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Publisher: John Wiley and Sons   (Total: 1579 journals)

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Showing 1 - 200 of 1579 Journals sorted alphabetically
Abacus     Hybrid Journal   (Followers: 12, SJR: 0.48, h-index: 22)
About Campus     Hybrid Journal   (Followers: 5)
Academic Emergency Medicine     Hybrid Journal   (Followers: 65, SJR: 1.385, h-index: 91)
Accounting & Finance     Hybrid Journal   (Followers: 46, SJR: 0.547, h-index: 30)
ACEP NOW     Free   (Followers: 1)
Acta Anaesthesiologica Scandinavica     Hybrid Journal   (Followers: 51, SJR: 1.02, h-index: 88)
Acta Archaeologica     Hybrid Journal   (Followers: 153, SJR: 0.101, h-index: 9)
Acta Geologica Sinica (English Edition)     Hybrid Journal   (Followers: 3, SJR: 0.552, h-index: 41)
Acta Neurologica Scandinavica     Hybrid Journal   (Followers: 5, SJR: 1.203, h-index: 74)
Acta Obstetricia et Gynecologica Scandinavica     Hybrid Journal   (Followers: 15, SJR: 1.197, h-index: 81)
Acta Ophthalmologica     Hybrid Journal   (Followers: 5, SJR: 0.112, h-index: 1)
Acta Paediatrica     Hybrid Journal   (Followers: 56, SJR: 0.794, h-index: 88)
Acta Physiologica     Hybrid Journal   (Followers: 6, SJR: 1.69, h-index: 88)
Acta Polymerica     Hybrid Journal   (Followers: 9)
Acta Psychiatrica Scandinavica     Hybrid Journal   (Followers: 35, SJR: 2.518, h-index: 113)
Acta Zoologica     Hybrid Journal   (Followers: 6, SJR: 0.459, h-index: 29)
Acute Medicine & Surgery     Hybrid Journal   (Followers: 4)
Addiction     Hybrid Journal   (Followers: 35, SJR: 2.086, h-index: 143)
Addiction Biology     Hybrid Journal   (Followers: 13, SJR: 2.091, h-index: 57)
Adultspan J.     Hybrid Journal   (SJR: 0.127, h-index: 4)
Advanced Energy Materials     Hybrid Journal   (Followers: 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: 50, SJR: 5.21, h-index: 203)
Advanced Healthcare Materials     Hybrid Journal   (Followers: 13, SJR: 0.232, h-index: 7)
Advanced Materials     Hybrid Journal   (Followers: 260, 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: 5, SJR: 2.488, h-index: 21)
Advanced Science     Open Access   (Followers: 5)
Advanced Synthesis & Catalysis     Hybrid Journal   (Followers: 17, SJR: 2.729, h-index: 121)
Advances in Polymer Technology     Hybrid Journal   (Followers: 13, SJR: 0.344, h-index: 31)
Africa Confidential     Hybrid Journal   (Followers: 19)
Africa Research Bulletin: Economic, Financial and Technical Series     Hybrid Journal   (Followers: 12)
Africa Research Bulletin: Political, Social and Cultural Series     Hybrid Journal   (Followers: 9)
African Development Review     Hybrid Journal   (Followers: 34, SJR: 0.275, h-index: 17)
African J. of Ecology     Hybrid Journal   (Followers: 15, SJR: 0.477, h-index: 39)
Aggressive Behavior     Hybrid Journal   (Followers: 15, SJR: 1.391, h-index: 66)
Aging Cell     Open Access   (Followers: 10, SJR: 4.374, h-index: 95)
Agribusiness : an Intl. J.     Hybrid Journal   (Followers: 6, SJR: 0.627, h-index: 14)
Agricultural and Forest Entomology     Hybrid Journal   (Followers: 15, SJR: 0.925, h-index: 43)
Agricultural Economics     Hybrid Journal   (Followers: 45, SJR: 1.099, h-index: 51)
AIChE J.     Hybrid Journal   (Followers: 30, SJR: 1.122, h-index: 120)
Alcoholism and Drug Abuse Weekly     Hybrid Journal   (Followers: 7)
Alcoholism Clinical and Experimental Research     Hybrid Journal   (Followers: 7, SJR: 1.416, h-index: 125)
Alimentary Pharmacology & Therapeutics     Hybrid Journal   (Followers: 33, SJR: 2.833, h-index: 138)
Alimentary Pharmacology & Therapeutics Symposium Series     Hybrid Journal   (Followers: 3)
Allergy     Hybrid Journal   (Followers: 50, SJR: 3.048, h-index: 129)
Alternatives to the High Cost of Litigation     Hybrid Journal   (Followers: 3)
American Anthropologist     Hybrid Journal   (Followers: 138, SJR: 0.951, h-index: 61)
American Business Law J.     Hybrid Journal   (Followers: 24, SJR: 0.205, h-index: 17)
American Ethnologist     Hybrid Journal   (Followers: 90, SJR: 2.325, h-index: 51)
American J. of Economics and Sociology     Hybrid Journal   (Followers: 28, SJR: 0.211, h-index: 26)
American J. of Hematology     Hybrid Journal   (Followers: 33, SJR: 1.761, h-index: 77)
American J. of Human Biology     Hybrid Journal   (Followers: 12, SJR: 1.018, h-index: 58)
American J. of Industrial Medicine     Hybrid Journal   (Followers: 16, SJR: 0.993, h-index: 85)
American J. of Medical Genetics Part A     Hybrid Journal   (Followers: 16, SJR: 1.115, h-index: 61)
American J. of Medical Genetics Part B: Neuropsychiatric Genetics     Hybrid Journal   (Followers: 4, SJR: 1.771, h-index: 107)
American J. of Medical Genetics Part C: Seminars in Medical Genetics     Partially Free   (Followers: 6, SJR: 2.315, h-index: 79)
American J. of Physical Anthropology     Hybrid Journal   (Followers: 37, SJR: 1.41, h-index: 88)
American J. of Political Science     Hybrid Journal   (Followers: 271, SJR: 5.101, h-index: 114)
American J. of Primatology     Hybrid Journal   (Followers: 15, SJR: 1.197, h-index: 63)
American J. of Reproductive Immunology     Hybrid Journal   (Followers: 3, SJR: 1.347, h-index: 75)
American J. of Transplantation     Hybrid Journal   (Followers: 17, SJR: 2.792, h-index: 140)
American J. on Addictions     Hybrid Journal   (Followers: 9, SJR: 0.843, h-index: 57)
Anaesthesia     Hybrid Journal   (Followers: 132, 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: 16)
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: 179)
Angewandte Chemie Intl. Edition     Hybrid Journal   (Followers: 217, SJR: 6.229, h-index: 397)
Animal Conservation     Hybrid Journal   (Followers: 38, SJR: 1.576, h-index: 62)
Animal Genetics     Hybrid Journal   (Followers: 9, SJR: 0.957, h-index: 67)
Animal Science J.     Hybrid Journal   (Followers: 6, SJR: 0.569, h-index: 24)
Annalen der Physik     Hybrid Journal   (Followers: 5, SJR: 1.46, h-index: 40)
Annals of Anthropological Practice     Partially Free   (Followers: 2, SJR: 0.187, h-index: 5)
Annals of Applied Biology     Hybrid Journal   (Followers: 7, SJR: 0.816, h-index: 56)
Annals of Clinical and Translational Neurology     Open Access   (Followers: 1)
Annals of Human Genetics     Hybrid Journal   (Followers: 9, SJR: 1.191, h-index: 67)
Annals of Neurology     Hybrid Journal   (Followers: 47, SJR: 5.584, h-index: 241)
Annals of Noninvasive Electrocardiology     Hybrid Journal   (Followers: 2, SJR: 0.531, h-index: 38)
Annals of Public and Cooperative Economics     Hybrid Journal   (Followers: 9, SJR: 0.336, h-index: 23)
Annals of the New York Academy of Sciences     Hybrid Journal   (Followers: 5, SJR: 2.389, h-index: 189)
Annual Bulletin of Historical Literature     Hybrid Journal   (Followers: 13)
Annual Review of Information Science and Technology     Hybrid Journal   (Followers: 14)
Anthropology & Education Quarterly     Hybrid Journal   (Followers: 25, SJR: 0.72, h-index: 31)
Anthropology & Humanism     Hybrid Journal   (Followers: 17, SJR: 0.137, h-index: 3)
Anthropology News     Hybrid Journal   (Followers: 15)
Anthropology of Consciousness     Hybrid Journal   (Followers: 11, SJR: 0.172, h-index: 5)
Anthropology of Work Review     Hybrid Journal   (Followers: 11, SJR: 0.256, h-index: 5)
Anthropology Today     Hybrid Journal   (Followers: 91, SJR: 0.545, h-index: 15)
Antipode     Hybrid Journal   (Followers: 47, SJR: 2.212, h-index: 69)
Anz J. of Surgery     Hybrid Journal   (Followers: 7, SJR: 0.432, h-index: 59)
Anzeiger für Schädlingskunde     Hybrid Journal   (Followers: 1)
Apmis     Hybrid Journal   (Followers: 1, SJR: 0.855, h-index: 73)
Applied Cognitive Psychology     Hybrid Journal   (Followers: 69, SJR: 0.754, h-index: 69)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 7, SJR: 0.632, h-index: 58)
Applied Psychology     Hybrid Journal   (Followers: 147, SJR: 1.023, h-index: 64)
Applied Psychology: Health and Well-Being     Hybrid Journal   (Followers: 49, SJR: 0.868, h-index: 13)
Applied Stochastic Models in Business and Industry     Hybrid Journal   (Followers: 5, SJR: 0.613, h-index: 24)
Aquaculture Nutrition     Hybrid Journal   (Followers: 14, SJR: 1.025, h-index: 55)
Aquaculture Research     Hybrid Journal   (Followers: 31, SJR: 0.807, h-index: 60)
Aquatic Conservation Marine and Freshwater Ecosystems     Hybrid Journal   (Followers: 36, SJR: 1.047, h-index: 57)
Arabian Archaeology and Epigraphy     Hybrid Journal   (Followers: 11, SJR: 0.453, h-index: 11)
Archaeological Prospection     Hybrid Journal   (Followers: 12, SJR: 0.922, h-index: 21)
Archaeology in Oceania     Hybrid Journal   (Followers: 13, SJR: 0.745, h-index: 18)
Archaeometry     Hybrid Journal   (Followers: 27, SJR: 0.809, h-index: 48)
Archeological Papers of The American Anthropological Association     Hybrid Journal   (Followers: 15, SJR: 0.156, h-index: 2)
Architectural Design     Hybrid Journal   (Followers: 25, SJR: 0.261, h-index: 9)
Archiv der Pharmazie     Hybrid Journal   (Followers: 4, SJR: 0.628, h-index: 43)
Archives of Drug Information     Hybrid Journal   (Followers: 4)
Archives of Insect Biochemistry and Physiology     Hybrid Journal   (SJR: 0.768, h-index: 54)
Area     Hybrid Journal   (Followers: 12, SJR: 0.938, h-index: 57)
Art History     Hybrid Journal   (Followers: 237, SJR: 0.153, h-index: 13)
Arthritis & Rheumatology     Hybrid Journal   (Followers: 51, 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: 14)
Asia & the Pacific Policy Studies     Open Access   (Followers: 15)
Asia Pacific J. of Human Resources     Hybrid Journal   (Followers: 314, SJR: 0.494, h-index: 19)
Asia Pacific Viewpoint     Hybrid Journal   (Followers: 1, SJR: 0.616, h-index: 26)
Asia-Pacific J. of Chemical Engineering     Hybrid Journal   (Followers: 8, SJR: 0.345, h-index: 20)
Asia-pacific J. of Clinical Oncology     Hybrid Journal   (Followers: 6, SJR: 0.554, h-index: 14)
Asia-Pacific J. of Financial Studies     Hybrid Journal   (SJR: 0.241, h-index: 7)
Asia-Pacific Psychiatry     Hybrid Journal   (Followers: 4, SJR: 0.377, h-index: 7)
Asian Economic J.     Hybrid Journal   (Followers: 8, SJR: 0.234, h-index: 21)
Asian Economic Policy Review     Hybrid Journal   (Followers: 4, SJR: 0.196, h-index: 12)
Asian J. of Control     Hybrid Journal   (SJR: 0.862, h-index: 34)
Asian J. of Endoscopic Surgery     Hybrid Journal   (SJR: 0.394, h-index: 7)
Asian J. of Organic Chemistry     Hybrid Journal   (Followers: 5, SJR: 1.443, h-index: 19)
Asian J. of Social Psychology     Hybrid Journal   (Followers: 5, SJR: 0.665, h-index: 37)
Asian Politics and Policy     Hybrid Journal   (Followers: 12, SJR: 0.207, h-index: 7)
Asian Social Work and Policy Review     Hybrid Journal   (Followers: 5, SJR: 0.318, h-index: 5)
Asian-pacific Economic Literature     Hybrid Journal   (Followers: 5, SJR: 0.168, h-index: 15)
Assessment Update     Hybrid Journal   (Followers: 4)
Astronomische Nachrichten     Hybrid Journal   (Followers: 2, SJR: 0.701, h-index: 40)
Atmospheric Science Letters     Open Access   (Followers: 29, SJR: 1.332, h-index: 27)
Austral Ecology     Hybrid Journal   (Followers: 14, 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: 7, SJR: 0.39, h-index: 22)
Australian & New Zealand J. of Statistics     Hybrid Journal   (Followers: 13, SJR: 0.275, h-index: 28)
Australian Accounting Review     Hybrid Journal   (Followers: 4, SJR: 0.709, h-index: 14)
Australian and New Zealand J. of Family Therapy (ANZJFT)     Hybrid Journal   (Followers: 3, SJR: 0.382, h-index: 12)
Australian and New Zealand J. of Obstetrics and Gynaecology     Hybrid Journal   (Followers: 46, SJR: 0.814, h-index: 49)
Australian and New Zealand J. of Public Health     Hybrid Journal   (Followers: 11, SJR: 0.82, h-index: 62)
Australian Dental J.     Hybrid Journal   (Followers: 7, SJR: 0.482, h-index: 46)
Australian Economic History Review     Hybrid Journal   (Followers: 4, SJR: 0.171, h-index: 12)
Australian Economic Papers     Hybrid Journal   (Followers: 29, SJR: 0.23, h-index: 9)
Australian Economic Review     Hybrid Journal   (Followers: 6, SJR: 0.357, h-index: 21)
Australian Endodontic J.     Hybrid Journal   (Followers: 3, SJR: 0.513, h-index: 24)
Australian J. of Agricultural and Resource Economics     Hybrid Journal   (Followers: 3, SJR: 0.765, h-index: 36)
Australian J. of Grape and Wine Research     Hybrid Journal   (Followers: 5, SJR: 0.879, h-index: 56)
Australian J. of Politics & History     Hybrid Journal   (Followers: 14, SJR: 0.203, h-index: 14)
Australian J. of Psychology     Hybrid Journal   (Followers: 18, SJR: 0.384, h-index: 30)
Australian J. of Public Administration     Hybrid Journal   (Followers: 409, SJR: 0.418, h-index: 29)
Australian J. of Rural Health     Hybrid Journal   (Followers: 5, SJR: 0.43, h-index: 34)
Australian Occupational Therapy J.     Hybrid Journal   (Followers: 71, SJR: 0.59, h-index: 29)
Australian Psychologist     Hybrid Journal   (Followers: 12, SJR: 0.331, h-index: 31)
Australian Veterinary J.     Hybrid Journal   (Followers: 19, SJR: 0.459, h-index: 45)
Autism Research     Hybrid Journal   (Followers: 32, 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: 10, SJR: 0.539, h-index: 70)
Basic and Applied Pathology     Open Access   (Followers: 2, SJR: 0.113, h-index: 4)
Basin Research     Hybrid Journal   (Followers: 5, SJR: 1.54, h-index: 60)
Bauphysik     Hybrid Journal   (Followers: 2, SJR: 0.194, h-index: 5)
Bauregelliste A, Bauregelliste B Und Liste C     Hybrid Journal  
Bautechnik     Hybrid Journal   (Followers: 1, SJR: 0.321, h-index: 11)
Behavioral Interventions     Hybrid Journal   (Followers: 9, SJR: 0.297, h-index: 23)
Behavioral Sciences & the Law     Hybrid Journal   (Followers: 24, SJR: 0.736, h-index: 57)
Berichte Zur Wissenschaftsgeschichte     Hybrid Journal   (Followers: 9, SJR: 0.11, h-index: 5)
Beton- und Stahlbetonbau     Hybrid Journal   (Followers: 2, SJR: 0.493, h-index: 14)
Biochemistry and Molecular Biology Education     Hybrid Journal   (Followers: 6, SJR: 0.311, h-index: 26)
Bioelectromagnetics     Hybrid Journal   (Followers: 1, SJR: 0.568, h-index: 64)
Bioengineering & Translational Medicine     Open Access  
BioEssays     Hybrid Journal   (Followers: 10, SJR: 3.104, h-index: 155)
Bioethics     Hybrid Journal   (Followers: 14, SJR: 0.686, h-index: 39)
Biofuels, Bioproducts and Biorefining     Hybrid Journal   (Followers: 1, SJR: 1.725, h-index: 56)
Biological J. of the Linnean Society     Hybrid Journal   (Followers: 16, SJR: 1.172, h-index: 90)
Biological Reviews     Hybrid Journal   (Followers: 3, SJR: 6.469, h-index: 114)
Biologie in Unserer Zeit (Biuz)     Hybrid Journal   (Followers: 42, SJR: 0.12, h-index: 1)
Biology of the Cell     Full-text available via subscription   (Followers: 9, SJR: 1.812, h-index: 69)
Biomedical Chromatography     Hybrid Journal   (Followers: 6, SJR: 0.572, h-index: 49)
Biometrical J.     Hybrid Journal   (Followers: 5, SJR: 0.784, h-index: 44)
Biometrics     Hybrid Journal   (Followers: 36, SJR: 1.906, h-index: 96)
Biopharmaceutics and Drug Disposition     Hybrid Journal   (Followers: 10, SJR: 0.715, h-index: 44)
Biopolymers     Hybrid Journal   (Followers: 18, SJR: 1.199, h-index: 104)
Biotechnology and Applied Biochemistry     Hybrid Journal   (Followers: 45, SJR: 0.415, h-index: 55)
Biotechnology and Bioengineering     Hybrid Journal   (Followers: 194, 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: 37, SJR: 0.763, h-index: 64)
Birth Defects Research Part A : Clinical and Molecular Teratology     Hybrid Journal   (Followers: 2, SJR: 0.727, h-index: 77)
Birth Defects Research Part B: Developmental and Reproductive Toxicology     Hybrid Journal   (Followers: 5, SJR: 0.468, h-index: 47)
Birth Defects Research Part C : Embryo Today : Reviews     Hybrid Journal   (SJR: 1.513, h-index: 55)
BJOG : An Intl. J. of Obstetrics and Gynaecology     Partially Free   (Followers: 230, SJR: 2.083, h-index: 125)

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Journal Cover Angewandte Chemie International Edition
  [SJR: 6.229]   [H-I: 397]   [217 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1433-7851 - ISSN (Online) 1521-3773
   Published by John Wiley and Sons Homepage  [1579 journals]
  • (4+3) Cycloaddition Reactions of N-Alkyl Oxidopyridinium Ions
    • Authors: Chencheng Fu; Nestor Lora, Patrick L. Kirchhoefer, Dong Reyoul Lee, Erich Altenhofer, Charles L. Barnes, Natasha L. Hungerford, Elizabeth H. Krenske, Michael Harmata
      Abstract: N-Methylation of methyl 5-hydroxynicotinate followed by reaction with a diene in the presence of triethylamine afforded (4+3) cycloadducts in good to excellent yields. High regioselectivity was observed with 1-substituted and 1,2-disubstituted butadienes. Density functional theory calculations indicate that the cycloaddition involves concerted addition of the diene onto the oxidopyridinium ion. The process provides rapid access to bicyclic nitrogenous structures resembling natural alkaloids.Greater than the sum of its parts: N-Methylated methyl 5-hydroxynicotinate reacted with dienes in the presence of triethylamine to afford bicyclic nitrogenous structures resembling natural alkaloids through (4+3) cycloaddition (see scheme). High regioselectivity was observed with 1-substituted and 1,2-disubstituted butadienes. DFT calculations indicate that the reaction involves concerted addition of the diene to the oxidopyridinium ion.
      PubDate: 2017-10-16T05:05:34.216302-05:
      DOI: 10.1002/anie.201708320
       
  • Main Group Metal Coordination Polymers. Structures and Nanostructures By
           Ali Morsali and Lida Hashemi.
    • Authors: Lars Öhrström
      Abstract: John Wiley and Sons, Hoboken 2017. 272 pp., hardcover, € 195.00.—ISBN 978-1119370239
      PubDate: 2017-10-16T05:05:20.583274-05:
      DOI: 10.1002/anie.201710246
       
  • Two-Dimensional Calix[4]arene-based Metal–Organic Coordination Networks
           of Tunable Crystallinity
    • Authors: Mina Moradi; Ludovico G. Tulli, Jan Nowakowski, Milos Baljozovic, Thomas A. Jung, Patrick Shahgaldian
      Abstract: A flexible and versatile method to fabricate two-dimensional metal–organic coordination networks (MOCNs) by bottom-up self-assembly is described. 2D crystalline layers were formed at the air–water interface, coordinated by ions from the liquid phase, and transferred onto a solid substrate with their crystallinity preserved. By using an inherently three-dimensional amphiphile, namely 25,26,27,28-tetrapropoxycalix[4]arene-5,11,17,23-tetracarboxylic acid, and a copper metal node, large and monocrystalline dendritic MOCN domains were formed. The method described allows for the fabrication of monolayers of tunable crystallinity on liquid and solid substrates. It can be applied to a large range of differently functionalized organic building blocks, also beyond macrocycles, which can be interconnected by diverse metal nodes.Transferable monolayer: A metal–organic coordination network consisting of a calix[4]arene derivative as the first example of 3D building blocks and copper nodes forms as a monolayer at the air–water interface. The monolayer can be transferred successfully onto a solid surface.
      PubDate: 2017-10-16T05:00:39.711181-05:
      DOI: 10.1002/anie.201703825
       
