and the effect of benzo-fusion on the antiaromaticity was elucidated. The benzo-fusion resulted in significant decrease of the HOMO–LUMO gaps and enhancement of the paratropic ring current effect. Furthermore, the introduction of the benzo groups induced singlet diradical character in the antiaromatic porphyrinoid.Der Effekt der Benzanellierung auf die Antiaromatizität des 16 π-Porphyrins NiII-Norcorrol wurde untersucht. Die zusätzlichen Benzolgruppen verkleinern den HOMO-LUMO-Abstand deutlich und verstärken den paratropen Ringstrom. NiII-Tetrabenzonorcorrol hat Singulettdiradikal-Charakter.
      PubDate: 2018-01-24T04:25:39.895097-05:
      DOI: 10.1002/ange.201712961
       
  • KCa(H2O)2[FeIII(CN)6]⋅H2O Nanoparticles as an Antimicrobial Agent
           against Staphylococcus aureus
    • Authors: Zhongxia Wang; Bing Yu, Huda Alamri, Sriramakrishna Yarabarla, Min-Ho Kim, Songping D. Huang
      Pages: 2236 - 2240
      Abstract: Biocompatible nanoparticles based on a calcium analogue of Prussian blue were designed and synthesized to take advantage of their ability to penetrate the cell membrane in Staphylococcus aureus and to undergo selective ion exchange with intracellular iron to disrupt iron metabolism in such pathogenic bacteria for antibacterial applications. KCa(H2O)2[FeIII(CN)6]⋅H2O nanoparticles penetrate the bacterial cell membrane and sequester intracellular iron by ion exchange to form insoluble Prussian blue, thus inhibiting bacterial growth.Eisenhart gegen bakterielle Infektionen: Nanopartikel aus KCa(H2O)2[FeIII(CN)6] ⋅H2O können die bakterielle Zellmembran durchdringen und intrazelluläres Eisen durch Ionenaustausch in Form von unlöslichem Preußischblau entziehen. Dieser Prozess hemmt das bakterielle Wachstum.
      PubDate: 2018-02-02T02:52:50.239173-05:
      DOI: 10.1002/ange.201713177
       
  • Hydrolysis Batteries: Generating Electrical Energy during Hydrogen
           Absorption
    • Authors: Rui Xiao; Jun Chen, Kai Fu, Xinyao Zheng, Teng Wang, Jie Zheng, Xingguo Li
      Pages: 2241 - 2245
      Abstract: The hydrolysis reaction of aluminum can be decoupled into a battery by pairing an Al foil with a Pd-capped yttrium dihydride (YH2–Pd) electrode. This hydrolysis battery generates a voltage around 0.45 V and leads to hydrogen absorption into the YH2 layer. This represents a new hydrogen absorption mechanism featuring electrical energy generation during hydrogen absorption. The hydrolysis battery converts 8–15 % of the thermal energy of the hydrolysis reaction into usable electrical energy, leading to much higher energy efficiency compared to that of direct hydrolysis.Strom aus Wärme: Bei der Hydrolyse von Aluminium kann in einer Batterie 8–15 % der Reaktionwärme in elektrische Energie umgewandelt werden. Außerdem wird ein neuer Wasserstoffabsorptionsmechanismus beobachtet, bei dem die H2-Absorption mit der Erzeugung von elektrischer Energie einhergeht.
      PubDate: 2018-01-12T05:51:49.436543-05:
      DOI: 10.1002/ange.201711666
       