  • New Insights into the Activation and Deactivation of Au/CeZrO4 in the
           Low-Temperature Water-Gas Shift Reaction
    • Authors: Graham John Hutchings; James Carter, Xi Liu, Qian He, Sultan Althahban, Ewa Nowicka, Simon Freakley, Liwei Niu, David Morgan, Yongwang Li, Hans Niemantsverdriet, Stanislaw Golunski, Christopher Kiely
      Abstract: Gold on ceria-zirconia is an active catalyst for the low-temperature water-gas shift reaction (LTS), a key stage of upgrading H2 reformate streams for fuel cells. However, this catalyst rapidly deactivates and the mechanism remains unclear. Using stop-start scanning transmission electron microscopy (STEM) to follow the exact same area of the sample at different stages of the LTS reaction, as well as complementary X-ray photoelectron spectroscopy, we observed the activation and deactivation of the catalyst at various stages. During the heating of the catalyst to reaction temperature, we observed the formation of small Au nanoparticles (1-2 nm) from sub-nm Au species. These nanoparticles then agglomerated further over 48 h on-stream, most rapidly in the first 5 h when the highest rate of deactivation was observed. These findings suggest that the primary deactivation process consists of the loss of active sites through the agglomeration and possible dewetting of Au nanoparticles.
      PubDate: 2017-10-16T03:50:20.842068-05:
      DOI: 10.1002/anie.201709708
       
  • Silicon Wafers Revealing Facet-Dependent Electrical Conductivity
           Properties
    • Authors: Chih-Shan Tan; Pei-Lun Hsieh, Lih-Juann Chen, Michael Hsuan-Yi Huang
      Abstract: By breaking intrinsic Si (100) and (111) wafers to expose sharp {111} and {112} facets, electrical conductivity measurements on single and different silicon crystal faces have been performed through contacts with two tungsten probes. While Si {100} and {110} faces are barely conductive at low applied voltages as expected, Si {112} surface is highly conductive and Si {111} surface also shows good conductivity. Asymmetrical I-V curves have been recorded for the {111}/{112}, {111}/{110}, and {112}/{110} facet combinations because of different degrees of conduction band bending at these crystal surfaces presenting different barrier heights to current flow. In particular, the {111}/{110}, and {112}/{110} facet combinations give I-V curves resembling those of p-n junctions, suggesting a novel field effect transistor design is possible capitalizing on the pronounced facet-dependent electrical conductivity properties of silicon.
      PubDate: 2017-10-16T03:18:26.320707-05:
      DOI: 10.1002/anie.201709020
       
  • Near-Infrared-Light-Driven Hydrogen Evolution from Water using a
           Polypyridyl Triruthenium Photosensitizer
    • Authors: Yutaro Tsuji; Keiya Yamamoto, Kosei Yamauchi, Ken Sakai
      Abstract: In order to realize the artificial photosynthetic devices splitting water to H2 and O2 (2H2O + hν 2H2 + O2), it is desirable to utilize a wider wavelength range of light that extends to a lower energy region of solar spectrum. Here we report a triruthenium photosensitizer [Ru3(dmbpy)6(μ-HAT)]6+ (dmbpy = 4,4'-dimethyl-2,2'-bipyridine, HAT = 1,4,5,8,9,12-hexaazatriphenylene), which absorbs near-infrared light up to 800 nm based on its 1MLCT transition. Importantly, [Ru3(dmbpy)6(μ-HAT)]6+ is found to be the first example of a photosensitizer which can drive H2 evolution under the illumination of near-infrared light above 700 nm. The electrochemical and photochemical studies reveal that the reductive quenching within the ion-pair adducts of [Ru3(dmbpy)6(μ-HAT)]6+ and ascorbate anions affords a singly reduced form of [Ru3(dmbpy)6(μ-HAT)]6+, which is used as a reducing equivalent in the subsequent water reduction process.
      PubDate: 2017-10-16T02:21:28.44548-05:0
      DOI: 10.1002/anie.201708996
       
  • Reduction of a CeIII Siloxide Complex Affords a Tetradecker Arene-bridged
           CeII Sandwich
    • Authors: Marinella Mazzanti; Rory Kelly, Laurent Maron, Rosario Scopelliti
      Abstract: Organometallic multiple-decker sandwich complexes containing f-elements remain rare in spite of their attractive magnetic and electronic properties. The reduction of the CeIII siloxide complex, [KCeL4] (1; L = OSi(OtBu)3) with excess potassium in a THF/toluene mixture affords a rare tetradecker arene-bridged complex [K(2.2.2-crypt)]2[{(KL3Ce)(µ-η6:η6-C7H8)}2Ce] (3). The structure of 3 features a [Ce(C7H8)2] sandwich capped by [KL3Ce] moieties with a linear arrangement of the Ce ions. Structural parameters, UV-Vis data and DFT studies indicate the presence of CeII ions involved in δ bonding between the Ce cations and toluene dianions. Complex 3 is a rare lanthanide multidecker complex and the first containing non-classical divalent lanthanide ions. Moreover, oxidation of 1 by AgOTf (OTf = O3SCF3) yielded the CeIV complex, [CeL4] (2), showing that siloxide ligands can stabilize Ce in three oxidation states.
      PubDate: 2017-10-16T01:55:48.228109-05:
      DOI: 10.1002/anie.201709769
       
  • Enantioselective Synthesis of Tetrahydropyrano[3,4-b]indoles:
           Palladium(II)-Catalyzed Aminopalladation/1,4-Addition Sequence
    • Authors: Junjie Chen; Xiuling Han, Xiyan Lu
      Abstract: A novel palladium(II)-catalyzed cyclization of aniline-tethered alkynyl cyclohexadienones is reported. This reaction offers an atom-economical and redox-neutral access to various cyclohexenone-fused tetrahydropyrano[3,4-b]indoles with high yield and excellent enantioselectivity. Remarkably, this work represents the first example on a transition-metal-catalyzed asymmetric intramolecular aminopalladation/1,4 addition sequence.At the end of a tether: Palladium(II)-catalyzed asymmetric cyclization of aniline-tethered alkynyl cyclohexadienones leads to functionalized tetrahydropyrano-[3,4-b]indoles in good yields and excellent enantioselectivities. The process involves a novel intramolecular aminopalladation/1,4 addition sequence.
      PubDate: 2017-10-16T01:17:15.159951-05:
      DOI: 10.1002/anie.201708900
       
  • An Epitope-Imprinted Biointerface with Dynamic Bioactivity for Modulating
           Cell–Biomaterial Interactions
    • Authors: Guoqing Pan; Sudhirkumar Shinde, Sing Yee Yeung, Miglė Jakštaitė, Qianjin Li, Anette Gjörloff Wingren, Börje Sellergren
      Abstract: In this study, an epitope-imprinting strategy was employed for the dynamic display of bioactive ligands on a material interface. An imprinted surface was initially designed to exhibit specific affinity towards a short peptide (i.e., the epitope). This surface was subsequently used to anchor an epitope-tagged cell-adhesive peptide ligand (RGD: Arg-Gly-Asp). Owing to reversible epitope-binding affinity, ligand presentation and thereby cell adhesion could be controlled. As compared to current strategies for the fabrication of dynamic biointerfaces, for example, through reversible covalent or host–guest interactions, such a molecularly tunable dynamic system based on a surface-imprinting process may unlock new applications in in situ cell biology, diagnostics, and regenerative medicine.Ad-here we go again: An epitope-peptide-imprinted polymeric film was used to reversibly anchor the cell-adhesive peptide RGD. Functionality was demonstrated by a controllable cell-adhesion behavior (see picture).
      PubDate: 2017-10-16T01:16:45.46469-05:0
      DOI: 10.1002/anie.201708635
       
  • Asymmetric Intermolecular Heck Reaction of Propargylic Acetates and
           Cycloalkenes to Access Fused Cyclobutenes
    • Authors: Zhiwei Jiao; Qi Shi, Jianrong Steve Zhou
      Abstract: An asymmetric Heck annulation of propargylic acetates with several types of cyclic olefins affords highly strained cyclobutenes in high enantioselectivity.An intermolecular Heck reaction between propargylic acetates and cyclic olefins results in the enantioselective synthesis of highly strained cyclobutenes.
      PubDate: 2017-10-16T01:15:54.999148-05:
      DOI: 10.1002/anie.201708435
       
  • Controlling Lanthanide Exchange in Triple-Stranded Helicates: A Way to
           Optimize Molecular Light-Upconversion
    • Authors: Davood Zare; Yan Suffren, Homayoun Nozary, Andreas Hauser, Claude Piguet
      Abstract: The kinetic lability of hexadentate gallium-based tripods is sufficient to ensure thermodynamic self-assembly of luminescent heterodimetallic [GaLn(L3)3]6+ helicates on the hour time scale, where Ln is a trivalent 4f-block cation. The inertness is, however, large enough for preserving the triple-helical structure when [GaLn(L3)3]6+ is exposed to lanthanide exchange. The connection of a second gallium-based tripod further slows down the exchange processes to such an extent that spectroscopically active [CrErCr(L4)3]9+ can be diluted into closed-shell [GaYGa(L4)3]9+ matrices without metal scrambling. This feature is exploited for pushing molecular-based energy-transfer upconversion (ETU) at room temperature.Inert noncovalent [GaL3]3+ ions promote an unprecedented keystone mechanism for the capture/release of labile trivalent lanthanides on hour time scales. The cooperative operation of two [GaL3]3+ tripods pushes the limit of inertness to over months, which makes these new materials compatible with the preparation of solid-state solutions displaying molecular-based energy-transfer upconversion at room temperature.
      PubDate: 2017-10-16T01:10:46.295957-05:
      DOI: 10.1002/anie.201709156
       
  • Synthesis of Anisotropic Hydrogels and Their Applications
    • Authors: Koki Sano; Yasuhiro Ishida, Takuzo Aida
      Abstract: Owing to their water-rich structures similar to biological tissues, hydrogels have long been regarded as promising scaffolds for artificial tissues and organs. However, in terms of structural anisotropy, most synthetic hydrogels are substantially different from biological systems. Synthetic hydrogels are usually composed of randomly oriented three-dimensional polymer networks, whereas biological systems adopt anisotropic structures with hierarchically integrated building units. Such anisotropic structures often play an essential role in biological systems to exhibit their particular functions, as represented by muscular textures comprising unidirectionally oriented actin-myosin units. In this context, anisotropic hydrogels provide an entry point for exploring the biomimetic applications of hydrogels. Reflecting these aspects, an increasing number of studies on anisotropic hydrogels have been reported recently. This Minireview highlights the outline and perspective of these anisotropic hydrogels, particularly focusing on their preparation, structures, and applications.
      PubDate: 2017-10-16T00:56:51.419184-05:
      DOI: 10.1002/anie.201708196
       
  • Ynamide Preactivation Allows a Regio- and Stereoselective Synthesis of
           α,β-disubstituted Enamides
    • Authors: Lucas Loss Baldassari; Aurelien de la Torre, Jing Li, Diogo Seibert Lüdtke, Nuno Maulide
      Abstract: A novel ynamide preactivation strategy enables the use of otherwise incompatible reagents and allows preparation of α,β-disubstituted enamides with high regio- and stereoselectivity. Mechanistic analysis reveals the intermediacy of a triflate-bound intermediate as a solution-stable, effective keteniminium reservoir, whilst still allowing subsequent addition of organometallic reagents.
      PubDate: 2017-10-15T20:55:47.300399-05:
      DOI: 10.1002/anie.201709128
       
  • Radical Heterocyclization and Heterocyclization Cascades Triggered by
           Electron Transfer to Amide-Type Carbonyl Compounds
    • Authors: Huan-Ming Huang; David J. Procter
      Abstract: Radical heterocyclizations triggered by electron transfer to amide-type carbonyls, using SmI2-H2O, provide straightforward access to bicyclic heterocyclic scaffolds containing bridgehead nitrogen centers. Furthermore, the first radical heterocyclization cascade triggered by reduction of amide-type carbonyls delivers novel, complex tetracyclic architectures containing five contiguous stereocenters with excellent diastereocontrol.Building bridges: Radical heterocyclization and heterocyclization cascades triggered by electron transfer to amide-type carbonyl groups provide straightforward access to heterocyclic scaffolds containing bridgehead nitrogen atoms. The radical cascade cyclizations deliver novel tetracyclic architectures, containing five contiguous stereocenters, with excellent diastereocontrol.
      PubDate: 2017-10-13T06:27:34.80529-05:0
      DOI: 10.1002/anie.201708354
       
  • Low-Temperature Reductive Aminolysis of Carbohydrates to Diamines and
           Aminoalcohols by Heterogeneous Catalysis
    • Authors: Michiel Pelckmans; Walter Vermandel, Frederik Van Waes, Kristof Moonen, Bert F. Sels
      Abstract: Short amines, such as ethanolamines and ethylenediamines, are important compounds in today's bulk and fine chemicals industry. Unfortunately, current industrial manufacture of these chemicals relies on fossil resources and requires rigorous safety measures when handling explosive or toxic intermediates. Inspired by the elegant working mechanism of aldolase enzymes, a novel heterogeneously catalyzed process—reductive aminolysis—was developed for the efficient production of short amines from carbohydrates at low temperature. High-value bio-based amines containing a bio-derived C2 carbon backbone were synthesized in one step with yields up to 87 C%, in the absence of a solvent and at a temperature below 405 K. A wide variety of available primary and secondary alkyl- and alkanolamines can be reacted with the carbohydrate to form the corresponding C2-diamine. The presented reductive aminolysis is therefore a promising strategy for sustainable synthesis of short, acyclic, bio-based amines.Carbon–carbon bond scission is facilitated by amine reagent in the reductive aminolysis of carbohydrates. Short diamines and aminoalcohols are formed, at low temperature, in the presence of heterogeneous metal catalysts.
      PubDate: 2017-10-13T06:27:08.07254-05:0
      DOI: 10.1002/anie.201708216
       
  • Total Syntheses of the Isomeric Aglain Natural Products Foveoglin A and
           Perviridisin B: Selective Excited-State Intramolecular Proton-Transfer
           Photocycloaddition
    • Authors: Wenyu Wang; Anthony Clay, Retheesh Krishnan, Neil J. Lajkiewicz, Lauren E. Brown, Jayaraman Sivaguru, John A. Porco
      Abstract: Selective excited-state intramolecular proton-transfer (ESIPT) photocycloaddition of 3-hydroxyflavones with trans, trans-1,4-diphenyl-1,3-butadiene is described. Using this methodology, total syntheses of the natural products (±)-foveoglin A and (±)-perviridisin B were accomplished. Enantioselective ESIPT photocycloaddition using TADDOLs as chiral hydrogen-bonding additives provided access to (+)-foveoglin A. Mechanistic studies have revealed the possibility for a photoinduced electron-transfer (PET) pathway.Light the way: Selective excited-state intramolecular proton-transfer (ESIPT) photocycloaddition of 3-hydroxyflavones with trans,trans-1,4-diphenyl-1,3-butadiene has enabled the total syntheses of isomeric aglain natural products foveoglin A and perviridisin B. Mechanistic studies have revealed the possibility of a photoinduced electron-transfer (PET) pathway.
      PubDate: 2017-10-13T06:26:22.957908-05:
      DOI: 10.1002/anie.201707539
       
  • Copper-Catalyzed Synthesis and Applications of Yndiamides
    • Authors: Steven J. Mansfield; Kirsten E. Christensen, Amber L. Thompson, Kai Ma, Michael W. Jones, Aroonroj Mekareeya, Edward A. Anderson
      Abstract: The first synthetic route to yndiamides, a novel class of double aza-substituted alkyne, has been established by the copper(I)-catalyzed cross-coupling of 1,1-dibromoenamides with nitrogen nucleophiles. The utility of these compounds is demonstrated in a range of transition-metal-catalyzed and acid-catalyzed transformations to afford a wide variety of 1,2-diamide functionalized products.Die, amide! The first synthetic route to yndiamides, a novel class of double aza-substituted alkyne, has been established by the copper(I)-catalyzed cross-coupling of 1,1-dibromoenamides with nitrogen nucleophiles. The utility of these compounds is demonstrated in a range of transition-metal-catalyzed and acid-catalyzed transformations to afford a wide variety of 1,2-diamide functionalized products.
      PubDate: 2017-10-13T06:26:03.325339-05:
      DOI: 10.1002/anie.201706915
       
  • Nickel-Catalyzed N-Alkylation of Acylhydrazines and Arylamines Using
           Alcohols and Enantioselective Examples
    • Authors: Peng Yang; Caili Zhang, Yu Ma, Caiyun Zhang, Aijie Li, Bo Tang, Jianrong Steve Zhou
      Abstract: A borrowing-hydrogen reaction between amines and alcohols is an atom-economic way to prepare alkylamines, ideally with water as the sole byproduct. Herein, nickel catalysts are used for direct N-alkylation of hydrazides and arylamines using racemic alcohols. Moreover, a nickel catalyst of (S)-binapine was used for an asymmetric N-alkylation of benzohydrazide with racemic benzylic alcohols.Hydrogen autotransfer: Herein, nickel catalysts are used for direct N-alkylation of hydrazides and arylamines using racemic alcohols. The reaction proceeds by a hydrogen-borrowing pathway. Also described is an asymmetric version of the reaction of N-acylhydrazines.
      PubDate: 2017-10-13T06:21:08.478832-05:
      DOI: 10.1002/anie.201708949
       
  • Photoluminescence Lifetime Imaging of Synthesized Proteins in Living Cells
           Using an Iridium–Alkyne Probe
    • Authors: Jinyu Wang; Jie Xue, Zihe Yan, Sichun Zhang, Juan Qiao, Xinrong Zhang
      Abstract: Designing probes for real-time imaging of dynamic processes in living cells is a continuous challenge. Herein, a novel near-infrared (NIR) photoluminescence probe having a long lifetime was exploited for photoluminescence lifetime imaging (PLIM) using an iridium-alkyne complex. This probe offers the benefits of deep-red to NIR emission, a long Stokes shift, excellent cell penetration, low cytotoxicity, and good resistance to photobleaching. This example is the first PLIM probe applicable to the click reaction of copper(I)-catalyzed azide–alkyne cycloaddition (CuAAC) with remarkable lifetime shifts of 414 ns, before and after click reaction. The approach fully eliminates the background interference and distinguishes the reacted probes from the unreacted probes, thus enabling the wash-free imaging of the newly synthesized proteins within single living cells. Based on the unique properties of the iridium complexes, it is anticipated to have applications for imaging other processes within living cells.It takes a lifetime: A novel bioorthogonal probe, an Ir-alkyne complex, was designed and synthesized. It showed deep-red to near-IR emission and unexpected large lifetime shifts of 414 ns before and after click reaction. This probe enabled the wash-free imaging of the newly synthesized proteins within living cells. NP=nanoparticle.
      PubDate: 2017-10-13T06:20:31.600647-05:
      DOI: 10.1002/anie.201708566
       
  • Decatwistacene with a 170 Torsion
    • Authors: Wei Fan; Thorsten Winands, Nikos L. Doltsinis, Yan Li, Zhaohui Wang
      Abstract: Two different lengths of twistacenes, namely hexatwistacene and decatwistacene induced by the steric-hindrance effect between imide groups and neighbouring annulated benzene rings, were synthesized via bottom-up synthesis of palladium-catalyzed Suzuki cross-coupling and C-H activation reaction. Single-crystal X-ray analyses revealed that decatwistacene, which is the longest twistacene reported until now, exhibits an astonishing overall end-to-end torsion angle of about 170, the largest torsion angle reported so far. Both twistacenes have an enhanced solubility and stability with respect to light and oxygen due to their large twisting deformations together with much lower LUMO levels caused by the introduction of imide groups, opening a window to the narrowest chiral graphene nanoribbons with good stability and processability.
      PubDate: 2017-10-13T05:25:57.58327-05:0
      DOI: 10.1002/anie.201709342
       
  • Theoretical Treatment of CH3NH3PbI3 Perovskite Solar Cells
    • Authors: Sining Yun; Xiao Zhou, Jacky Even, Anders Hagfeldt
      Abstract: Hybrid halide perovskite solar cells (PSCs) giving over 22 % power conversion efficiencies (PCEs) have attracted considerable attention. Although perovskite plays a significant role in the operation of PSCs, the fundamental theories associated with perovskites have not been resolved in spite of the increase in research. In this Minireview, we assess the current understanding, based on the first-principles calculations, of structural and electronic properties, defects, ionic diffusion, and shift current for CH3NH3PbI3 perovskite, and the effect of ionic transport on the hysteresis of current–voltage curves in PSCs. The shift current connected to the possible presence of ferroelectricity is also discussed. The current state-of-the-art and some open questions regarding PSCs are also highlighted, and the benefits, challenges, and potentials of perovskite for use in PSCs are stressed.Better by calculation: First principles calculations of CH3NH3PbI3, including structural and electronic properties, defects, ionic diffusion, and shift current, can provide valuable support for further developing perovskite solar cells (PSCs).
      PubDate: 2017-10-13T04:36:06.493665-05:
      DOI: 10.1002/anie.201702660
       
  • An NMR Method To Pinpoint Supramolecular Ligand Binding to Basic Residues
           on Proteins
    • Authors: Anna Hogeweg; Andrea Sowislok, Thomas Schrader, Christine Beuck
      Abstract: Targeting protein surfaces involved in protein–protein interactions by using supramolecular chemistry is a rapidly growing field. NMR spectroscopy is the method of choice to map ligand-binding sites with single-residue resolution by amide chemical shift perturbation and line broadening. However, large aromatic ligands affect NMR signals over a greater distance, and the binding site cannot be determined unambiguously by relying on backbone signals only. We herein employed Lys- and Arg-specific H2(C)N NMR experiments to directly observe the side-chain atoms in close contact with the ligand, for which the largest changes in the NMR signals are expected. The binding of Lys- and Arg-specific supramolecular tweezers and a calixarene to two model proteins was studied. The H2(C)N spectra track the terminal CH2 groups of all Lys and Arg residues, revealing significant differences in their binding kinetics and chemical shift perturbation, and can be used to clearly pinpoint the order of ligand binding.Lysine- and arginine-specific NMR experiments were conducted to selectively observe the side-chain atoms involved in the binding of supramolecular tweezers and to reveal the distinct binding order to multiple sites on a protein surface.
      PubDate: 2017-10-13T04:00:56.984693-05:
      DOI: 10.1002/anie.201707950
       
  • Chemical and Biological Aspects of Nutritional Immunity—Perspectives for
           New Anti-Infectives that Target Iron Uptake Systems
    • Authors: Ursula Bilitewski; Joshua A. V. Blodgett, Anne-Kathrin Duhme-Klair, Sabrina Dallavalle, Sabine Laschat, Anne Routledge, Rainer Schobert
      Abstract: Upon bacterial infection, one of the defense mechanisms of the host is the withdrawal of essential metal ions, in particular iron, which leads to “nutritional immunity”. However, bacteria have evolved strategies to overcome iron starvation, for example, by stealing iron from the host or other bacteria through specific iron chelators with high binding affinity. Fortunately, these complex interactions between the host and pathogen that lead to metal homeostasis provide several opportunities for interception and, thus, allow the development of novel antibacterial compounds. This Review focuses on iron, discusses recent highlights, and gives some future perspectives which are relevant in the fight against antibiotic resistance.Fighting fit: The fight for essential metal ions is like a tug of war between pathogens and host cells. Interference in this struggle can lead to new ways to fight antibiotic resistance.
      PubDate: 2017-10-13T01:30:45.267323-05:
      DOI: 10.1002/anie.201701586
       
  • The Rolling-Up of Oligophenylenes to Nanographenes by a HF-Zipping
           Approach
    • Authors: Ann-Kristin Steiner; Konstantin Y. Amsharov
      Abstract: Intramolecular aryl–aryl coupling is the key transformation in the rational synthesis of nanographenes and nanoribbons. In this respect the C−F bond activation was shown to be a versatile alternative enabling the synthesis of several unique carbon-based nanostructures. Herein we describe an unprecedentedly challenging transformation showing that the C−F bond activation by aluminum oxide allows highly effective domino-like C−C bond formation. Despite the flexible nature of oligophenylene-based precursors efficient regioselective zipping to the target nanostructures was achieved. We show that fluorine positions in the precursor structure unambiguously dictate the “running of the zipping-program” which results in rolling-up of linear oligophenylene chains around phenyl moieties yielding target nanographenes. The high efficiency of zipping makes this approach attractive for the synthesis of unsubstituted nanographenes which are difficult to obtain in pure form by other methods.Roll up, roll up: Virtually linear fluorinated oligophenylenes are converted into the “preprogrammed” challenging nanographenes via effective domino-like aryl–aryl coupling. The fluorine positions in the precursor structure unambiguously dictate the running of the “HF-zipping-program” leading to the formation of the target nanographene structure.
      PubDate: 2017-10-13T01:15:33.497558-05:
      DOI: 10.1002/anie.201707272
       
  • Flexible Viologen-Based Porous Framework Showing X-ray Induced
           Photochromism with Single-Crystal-to-Single-Crystal Transformation
    • Authors: Cheng Chen; Jian-Ke Sun, Ya-Jun Zhang, Xiao-Dong Yang, Jie Zhang
      Abstract: A viologen-based Borromean entangled porous framework was found to be sensitive to both CuKα and MoKα X-ray sources, showing rapid photochromic response and recovery within one minute. The X-ray-induced photochromic process is accompanied by a reversible single-crystal-to-single-crystal (SC-SC) structural transformation, an unprecedented phenomenon for X-ray sensitive materials. The complex can be further processed into portable thin films for detecting the dose of the X-ray exposure. Moreover, the photochromism can occur over a broad temperature range of 100–333 K, both in the form of single crystals and thin films, making it a potential candidate for practical indoor and outdoor applications.X-ray specs: A viologen-based Borromean-entangled porous framework was found sensitive to X-rays and undergo a rapid photochromic response and recovery. This process is accompanied by a reversible single-crystal-to-single-crystal transformation. The material can be further processed into a thin film for detecting the dose of X-ray exposure.
      PubDate: 2017-10-13T01:10:51.189007-05:
      DOI: 10.1002/anie.201707290
       
  • Improved Biocompatibility of Black Phosphorus Nanosheets by Chemical
           Modification
    • Authors: Guangbo Qu; Wei Liu, Yuetao Zhao, Jie Gao, Tian Xia, Jianbo Shi, Ligang Hu, Wenhua Zhou, Jiejun Gao, Huaiyu Wang, Qian Luo, Qunfang Zhou, Sijin Liu, Xue-Feng Yu, Guibin Jiang
      Abstract: Ultrasmall black phosphorus nanosheets (BPs) can trigger systemic inflammations. In their Communication (
      DOI : 10.1002/anie.201706228) X.-F. Yu, G. Jiang et al. report a method to reduce this side effect by surface modification of bare BPs with titanium sulfate (TiL4@BPs). The girl represents a potential candidate exposed to bare BPs through various routes during a wide application of this material. The effect of the bare BPs is shown by red shading. The BPs are less harmful after conversion to TiL4@BPs.
      PubDate: 2017-10-13T01:10:27.378412-05:
       
  • Characterization of Doubly Ionic Hydrogen Bonds in Protic Ionic Liquids by
           NMR Deuteron Quadrupole Coupling Constants: Differences to H-bonds in
           Amides, Peptides, and Proteins
    • Authors: Alexander E. Khudozhitkov; Peter Stange, Benjamin Golub, Dietmar Paschek, Alexander G. Stepanov, Daniil I. Kolokolov, Ralf Ludwig
      Abstract: Hydrogen bonds between ions are identified by the first deuteron quadrupole coupling constants (DQCCs) for protic ionic liquids (PILs), measured by solid-state NMR spectroscopy. In their Communication (
      DOI : 10.1002/anie.201708340) D. I. Kolokolov, R. Ludwig, et al. show that this NMR parameter is a sensitive probe of the doubly ionic hydrogen bonds present in PILs. The picture shows the NMR spectra as bridges symbolizing the doubly ionic hydrogen bonds between oppositely charged ions in PILs and mimicking the rocky mountains in the background.
      PubDate: 2017-10-13T01:10:24.858368-05:
       
  • A Strategy for Specific Fluorescence Imaging of Monoamine Oxidase A in
           Living Cells
    • Authors: Huimin Ma; Xiaofeng Wu, Wen Shi, Xiaohua Li
      Abstract: Monoamine oxidase (MAO) has two isoforms, MAO-A and MAO-B, which show different functions and thus selective fluorescence imaging of which is important for biological studies. Currently, however, specific detection of MAO-A remains a great challenge. Herein, we report a new strategy for specific imaging of MAO-A via designing fluorescent probes by combining the characteristic structure of the enzymatic inhibitor with propylamine as a recognition moiety. The high specificity of our representative probe is demonstrated by imaging MAO-A in different live cells such as SH-SY5Y (high level of MAO-A) and HepG2 (high level of MAO-B), as further validated by both control probe and western blot analyses. The superior specificity of the probe may benefit the accurate detection of MAO-A in complex biosystems. Importantly, in this work the use of the characteristic structure of an inhibitor may serve as a general strategy to design a specific recognition moiety of fluorescent probes for an enzyme.
      PubDate: 2017-10-12T21:30:39.096734-05:
      DOI: 10.1002/anie.201708428
       
  • Feedback kinetics in mechanochemistry; the importance of cohesive states
    • Authors: Stuart Lloyd James; Ben Hutchings, Peijun Hu, Lei Gao, Deborah Elizabeth Crawford
      Abstract: Abstract: Although mechanochemical synthesis is becoming more widely applied and even commercialised, greater basic understanding is needed if the field is to progress on less of a trial-and-error basis. We report that a mechanochemical reaction in a ball mill exhibits unusual sigmoidal feedback kinetics that differ dramatically from the simple first-order kinetics for the same reaction in solution. An induction period followed by a rapid increase in reaction rate before the rate decreases again as the reaction goes to completion. The origin of these unusual kinetics is found to be a feedback cycle involving both chemical and mechanical factors. During the reaction the physical form of the reaction mixture changes from a powder to a cohesive rubber-like state, and this results in the observed reaction rate increase. The study reveals that non-obvious and dynamic rheological changes in the reaction mixture must be appreciated to understand how mechanochemical reactions progress.
      PubDate: 2017-10-12T14:32:04.338205-05:
      DOI: 10.1002/anie.201706723
       
  • Diastereoselective C-H bond amination for disubstituted pyrrolidines
    • Authors: Theodore Alexander Betley; Diana A Iovan, Matthew J. T. Wilding, Elisabeth T. Hennessy, Yunjung Baek
      Abstract: We report herein on the improved diastereoselective synthesis of 2,5-disubstituted pyrrolidines from aliphatic azides. Experimental and theoretical studies of the C-H amination reaction mediated by the iron dipyrrinato complex (AdL)FeCl(OEt2) provided a model for diastereoinduction and allowed for systematic variation of the catalyst to enhance selectivity. Among the iron alkoxide and aryloxide catalysts evaluated, the iron-phenoxide complex exhibited superior performance towards the generation of syn 2,5-disubstituted pyrrolidines with high diastereoselectivity.
      PubDate: 2017-10-12T13:25:26.718369-05:
      DOI: 10.1002/anie.201708519
       
  • Biocatalytic Routes to Enantiomerically Enriched Dibenz[c,e]azepines
    • Authors: Scott P France; Godwin A Aleku, Mahima Sharma, Juan Mangas-Sanchez, Roger M Howard, Jeremy Steflik, Rajesh Kumar, Ralph W Adams, Iustina Slabu, Robert Crook, Gideon Grogan, Timothy W Wallace, Nicholas John Turner
      Abstract: Biocatalytic retrosynthetic analysis of dibenz[c,e]azepines has highlighted the use of imine reductase (IRED) and w-transaminase (w-TA) biocatalysts to establish the key stereocentres of these molecules. Several enantiocomplementary IREDs were identified for the synthesis of (R)- and (S)-5-methyl-6,7-dihydro-5H-dibenz[c,e]azepine with excellent enantioselectivity by reduction of the parent imines. Crystallographic evidence suggests that IREDs may be able to bind one conformer of the imine substrate such that, upon reduction, the major product conformer is generated directly. ω-TA biocatalysts were also successfully employed for the production of enantiopure 1-(2-bromophenyl)ethan-1-amine enabling an orthogonal route for the installation of chirality into dibenz[c,e]azepine frameworks.
      PubDate: 2017-10-12T08:25:40.322619-05:
      DOI: 10.1002/anie.201708453
       
  • Enzyme Encapsulation by a Ferritin Cage
    • Authors: Stephan Tetter; Donald Hilvert
      Abstract: Ferritins, conserved across all kingdoms of life, are protein nanocages that evolved to mineralize iron. The last several decades have shown that these cages have considerable technological and medical potential owing to their stability and tolerance to modification, as well as their ability to template nanoparticle synthesis and incorporate small molecules. Here we show that it is possible to encapsulate proteins in a ferritin cage by exploiting electrostatic interactions with its negatively charged interior. Positively supercharged green fluorescent protein is efficiently taken up by Archaeoglobus fulgidus ferritin in a tunable fashion. Moreover, several enzymes were readily incorporated when genetically tethered to this fluorescent protein. These fusion proteins retained high catalytic activity and showed increased tolerance to proteolysis and heat. Equipping ferritins with enzymatic activity paves the way for many new nanotechnological and pharmacological applications.The caged bird sings: The natural ferritin nanocage from Archaeoglobus fulgidus can encapsulate positively charged proteins (green) within its lumenal cavity through electrostatic interactions. Enzymes (gray) attached to such charged guests retain their activity [substrate (S)product (P)], thus equipping the ferritin cages with new catalytic functions and opening new avenues for their use in nanotechnology and pharmacology.
      PubDate: 2017-10-12T08:11:19.442953-05:
      DOI: 10.1002/anie.201708530
       
  • C-H Functionalization for Hydrogen Isotope Exchange
    • Authors: Jens Atzrodt; Volker Derdau, William John Kerr, Marc Reid
      Abstract: The varied applications of hydrogen isotopes (deuterium, D, and tritium, T) in the physical and life sciences demands a range of methods for their installation in an array of molecular architectures. In this review, we describe recent advances in synthetic C-H functionalization for hydrogen isotope exchange.
      PubDate: 2017-10-12T06:55:53.419279-05:
      DOI: 10.1002/anie.201708903
       
  • Far-UV-Excited Luminescence of Nitrogen-Vacancy Centers: Evidence for
           Diamonds in Space
    • Authors: Hsiao-Chi Lu; Yu-Chain Peng, Sheng-Lung Chou, Jen-Iu Lo, Bing-Ming Cheng, Huan-Cheng Chang
      Abstract: The nitrogen-vacancy (NV) centers in diamond are among the most thoroughly investigated defects in solid-state matter; however, our understanding of their properties upon far-UV excitation of the host matrix is limited. This knowledge is crucial for the identification of NV as the carrier of extended red emission (ERE) bands detected in a wide range of astrophysical environments. Herein, we report a study on the photoluminescence spectra of NV-containing nanodiamonds excited with synchrotron radiation over the wavelength range of 125–350 nm. We observed, for the first time, an emission at 520–850 nm with a quantum yield greater than 20 %. Our results share multiple similarities with the ERE phenomena, suggesting that nanodiamonds are a common component of dust in space.Luces in the sky, with diamonds: The fluorescence emission of nitrogen-vacancy centers at 520–850 nm upon far-UV excitation and with a quantum yield greater than 20 % is demonstrated. Sharing multiple similarities with the extended red emission observed in the interstellar medium, these results provide strong evidence for nanodiamonds as an important component of cosmic dust.
      PubDate: 2017-10-12T06:55:47.98179-05:0
      DOI: 10.1002/anie.201707389
       
  • Direct Observation of Hemithioindigo-Motor Unidirectionality
    • Authors: Ludwig Alexander Huber; Kerstin Hoffmann, Stefan Thumser, Niklas Böcher, Peter Mayer, Henry Dube
      Abstract: Hemithioindigo molecular motors undergo very fast unidirectional rotation upon irradiation with visible light, which has prevented a complete analysis of their working mechanism. In this work, we have considerably slowed down their motion by using a new synthesis for sterically hindered motor derivatives. This method allowed the first observation of all four intermediate states populated during rotation. The exact order in which each isomeric state is formed under irradiation conditions was elucidated using low temperature 1H NMR spectroscopy in conjunction with other analytical methods. At the same time, complete unidirectionality could also be directly shown. Access to slowly rotating hemithioindigo motors opens up a plethora of new applications for visible-light-induced unidirectional motions, especially in areas such as catalysis, smart materials, and supramolecular chemistry.Rotation is a one-way street: Using a new methodology for the synthesis of sterically hindered hemithioindigo-based molecular motors, the full rotation cycle and its complete unidirectionality could be experimentally demonstrated for the first time. The new synthetic access allows the reliable synthesis of substituted hemithioindigo motors for advanced molecular machinery.
      PubDate: 2017-10-12T06:25:44.105627-05:
      DOI: 10.1002/anie.201708178
       
  • Gold Catalysis for Heterocyclic Chemistry: A Representative Case Study on
           Pyrone Natural Products
    • Authors: Alois Fürstner
      Abstract: 2-Pyrones and 4-pyrones are common structural motifs in bioactive natural products. However, traditional methods for their synthesis, which try to emulate the biosynthetic pathway of cyclization of a 1,3,5-tricarbonyl precursor, are often harsh and, therefore, not particularly suitable for applications to polyfunctionalized and/or sensitive target compounds. π-Acid catalysis, in contrast, has proved to be better for a systematic exploration of the pyrone estate. To this end, alkynes are used as stable ketone surrogates, which can be activated under exceedingly mild conditions due to the pronounced carbophilicity of [LAu]+ fragments (L=two electron donor ligand); attack of a tethered ester carbonyl group onto the transient alkyne–gold complex then forges the pyrone ring in a fully regiocontrolled manner.Pars pro toto: Various total syntheses of pyrone natural products showcase the practicality, efficiency, functional-group tolerance, and flexibility of heterocyclic chemistry based on π-acid catalysis. In conceptual terms, these case studies are representative of a modern approach to heterocycles that is largely complementary to established carbonyl condensation reactions.
      PubDate: 2017-10-12T06:21:11.698929-05:
      DOI: 10.1002/anie.201707260
       
  • Lanthanide-Coordinated Semiconducting Polymer Dots Used for Flow Cytometry
           and Mass Cytometry
    • Authors: Xu Wu; Quinn DeGottardi, I-Che Wu, Jiangbo Yu, Li Wu, Fangmao Ye, Chun-Ting Kuo, William W. Kwok, Daniel T. Chiu
      Abstract: Simultaneous monitoring of biomarkers as well as single-cell analyses based on flow cytometry and mass cytometry are important for investigations of disease mechanisms, drug discovery, and signaling-network studies. Flow cytometry and mass cytometry are complementary to each other; however, probes that can satisfy all the requirements for these two advanced technologies are limited. In this study, we report a probe of lanthanide-coordinated semiconducting polymer dots (Pdots), which possess fluorescence and mass signals. We demonstrated the usage of this dual-functionality probe for both flow cytometry and mass cytometry in a mimetic cell mixture and human peripheral blood mononuclear cells as model systems. The probes not only offer high fluorescence signal for use in flow cytometry, but also show better performance in mass cytometry than the commercially available counterparts.Lanthanide-coordinated semiconducting polymer nanoparticles with bright fluorescence show outstanding performances in both flow cytometry and mass cytometry for cell analyses.
      PubDate: 2017-10-12T06:20:40.818779-05:
      DOI: 10.1002/anie.201708463
       
  • Visible light-driven and Iron-promoted Thiocarboxylation of Styrenes and
           Acrylates with CO2
    • Authors: Jian-Heng Ye; Meng Miao, He Huang, Si-Shun Yan, Zhu-Bao Yin, Wen-Jun Zhou, Da-Gang Yu
      Abstract: The first thiocarboxylation of styrenes and acrylates with CO2 is realized by using visible light as a driving force and catalytic iron salts as promoters. A variety of important β-thioacids are obtained in high yields. This multicomponent reaction proceeds in an atom- and redox-economical way with broad substrate scope under mild reaction conditions. Notably, high regio-, chemo- and diastero-selectivity are observed. Mechanistic studies indicate that a radical pathway can account for the unusual regioselectivity.
      PubDate: 2017-10-12T05:30:47.898895-05:
      DOI: 10.1002/anie.201707862
       
  • A Zwitterionic, 10 π Aromatic Hemisphere
    • Authors: Nema Hafezi; Wondimagegn T. Shewa, James C. Fettinger, Mark Mascal
      Abstract: A new concept in anionic 10 π aromaticity is described by the embedding of a compensating charge within an aromatic cyclononatetraenide ring by the symmetric superposition of an alkyl ammonium bridge. This is accomplished by the methylation of azatriquinacene to give a quaternary ammonium salt, followed by oxidation to the tetraene and final deprotonation. The resulting zwitterion is a stable [9]annulene with strong aromaticity as shown by its degree of C−C bond equalization and a nucleus-independent chemical shift value lower than that of benzene. The solid-state structure shows an eclipsed stacking motif with the electron-poor ammonium methyl groups occupying the electron-rich cavity of the aromatic bowl.Opposites do more than just attract: An ammonium center is suspended above an anionic, 10 π carbon toroid, leading to a novel, symmetric, bowl-shaped, strongly aromatic system that, despite being zwitterionic, is hydrocarbon soluble. Internal charge compensation results in unusual stability for an anionic annulene.
      PubDate: 2017-10-12T05:21:00.28454-05:0
      DOI: 10.1002/anie.201708521
       
  • A Chemical Disruptor of the ClpX Chaperone Complex Attenuates the
           Virulence of Multidrug-Resistant Staphylococcus aureus
    • Authors: Christian Fetzer; Vadim S. Korotkov, Robert Thänert, Kyu Myung Lee, Martin Neuenschwander, Jens Peter von Kries, Eva Medina, Stephan A. Sieber
      Abstract: The Staphylococcus aureus ClpXP protease is an important regulator of cell homeostasis and virulence. We utilized a high-throughput screen against the ClpXP complex and identified a specific inhibitor of the ClpX chaperone that disrupts its oligomeric state. Synthesis of 34 derivatives revealed that the molecular scaffold is restrictive for diversification, with only minor changes tolerated. Subsequent analysis of the most active compound revealed strong attenuation of S. aureus toxin production, which was quantified with a customized MS-based assay platform. Transcriptome and whole-proteome studies further confirmed the global reduction of virulence and revealed characteristic signatures of protein expression in the compound-treated cells. Although these partially matched the pattern of ClpX knockout cells, further depletion of toxins was observed, leading to the intriguing perspective that additional virulence pathways may be directly or indirectly addressed by the small molecule.Clp its wings: A high-throughput screen against the ClpXP protease revealed the first non-covalent inhibitors of the chaperone ClpX. Binding of the inhibitors induces disruption of the ClpX hexamer and even of the whole ClpXP proteolytic complex. Treatment of Staphylococcus aureus with the compounds leads to the global down-regulation of a plethora of secreted virulence factors.
      PubDate: 2017-10-12T05:15:45.64191-05:0
      DOI: 10.1002/anie.201708454
       
  • A Space-Charge Treatment of the Increased Concentration of Reactive
           Species at the Surface of a Ceria Solid Solution
    • Authors: Alexander F. Zurhelle; Xiaorui Tong, Andreas Klein, David S. Mebane, Roger A. De Souza
      Abstract: A space-charge theory applicable to concentrated solid solutions (Poisson–Cahn theory) was applied to describe quantitatively as a function of temperature and oxygen partial pressure published data obtained by in situ X-ray photoelectron spectroscopy (XPS) for the concentration of Ce3+ (the reactive species) at the surface of the oxide catalyst Ce0.8Sm0.2O1.9. In contrast to previous theoretical treatments, these calculations clearly indicate that the surface is positively charged and compensated by an attendant negative space-charge zone. The high space-charge potential that develops at the surface (>0.8 V) is demonstrated to be hardly detectable by XPS measurements because of the short extent of the space-charge layer. This approach emphasizes the need to take into account defect interactions and to allow deviations from local charge neutrality when considering the surfaces of oxide catalysts.A Poisson–Cahn treatment explains the experimentally observed complex behaviour of [Ce3+] at the surface of the ceria-based catalyst, Ce0.8Sm0.2O1.9. Even at the surface of such a highly concentrated solid solution, local charge neutrality is found to be violated, with the formation of a positively charged surface and an extended negative space-charge zone.
      PubDate: 2017-10-12T05:15:34.262363-05:
      DOI: 10.1002/anie.201708118
       