  • Interconversion of Molybdenum Imido and Amido Complexes by Proton-Coupled
           Electron Transfer
    • Authors: Máté J. Bezdek; Paul J. Chirik
      Pages: 2246 - 2250
      Abstract: Interconversion of the molybdenum amido [(PhTpy)(PPh2Me)2Mo(NHtBuAr)][BArF24] (PhTpy=4′-Ph-2,2′,6′,2“-terpyridine; tBuAr=4-tert-butyl-C6H4; ArF24=(C6H3-3,5-(CF3)2)4) and imido [(PhTpy)(PPh2Me)2Mo(NtBuAr)][BArF24] complexes has been accomplished by proton-coupled electron transfer. The 2,4,6-tri-tert-butylphenoxyl radical was used as an oxidant and the non-classical ammine complex [(PhTpy)(PPh2Me)2Mo(NH3)][BArF24] as the reductant. The N−H bond dissociation free energy (BDFE) of the amido N−H bond formed and cleaved in the sequence was experimentally bracketed between 45.8 and 52.3 kcal mol−1, in agreement with a DFT-computed value of 48 kcal mol−1. The N−H BDFE in combination with electrochemical data eliminate proton transfer as the first step in the N−H bond-forming sequence and favor initial electron transfer or concerted pathways.Imido- und Amidokomplexe des Molybdäns mit Terpyridin- und zwei Phosphanliganden gehen einen protonengekoppelten Elektronentransfer (PCET) ein. Thermochemische Messungen belegen die Bildung und Spaltung einer schwachen N-H-Bindung, schließen einen Protonentransfer als ersten Schritt der N-H-Verknüpfungssequenz aus und stützen konzertierte Pfade oder solche mit anfänglichem Elektronentransfer. BDFE=Freie Bindungsdissoziationsenergie.
      PubDate: 2018-01-31T03:09:08.484115-05:
      DOI: 10.1002/ange.201708406
       
  • Catalytic Asymmetric Synthesis of Trifluoromethylated γ-Amino Acids
           through the Umpolung Addition of Trifluoromethyl Imines to Carboxylic Acid
           Derivatives
    • Authors: Bin Hu; Li Deng
      Pages: 2255 - 2259
      Abstract: Novel cinchona alkaloid derived chiral phase-transfer catalysts enabled the highly chemo-, regio-, diastereo-, and enantioselective umpolung addition of trifluoromethyl imines to α,β-unsaturated N-acyl pyrroles. With a catalyst loading ranging from 0.2 to 5.0 mol %, this new catalytic asymmetric transformation provides facile and high-yielding access to highly enantiomerically enriched chiral trifluoromethylated γ-amino acids and γ-lactams.Neuartige Phasentransferkatalysatoren mit Cinchona-Alkaloid-Liganden ermöglichen die chemo-, regio-, diastereo- und enantioselektive Umpolungsaddition von Trifluormethyliminen an α,β-ungesättigte N-Acylpyrrole (siehe Schema). Diese Transformation bietet effizienten Zugang zu hoch enantiomerenangereicherten trifluormethylierten γ-Aminosäuren und γ-Lactamen.
      PubDate: 2018-01-18T05:46:11.719077-05:
      DOI: 10.1002/ange.201710915
       
  • Cobalt(II)-based Metalloradical Activation of 2-(Diazomethyl)pyridines for
           Radical Transannulation and Cyclopropanation
    • Authors: Satyajit Roy; Sandip Kumar Das, Buddhadeb Chattopadhyay
      Pages: 2260 - 2265
      Abstract: A new catalytic method for the denitrogenative transannulation/cyclopropanation of in-situ-generated 2-(diazomethyl)pyridines is described using a cobalt-catalyzed radical-activation mechanism. The method takes advantage of the inherent properties of a CoIII-carbene radical intermediate and is the first report of denitrogenative transannulation/cyclopropanation by a radical-activation mechanism, which is supported by various control experiments. The synthetic benefits of the metalloradical approach are showcased with a short total synthesis of (±)-monomorine.Eine Transanellierung/Cyclopropanierung unter Stickstoffabspaltung aus einem in situ gebildeten 2-(Diazomethyl)pyridin verläuft über cobaltkatalysierte Radikalaktivierung. Ein Cobalt(II)-Metalloradikal addiert dabei an Alkine bzw. Alkene unter Bildung von Indolizinen oder Cyclopropanderivaten.
      PubDate: 2018-01-19T04:42:09.04583-05:0
      DOI: 10.1002/ange.201711209
       