  • Ligand and Solvent Controlled Regio- and Chemo-divergent Carbonylative
           Reactions
    • Authors: Xiao-Feng Wu; Jin-Bao Peng
      Abstract: The development of high selective procedures is one of the core goals in organic chemistry, and the target which generations of chemists are pursuing. Among the known organic transformations, carbonylation reactions present an ideal choice for carbonyl-containing compounds preparation. In this review, the recent achievements on selectivity controlled carbonylation reactions have been summarized. The effects of ligands, solvents and bases on the selectivity have been discussed.
      PubDate: 2017-10-12T04:26:05.072221-05:
      DOI: 10.1002/anie.201709807
       
  • Unprecedented Sensitivity in a Probe for Detection and Imaging of
           Cathepsin B: Chemiluminescence Microscopy Cell Images of
           Natively-Expressed Enzyme
    • Authors: Doron Shabat; Michal Roth-Konforti, Christoph Bauer
      Abstract: Until recently, chemiluminescence cell images could be obtained only using luciferase-activated probes. Moreover, chemiluminescence microscopy cell-imaging was never demonstrated for natively expressed enzymes like cathepsin B. Here we describe the design synthesis and evaluation of the first chemiluminescence probe for detection and imaging of cathepsin B. The probe activation mechanism relies on the release of a dioxetane intermediate, which undergoes chemiexcitation to emit green light with high efficiency under physiological conditions. Using the probe, we obtained clear images of cancerous leukemia and colon cells. This is the first demonstration of chemiluminescence cell images obtained by a probe for a natively-expressed endogenous enzyme. We anticipate that the concept presented in this study will be broadly used to develop analogous probes for other important proteases relevant to biomolecular processes.
      PubDate: 2017-10-11T20:55:54.902011-05:
      DOI: 10.1002/anie.201709347
       
  • Lanthanide-based T2ex and CEST complexes provide new insights into the
           design of pH sensitive MRI agents
    • Authors: Lei Zhang; Andre F. Martins, Piyu Zhao, Yunkou Wu, Gyula Tircso, Dean Sherry
      Abstract: A series of Eu3+ and Dy3+ DOTA-tetraamide complexes with four appended primary amine groups were prepared and their CEST and T1/T2 relaxation properties measured as a function of pH. The CEST signals in the Eu3+ complexes show a surprisingly strong CEST signal after the pH was reduced from 8 to 5. The opposite trend was observed for the Dy3+ complexes where the r2ex of bulk water protons increased dramatically from ~1.5 mM-1s-1 to ~13 mM-1s-1, while r1 remained unchanged. A fit of the CEST data (Eu3+ complexes) to Bloch theory and the T2 data (Dy3+ complexes) to Swift-Connick theory provided the proton exchange rates as a function of pH. These data showed that the four amine groups contribute significantly to proton catalyzed exchange of the Ln3+-bound water protons even though their pka's are much higher than the observed CEST or T2ex effects. This demonstrated the utility of using appended acidic/basic groups to catalyze prototropic exchange for imaging tissue pH by MRI.
      PubDate: 2017-10-11T14:25:22.653647-05:
      DOI: 10.1002/anie.201707959
       
  • Sequence Mandated, Distinct Assembly of Giant Molecules
    • Authors: Wei Zhang; Xinlin Lu, Jialin Mao, Chih-Hao Hsu, Gaoyan Mu, Mingjun Huang, Qingyun Guo, Hao Liu, Chrys Wesdemiotis, Tao Li, Wen-Bin Zhang, Yiwen Li, Stephen Z. D. Cheng
      Abstract: Although controlling primary structures is by itself an enormous challenge for synthetic polymers, the potential of sequence control for tailoring hierarchical structures remains to be exploited, especially in the creation of new and unconventional phases. Herein, we design a series of model amphiphilic chain-like giant molecules by connecting both hydrophobic and hydrophilic molecular nanoparticles in precisely defined sequence and composition to investigate their intriguing sequence-dependent phase structures. Not only has composition changed the self-assembled phases, but also specific sequences are found to induce unconventional phase formation, including Frank-Kasper phases. The formation mechanism has been attributed to the conformational change driven by the collective hydrogen bonding and the sequence-mandated topology of the molecules. These results support that sequence-control in synthetic polymers can have dramatic impacts on the polymer properties and self-assembly.
      PubDate: 2017-10-11T13:55:31.41236-05:0
      DOI: 10.1002/anie.201709354
       
  • Double Catalytic Kinetic Resolution (DoCKR) of Acyclic anti-1,3-Diols
           using Additive Horeau Amplification
    • Authors: Cyril Bressy; Jérémy Merad, Prashant Borkar, Frédéric Caijo, Jean-Marc Pons, Jean-Luc Parrain, Olivier Chuzel
      Abstract: The concept of synergistic double catalytic kinetic resolution (DoCKR) described in this article, was successfully applied to racemic acyclic anti-1,3-diols, a common motif in natural products. This process takes advantage of an additive Horeau amplification involving two successive enantioselective organocatalytic acylations reactions, and leading to diesters and recovered diols with high enantiopurities. It was first developed with C2-symmetrical diols and then further extended to non-C2-symmetrical anti diols to prepare useful chiral building blocks. The protocol is highly practical as it only requires 1 mol% of a commercially available organocatalyst and leads to easily separable products. This procedure was applied to the shortest reported total synthesis of (+)-cryptocaryalactone, a natural product with anti-germinative activity.
      PubDate: 2017-10-11T10:55:39.807237-05:
      DOI: 10.1002/anie.201709844
       
  • Detailed Evidence for an Unparalleled Interaction Mode between Calmodulin
           and Orai Proteins
    • Authors: Lukas Traxler; Petr Rathner, Marc Fahrner, Michael Stadlbauer, Felix Faschinger, Tatsiana Charnavets, Norbert Müller, Christoph Romanin, Peter Hinterdorfer, Hermann J. Gruber
      Abstract: Calmodulin (CaM) binds most of its targets by wrappingaround an amphipathic α-helix. The N-terminus of Orai proteins contains a conserved CaM-binding segment but the binding mechanism is only partially characterized. Here, microscale thermophoresis (MST), surface plasmon resonance (SPR), andatomic force microscopy (AFM) were employed to study the binding equilibria, the kinetics, and the single-molecular interaction forces involved in the binding of CaM to the conserved helical segments of Orai1 and Orai3. The results consistently indicated step-wise binding of two separate target peptides to the two lobes of CaM. An unparalleled high affinity was found when two Orai peptides were dimerized or immobilized at high lateral density, thereby mimicking the close proximity of the N-termini in native Orai oligomers. The analogous experiments with smooth muscle myosin light chain kinase (smMLCK) showed only the expected 1:1 binding, confirming the validity of our methods.
      PubDate: 2017-10-11T09:56:32.025496-05:
      DOI: 10.1002/anie.201708667
       
  • Total Synthesis of Lycoricidine and Narciclasine via Chemical
           Dearomatization of Bromobenzene
    • Authors: Emma Southgate; Daniel Holycross, David Sarlah
      Abstract: The total synthesis of lycoricidine and narciclasine is enabled by the use of arenophile-mediated dearomative dihydroxylation of bromobenzene. Subsequent transpositive Suzuki coupling and cycloreversion deliver a key biaryl dihydrodiol intermediate, which is rapidly converted to lycoricidine through site-selective syn-1,4-hydroxyamination and deprotection. The total synthesis of narciclasine is accomplished via a late stage, amide-directed C-H hydroxylation of a lycoricidine intermediate. Moreover, the general applicability of this strategy to access dihydroxylated biphenyls has been demonstrated with several examples.
      PubDate: 2017-10-11T09:56:19.348498-05:
      DOI: 10.1002/anie.201709712
       
  • CODH-IV: A novel high efficiency CO-scavenging CO dehydrogenase with
           increased resistance to O2
    • Authors: Lilith Domnik; Meriem Merrouch, Sebastian Goetzl, Jae-Hun Jeoung, Christophe Leger, Sebastien Dementin, Vincent Fourmond, Holger Dobbek
      Abstract: CO dehydrogenases (CODHs) catalyse the reversible conversion between CO and CO2. Genomic analysis indicated that the metabolic functions of CODHs vary. The genome of Carboxydothermus hydrogenoformans encodes five CODHs (CODH-I - V), of which CODH-IV is found in a gene cluster near a peroxide reducing enzyme. Our kinetic and crystallographic experiments reveal that CODH-IV differs from other CODHs by characteristic properties: it has a very high affinity for CO, oxidizes CO at diffusion-limited rate over a wide range of temperatures, and is more tolerant to oxygen than CODH-II. Thus, our observations support the idea that CODH-IV is a CO scavenger in defence against oxidative stress and highlight that CODHs are more diverse in terms of reactivity than expected.
      PubDate: 2017-10-11T08:57:58.01978-05:0
      DOI: 10.1002/anie.201709261
       
  • Mass-production of Mesoporous MnCo2O4 Spinel with MnIV- and CoII-rich
           Surface for Superior Bifunctional Oxygen Electrocatalysis
    • Authors: Wenhai Wang; Long Kuai, Wei Cao, Marko Huttula, Sami Ollikkala, Taru Ahopelto, Ari-Pekka Honkanen, Simo Huotari, Mengkang Yu, Baoyou Geng
      Abstract: A mesoporous MnCo2O4 electrode materials is successfully fabricated for bifunctional oxygen electrocatalysis. The MnCo2O4 exhibits both Co3O4-like activity for oxygen evolution reaction (OER) and Mn2O3-approaching performance for oxygen reduction reaction (ORR). The potential difference between ORR metric and OER metric of MnCo2O4 is as low as 0.84 V. By XANES and XPS investigation, the notable activity is resulted from the preferred MnIV- and CoII-rich surface. Valuably, the products can be obtained in large-scale with the precise chemical components at relatively low temperature. The surface state engineering maybe open a new avenue to optimize electrocatalysis performance of electrode materials. The prominent bifunctional activity shows that MnCo2O4 has the possibility of being used in metal-air batteries and/or other energy devices.
      PubDate: 2017-10-11T08:57:30.235507-05:
      DOI: 10.1002/anie.201708765
       
  • A Lewis Base Catalysis Approach for the Photoredox Activation of Boronic
           Acids and Esters
    • Authors: Fabio Lima; Upendra K Sharma, Lars Grunenberg, Debasmita Saha, Sandra Johannsen, Joerg Sedelmeier, Erik V Van der Eycken, Steven Victor Ley
      Abstract: We report herein the use of a dual catalytic system comprising of a Lewis base catalyst such as quinuclidin-3-ol or 4-dimethylaminopyridine combined with a photoredox catalyst to generate carbon radicals from either boronic acids or esters. This system enabled a wide range of alkyl boronic esters and aryl or alkyl boronic acids to react via radical addition with electron-deficient olefins to efficiently form C-C coupled products in a redox neutral fashion. The Lewis base catalyst was shown to form a redox-active complex with either boronic esters or the trimeric form of the boronic acids (boroxines) in solution.
      PubDate: 2017-10-11T08:56:54.550257-05:
      DOI: 10.1002/anie.201709690
       
  • Selective Radical Fluorination of Tertiary Alkyl Halides at Room
           Temperature
    • Authors: He Chen; Zhonglin Liu, Ying Lv, Xinqiang Tan, Haigen Shen, Hai-Zhu Yu, Chaozhong Li
      Abstract: Direct fluorination of tertiary alkyl bromides and iodides with Selectfluor reagent is described. The halogen-exchange fluorination proceeds efficiently in acetonitrile at room temperature under metal-free conditions and exhibits a wide range of functional group compatibility. Furthermore, the reactions are highly selective in that alkyl chlorides and primary and secondary alkyl bromides remain intact. A radical mechanism is proposed for this selective fluorination.
      PubDate: 2017-10-11T08:26:03.108538-05:
      DOI: 10.1002/anie.201708197
       
  • Non-Uniform Optical Inscription of Actuation Domains in a Liquid Crystal
           Polymer of Uniaxial Orientation: An Approach to Complex and Programmable
           Shape Changes
    • Authors: Rong Yang; Yue Zhao
      Abstract: Achieving complex shape change of liquid-crystal polymer networks (LCNs) under stimulation generally requires spatial configuration of the orientation direction, that is, patterned directors, of liquid crystal monomers prior to polymerization by means of treated surfaces. A strategy is demonstrated that needs only the simple uniaxial orientation of mesogens (monodomain) induced by mechanical stretching of LCNs. Using a rationally designed liquid crystal polymer, photocrosslinking is utilized to pattern or spatially organize the actuating monodomains in order to generate a differential contractile and/or extensional force field required for targeted shape change. Moreover, the approach enables versatile actuation modes and allows multiple shape changes to be programmed on a single piece of the polymer. This important feature is demonstrated with a specimen cut to have eight strips that, upon thermal stimulation, simultaneously display eight types of shape morphing.Roll with the changes: An easily processable liquid crystal polymer with only uniaxial orientation of mesogens can be programmed to display multiple, complex shape morphing on a single piece of the material (eight changes are shown in the picture). The approach consists in using photocrosslinking to spatially configure and organize the actuation domains in mechanically stretched specimen.
      PubDate: 2017-10-11T08:10:31.1275-05:00
      DOI: 10.1002/anie.201709528
       
  • Singlet Oxygen during Cycling of the Aprotic Na-O2 Battery
    • Authors: Lukas Schafzahl; Nika Mahne, Bettina Schafzahl, Martin Wilkening, Christian Slugovc, Sergey M Borisov, Stefan A. Freunberger
      Abstract: Aprotic sodium-O2 batteries require the reversible formation/dissolution of sodium superoxide (NaO2) on cycling. Poor cycle life has been associated with parasitic chemistry caused by the reactivity of electrolyte and electrode with NaO2, a strong nucleophile and base. Its reactivity can, however, not consistently explain the side reactions and irreversibility. Here we show that singlet oxygen (1O2) forms at all stages of cycling and that it is a main driver for parasitic chemistry. It was detected in- and ex-situ via a 1O2 trap that selectively and rapidly forms a stable adduct with 1O2. The 1O2 formation mechanism involves proton mediated superoxide disproportionation on discharge, rest, and charge below ~3.3 V, and direct electrochemical 1O2 evolution above ~3.3 V. Trace water, which is needed for high capacities drives at the same time parasitic chemistry. Controlling the highly reactive singlet oxygen is thus crucial for achieving highly reversible cell operation.
      PubDate: 2017-10-11T07:55:20.530209-05:
      DOI: 10.1002/anie.201709351
       
  • Hydrogen-bonded Hexagonal Buckybowl Framework
    • Authors: Ichiro Hisaki; Hideaki Toda, Hiroyasu Sato, Norimitsu Tohnai, Hidehiro Sakurai
      Abstract: We report a hydrogen-bonded two-dimensionally networked buckybowl architecture for the first time. Two types of hexagonal network (HexNet) structures (CPSM-1 and -2) have been achieved based on a sumanene derivative (CPSM) possessing 4,4'-dicarboxy-o-terphenyl groups in the periphery. CPSM-1 has a waved HexNet structure with an alternate alignment of upward and downward bowls. CPSM-2 has a bilayered HexNet structure composed of hamburger-shaped dimers of the bowls. This demonstrates that non-planar π-systems can be networked two-dimensionally by an appropriate supramolecular synthon to achieve structurally well-defined unique bumpy π-sheets. Furthermore, we revealed that CPSM-2 undergoes anisotropic shrinking along the c axis by 11% under high pressure conditions (970 MPa). The shrinkage is brought about by offset sliding between bumpy π-surfaces of the bilayered HexNet sheets.
      PubDate: 2017-10-11T07:25:33.985639-05:
      DOI: 10.1002/anie.201708115
       
  • Active Cocatalysts for Photocatalytic Hydrogen Evolution Derived from
           Nickel or Cobalt Amine Complexes
    • Authors: Yi Huang; Bin Zhang
      Abstract: A cost-effective and robust strategy for the anchoring of molecular hydrogen evolution cocatalysts onto semiconductors has recently been reported. The composite materials were highly efficient and stable towards photocatalytic H2 evolution. This study provides guidance for the design and construction of highly active heterogeneous photocatalysts.
      PubDate: 2017-10-11T07:25:21.688528-05:
      DOI: 10.1002/anie.201708844
       
  • Construction of Discrete Pentanuclear Platinum(II) Stacks with Extended
           Metal–Metal Interactions by Using Phosphorescent Platinum(II) Tweezers
    • Authors: Fred Ka-Wai Kong; Alan Kwun-Wa Chan, Maggie Ng, Kam-Hung Low, Vivian Wing-Wah Yam
      Abstract: Discrete pentanuclear PtII stacks were prepared by the host-guest adduct formation between multinuclear tweezer-type PtII complexes. The formation of the PtII stacks in solution was accompanied by color changes and the turning on of near-infrared emission resulting from Pt⋅⋅⋅Pt and π–π interactions. The X-ray crystal structure revealed the formation of a discrete 1:1 adduct, in which a linear stack of five PtII centers with extended Pt⋅⋅⋅Pt interactions was observed. Additional binding affinity and stability have been achieved through a multinuclear host-guest system. The binding behaviors can be fine-tuned by varying the spacer between the two PtII moieties in the guests. This work provides important insights for the construction of discrete higher-order supramolecular metal-ligand aggregates using a tweezer-directed approach.Stack up: Discrete pentanuclear PtII stacks were prepared by the host-guest adduct formation between multinuclear tweezer-type PtII complexes, with color changes and the turning on of near-infrared emission resulting from Pt⋅⋅⋅Pt and π–π interactions. The X-ray crystal structure revealed the formation of a discrete 1:1 adduct, in which a linear stack of five PtII centers with extended Pt⋅⋅⋅Pt interactions was observed.
      PubDate: 2017-10-11T07:15:30.538746-05:
      DOI: 10.1002/anie.201708504
       
  • The Surface of Ice Is Like Supercooled Liquid Water
    • Authors: Wilbert J. Smit; Huib J. Bakker
      Abstract: The surface of ice has been reported to be disordered at temperatures well below the bulk melting point. However, the precise nature of this disorder has been a topic of intense debate. Herein, we study the molecular properties of the surface of ice as a function of temperatures using heterodyne-detected sum-frequency generation spectroscopy. We observe that, down to 245 K, the spectral response of the surface of ice contains a component that is indistinguishable from supercooled liquid water.Ice, ice, maybe: The molecular properties of the surface of ice are studied in the temperature region 245–270 K using heterodyne-detected sum-frequency generation spectroscopy. Down to 245 K, the spectral response of the quasi-liquid layer is indistinguishable from that of supercooled liquid water.
      PubDate: 2017-10-11T06:22:05.330198-05:
      DOI: 10.1002/anie.201707530
       
  • Encapsulation of Isolated Luminophores within Supramolecular Cages
    • Authors: Marcel Handke; Takuji Adachi, Chunhua Hu, Michael D. Ward
      Abstract: Organic solid-state dye lasers promise versatility with respect to spectral tuning, but often face challenges owing to self-quenching by aggregation. In their Communication (
      DOI : 10.1002/anie.201707097), M. D. Ward et al. describe an approach to solid-state lasing compounds in which isolated luminescent guest molecules, some well-known laser dyes, are encapsulated in cages of a crystalline hydrogen-bonded zeolite-like framework. The luminescence of each compound is consistent with the absence of self-quenching, and the emission color can be tuned from blue to red by the choice of guest molecule.
      PubDate: 2017-10-11T06:22:00.395727-05:
       
  • The Rolling-Up of Oligophenylenes to Nanographenes by a HF-Zipping
           Approach
    • Authors: Ann-Kristin Steiner; Konstantin Y. Amsharov
      Abstract: The HF-zipping strategy allows an unprecedentedly challenging transformation to be performed. It consists of “zipping” virtually linear fluorinated oligophenylenes together to give “preprogrammed” nanographenes via domino-like cyclodehydrofluorination. In their Communication (
      DOI : 10.1002/anie.201707272), A.-K. Steiner and K. Y. Amsharov demonstrate that fluorine positions in the precursor structure unambiguously dictate the running of the “zipping-program” leading exclusively to the target atomically precise nanographene.
      PubDate: 2017-10-11T06:21:57.738217-05:
       
  • Ring Expansion, Photoisomerization, and Retrocyclization of
           1,4,2-Diazaboroles
    • Authors: Bochao Su; Yongxin Li, Rakesh Ganguly, Rei Kinjo
      Abstract: Diverse skeletal transformations of 1,4,2-diazaboroles through ring expansion, photoisomerization, and retrocyclization led to the isolation of various B,N-dihydroindole (compounds 3 and 6), 1,3-azaborolidin-2-imine (compound 7), and 1,4,2-diazaborol-3-imine derivatives (compound 11).NB: Diverse skeletal transformations of 1,4,2-diazaboroles through ring expansion, photoisomerization, and retrocyclization (see picture) provided various B,N-heterocyclic compounds, including B,N-dihydroindole, 1,3-azaborolidin-2-imine, and 1,4,2-diazaborol-3-imine derivatives. These newly formed B,N heterocycles were fully characterized by NMR spectroscopy and X-ray diffraction analysis.
      PubDate: 2017-10-11T06:21:54.885798-05:
      DOI: 10.1002/anie.201708720
       
  • Forcing Ladderenes into Plastic Semiconductors with Mechanochemistry
    • Authors: Samuel W. Thomas
      Abstract: May the force be with you: Xia, Burns, Martinez, and co-workers harnessed the ring strain of ladderenes to enable both their polymerization and mechanochemical unzipping to yield semiconducting polyacetylene-based block copolymers. These materials have promise as functional polymers for applications such as detection of physical stress.
      PubDate: 2017-10-11T06:21:46.993778-05:
      DOI: 10.1002/anie.201709598
       