  • An Exceptionally Close, Non-Bonded Hydrogen–Hydrogen Contact with Strong
           Through-Space Spin–Spin Coupling
    • Authors: Yonglong Xiao; Joel T. Mague, Robert A. Pascal
      Pages: 2266 - 2269
      Abstract: Condensation of 1,8,13-tris(mercaptomethyl)triptycene and tris(bromomethyl)methane yields an in,in-cyclophane with two inwardly directed methine groups. Based on X-ray analysis and DFT and MP2 calculations, the hydrogen–hydrogen non-bonded contact distance is estimated to be 1.50–1.53 Å. Furthermore, the two in-hydrogen atoms show obvious spin–spin coupling with J=2.0 Hz.Spürbar nahe: Die in-Wasserstoffatome HA und HB des gezeigten in,in-Cyclophans sind nur 1.50–1.53 Å voneinander entfernt – ein sehr kleiner Abstand für einen nichtbindenden Kontakt. Zwischen ihnen besteht eine außergewöhnlich starke Spin-Spin-Kopplung durch den Raum (JAB=2.0 Hz).
      PubDate: 2018-01-26T05:05:25.711482-05:
      DOI: 10.1002/ange.201712304
       
  • Ultrathin FeOOH Nanolayers with Abundant Oxygen Vacancies on BiVO4
           Photoanodes for Efficient Water Oxidation
    • Authors: Beibei Zhang; Lei Wang, Yajun Zhang, Yong Ding, Yingpu Bi
      Pages: 2270 - 2274
      Abstract: Photoelectrochemical (PEC) water splitting is a promising method for storing solar energy in the form of hydrogen fuel, but it is greatly hindered by the sluggish kinetics of the oxygen evolution reaction (OER). Herein, a facile solution impregnation method is developed for growing ultrathin (2 nm) highly crystalline β-FeOOH nanolayers with abundant oxygen vacancies on BiVO4 photoanodes. These exhibited a remarkable photocurrent density of 4.3 mA cm−2 at 1.23 V (vs. reversible hydrogen electrode (RHE), AM 1.5 G), which is approximately two times higher than that of amorphous FeOOH fabricated by electrodeposition. Systematic studies reveal that the excellent PEC activity should be attributed to their ultrathin crystalline structure and abundant oxygen vacancies, which could effectively facilitate the hole transport/trapping and provide more active sites for water oxidation.Durch Imprägnieren mit einer Lösung wurden hochkristalline 2 nm dünne FeOOH-Nanoschichten (siehe Einschub) mit einem großen Aufkommen an Sauerstoff-Leerstellen auf BiVO4-Photoanoden aufgebracht. Die resultierenden Elektroden ergaben eine Photostromdichte von 4.3 mA cm−2 bei 1.23 V (gegen die reversible Wasserstoffelektrode, AM 1.5 G).
      PubDate: 2018-02-01T05:11:10.909183-05:
      DOI: 10.1002/ange.201712499
       
  • Catalytic Desymmetrizing Dehydrogenation of 4-Substituted Cyclohexanones
           through Enamine Oxidation
    • Authors: Lihui Zhu; Long Zhang, Sanzhong Luo
      Pages: 2275 - 2280
      Abstract: A desymmetrizing dehydrogenation process catalyzed by a chiral primary amine is described herein. The reaction proceeds through the oxidation of a ketone enamine by IBX and enables the highly enantioselective desymmetrization of 4-substituted cyclohexanones with the generation of chiral 4-substituted cyclohexenones containing a remote γ-stereocenter.Fernkommunikation: Ein asymmetrischer Dehydrierungsprozess, der durch ein primäres Amin katalysiert wird, ermöglicht die Desymmetrisierung von 4-substituierten Cyclohexanonen unter milden Bedingungen. Die Oxidation der Ketonamin-Zwischenstufe durch 2-Iodoxybenzoesäure (IBX) liefert Cyclohexenone mit einem γ-Stereozentrum mit hoher Enantioselektivität (siehe Schema).
      PubDate: 2018-02-02T02:53:03.782776-05:
      DOI: 10.1002/ange.201713327
       
  • Innenrücktitelbild: Light-Driven C−H Oxygenation of Methane into
           Methanol and Formic Acid by Molecular Oxygen Using a Perfluorinated
           Solvent (Angew. Chem. 8/2018)
    • Authors: Kei Ohkubo; Kensaku Hirose
      Pages: 2281 - 2281
      Abstract: Die Oxygenierung von Methan mittels Sauerstoff erfolgt in einem Zweiphasensystem aus Perfluorhexan und Wasser unter Umgebungsbedingungen. In ihrer Zuschrift auf S. 2148 zeigen K. Ohkubo und K. Hirose, dass das Chlordioxidradikal (ClO2.) ein effektives Oxidationsmittel ist für die aerobe Oxygenierung von Methan zu Methanol und Ameisensäure unter Lichteinstrahlung. Die Methanol- und Ameisensäure-Ausbeuten waren 14 und 85 %.
      PubDate: 2018-02-02T02:52:54.296971-05:
      DOI: 10.1002/ange.201800576
       
  • Rücktitelbild: Hydrolysis Batteries: Generating Electrical Energy during
           Hydrogen Absorption (Angew. Chem. 8/2018)
    • Authors: Rui Xiao; Jun Chen, Kai Fu, Xinyao Zheng, Teng Wang, Jie Zheng, Xingguo Li
      Pages: 2282 - 2282
      Abstract: Wärme und Wasserstoff …… entstehen bei der Hydrolyse von Aluminium. In ihrer Zuschrift auf S. 2241 zeigen J. Zheng, X. Li und Mitarbeiter, dass die Hydrolysewärme in einer Batterie mit einer Aluminium- und einer Yttriumhydrid-Elektrode in elektrische Energie umgewandelt werden kann. Die Hydrolysebatterie ist ein erstes Beispiel für kombinierte Stromerzeugung und Wasserstoffabsorption.
      PubDate: 2018-01-25T08:06:47.652936-05:
      DOI: 10.1002/ange.201800577
       
  • Renato Zenobi
    • Pages: 2046 - 2046
      Abstract: „Mein Lieblingsautor ist John Steinbeck. Mein Lieblingsessen ist Rinderzunge ...“ Dies und mehr von und über Renato Zenobi finden Sie auf Seite 2046.
      PubDate: 2017-10-17T06:20:58.13143-05:0
      DOI: 10.1002/ange.201710183
       
  • Light-Driven C−H Oxygenation of Methane into Methanol and Formic Acid by
           Molecular Oxygen Using a Perfluorinated Solvent
    • Authors: Kei Ohkubo; Kensaku Hirose
      Pages: 2148 - 2151
      Abstract: The 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 (80 %). 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..Oxidation von Kohlenwasserstoffen: Das Chlordioxidradikal (ClO2.) ist ein effektives Oxidationsmittel für die aerobe Oxygenierung von Methan zu Methanol und Ameisensäure unter Lichteinstrahlung. Die Methanol- und Ameisensäure-Ausbeuten waren 14 und 85 % bei einem Methanumsatz von 99 % unter Umgebungsbedingungen (298 K, 1 atm) in einem Zweiphasen-System aus Perfluorhexan und Wasser.
      PubDate: 2017-12-29T03:50:30.852176-05:
      DOI: 10.1002/ange.201710945
       
  • Total Synthesis of (+)-Gracilamine Based on an Oxidative Phenolic Coupling
           Reaction and Determination of Its Absolute Configuration
    • Authors: Minami Odagi; Yoshiharu Yamamoto, Kazuo Nagasawa
      Pages: 2251 - 2254
      Abstract: The enantioselective total synthesis of (+)-gracilamine (1) is described. The strategy features a diastereoselective phenolic coupling reaction followed by a regioselective intramolecular aza-Michael reaction to construct the ABCE ring system. The configuration at C3a in 1 was controlled by the stereocenter at C9a, which was selectively generated (91 % ee) by an organocatalytic enantioselective aza-Friedel–Crafts reaction developed by our research group. This synthesis revealed that the absolute configuration of (+)-gracilamine is 3aR, 4S, 5S, 6R, 7aS, 8R, 9aS.Geheimnis gelüftet: Das ABCE-Ringsystem in (+)-Gracilamin wurde in drei Schlüsselschritten aufgebaut: einer organokatalytischen Aza-Friedel-Crafts-Reaktion, einer diastereoselektiven oxidativen Phenolkupplung und einer regioselektiven Aza-Michael-Reaktion (siehe Schema). Die effiziente enantioselektive Totalsynthese erlaubte die Bestimmung der absoluten Konfiguration des Naturstoffs.
      PubDate: 2017-10-11T06:16:28.692138-05:
      DOI: 10.1002/ange.201708575
       
 
 
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