  • Total Synthesis of (+)-Gracilamine Based on an Oxidative Phenolic Coupling
           Reaction and Determination of Its Absolute Configuration
    • Authors: Minami Odagi; Yoshiharu Yamamoto, Kazuo Nagasawa
      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.Forced to give up its secret: The ABCE ring system in (+)-gracilamine was constructed by means of three key steps: an organocatalytic 1,2-type aza-Friedel–Crafts (aza-F-C) reaction and a diastereoselective oxidative phenolic coupling reaction followed by a regioselective aza-Michael reaction (see scheme). The efficient enantioselective total synthesis revealed the absolute configuration of the natural product.
      PubDate: 2017-10-11T06:21:44.094427-05:
      DOI: 10.1002/anie.201708575
       
  • Electronic Delocalization in Two and Three Dimensions: Differential
           Aggregation in Indium “Metalloid” Clusters
    • Authors: Andrey V. Protchenko; Juan Urbano, Joseph A. B. Abdalla, Jesús Campos, Dragoslav Vidovic, Andrew D. Schwarz, Matthew P. Blake, Philip Mountford, Cameron Jones, Simon Aldridge
      Abstract: Reduction of indium boryl precursors to give two- and three-dimensional M−M bonded networks is influenced by the choice of supporting ligand. While the unprecedented nanoscale cluster [In68(boryl)12]− (with an In12@In44@In12(boryl)12 concentric structure), can be isolated from the potassium reduction of a bis(boryl)indium(III) chloride precursor, analogous reduction of the corresponding (benzamidinate)InIIIBr(boryl) system gives a near-planar (and weakly aromatic) tetranuclear [In4(boryl)4]2− system.Clusters à la carte: Reduction of indium boryl complexes to give 2D and 3D aggregates can be controlled by the choice of supporting ligand. The unprecedented nanoscale cluster In12@In44@In12(boryl)12 (see picture) is isolated from the potassium reduction of a bis(boryl) precursor, while reduction of (amidinate)InIIIBr(boryl) gives a (weakly aromatic) planar tetranuclear [In4(boryl)4]2− system.
      PubDate: 2017-10-11T06:21:31.252465-05:
      DOI: 10.1002/anie.201708496
       
  • Structure and Mechanism of the Monoterpene Cyclolavandulyl Diphosphate
           Synthase that Catalyzes Consecutive Condensation and Cyclization
    • Authors: Takeo Tomita; Masaya Kobayashi, Yuma Karita, Yoko Yasuno, Tetsuro Shinada, Makoto Nishiyama, Tomohisa Kuzuyama
      Abstract: We report the three-dimensional structure of cyclolavandulyl diphosphate (CLPP) synthase (CLDS), which consecutively catalyzes the condensation of two molecules of dimethylallyl diphosphate (DMAPP) followed by cyclization to form a cyclic monoterpene, CLPP. The structures of apo-CLDS and CLDS in complex with Tris, pyrophosphate, and Mg2+ ion were refined at 2.00 Å resolution and 1.73 Å resolution, respectively. CLDS adopts a typical fold for cis-prenyl synthases and forms a homo-dimeric structure. An in vitro reaction using a regiospecifically 2H-substituted DMAPP substrate revealed the intramolecular proton transfer mechanism of the CLDS reaction. The CLDS structure and structure-based mutagenesis provide mechanistic insights into this unprecedented terpene synthase. The combination of structural and mechanistic insights advances the knowledge of intricate terpene synthase-catalyzed reactions.A synthase that can do both: Cyclolavandulyl diphosphate (CLPP) synthase (CLDS) catalyzes “head-to-middle” condensation of two molecules of dimethylallyl diphosphate (DMAPP) and subsequent cyclization to produce CLPP. The crystal structure of CLDS in complex with Tris, pyrophosphate, and Mg2+ ion was refined at 1.73 Å resolution. An in vitro reaction using a regiospecifically deuterated DMAPP, the CLDS structure, and mutagenesis provide mechanistic insights into this unique terpene synthase.
      PubDate: 2017-10-11T06:21:14.299235-05:
      DOI: 10.1002/anie.201708474
       
  • Hughes and Gleason's Virosaine A—Appreciating the Art in
           Synthesis
    • Authors: Bryan D. Ellis; Christopher D. Vanderwal
      Abstract: The synthesis of the Securinega alkaloid virosaine A by Hughes and Gleason is a perfect example of the intersection of art and chemical synthesis. An ingenious cascade reaction builds most of the polycyclic architecture, but necessitates a challenging C−H functionalization, which is ultimately accomplished by an unusual directed lithiation reaction.
      PubDate: 2017-10-11T06:21:02.271598-05:
      DOI: 10.1002/anie.201708051
       
  • Gold(I)-Catalyzed Synthesis of Indenes and Cyclopentadienes: Access to
           (±)-Laurokamurene B and the Skeletons of the Cycloaurenones and
           Dysiherbols
    • Authors: Xiang Yin; Mauro Mato, Antonio M. Echavarren
      Abstract: The formal (3+2) cycloaddition between terminal allenes and aryl or styryl gold(I) carbenes generated by a retro-Buchner reaction of 7-substituted 1,3,5-cycloheptatrienes led to indenes and cyclopentadienes, respectively. These cycloaddition processes have been applied to the construction of the carbon skeleton of the cycloaurenones and the dysiherbols as well as to the total synthesis of (±)-laurokamurene B.The golden touch: Formal (3+2) cycloaddition between terminal allenes and gold(I) carbenes generated by a retro-Buchner reaction led to indenes and cyclopentadienes. These cycloaddition reactions were applied to the construction of the carbon skeleton of the cycloaurenones and the dysiherbols and to the total synthesis of (±)-laurokamurene B (see scheme).
      PubDate: 2017-10-11T06:20:58.576471-05:
      DOI: 10.1002/anie.201708947
       
  • Near-Infrared Free-Radical and Free-Radical-Promoted Cationic
           Photopolymerizations by In-Source Lighting Using Upconverting Glass
    • Authors: Azra Kocaarslan; Sevcan Tabanli, Gonul Eryurek, Yusuf Yagci
      Abstract: A method is presented for the initiation of free-radical and free-radical-promoted cationic photopolymerizations by in-source lighting in the near-infrared (NIR) region using upconverting glass (UCG). This approach utilizes laser irradiation of UCG at 975 nm in the presence of fluorescein (FL) and pentamethyldiethylene triamine (PMDETA). FL excited by light emitted from the UCG undergoes electron-transfer reactions with PMDETA to form free radicals capable of initiating polymerization of methyl methacrylate. To execute the corresponding free-radical-promoted cationic polymerization of cyclohexene oxide, isobutyl vinyl ether, and N-vinyl carbazole, it was necessary to use FL, dimethyl aniline (DMA), and diphenyliodonium hexafluorophosphate as sensitizer, coinitiator, and oxidant, respectively. Iodonium ions promptly oxidize DMA radicals formed to the corresponding cations. Thus, cationic polymerization with efficiency comparable to the conventional irradiation source was achieved.Free-radical and free-radical-promoted cationic polymerization is stimulated by in-source lighting in the near-infrared region. Yb3+/Tm3+ codoped tungsten–tellurite upconverting glass (UCG) irradiated by a laser, in the presence of fluorescein (FL) dye/amine and iodonium salt combinations, generates free radicals capable of initiating polymerization. Key: dimethyl aniline (DMA), pentamethyldiethylene triamine (PMDETA).
      PubDate: 2017-10-11T06:20:37.02234-05:0
      DOI: 10.1002/anie.201707944
       
  • Highly 2,3-Selective Polymerization of Phenylallene and Its Derivatives
           with Rare-Earth Metal Catalysts: From Amorphous to Crystalline Products
    • Authors: Fei Lin; Zhaohe Liu, Tiantian Wang, Dongmei Cui
      Abstract: Rare-earth metal complexes (Flu-CH2-Py)Ln(CH2SiMe3)2(THF)n (Ln=Sc(1), Lu(2), Tm(3), Y(4) and Gd(5)), upon the activation of [Ph3C][B(C6F5)4] and AliBu3, were employed to catalyze the polymerization of allene derivatives under mild conditions. The Gd, Y, Tm, Lu metal based precursors exhibited distinguished 2,3-selectivity (>99.9 %) for phenylallene (PA) polymerization, whereas the smallest Sc metal based precursor showed a moderate 2,3-selectivity. The activity increased with the central metal size following the trend of Gd(5)>Tm(4)>Y(3)>Lu(2)>Sc(1). Moreover, Gd(5) also realized the purely 2,3-selective polymerizations of polar or nonpolar allene derivatives, para-methylphenylallene, para-flourophenylallene and para-methoxyphenylallene, regardless of electron-donating or -withdrawing substituents. Owing to the highly regular backbones, these polymers (except PPA) were crystalline, thus being the first crystalline polymers based on allene derivatives.Rare-earth metal complexes (Flu-CH2-Py)Ln(CH2SiMe3)2(THF)n (Ln=Sc, Lu, Tm, Y and Gd), upon the activation of [Ph3C][B(C6F5)4] and AliBu3, were employed to catalyze the 2,3-selective polymerization of phenylallene (PA) and its derivatives bearing polar or nonpolar substituent groups. Owing to the highly regular backbones, most obtained polymers were crystalline, thus being the first crystalline polymers based on allene derivatives.
      PubDate: 2017-10-11T06:20:33.050145-05:
      DOI: 10.1002/anie.201707601
       
  • Precise Assembly of Particles for Zigzag or Linear Patterns
    • Authors: Dan Guo; Chang Li, Yang Wang, Yanan Li, Yanlin Song
      Abstract: Precise control of particles assembly has tremendous potential for fabricating intricate structures and functional materials. However, it is still a challenge to achieve one-dimensional assembly with precisely controlled morphology. In this work, we report an effective strategy to precisely assemble particles into well-defined patterns by liquid confinement through controlling the viscosity of the assembly system. It is found that high viscosity of the system impedes particles rearrangement, and facilitates the generation of zigzag or twined zigzag assembly structures; while low viscosity of the system allows particles to rearrange into linear or zipper structures driven by lowering the surface deformation of the liquid. As a result, precise control of different assembly patterns can be achieved through tuning the viscosity of solvent and size confinement ratios. This facile approach shows generality for particles assembly of different sizes and materials.
      PubDate: 2017-10-11T05:55:50.566636-05:
      DOI: 10.1002/anie.201709115
       
  • Non-enzymatic Oxidation of a Pentagalloylglucose Analog to Ellagitannins
    • Authors: Seiya Ashibe; Kazutada Ikeuchi, Yuji Kume, Shinnosuke Wakamori, Yuri Ueno, Takashi Iwashita, Hidetoshi Yamada
      Abstract: The occurrence of more than 1,000 structural diversity in ellagitannins has been hypothesized to begin with oxidation of penta-O-galloyl--D-glucose (-PGG) to couple the galloyl groups. However, the non-enzymatic behavior of -PGG in the oxidation is unknown. Here, we disclose which galloyl groups on glucose tended to couple and which axial chirality was predominant in the derived hexahydroxydiphenoyl groups, when an analog of -PGG was subjected to oxidation. The study revealed that the galloyl groups coupled, in the following order of production ratio: at the 4,6-, 1,6-, 1,2-, 2,3-, and 3,6-positions with respective S, S, R, S, and R-axial chirality. Among them, the most preferred 4,6-coupling reflected the tendency observed in natural ellagitannins. An astonishing fact was that the second best was the 1,6-coupling. With the detection of a 3,6-coupled product, this work demonstrated that even ellagitannin skeletons with an axial-rich glucose core may generate non-enzymatically.
      PubDate: 2017-10-11T05:55:31.597798-05:
      DOI: 10.1002/anie.201708703
       
  • O2 Activation on Ceria Catalysts - The Importance of Substrate
           Crystallographic Orientation
    • Authors: Chengwu Yang; Xiaojuan Yu, Stefan Heissler, Peter Weidler, Alexei Nefedov, Yuemin Wang, Christof Wöll, Thomas Kropp, Joachim Paier, Joachim Sauer
      Abstract: An atomic-level understanding of dioxygen activation on metal oxides remains one of the major challenges in heterogeneous catalysis. By performing a thorough surface-science study of all three low-index single-crystal surfaces of ceria, probably the most important redox catalysts, we provide a direct spectroscopic characterization of reactive dioxygen species at defect sites on the reduced ceria (110) and (100) surfaces. Surprisingly, neither of these superoxo and peroxo species was found on ceria (111), the thermodynamically most stable surface of this oxide. Applying density functional theory, we could relate these apparently inconsistent findings to a sub-surface diffusion of O-vacancies on (111) substrates, but not on the less closely packed surfaces. These observations resolve a long standing debate concerning the location of O-vacancies on ceria surfaces and the activation of O2 on ceria powders.
      PubDate: 2017-10-11T05:25:46.990973-05:
      DOI: 10.1002/anie.201709199
       
  • Phosphorylation-Responsive Membrane Transport of Peptides
    • Authors: Shu Peng; Andrea Barba-Bon, Yu-Chen Pan, Werner M. Nau, Dong-Sheng Guo, Andreas Hennig
      Abstract: Phosphorylation and dephosphorylation of peptides by kinases and phosphatases is essential for signal transduction in biological systems and many diseases involve abnormal activities of these enzymes. Herein, we introduce amphiphilic calixarenes as key components for supramolecular, phosphorylation-responsive membrane transport systems. Dye efflux experiments with liposomes demonstrated that calixarenes are highly active counterion activators for established cell-penetrating peptides with EC50 values in the low nanomolar range. We have now found that they can even activate membrane transport of short peptide substrates for kinases involved in signal transduction, whereas the respective phosphorylated products are much less efficiently transported. This allows regulation of membrane transport activity by protein kinase A (PKA) and protein kinase C (PKC) as well as monitoring their activity in a label-free kinase assay.
      PubDate: 2017-10-11T05:25:40.182024-05:
      DOI: 10.1002/anie.201707979
       
  • Quantitative and Comparative Profiling of Protease Substrates through a
           Genetically Encoded Multifunctional Photocrosslinker
    • Authors: Dan He; Xiao Xie, Fan Yang, Heng Zhang, Haomiao Su, Yun Ge, Haiping Song, Peng R. Chen
      Abstract: A genetically encoded, multifunctional photocrosslinker was developed for quantitative and comparative proteomics. By bearing a bioorthogonal handle and a releasable linker in addition to its photoaffinity warhead, this probe enables the enrichment of transient and low-abundance prey proteins after intracellular photocrosslinking and prey–bait separation, which can be subject to stable isotope dimethyl labeling and mass spectrometry analysis. This quantitative strategy (termed isoCAPP) allowed a comparative proteomic approach to be adopted to identify the proteolytic substrates of an E. coli protease–chaperone dual machinery DegP. Two newly identified substrates were subsequently confirmed by proteolysis experiments.A genetically encoded trifunctional photocrosslinker was developed that bears a bioorthogonal handle and a releasable linker in addition to its photoaffinity warhead. This probe enabled the enrichment of transient and low-abundance prey proteins after intracellular photocrosslinking and prey–bait separation. A quantitative and comparative proteomic strategy using this probe revealed the substrates of a protease.
      PubDate: 2017-10-11T04:36:54.982905-05:
      DOI: 10.1002/anie.201708151
       
  • Alkynylation of Csp2 (O)–H Bonds Enabled by Photoredox-Mediated
           Hydrogen-Atom Transfer
    • Authors: Satobhisha Mukherjee; R. Aleyda Garza-Sanchez, Adrian Tlahuext-Aca, Frank Glorius
      Abstract: The development of new hydrogen-atom transfer (HAT) strategies within the framework of photoredox catalysis is highly appealing for its power to activate a desired C−H bond in the substrate leading to its selective functionalization. Reported here is the first photoredox-mediated hydrogen-atom transfer method for the efficient synthesis of ynones, ynamides, and ynoates with high regio- and chemoselectivity by direct functionalization of Csp2(O)−H bonds. The broad synthetic application of this method has been demonstrated by the selective functionalization of C(O)−H bonds within complex molecular scaffolds.Tip your HAT: A photoredox-catalyzed hydrogen-atom transfer (HAT) method has been developed for the successful generation of carbonyl radicals from aldehydes and analogous compounds with an XC(O)−H (X=N, O) group. The successful trapping of the carbonyl radicals with ethynylbenziodoxolone (EBX) reagents provides a route for the synthesis of ynones, ynamides, and ynoates from readily available starting materials.
      PubDate: 2017-10-11T04:36:47.413275-05:
      DOI: 10.1002/anie.201708037
       
  • Switchable Hydrolase Based on Reversible Formation of Supramolecular
           Catalytic Site Using a Self-Assembling Peptide
    • Authors: Chunqiu Zhang; Ramim Shafi, Ayala Lampel, Douglas MacPherson, Charalampos G. Pappas, Vishal Narang, Tong Wang, Charles Maldarelli, Rein V. Ulijn
      Abstract: The reversible regulation of catalytic activity is a feature found in natural enzymes which is not commonly observed in artificial catalytic systems. Here, we fabricate an artificial hydrolase with pH-switchable activity, achieved by introducing a catalytic histidine residue at the terminus of a pH-responsive peptide. The peptide exhibits a conformational transition from random coil to β-sheet by changing the pH from acidic to alkaline. The β-sheet self-assembles to form long fibrils with the hydrophobic edge and histidine residues extending in an ordered array as the catalytic microenvironment, which shows significant esterase activity. Catalytic activity can be reversible switched by pH-induced assembly/disassembly of the fibrils into random coils. At higher concentrations, the peptide forms a hydrogel which is also catalytically active and maintains its reversible (de-)activation.A pH-switchable artificial hydrolase was constructed by introducing a catalytic histidine residue to a pH-responsive β-hairpin peptide (VK2H). The conformation of VK2H can be regulated between random coil and β-sheet fibrils by the pH. The catalytic activity follows the self-assembly “switch” by the reversible alignment of catalytic and binding sites with the unassembled random coils inactive and the fibrils able to catalyze the hydrolysis of substrate.
      PubDate: 2017-10-11T04:36:35.751364-05:
      DOI: 10.1002/anie.201708036
       
  • Malonic Acid Diazoesters for C−H Insertion Crosslinking (CHic)
           Reactions: A Versatile Method for the Generation of Tailor-Made Surfaces
    • Authors: Philip F. Kotrade; Jürgen Rühe
      Abstract: A simple and versatile method for the modification of a broad spectrum of surfaces with thin polymer films through the thermally or photochemically induced generation of surface-attached polymer networks is reported. The system is based on copolymers containing diazomalonate groups, which can be activated by heat or light. To this end, the copolymers are deposited from solution onto solid substrates by standard techniques of thin-film deposition (spin coating, dip coating). Upon activation the diazomalonate group decomposes and forms a carbene, which induces C−H insertion crosslinking (CHic) reactions. In the course of this process network formation and covalent surface attachment occur at the same time. The crosslinking process proceeds very rapidly, especially when the carbenes generated in the activation process cannot undergo Wolff-rearrangement. The presented system can be used for the generation of a wide range of polymer layers and microstructures on a broad spectrum of surfaces.Polymer networks generated by means of C−H insertion reactions, from copolymers containing diazomalonate groups, allow a simple and versatile modification of a broad range of materials. For example, tailor-made surfaces can be obtained that allow simple immobilization of DNA or proteins for use in microarrays or immunoassays.
      PubDate: 2017-10-11T04:36:07.772652-05:
      DOI: 10.1002/anie.201704486
       
  • Adenylation Activity of Carboxylic Acid Reductases Enables the Synthesis
           of Amides
    • Authors: Alexander J. L. Wood; Nicholas J. Weise, Joseph D. Frampton, Mark S. Dunstan, Michael A. Hollas, Sasha R. Derrington, Richard C. Lloyd, Daniela Quaglia, Fabio Parmeggiani, David Leys, Nicholas J. Turner, Sabine L. Flitsch
      Abstract: Carboxylic acid reductases (CARs) catalyze the reduction of a broad range of carboxylic acids to aldehydes using the cofactors adenosine triphosphate and nicotinamide adenine dinucleotide phosphate, and have become attractive biocatalysts for organic synthesis. Mechanistic understanding of CARs was used to expand reaction scope, generating biocatalysts for amide bond formation from carboxylic acid and amine. CARs demonstrated amidation activity for various acids and amines. Optimization of reaction conditions, with respect to pH and temperature, allowed for the synthesis of the anticonvulsant ilepcimide with up to 96 % conversion. Mechanistic studies using site-directed mutagenesis suggest that, following initial enzymatic adenylation of substrates, amidation of the carboxylic acid proceeds by direct reaction of the acyl adenylate with amine nucleophiles.CARpe diem: Carboxylic acid reductases can be used as biocatalysts for the activation and subsequent amidation of a range of carboxylic acids with primary and secondary amines, as well as ammonia. The enzymes were used to synthesize the anticonvulsant ilepcimide. Key: adenosine triphosphate (ATP), nicotinamide adenine dinucleotide phosphate (NADPH).
      PubDate: 2017-10-11T04:35:46.354509-05:
      DOI: 10.1002/anie.201707918
       
  • Fully Automated Quantum-Chemistry-Based Computation of Spin–Spin-Coupled
           Nuclear Magnetic Resonance Spectra
    • Authors: Stefan Grimme; Christoph Bannwarth, Sebastian Dohm, Andreas Hansen, Jana Pisarek, Philipp Pracht, Jakob Seibert, Frank Neese
      Abstract: We present a composite procedure for the quantum-chemical computation of spin–spin-coupled 1H NMR spectra for general, flexible molecules in solution that is based on four main steps, namely conformer/rotamer ensemble (CRE) generation by the fast tight-binding method GFN-xTB and a newly developed search algorithm, computation of the relative free energies and NMR parameters, and solving the spin Hamiltonian. In this way the NMR-specific nuclear permutation problem is solved, and the correct spin symmetries are obtained. Energies, shielding constants, and spin–spin couplings are computed at state-of-the-art DFT levels with continuum solvation. A few (in)organic and transition-metal complexes are presented, and very good, unprecedented agreement between the theoretical and experimental spectra was achieved. The approach is routinely applicable to systems with up to 100–150 atoms and may open new avenues for the detailed (conformational) structure elucidation of, for example, natural products or drug molecules.A composite procedure for the quantum-chemical computation of spin–spin-coupled 1H NMR spectra for flexible molecules in solution consists of four main steps, namely conformer/rotamer ensemble (CRE) generation by the fast tight-binding method GFN-xTB and a newly developed search algorithm, DFT computation of the relative free energies and NMR parameters, and solution of the spin Hamiltonian.
      PubDate: 2017-10-11T04:31:11.119129-05:
      DOI: 10.1002/anie.201708266
       
  • A Simple and Broadly Applicable C−N Bond Forming Dearomatization
           Protocol Enabled by Bifunctional Amino Reagents
    • Authors: Xiaofeng Ma; Joshua J. Farndon, Tom A. Young, Natalie Fey, John F. Bower
      Abstract: A C−N bond forming dearomatization protocol with broad scope is outlined. Specifically, bifunctional amino reagents are used for sequential nucleophilic and electrophilic C−N bond formations, with the latter effecting the key dearomatization step. Using this approach, γ-arylated alcohols are converted to a wide range of differentially protected spirocyclic pyrrolidines in just two or three steps.A simple guide to complexity: A C−N bond forming dearomatization protocol with broad scope is outlined. Specifically, bifunctional amino reagents are used for sequential nucleophilic and electrophilic C−N bond formations, with the latter effecting the key dearomatization step. Using this approach, γ-arylated alcohols are converted to spirocyclic pyrrolidines in just two or three steps.
      PubDate: 2017-10-11T04:30:55.813464-05:
      DOI: 10.1002/anie.201708176
       
  • Trapping White Phosphorus within a Purely Organic Molecular Container
           Produced by Imine Condensation
    • Authors: Tianyu Jiao; Liang Chen, Dong Yang, Xin Li, Guangcheng Wu, Pingmei Zeng, Ankun Zhou, Qi Yin, Yuanjiang Pan, Biao Wu, Xin Hong, Xueqian Kong, Vincent M. Lynch, Jonathan L. Sessler, Hao Li
      Abstract: Three tetrahedral organic cages have been obtained by condensing a triamino linker with a set of three ostensibly analogous triformyl precursors. Despite the large number of imine bonds formed, the corresponding cages were obtained in exceptionally high yields. Both theory and experimental results demonstrate that intramolecular CH⋅⋅⋅π interactions within all of the cage frameworks play an important role in abetting the condensations and contributing to the near-quantitative synthetic yields. The three cages of this study exhibit high thermodynamic and kinetic stability. A variety of small neutral guest molecules with complementary sizes and geometries may be used as templates in the cage forming reactions. Among the guests that may be used in this way is white phosphorus (P4), whose inherent reactivity towards oxygen is almost fully attenuated when bound within one of the cages.Taming white phosphorus: Three highly stable tetrahedral organic cages were synthesized by means of imine condensation in close to quantitative yields. Two of the three cages encapsulated a variety of guests with complementary sizes and geometries, including white phosphorus in one case. The latter system was remarkably stable, both in solution and solid state, even upon exposure to oxygen.
      PubDate: 2017-10-11T04:30:33.886334-05:
      DOI: 10.1002/anie.201708246
       
  • Frontispiece: Supramolecular Organization and Functional Implications of
           K+ Channel Clusters in Membranes
    • Authors: Koen M. Visscher; João Medeiros-Silva, Deni Mance, João P. G. L. M. Rodrigues, Mark Daniëls, Alexandre M. J. J. Bonvin, Marc Baldus, Markus Weingarth
      Abstract: Protein NMR Spectroscopy In their Communication on page 13222 ff., M. Weingarth et al. describe the use of solid-state NMR spectroscopy and large-scale computer simulations to reveal that potassium channels aggregate and dissolve in reference to their gating cycle.
      PubDate: 2017-10-11T02:18:15.560004-05:
      DOI: 10.1002/anie.201784361
       
  • Blockable Zn10L15 ion channels via subcomponent self-assembly
    • Authors: Cally Jo Elizabeth Haynes; Jinbo Zhu, Imogen Riddell, Catalin Chimerel, Silvia Hernández-Ainsa, Tanya Ronson, Ulrich Keyser, Jonathan Nitschke
      Abstract: Metal-organic ion channels based on Zn10L15 pentagonal prisms have been prepared by subcomponent self-assembly. The insertion of these prisms into lipid membranes was investigated by ion-current and fluorescence measurements. The channels were found to mediate the transport of Cl- anions through planar lipid bilayers and into vesicles. Toluenesulfonate anions were observed to bind and plug the central channels of the prisms in the solid state and in solution. In membranes, adding dodecylsulfate impeded ion transport by channel blocking. Our Zn10L15 prism thus inserts into lipid bilayers to turn on ion transport, which can then be turned off through addition of the blocker dodecylsulfate.
      PubDate: 2017-10-11T01:55:37.157681-05:
      DOI: 10.1002/anie.201709544
       
  • Facile Supramolecular Processing of Carbon Nanotubes and Polymers Enabling
           Electromechanical Sensors
    • Authors: Chae Bin Kim; Ki-Beom Jeong, Beom Joo Yang, Jong-Won Song, Bon Cheol Ku, Seunghyun Lee, Seung Ki Lee, Chiyoung Park
      Abstract: We herein report a facile, cost-competitive, and scalable method for producing viscoelastic conductors via one-pot melt-blending using polymers and supramolecular gels composed of carbon nanotubes (CNTs), diphenylamine (DP), and benzophenone (BP). When mixed, a non-volatile eutectic liquid (EL) produced by simply blending DP with BP (1:1 molar ratio) enabled not only the gelation of CNTs (EL-CNTs) but also the dissolution of a number of commodity polymers. In order to take these advantages, viscoelastic conductors were produced via one-pot melt-blending the EL and CNTs with a model thermoplastic elastomer, poly(styrene-b-butadiene-b-styrene) (SBS, styrene 30 wt%). The resulting composites displayed an excellent electromechanical sensory along with re-mendable properties. This simple method using cost-competitive EL components is expected to provide an alternative to the use of expensive ionic liquids as well as to facilitate the fabrication of novel composites for various purposes.
      PubDate: 2017-10-10T23:50:25.092035-05:
      DOI: 10.1002/anie.201708111
       
  • Evolving accelerated amidation by SpyTag/SpyCatcher to analyze membrane
           dynamics
    • Authors: Anthony Howard Keeble; Anusuya Banerjee, Samuel C Reddington, Matteo Paolo Ferla, Mark Howarth, Irsyad Noor Abadi Khairil Anuar
      Abstract: SpyTag is a peptide that forms a spontaneous amide bond with its protein partner SpyCatcher. This protein superglue is a broadly useful tool for molecular assembly, locking together biological building blocks efficiently and irreversibly in diverse architectures. We initially developed SpyTag and SpyCatcher by rational design, through splitting a domain from a Gram-positive bacterial adhesin. Here we establish a phage display platform able to select for specific amidation, achieving an order of magnitude acceleration for interaction of the SpyTag002 variant with the SpyCatcher002 variant. We show that the 002 pair bonds rapidly under a wide range of conditions and at either protein terminus. SpyCatcher002 was fused to an intimin derived from enterohemorrhagic Escherichia coli. SpyTag002 reaction enabled specific and covalent decoration of intimin, for live cell fluorescent imaging of the dynamics of the bacterial outer membrane as cells divide.
      PubDate: 2017-10-10T20:55:56.920356-05:
      DOI: 10.1002/anie.201707623
       
  • Size and Interface Modulated Metal-Insulator Transition in
           Solution-Synthesized Nanoscale VO2-TiO2-VO2 Heterostructures
    • Authors: Raymond E Schaak; Xuefei Li
      Abstract: The M1 form of vanadium dioxide, which exhibits a reversible insulator-metal transition above room temperature, has been incorporated into nanoscale heterostructures through solution-phase epitaxial growth on the tips of rutile TiO2 nanorods. Four distinct classes of VO2-TiO2-VO2 nanorod heterostructures are accessible by modulating the growth conditions. Each type of VO2-TiO2-VO2 nanostructure has a different insulator-metal transition temperature that depends on the VO2 domains sizes and the TiO2-VO2 interfacial strain characteristics.
      PubDate: 2017-10-10T20:55:37.316873-05:
      DOI: 10.1002/anie.201706599
       
  • Copper-Catalyzed Synthesis of gamma-Amino Acids Featuring Quaternary
           Stereocenters
    • Authors: Arjan Willem Kleij; Jose Enrique Gómez, Silvia Gaspa, Wusheng Guo
      Abstract: The first general asymmetric synthesis of gamma,gamma-disubstituted gamma-amino acids via Cu-catalyzed ring opening of non-strained lactones with amines is reported. This approach features ample scope, operational simplicity and wide functional group diversity. The catalytic process allows to access a series of highly functionalized enantioenriched gamma-amino acids featuring quaternary stereocenters with excellent enantiomeric ratios up to 98:2 and excellent yields up to 98%.
      PubDate: 2017-10-10T07:50:45.000933-05:
      DOI: 10.1002/anie.201709511
       
  • Post Graphene 2D Chemistry: The Emerging Field of Molybdenum Disulfide and
           Black Phosphorus Functionalization
    • Authors: Andreas Hirsch; Frank Hauke
      Abstract: The current state of the chemical functionalization of three types of single sheet 2D materials, namely, graphene, molybdenum disulfide (MoS2), and black phosphorus (BP) is summarized. Such 2D sheet polymers represent currently an emerging field at the interface of synthetic chemistry, physics, and materials science. Both covalent and non-covalent functionalization of sheet architectures allows for a systematic modification of their properties, i.e. an improvement of solubility and processability, the prevention of re-aggregation or a band gap tuning. Next to successful functionalization concepts also fundamental challenges are addressed. These include the insolubility and polydispersity of most 2D sheet polymers, the development of suitable characterization tools, the identification of effective binding strategies, the chemical activation of the usually rather unreactive basal planes for covalent addend binding, and the regioselectivity of plane addition reactions. Although a number of these questions remain elusive in this review, the first promising concepts to overcome such hurdles have been listed.
      PubDate: 2017-10-10T07:50:23.272588-05:
      DOI: 10.1002/anie.201708211
       
  • The Thermodynamic Basis of the Fuzzy Interaction of an Intrinsically
           Disordered Protein
    • Authors: San Hadži; Andrej Mernik, Črtomir Podlipnik, Remy Loris, Jurij Lah
      Abstract: Many intrinsically disordered proteins (IDP) that fold upon binding retain conformational heterogeneity in IDP-target complexes. The thermodynamics of such fuzzy interactions is poorly understood. Herein we introduce a thermodynamic framework, based on analysis of ITC and CD spectroscopy data, that provides experimental descriptions of IDP association in terms of folding and binding contributions which can be predicted using sequence folding propensities and molecular modeling. We show how IDP can modulate the entropy and enthalpy by adapting their bound-state structural ensemble to achieve optimal binding. This is explained in terms of a free-energy landscape that provides the relationship between free-energy, sequence folding propensity, and disorder. The observed “fuzzy” behavior is possible because of IDP flexibility and also because backbone and side-chain interactions are, to some extent, energetically decoupled allowing IDP to minimize energetically unfavorable folding.Fuzz box: A thermodynamic framework rationalizes the energetics of intrinsically disordered protein (IDP)–target interactions in terms of folding and binding contributions and clarifies the relationship between IDP sequence folding propensity, helix fraction, and the free energy of IDP–target association. The IDPs respond to sequence perturbations by adjusting fuzziness of the bound-state ensemble in a manner similar to the Le Châtelier's principle.
      PubDate: 2017-10-10T07:12:21.7866-05:00
      DOI: 10.1002/anie.201707853
       
  • One-Pot, Three-Component Sulfonimidamide Synthesis Exploiting the
           Sulfinylamine Reagent N-Sulfinyltritylamine, TrNSO
    • Authors: Thomas Q. Davies; Adrian Hall, Michael C. Willis
      Abstract: Sulfonimidamides are increasingly important molecules in medicinal chemistry and agrochemistry, but their preparation requires lengthy synthetic sequences, which has likely limited their use. We describe a one-pot de novo synthesis of sulfonimidamides from widely available organometallic reagents and amines. This convenient and efficient process uses a stable sulfinylamine reagent, N-sulfinyltritylamine (TrNSO), available in one step on 10 gram scale, as a linchpin. In contrast to classical approaches starting from thiols or their derivatives, our TrNSO-based approach facilitates the rapid assembly of the three reaction components into a variety of differentially substituted sulfonimidamides containing medicinally relevant moieties, including pyridines and indoles. Analogues of the sulfonamide-containing COX-2 inhibitor Celecoxib were prepared and evaluated.Come and join us: The stable, readily prepared sulfinylamine reagent TrNSO is exploited as a linchpin to join organometallic reagents and amines to provide sulfonimidamides in a high yielding one-pot process. Good variation of both reaction components is possible.
      PubDate: 2017-10-10T07:08:15.884506-05:
      DOI: 10.1002/anie.201708590
       
  • Closed Pentaaza[9]helicene and Hexathia[9]/[5]helicene: Oxidative Fusion
           Reactions of ortho-Phenylene-Bridged Cyclic Hexapyrroles and
           Hexathiophenes
    • Authors: Fengkun Chen; Takayuki Tanaka, Yong Seok Hong, Tadashi Mori, Dongho Kim, Atsuhiro Osuka
      Abstract: Oxidative fusion reactions of ortho-phenylene-bridged cyclic hexapyrroles and hexathiophenes furnished novel closed helicenes in a selective manner. X-Ray diffraction analysis unambiguously revealed the structures to be a closed pentaaza[9]helicene, the longest azahelicene reported so far, and an unexpected double-helical structure of hexathia[9]/[5]helicene, whose formation was assumed to result from multiple oxidative fusion along with a 1,2-aryl shift. The pentaaza[9]helicene exhibited well-defined emission with high fluorescence quantum yield (ΦF=0.31) among the known [9]helicenes. Chiral resolution of the racemic pentaaza[9]helicene and hexathia[9]/[5]helicene were achieved by chiral-phase HPLC and the enantiomers were characterized by circular dichroism spectra and DFT calculations.Case closed: Oxidative fusion reactions of ortho-phenylene-bridged cyclic oligomers furnished novel closed heterohelicenes in a selective manner. X-ray diffraction analysis revealed the structures to be the closed pentaaza[9]helicene and hexathia[9]/[5]helicene, rare examples of a heteroaromatic closed helicene and an asymmetric double helicene, respectively. Their optical properties were studied and the enantiomeric separation was performed by chiral-phase HPLC.
      PubDate: 2017-10-10T07:07:56.935165-05:
      DOI: 10.1002/anie.201708429
       
  • Stereospecific Reactions of Donor–Acceptor Cyclopropanes with
           Thioketones: Access to Highly Substituted Tetrahydrothiophenes
    • Authors: André U. Augustin; Maximilian Sensse, Peter G. Jones, Daniel B. Werz
      Abstract: Lewis-acid-catalyzed reactions of 2-substituted cyclopropane 1,1-dicarboxylates with thioketones are described. Highly substituted tetrahydrothiophenes with two adjacent quaternary carbon atoms were obtained in a stereospecific manner under mild conditions and in high yield when using AlCl3 as Lewis acid. Moreover, an intramolecular approach was successfully implemented to gain access to sulfur-bridged [n.2.1] bicyclic ring systems. Conversion of selenoketones, the heavier analogues, under similar conditions resulted in the formation of various tetrahydroselenophenes.Thiocarbonyl Insertion: Donor–Acceptor cyclopropanes undergo a formal [3+2] cycloaddition with thioketones under AlCl3 catalysis and mild conditions to yield highly substituted tetrahydrothiophenes. An intramolecular variant led to bicyclic products. Similar cycloadditions with bisarylselenoketones were also achieved.
      PubDate: 2017-10-10T07:07:27.739135-05:
      DOI: 10.1002/anie.201708346
       
  • Reaction of a Programmable Glycan Presentation of Glycodendrimersomes and
           Cells with Engineered Human Lectins To Show the Sugar Functionality of the
           Cell Surface
    • Authors: Jürgen Kopitz; Qi Xiao, Anna-Kristin Ludwig, Antonio Romero, Malwina Michalak, Samuel E. Sherman, Xuhao Zhou, Cody Dazen, Sabine Vértesy, Herbert Kaltner, Michael L. Klein, Hans-Joachim Gabius, Virgil Percec
      Abstract: Chemical and biological tools are harnessed to investigate the impact of spatial factors for functional pairing of human lectins with counterreceptors. The homodimeric adhesion/growth-regulatory galectin-1 and a set of covalently linked homo-oligomers from di- to tetramers serve as proof-of-principle test cases. Glycodendrimersomes provide a versatile and sensitive diagnostic platform to reveal thresholds for ligand density and protein concentration in aggregation assays (trans-activity), irrespective of linker length between lectin domains. Monitoring the affinity of cell binding and ensuing tumor growth inhibition reveal the linker length to be a bidirectional switch for cis-activity. The discovery that two aspects of lectin functionality (trans- versus cis-activity) respond non-uniformly to a structural change underscores the power of combining synthetic and biological tools to advance understanding of the sugar functionality of the cell surface.Carbohydrate-directed cell adhesion: Chemical programming of the glycan presentation of glycodendrimersomes (GDSs) and the responsiveness of cells to lectin binding have been combined to define the structure–activity relationships for trans-bridging and cis-crosslinking of human lectins. Consequences of structural engineering of both lectin and glycan topology are explored and quantified (Gal-1=galectin-1).
      PubDate: 2017-10-10T07:07:14.854522-05:
      DOI: 10.1002/anie.201708237
       
  • Terminal Molybdenum Phosphides with d Electrons: Radical Character
           Promotes Coupling Chemistry
    • Authors: Joshua A. Buss; Paul H. Oyala, Theodor Agapie
      Abstract: A terminal Mo phosphide was prepared through the group transfer of both P and Cl atoms from chloro-substituted dibenzo-7λ3-phosphanorbornadiene. This compound represents the first structurally characterized terminal transition-metal phosphide with valence d electrons. In the tetragonal ligand field, these electrons populate an orbital of dxy parentage, an electronic configuration that accommodates both metal d electrons and a formal M≡P triple bond. Single-electron oxidation affords a transient open-shell terminal phosphide cation with significant spin density on P, as corroborated by continuous wave (CW) and pulse electron paramagnetic resonance (EPR) characterization. Facile P−P bond formation occurs from this species through intermolecular phosphide coupling.Two Ps in a pod: A MoIV terminal phosphide complex is formed through P and Cl atom transfer. Single-electron oxidation affords a MoV phosphide cation with radical character on Mo and P. This species readily undergoes intermolecular P−P bond formation.
      PubDate: 2017-10-10T07:06:49.325485-05:
      DOI: 10.1002/anie.201707921
       
  • Anion Relay Chemistry: Development of an Effective Diastereoselective
           [3+2] Annulation Tactic Exploiting an Aldol/Brook
           Rearrangement/Cyclization Cascade
    • Authors: Heeoon Han; Amos B. Smith
      Abstract: An effective [3+2] annulation tactic for the construction of diverse bicyclic compounds possessing highly functionalized cyclopentane rings has been developed employing soft ketone enolates as the initial nucleophile for anion relay chemistry (ARC). The protocol entails a highly diastereoselective aldol/Brook rearrangement/cyclization cascade.One-pot tactic: An effective [3+2] annulation for the construction of diverse bicyclic compounds possessing highly functionalized cyclopentane rings has been developed employing soft ketone enolates as the initial nucleophile for anion relay chemistry (ARC). The protocol entails a highly diastereoselective aldol/Brook rearrangement/cyclization cascade.
      PubDate: 2017-10-10T07:05:47.173883-05:
      DOI: 10.1002/anie.201708017
       
  • Diols as Dienophiles: Bridged Carbocycles via Ruthenium(0)-Catalyzed
           Transfer Hydrogenative Cycloadditions of Cyclohexadiene or Norbornadiene
    • Authors: Hiroki Sato; Keisuke Fukaya, Binit Sharma Poudel, Michael J. Krische
      Abstract: Highly exo-selective ruthenium(0) catalyzed transfer hydrogenative cycloadditions of 1,2-diols with cyclohexadiene or norbornadiene are described. Novel bridged bicyclic ring systems are accessible from the diol, α-ketol or 1,2-dione oxidation levels with complete control of diastereoselectivity.The influence of alcohols: Highly exo-selective ruthenium(0) catalyzed transfer hydrogenative cycloadditions of 1,2-diols with cyclohexadiene or norbornadiene are described. Novel bridged bicyclic ring systems are accessible from the diol, α-ketol or 1,2-dione oxidation levels with complete control of diastereoselectivity.
      PubDate: 2017-10-10T07:05:38.095419-05:
      DOI: 10.1002/anie.201708189
       
  • Enzymatic Synthesis, Amplification, and Application of DNA with a
           Functionalized Backbone
    • Authors: Tingjian Chen; Floyd E. Romesberg
      Abstract: The ability to amplify DNA along with its unprecedented sequence control has led to its use for different applications, but all are limited by the properties available to natural nucleotides. We previously reported the evolution of polymerase SFM4-3, which better tolerates 2′-modified substrates. To explore the utility of SFM4-3, we now report the characterization of its recognition of substrates with 2′-azido, 2′-chloro, 2′-amino, or arabinose sugars. We find that SFM4-3 can efficiently synthesize polymers composed of these nucleotides, and most interestingly, that SFM4-3 can also PCR amplify these modified oligonucleotides. When combined with post-amplification modification, the latter allows for the exponential amplification of polymers that may be functionalized with desired moieties arrayed in a controlled fashion, the utility of which we demonstrate with extensive small molecule functionalization and the production and initial characterization of a novel DNA hydrogel.Novel DNA materials: Highly functionalized DNA is produced by polymerase chain reaction using the evolved thermostable polymerase mutant SFM4-3. Novel materials, such as molecular arrays and biocompatible hydrogels with novel properties, may then be produced by post-amplification modification.
      PubDate: 2017-10-10T06:31:24.903258-05:
      DOI: 10.1002/anie.201707367
       
  • Characterization of conjugation pattern in large polysaccharide-protein
           conjugates by NMR
    • Authors: Stefano Giuntini; Evita Balducci, Linda Cerofolini, Enrico Ravera, Marco Fragai, Francesco Berti, Claudio Luchinat
      Abstract: Carbohydrate-based vaccines are among the safest and most effective vaccines and represent potent tools for prevention of life-threatening bacterial infectious diseases, like meningitis and pneumonia. The chemical conjugation of a weak antigen to protein as a source of T-cell epitopes generates a glycoconjugate vaccine, that results more immunogenic. Several methods have been used so far to characterize the resulting polysaccharide-protein conjugates. However, a reduced number of methodologies has been proposed for measuring the degree of saccharide conjugation at the possible protein sites. Here we show that detailed information on large proteins conjugated with large polysaccharides can be achieved by a combination of solution and solid state NMR. As a test case, a large protein assembly, L-asparaginase II, has been conjugated with Neisseria meningitidis serogroup C capsular polysaccharide and the pattern and degree of conjugation were determined.
      PubDate: 2017-10-10T06:20:32.716395-05:
      DOI: 10.1002/anie.201709274
       
  • Catalytic Enantioselective Synthesis of Mariline A and Related
           Isoindolinones via a Biomimetic Approach
    • Authors: Chang Min; Yingfu Lin, Daniel Seidel
      Abstract: The catalytic enantioselective synthesis of isoindolinones was achieved via the condensation of ortho-formyl-arylketones and anilines. In the presence of 1 mol% of a chiral phosphoric acid catalyst, reactions reach completion within 10 minutes and provide products with up to 98% ee. Anilines with an ortho t-butyl group form atropisomeric products, enabling the simultaneous generation of axial and point chirality from two achiral substrates. This method was applied to the first synthesis of mariline A.
      PubDate: 2017-10-10T05:50:54.208428-05:
      DOI: 10.1002/anie.201709182
       
  • Three-dimensionally π-Conjugated Diradical Molecular Cage
    • Authors: Jishan Wu; Xiao Gu, Tullimilli Y. Gopalakrishna, Hoa Phan, Yong Ni, Tun Seng Herng, Jun Ding
      Abstract: π-Conjugated molecular cages are very challenging targets in structural organic chemistry, supramolecular chemistry and materials science. Herein, we report the synthesis and physical characterizations of the first three-dimensionally π-conjugated diradical molecular cage PTM-C, in which two polychlorotriphenylmethyl (PTM) radicals are linked by three bis(3,6-carbazolyl) bridges. This cage compound was synthesized mainly by intermolecular Yamamoto coupling followed by deprotonation and oxidation. It is stable and its structure was confirmed by X-ray crystallographic analysis. The two carbon-centered PTM radicals are weakly coupled through electronic interactions with the carbazole spacers, as revealed by optical, electronic and magnetic measurements as well as theoretical calculations.
      PubDate: 2017-10-10T05:20:42.624642-05:
      DOI: 10.1002/anie.201709537
       
  • Decoupled Thermo- and pH-responsive Hydrogel Microspheres Cross-linked by
           Rotaxane Networks
    • Authors: Takuma Kureha; Daichi Aoki, Seina Hiroshige, Keisuke Iijima, Daisuke Aoki, Toshikazu Takata, Daisuke Suzuki
      Abstract: Rotaxane cross-linked (RC) microgels that exhibit a decoupled thermo- and pH-responsive volume transition were developed. The pH-induced changes of the aggregation/disaggregation states of cyclodextrin in the RC networks were used to control the swelling capacity of the entire microgels. Different from conventional thermo- and pH-responsive microgels, which are usually obtained from copolymerizations involving charged monomers, the RC microgels respond to temperature as intended, even in the presence of charged functional molecules such as dyes in the microgel dispersion. The results of this study should lead to new applications, including drug delivery systems, that require a retention of their "smart" functions even in environments that may contain foreign ions, e.g. in in vivo experiments.
      PubDate: 2017-10-10T05:20:32.58349-05:0
      DOI: 10.1002/anie.201709633
       
  • Selective activation of C-H bonds by cascading photochemistry with
           biocatalysis
    • Authors: Wuyuan Zhang; Bastien O. Burek, Elena Fernández-Fueyo, Miguel Alcalde, Jonathan Z. Bloh, Frank Hollmann
      Abstract: Selective oxyfunctionalisation of inert C-H bonds under mild conditions can be achieved using peroxygenases. This approach, however, is impaired by the poor robustness of these enzymes in the presence of hydrogen peroxide as the stoichiometric oxidant. Here, we demonstrate that inorganic photocatalysts such as gold-titanium dioxide efficiently provide H2O2 from methanol-driven reductive activation of ambient oxygen in suitable amounts to ensure high reactivity and robustness of the enzyme. Using this approach stereoselective hydroxylation of ethyl benzene to (R)-1-phenyl ethanol in high enantioselectivity (>98% ee) and excellent turnover numbers of the biocatalyst (>71.000) was achieved.
      PubDate: 2017-10-10T04:28:00.780484-05:
      DOI: 10.1002/anie.201708668
       
  • Targeting the Protein Kinases Cysteinome
    • Authors: Apirat Chaikuad; Pierre Koch, Stefan Laufer, Stefan Knapp
      Abstract: Drugs that function by covalent bond formation represent a considerable fraction of our repository of effective medicines but safety concerns and the complexity of developing covalent inhibitors has rendered covalent targeting a less attractive strategy for rational drug design. The recent approval of four covalent kinase inhibitors and the development of highly potent covalent kinase probes with exceptional selectivity has raised significant interest in industry and academic research and validated the concept of covalent kinase targeting for clinical applications. The abundance of cysteines at diverse positions in and around the kinase active site suggests that a large fraction of kinases can be targeted by covalent inhibitors. Here we review recent developments of this rapidly growing area in kinase drug development and highlight the unique opportunities and challenges of this strategy.
      PubDate: 2017-10-10T04:27:53.388645-05:
      DOI: 10.1002/anie.201707875
       
  • Effects of Bithiophene Imide Fusion on Device Performance of Organic
           Thin-Film Transistors and All-Polymer Solar Cells
    • Authors: Xugang Guo; Yingfeng Wang, Zhenglong Yan, Han Guo, Mohammad Afsar Uddin, Shaohua Ling, Xin Zhou, Huimin Su, Junfeng Dai, Han Young Woo
      Abstract: Two new bithiophene imide (BTI)-based n-type polymers are synthesized. The fused BTI dimer-based f-BTI2-FT shows a smaller bandgap, lower LUMO, and higher crystallinity than s-BTI2-FT containing a single bond connected BTI dimer. s-BTI2-FT exhibits a remarkable electron mobility of 0.82 cm2 V-1 s-1 and f-BTI2-FT shows a further improved mobility of 1.13 cm2 V-1 s-1 in transistors. When blended with a polymer donor PTB7-Th, the f-BTI2-FT-based all-polymer solar cells (all-PSCs) achieve a PCE of 6.85%, the highest value for all-PSCs not based on naphthalene (or perylene) diimide polymer acceptors. However, the s-BTI2-FT all-PSCs show nearly no photovoltaic effect. The results demonstrate that f-BTI2-FT is one of most promising n-type polymers and ring fusion offers an effective approach for designing polymers with improved electrical properties.
      PubDate: 2017-10-10T04:27:42.23652-05:0
      DOI: 10.1002/anie.201708421
       
  • Dimethylamine as Substrate in Hydroaminoalkylation Reactions
    • Authors: Jens Bielefeld; Sven Doye
      Abstract: Transition metal catalyzed hydroaminoalkylations of alkenes have made great progress over the last decade and are heading to become a viable alternative to the industrial synthesis of amines through hydroformylation of alkenes and subsequent reductive amination. In the past, one major obstacle of this progress has been the inability to apply these reactions to the most important amines, methylamine and dimethylamine. Herein, we report the first successful use of dimethylamine in catalytic hydroaminoalkylations of alkenes with good yields. We also report the applicability for a variety of alkenes to show the tolerance of the reaction towards different functional groups. Additionally, we present the dihydroaminoalkylation reaction using dimethylamine, which has never been reported before.
      PubDate: 2017-10-10T03:50:30.81658-05:0
      DOI: 10.1002/anie.201708959
       
  • General and Efficient Intermolecular [2+2] Photodimerization of Chalcones
           
    • Authors: Li-Zhu Wu; Tao Lei, Chao Zhou, Mao-Yong Huang, Lei-Min Zhao, Bing Yang, Chen Ye, Hongyan Xiao, Qing-Yuan Meng, Vaidhyanathan Ramamurthy, Chen-Ho Tung
      Abstract: Represented by dimerization of chalcones and cinnamic acid derivatives, photo [2+2] cycloaddition is a unique strategy to construct cyclobutanes, the building blocks for a variety of biologically active molecules existing in nature. However, most attempts for the above [2+2] addition focused on solid-state, molten-state or host-guest systems under ultraviolet light irradiation in order to overcome the competition of facile geometric isomerization of nonrigid olefins. Here, we report a general and simple method to realize the intermolecular [2+2] dimerization reaction of these acyclic olefins to construct cyclobutanes in a highly stereo- and diastereoselective manner in solution under visible light, which provides an efficient solution to the long pending problem.
      PubDate: 2017-10-10T03:20:59.407844-05:
      DOI: 10.1002/anie.201708559
       
  • Lithium azide as a novel electrolyte additive for all-solid-state Li-S
           batteries
    • Authors: Gebrekidan Gebreslase Eshetu; Xabier Judez, Chunmei Li, Alex Bondarchuk, Lide Mercedes Rodriguez-Martinez, Heng Zhang, Michel Armand
      Abstract: Of the various beyond lithium-ion battery technologies, lithium-sulphur (Li-S) batteries have an appealing theoretical energy density and are being intensely investigated as next generation rechargeable lithium metal batteries. However, the stability of the Li° anode is among the most urgent challenges that need to be addressed to ensure the long-term stability of Li-S batteries. In this work, we report lithium azide (LiN3) as a novel electrolyte additive for all-solid-state Li-S batteries (ASSLSBs). It results in the formation of a thin, compact and highly conductive passivation layer on Li° anode, thereby avoiding dendrite formation, and polysulfide shuttling. It superbly enhances the cycling performance, Coulombic and energy efficiencies of ASSLSBs, outperforming the state-of-the-art additive lithium nitrate (LiNO3)
      PubDate: 2017-10-10T02:56:03.231225-05:
      DOI: 10.1002/anie.201709305
       
  • New and Mild Reduction of Phosphine Oxides with Phosphites to access
           Phosphines
    • Authors: Pascal Yves METIVIER; Peng Li, Raphael Wischert
      Abstract: A new protocol for iodine-catalyzed reduction of phosphine oxides with phosphites at room temperature is reported. The mild conditions, scalability of the reaction, and simple purification requirements make it a method of choice for the large-scale production and easy regeneration of a variety of phosphines. Mechanistic studies, supported by DFT calculations about the oxygen transfer between the starting phosphine oxide and the phosphite reagent, are also presented. On top of the novelty of this reaction, such transmutation of phosphorous species is unknown.
      PubDate: 2017-10-10T02:55:57.657087-05:
      DOI: 10.1002/anie.201709519
       
  • Electrostatic-assisted Liquefaction of Porous Carbons
    • Authors: Sheng Dai; PeiPei Li, Jennifer A. Schott, Jinshui Zhang, Shannon M. Mahurin, Yujie Sheng, Xunxiang Hu, Guokai Cui, Dongdong Yao, Suree Brown, Yaping Zheng, Zhen-An Qiao
      Abstract: Porous liquids are a newly developed porous material that combine unique fluidity with permanent porosity, which exhibit promising functionalities for a variety of applications. However, the apparent incompatibility between fluidity and permanent porosity makes the stabilization of porous nanoparticle with still empty pores in the dense liquid phase a significant challenging. Herein, by exploiting the electrostatic interaction between carbon networks and polymerized ionic liquids, we demonstrate that carbon-based porous nanoarchitectures can be well stabilized in liquids to afford permanent porosity, and thus opens up a new approach to prepare porous carbon liquids. Furthermore, we hope this facile synthesis strategy can be widely applicated to fabricate other types of porous liquids, such as those also having the electrostatic interaction with polymerized ionic liquids, evidently advancing the development and understanding of porous liquids.
      PubDate: 2017-10-10T02:20:42.463481-05:
      DOI: 10.1002/anie.201708843
       
  • Transient Behavior of the Metal Interface in Li Metal-Garnet Batteries
    • Authors: Kun Fu; Yunhui Gong, Zhezhen Fu, Hua Xie, Yonggang Yao, Boyang Liu, Marcus Carter, Eric Wachsman, Liangbing Hu
      Abstract: The interface between solid electrolytes and Li metal is a primary issue for solid-state batteries. Introducing a metal interlayer to conformally coat solid electrolytes can improve the interface wettability of Li metal and reduce the interfacial resistance, but the mechanism of the metal interlayer is unknown. In this work, we used magnesium (Mg) as a model to investigate the effect of a metal coating on the interfacial resistance of a solid electrolyte and Li metal anode. Our motivation is to understand how the metal interlayer behaves at the interface to promote increased Li-metal wettability of the solid electrolyte surface and reduce interfacial resistance. Surprisingly, we found that the metal coating dissolved in the molten piece of Li and diffused into the bulk Li metal, leading to a small and stable interfacial resistance between the garnet solid electrolyte and the Li metal.
      PubDate: 2017-10-09T20:56:11.31112-05:0
      DOI: 10.1002/anie.201708637
       
  • Analysis of Molecular Orientation in Organic Semiconducting Thin Films
           Using Static Dynamic Nuclear Polarization Enhanced Solid-State NMR
    • Authors: Katsuaki Suzuki; Shosei Kubo, Fabien Aussenac, Frank Engelke, Tatsuya Fukushima, Hironori Kaji
      Abstract: Molecular orientation in amorphous organic semiconducting thin film devices is an important issue affecting device performances. However, to date it has not been possible to analyze the "distribution" of the orientations. Although solid-state NMR (ssNMR) can provide information on the distribution of molecular orientations, the technique is limited because of the small amounts of sample in the devices and the low sensitivity of ssNMR. Here, we report the first application of dynamic nuclear polarization enhanced ssNMR (DNP-ssNMR) to orientational analysis of amorphous phenyldi(pyren-1-yl)phosphine oxide (POPy2). The 31P DNP-ssNMR spectra exhibited a sufficient signal-to-noise ratio to quantify the distribution of molecular orientations in amorphous films: the P=O axis of the vacuum-deposited and drop-cast POPy2 shows anisotropic and isotropic distribution, respectively. The different molecular orientations reflect the molecular origin of the different charge transport behaviors.
      PubDate: 2017-10-09T20:55:48.75182-05:0
      DOI: 10.1002/anie.201707208
       
  • Large Continuous Mechanical Gradient Formation via Metal-Ligand
           Interactions
    • Authors: James A Neal; Nathan J Oldenhuis, Emil Samson, Andrea L Novitsky, William J Thrift, Regina Ragan, Zhibin NM Guan
      Abstract: Mechanical gradients are often employed in nature to prevent damage from large forces by creating a smooth transition from strong to weak biological materials. Synthetic mimics of these natural structures are highly desired to improve distribution of stresses at interfaces and reduce contact deformation in manmade materials. Current synthetic gradient materials commonly suffer from non-continuous transitions, relatively small gradients in mechanical properties, and difficult syntheses. Inspired by the polychaete worm jaw, we report a novel approach to generate stiffness gradients in polymeric materials via incorporation of monodentate, dynamic metal-ligand crosslinks. Through spatial control of metal ion content, we create a continuous mechanical gradient that spans over a 200-fold difference in stiffness, approaching the mechanical contrast observed in biological gradient materials.
      PubDate: 2017-10-09T20:55:45.531975-05:
      DOI: 10.1002/anie.201707587
       
  • Assembly, thermodynamics and structures of a two-wheeled composite of a
           dumbbell-shaped molecule and cylindrical molecules with different edges
    • Authors: Taisuke Matsuno; Sho Kamata, Sota Sato, Atsutoshi Yokoyama, Parantap Sarkar, Hiroyuki Isobe
      Abstract: A carbonaceous dumbbell can spontaneously glue two tubular receptors to form a unique two-wheeled composite via van der Waals interactions. The wheel components forcibly make contact with each other at the edge, and diastereoisomerism has been demonstrated as a source for self-sorting of receptors. In the present study, two tubular receptors with an enantiomeric carbon networks were assembled on the dumbbell joint, and the handedness of the receptors was discriminated to lead the self-sorting of homomeric receptors from a mixture of enantiomeric tubes. The crystal structures of the composites reveal the structural origins of the van-der-Waals-driven molecular recognition as well as the presence of a columnar array of C120 molecules in a 1:1 composite.
      PubDate: 2017-10-09T20:55:37.257659-05:
      DOI: 10.1002/anie.201709442
       
  • Lysosome-targeting amplifiers of reactive oxygen species as anticancer
           prodrugs
    • Authors: Andriy Mokhir; Steffen Daum, Viktor Reshetnikov, Miroslav Sisa, Tetyana Dymych, Maxim D Lootski, Rostyslav Bilyy, Evgenia Bila, Christina Janko, Christoph Alexiou, Martin Herrmann, Leopold Sellner
      Abstract: Cancer cells produce elevated amounts of reactive oxygen species that has been used to design cancer specific prodrugs. Their activation relies on at least a bimolecular process, where a prodrug reacts with ROS. However, at low µM concentrations of the prodrugs and ROS the activation is usually inefficient. Herein we suggested and validated a potentially general approach for solving this intrinsic problem of ROS-dependent prodrugs. In particular, known 4-(N-ferrocenyl-N-benzylaminocarbonyloxymethyl)phenylboronic acid pinacol ester was converted to its lysosome specific analogue. Since lysosomes contain the higher concentration of active ROS than cytoplasm, activation of the latter prodrug was facilitated with respect to the parent compound. In particular, it was found to exhibit high anticancer activity in a variety of cancer cell lines (IC50 3.5-7.2 µM) and in vivo (40 mg/kg, NK/Ly murine model), but remained weakly toxic towards non-malignant cells (IC50 15-30 µM).
      PubDate: 2017-10-09T20:55:28.170136-05:
      DOI: 10.1002/anie.201706585
       
  • "On-Droplet" Chemistry: The Cycloaddition of Diethyl Azodicarboxylate and
           Quadricyclane
    • Authors: Richard Neil Zare; Ryan M. Bain, Shyam Sathyamoorthi
      Abstract: Sharpless and coworkers previously studied the [2σ + 2σ + 2π] cycloaddition of diethyl azodicarboxylate (DEAD) and quadricyclane and reported that the addition of water to the neat reagents caused an acceleration in the reaction rate, giving birth to what has been called "on-water" chemistry. We have examined the same reaction in aqueous microdroplets (ca. 5 µm diameter) and find that the cycloaddition reaction is accelerated even further (by a factor of 102) compared to that of the "on-water" reaction reported previously. The trends of acceleration in solvents other than water demonstrated by Sharpless and colleagues were replicated in the corresponding microdroplet experiments. We also find that DEAD reacts with itself to form a variety of hydrazine carboxylates and intercept intermediates of this reaction in microdroplets to validate a mechanism proposed herein. We suggest that "on-droplet" chemistry, similar to "on-water" chemistry, may be a general process of synthetic interest.
      PubDate: 2017-10-09T14:20:30.20842-05:0
      DOI: 10.1002/anie.201708413
       
  • Breaking the limits in analyzing carbohydrate recognition by NMR:
           Resolving Branch-Selective Interaction of a Tetraantennary N-Glycan with
           lectins
    • Authors: Angeles Canales; Irene Boos, Lukas Perkams, L. Karst, Thomas Luber, Theodoros KARAGIANNIS, Gemma Dominguez, F. Javier Cañada, Javier Perez-Castells, D. Häussinger, Carlo Unverzagt, Jesus Jimenez-Barbero
      Abstract: Abstract: The biological recognition of complex-type N-glycans is part of many key physiological and pathological events. Despite their importance, the structural characterization of these events remains an unsolved task. The inherent flexibility of N-glycans hampers crystallization and the chemical equivalence of individual branches precludes their NMR characterization. By using a chemoenzymatically synthesized tetraantennary N-glycan conjugated to a lanthanide binding tag, the NMR signals under paramagnetic conditions discriminated all four N-acetyl lactosamine antennae with unprecedented resolution. The NMR data revealed the conformation of the N-glycan and permitted for the first time the direct identification of individual branches involved in the recognition by two N-acetyllactosamine-binding lectins, Datura stramonium seed lectin (DSL) and Ricinus Communis agglutinin (RCA120).
      PubDate: 2017-10-09T10:20:25.951619-05:
      DOI: 10.1002/anie.201709130
       
  • In-situ Spatial Complementation of Aptamer-mediated Recognition Enables
           Live-cell Imaging of Native RNA Transcripts in Real Time
    • Authors: Zejun Wang; Yao Luo, Xiaodong Xie, Xingjie Hu, Haiyun Song, Yun Zhao, Jiye Shi, Lihua Wang, Gennadi Glinsky, Nan Chen, Ratnesh Lal, Chunhai Fan
      Abstract: Direct cellular imaging of the localization and dynamics of biomolecules helps to understand their functions and reveals novel mechanisms at the single-cell resolution. Here, we report the development of an aptamer-initiated fluorescence complementation (AiFC) method for RNA imaging by engineering a green fluorescence protein (GFP)-mimicking turn-on RNA aptamer, Broccoli, into two split fragments that could tandemly bind to target mRNA. When genetically encoded in cells, nascent mRNA molecules recruited split Broccoli and brought the two fragments to the spatial proximity, which in-situ formed a fluorophore-binding site and turned on fluorescence. Significantly, we demonstrated the use of AiFC for real-time imaging of endogenous RNA molecules in living mammalian cells. We envision wide application and practical utility of this enabling technology to in vivo single-cell visualization and mechanistic analyses of macromolecular interactions.
      PubDate: 2017-10-09T08:52:00.183611-05:
      DOI: 10.1002/anie.201707795
       
  • Hydrogen peroxide insular dodecameric and pentameric clusters in
           peroxosolvate structures
    • Authors: Dmitry A. Grishanov; Mger A. Navasardyan, Alexander G. Medvedev, Ovadia Lev, Petr V. Prikhodchenko, Andrei Churakov
      Abstract: Peroxosolvates of 2-aminonicotinic acid (I) and lidocaine N-oxide (II) including the largest insular hydrogen peroxide (HP) clusters were isolated and their crystal structures were determined by single crystal X-ray diffraction. An unprecedented dodecameric hydrogen peroxide insular cluster was found in I. An unusual cross-like pentameric cluster was observed in the structure of II. The reported topology of the (H2O2)12 assembly was never observed for small-molecule clusters. In I and II new double and triple cross-orientational disorders of HP were found. II is the first example of peroxosolvate crystal structure containing H2O2 molecules with a homoleptic hydrogen peroxide environment. In II, a hydrogen bond between an HP molecule and a peptide group CONH…O2H2 was observed for the first time.
      PubDate: 2017-10-09T08:51:56.586679-05:
      DOI: 10.1002/anie.201709699
       
  • Single-Molecule Monitoring of Structural Switching Dynamics of Nucleic
           Acids by Controlling Fluorescence Blinking
    • Authors: Kiyohiko Kawai; Takafumi Miyata, Naohiko Shimada, Syoji Ito, Hiroshi Miyasaka, Atsushi Maruyama
      Abstract: Single-molecule fluorescence energy transfer (smFRET) is a powerful tool to investigate the dynamics of biomolecular events in real time. However, it requires two fluorescent molecules and can be applied only to dynamics that accompany large changes in distance between the molecules. Herein, we introduce a kinetic analysis based on the control of fluorescence blinking (KACB), a general approach to investigate the dynamics of biomolecules by using a single fluorescent molecule. By controlling the kinetics of the redox reaction so as to control the blinking kinetics or pattern to be affected by micro-environmental changes around a fluorescent molecule (rKACB), we demonstrate the real-time single-molecule measurement of the structure-changing dynamics of nucleic acids.
      PubDate: 2017-10-09T05:21:24.788677-05:
      DOI: 10.1002/anie.201708705
       
  • Generalized Self-Doping Engineering towards Ultrathin and Large Sized
           Two-Dimensional Homologous Perovskite
    • Authors: Junnian Chen; Yaguang Wang, Lin Gan, Yunbin He, Huiqiao Li, Tianyou Zhai
      Abstract: Two dimensional (2D) homologous perovskites are now arousing intense interest in photovoltaic and light emitting fields. However, investigations on 2D homologous perovskites with ultrathin thickness and large lateral dimension have been seldom reported to date, mainly hindered by the challenge in synthesis. Here, we present a generalized self-doping directed synthesis of ultrathin 2D homologous (BA)2(MA)n-1PbnBr3n+1 (1
      PubDate: 2017-10-09T03:15:25.439933-05:
      DOI: 10.1002/anie.201708434
       
  • Flexible Zr-MOFs as Bromine-Nanocontainers for Bromination Reactions under
           Ambient Conditions
    • Authors: Jiandong Pang; Shuai Yuan, Dongying Du, Christina Lollar, Liangliang Zhang, Mingyan Wu, Daqiang Yuan, Hongcai Zhou, Maochun Hong
      Abstract: A series of flexible MOFs (PCN-605, -606 and -700) are synthesized and applied to reversible bromine encapsulation and release. The chemical stability of these Zr-MOFs ensures the framework's integrity during the bromine adsorption, while the framework's flexibility allows for structural adaptation upon bromine uptake to afford stronger host-guest interactions and therefore higher bromine adsorption capacities. The flexible MOFs act as bromine-nanocontainers which elongate the storage time of volatile halides under ambient conditions. Furthermore, the bromine pre-adsorbed flexible MOFs can be used as generic bromine sources for bromination reactions with improved yields and selectivities under ambient conditions as compared with liquid bromine.
      PubDate: 2017-10-09T01:50:59.173202-05:
      DOI: 10.1002/anie.201709186
       
  • Rational Design of a Robust Fluorescent Probe for the Detection of
           Endogenous Carbon Monoxide in Living Zebrafish Embryos and Mouse Tissue
    • Authors: Keyin Liu; Xiuqi Kong, Yanyan Ma, Weiying Lin
      Abstract: Carbon monoxide (CO) is one of the most important gaseous signal molecules in biological systems. However, the investigation of the functions of CO in living organisms is restricted by the lack of functional molecular tools. To address this critical challenge, we present herein the rational design, synthesis, and in vivo imaging studies of a powerful two-photon excited near-infrared fluorescent probe (1-Ac) for endogenous CO monitoring. The advantageous features of the new probe include high stability, low background fluorescence, large fluorescence enhancement, high sensitivity, and two-photon excitation with emission in the near-infrared region. Significantly, these merits of the probe enable the tracking of endogenous CO in zebrafish embryos and mouse tissues for the first time.CO sensing in vivo: A unique PdII-based two-photon-excited near-infrared fluorescent probe for endogenous CO was rationally designed and constructed. The robust probe exhibited superior properties, which allow the tracking of endogenous CO in zebrafish embryos and mouse tissues for the first time.
      PubDate: 2017-10-06T02:47:39.474395-05:
      DOI: 10.1002/anie.201707518
       
  • Cover Picture: Colossal Stability of Gas-Phase Trianions: Super-Pnictogens
           (Angew. Chem. Int. Ed. 43/2017)
    • Authors: Tianshan Zhao; Jian Zhou, Qian Wang, Puru Jena
      Pages: 13153 - 13153
      Abstract: It′s a bird, it′s a plane, it′s a super-pnictogen!. Strong electrostatic repulsion renders multiply charged anions unstable in the gas phase. In their Communication on page 13421 ff., Q. Wang, P. Jena, and co-workers report the design of BeB11(X)123− (X=CN, SCN, BO) trianions, which are stable against spontaneous electron emission in the gas phase by up to 2.65 eV. The chemistry of the anions mimics that of Group 15 elements, and extends to reactivity with the noble gas xenon.
      PubDate: 2017-08-28T12:40:53.722428-05:
      DOI: 10.1002/anie.201708386
       
  • Inside Cover: Picomolar Traces of Americium(III) Introduce Drastic Changes
           in the Structural Chemistry of Terbium(III): A Break in the “Gadolinium
           Break” (Angew. Chem. Int. Ed. 43/2017)
    • Authors: Jan M. Welch; Danny Müller, Christian Knoll, Martin Wilkovitsch, Gerald Giester, Johannes Ofner, Bernhard Lendl, Peter Weinberger, Georg Steinhauser
      Pages: 13154 - 13154
      Abstract: Americium acts as a “pied piper” and lures the heavy lanthanide terbium across the “gadolinium break” into forming a structure that is normally preferred by the light lanthanides only. Terbium azobis(tetrazolide) usually crystallizes as a salt-like compound. Traces of americium in the mother liquor change the structural behavior of the compound by introducing a coordinative bond between the cation and the azobis(tetrazolide) anion, as shown by G. Steinhauser et al. in their Communication on page 13264 ff.
      PubDate: 2017-09-05T06:32:56.268395-05:
      DOI: 10.1002/anie.201708388
       
  • Graphical Abstract: Angew. Chem. Int. Ed. 43/2017
    • Pages: 13157 - 13174
      PubDate: 2017-10-11T02:18:28.105117-05:
      DOI: 10.1002/anie.201784311
       
  • Spotlights on our sister journals: Angew. Chem. Int. Ed. 43/2017
    • Pages: 13176 - 13179
      PubDate: 2017-10-11T02:18:14.043939-05:
      DOI: 10.1002/anie.201784313
       
  • Sven Schneider
    • Pages: 13180 - 13180
      Abstract: “I can never resist good food. My favorite author (fiction) is Haruki Murakami. ...” This and more about Sven Schneider can be found on page 13180.
      PubDate: 2017-07-28T03:22:26.317235-05:
      DOI: 10.1002/anie.201705292
       
  • Burrows Medal: S. Brooker / Breyer Medal: P. N. Bartlett / R. H.
           Stokes Medal: H. Zhao / A. M. Bond Medal: S. Ciampi
    • Pages: 13181 - 13181
      PubDate: 2017-09-22T06:31:04.842168-05:
      DOI: 10.1002/anie.201709209
       
  • Modern Heterogeneous Catalysis. An Introduction By Rutger
           van Santen.
    • Authors: Evgenii V. Kondratenko
      Pages: 13182 - 13182
      Abstract: Wiley-VCH, Weinheim 2017. 564 pp., softcover, € 89.00.—ISBN 978-3527339617
      PubDate: 2017-09-22T02:46:40.547767-05:
      DOI: 10.1002/anie.201709088
       
  • Pseudouridimycin: The First Nucleoside Analogue That Selectively Inhibits
           Bacterial RNA Polymerase
    • Authors: Mathieu F. Chellat; Rainer Riedl
      Pages: 13184 - 13186
      Abstract: Seek, and ye shall find: After years of focusing research on synthetic antibiotics out of fear that all the useful natural ones had already been found, a novel antibacterial compound has been discovered through conventional microbial extract screening. The broad-spectrum nucleoside-analogue inhibitor pseudouridimycin is selective for bacterial RNA polymerase and elicits very low resistance rates.
      PubDate: 2017-09-12T01:41:02.073082-05:
      DOI: 10.1002/anie.201708133
       
  • Fluorescent Probes with Multiple Binding Sites for the Discrimination of
           Cys, Hcy, and GSH
    • Authors: Cai-Xia Yin; Kang-Ming Xiong, Fang-Jun Huo, James C. Salamanca, Robert M. Strongin
      Pages: 13188 - 13198
      Abstract: Biothiols such as cysteine (Cys), homocysteine (Hcy), and glutathione (GSH) play crucial roles in maintaining redox homeostasis in biological systems. This Minireview summarizes the most significant current challenges in the field of thiol-reactive probes for biomedical research and diagnostics, emphasizing the needs and opportunities that have been under-investigated by chemists in the selective probe and sensor field. Progress on multiple binding site probes to distinguish Cys, Hcy, and GSH is highlighted as a creative new direction in the field that can enable simultaneous, accurate ratiometric monitoring. New probe design strategies and researcher priorities can better help address current challenges, including the monitoring of disease states such as autism and chronic diseases involving oxidative stress that are characterized by divergent levels of GSH, Cys, and Hcy.Probing biothiols: Cysteine (Cys), homocysteine (Hcy), and glutathione (GSH) play crucial roles in human health. There are very few molecular probes and abiotic sensors that can simultaneously discriminate among biothiols. Recent progress on probes featuring multiple binding sites to distinguish Cys, Hcy, and GSH is summarized, and a variety of unmet critical needs and opportunities for chemists in the thiol probe field are discussed.
      PubDate: 2017-09-22T02:20:25.330009-05:
      DOI: 10.1002/anie.201704084
       
  • Modern Inorganic Aerogels
    • Authors: Christoph Ziegler; André Wolf, Wei Liu, Anne-Kristin Herrmann, Nikolai Gaponik, Alexander Eychmüller
      Pages: 13200 - 13221
      Abstract: Essentially, the term aerogel describes a special geometric structure of matter. It is neither limited to any material nor to any synthesis procedure. Hence, the possible variety of materials and therefore the multitude of their applications are almost unbounded. In fact, the same applies for nanoparticles. These are also just defined by their geometrical properties. In the past few decades nano-sized materials have been intensively studied and possible applications appeared in nearly all areas of natural sciences. To date a large variety of metal, semiconductor, oxide, and other nanoparticles are available from colloidal synthesis. However, for many applications of these materials an assembly into macroscopic structures is needed. Here we present a comprehensive picture of the developments that enabled the fusion of the colloidal nanoparticle and the aerogel world. This became possible by the controlled destabilization of pre-formed nanoparticles, which leads to their assembly into three-dimensional macroscopic networks. This revolutionary approach makes it possible to use precisely controlled nanoparticles as building blocks for macroscopic porous structures with programmable properties.Make something big! The controlled destabilization of colloidal nanoparticles and the resulting assembly into macroscopic 3D structures enables the fusion of the nano and the macro worlds. Nanoparticles can be used like a toolbox to create materials with designed properties. This Review summarizes this exciting area of modern nanotechnology.
      PubDate: 2017-09-22T02:25:48.73899-05:0
      DOI: 10.1002/anie.201611552
       
  • Supramolecular Organization and Functional Implications of
           K+ Channel Clusters in Membranes
    • Authors: Koen M. Visscher; João Medeiros-Silva, Deni Mance, João P. G. L. M. Rodrigues, Mark Daniëls, Alexandre M. J. J. Bonvin, Marc Baldus, Markus Weingarth
      Pages: 13222 - 13227
      Abstract: The segregation of cellular surfaces in heterogeneous patches is considered to be a common motif in bacteria and eukaryotes that is underpinned by the observation of clustering and cooperative gating of signaling membrane proteins such as receptors or channels. Such processes could represent an important cellular strategy to shape signaling activity. Hence, structural knowledge of the arrangement of channels or receptors in supramolecular assemblies represents a crucial step towards a better understanding of signaling across membranes. We herein report on the supramolecular organization of clusters of the K+ channel KcsA in bacterial membranes, which was analyzed by a combination of DNP-enhanced solid-state NMR experiments and MD simulations. We used solid-state NMR spectroscopy to determine the channel–channel interface and to demonstrate the strong correlation between channel function and clustering, which suggests a yet unknown mechanism of communication between K+ channels.Multichannel communication: The anatomy of K+ channel clusters was dissected by combining DNP-enhanced solid-state NMR spectroscopy with large-scale molecular dynamics simulations. The results discussed herein demonstrate that there is a correlation between ion channel clustering and function.
      PubDate: 2017-08-09T03:37:04.021523-05:
      DOI: 10.1002/anie.201705723
       
  • A DNA-Programmed Liposome Fusion Cascade
    • Authors: Philipp M. G. Löffler; Oliver Ries, Alexander Rabe, Anders H. Okholm, Rasmus P. Thomsen, Jørgen Kjems, Stefan Vogel
      Pages: 13228 - 13231
      Abstract: Chemically engineered and functionalized nanoscale compartments are used in bottom-up synthetic biology to construct compartmentalized chemical processes. Progressively more complex designs demand spatial and temporal control over entrapped species. Here, we address this demand with a DNA-encoded design for the successive fusion of multiple liposome populations. Three individual stages of fusion are induced by orthogonally hybridizing sets of membrane-anchored oligonucleotides. Each fusion event leads to efficient content mixing and transfer of the recognition unit for the subsequent stage. In contrast to fusion-protein-dependent eukaryotic vesicle processing, this artificial fusion cascade exploits the versatile encoding potential of DNA hybridization and is generally applicable to small and giant unilamellar vesicles. This platform could thus enable numerous applications in artificial cellular systems and liposome-based synthetic pathways.Hot fusion: Membrane fusion mediated by the hybridization of lipid-oligonucleotide conjugates (LiNAs) allows rapid content mixing with low leakage for small liposomes and giant unilamellar vesicles at elevated temperatures of 37 °C and 50 °C. A three-stage fusion sequence controlled by orthogonal sets of complementary LiNAs was demonstrated at 50 °C.
      PubDate: 2017-08-23T12:40:38.982785-05:
      DOI: 10.1002/anie.201703243
       
  • Covalent Lipid Pocket Ligands Targeting p38α MAPK Mutants
    • Authors: Mike Bührmann; Julia Hardick, Jörn Weisner, Lena Quambusch, Daniel Rauh
      Pages: 13232 - 13236
      Abstract: A chemical genetic approach is presented to covalently target a unique lipid binding pocket in the protein kinase p38α, whose function is not yet known. Based on a series of cocrystal structures, a library of 2-arylquinazolines that were decorated with electrophiles were designed and synthesized to covalently target tailored p38α mutants containing artificially introduced cysteine residues. Matching protein–ligand pairs were identified by MS analysis and further validated by MS/MS studies and protein crystallography. The covalent ligands that emerged from this approach showed excellent selectivity towards a single p38α mutant and will be applicable as suitable probes in future studies of biological systems to dissect the function of the lipid pocket by means of pharmacological perturbations.Pocket picking: Electrophile-modified quinazolines have been developed as covalent ligands of a lipid binding pocket in p38α, the biological function of which is as yet unknown. Their binding to tailor-made kinase mutants was validated by mass spectrometry and protein X-ray crystallography. This chemical genetic approach led to the identification of specific protein–ligand pairs suitable for application in future studies.
      PubDate: 2017-09-22T02:20:53.336112-05:
      DOI: 10.1002/anie.201706345
       
  • An Icosidodecahedral Supramolecule Based on Pentaphosphaferrocene: From a
           Disordered Average Structure to Individual Isomers
    • Authors: Claudia Heindl; Eugenia Peresypkina, Alexander V. Virovets, Ivan S. Bushmarinov, Michael G. Medvedev, Barbara Krämer, Birger Dittrich, Manfred Scheer
      Pages: 13237 - 13243
      Abstract: Pentaphosphaferrocenes [CpRFe(η5-P5)] (1) and CuI halides are excellent building blocks for the formation of discrete supramolecules. Herein, we demonstrate the potential of Cu(CF3SO3) for the construction of the novel 2D polymer [{Cp*Fe(μ4,η5:1:1:1-P5)}{Cu(CF3SO3)}]n (2) and the unprecedented nanosphere (CH2Cl2)1.4@[{CpBnFe(η5-P5)}12{Cu(CF3SO3)}19.6] (3). The supramolecule 3 has a unique scaffold beyond the fullerene topology, with 20 copper atoms statistically distributed over the 30 vertices of an icosidodecahedron. Combinatorics was used to interpret the average disordered structure of the supramolecules. In this case, only two pairs of enantiomers with D5 and D2 symmetry are possible for bidentate bridging coordination of the triflate ligands. DFT calculations showed that differences in the energies of the isomers are negligible. The benzyl ligands enhance the solubility of 3, enabling NMR-spectroscopic and mass-spectrometric investigations.With the CF3SO3− anion as a spacer, a new type of giant supramolecule was obtained from pentaphosphaferrocene and Cu+. With 20 copper atoms distributed over the 30 vertices of a giant icosidodecahedron, its unprecedented scaffold contains intrinsic vacancies and exists as four isomers.
      PubDate: 2017-09-18T08:57:49.291701-05:
      DOI: 10.1002/anie.201706756
       
  • Anionic Palladium(0) and Palladium(II) Ate Complexes
    • Authors: Marlene Kolter; Katharina Böck, Konstantin Karaghiosoff, Konrad Koszinowski
      Pages: 13244 - 13248
      Abstract: Palladium ate complexes are frequently invoked as important intermediates in Heck and cross-coupling reactions, but so far have largely eluded characterization at the molecular level. Here, we use electrospray-ionization mass spectrometry, electrical conductivity measurements, and NMR spectroscopy to show that the electron-poor catalyst [L3Pd] (L=tris[3,5-bis(trifluoromethyl)phenyl]phosphine) readily reacts with Br− ions to afford the anionic, zero-valent ate complex [L3PdBr]−. In contrast, more-electron-rich Pd catalysts display lower tendencies toward the formation of ate complexes. Combining [L3Pd] with LiI and an aryl iodide substrate (ArI) results in the observation of the PdII ate complex [L2Pd(Ar)I2]−.Ate anions analyzed: Palladium ate complexes are presumed to act as central intermediates in Heck and cross-coupling reactions, but so far have escaped an in-depth characterization. These complexes can be stabilized by ligation with an electron-poor phosphine, thus enabling their analysis by a combination of ESI mass spectrometry, electrical conductivity measurements, and multinuclear NMR spectroscopy.
      PubDate: 2017-09-22T02:45:28.517638-05:
      DOI: 10.1002/anie.201707362
       
  • Polysulfide Coordination Clusters of the Lanthanides
    • Authors: Ying-Zhao Ma; Sebastian Bestgen, Michael T. Gamer, Sergey N. Konchenko, Peter W. Roesky
      Pages: 13249 - 13252
      Abstract: The reaction of [(DippForm)2Ln(thf)2] with an excess of elemental sulfur in toluene resulted in the formation of the trinuclear polysulfide coordination clusters [(DippForm)3Ln3S12] (Ln=Sm, Yb; DippForm=N,N′-bis(2,6-diisopropylphenyl)formamidinate). These are the first f element coordination clusters (LnnSx) with a larger polysulfide unit (n and x>2). The formation of the coordination clusters can be rationalized by the reductive cleavage of S8 with divalent lanthanides.Stocking up on sulfur: The trinuclear polysulfide coordination clusters [(DippForm)3Ln3S12] (Ln=Sm, Yb; DippForm=N,N′-bis(2,6-diisopropylphenyl)formamidinate) were synthesized (see picture). They are the largest f element polysulfide coordination clusters with a larger polysulfide unit.
      PubDate: 2017-09-26T09:26:40.376786-05:
      DOI: 10.1002/anie.201707578
       
  • Between Localization and Delocalization: Ru(cod)2+ Units in the Zintl
           Clusters [Bi9{Ru(cod)}2]3− and [Tl2Bi6{Ru(cod)}]2−
    • Authors: Niels Lichtenberger; Nils Spang, Andreas Eichhöfer, Stefanie Dehnen
      Pages: 13253 - 13258
      Abstract: Reactions of [K(crypt-222)]2(TlBi3)⋅0.5 en (1 b) with [Ru(cod)(H2CC(Me)CH2)2] (A) in 1,2-diaminoethane (en) led to the formation of two compounds with new bismuth-rich cluster anions, [K(crypt-222)]3[Bi9{Ru(cod)}2]⋅1.5 en (2) and [K(crypt-222)]2[Tl2Bi6{Ru(cod)}]⋅2 tol (3), alongside the salt of a binary nido cluster, [K(crypt-222)]3(Tl4Bi5)⋅2 en (4). The anions in 2 and 3 are two further examples of rare heterometallic clusters containing Ru atoms. As one cod ligand is retained on each Ru atom in both clusters, the anions may be viewed as intermediates on the way towards larger, ligand-free intermetalloid clusters. Quantum-chemical studies provided insight into the bonding situation in these clusters. According to these studies, the anion of 2 features both electron-precise and electron-deficient parts. Electrospray ionization mass spectrometry analysis indicated that the clusters undergo stepwise fragmentation.A little bit of each: DFT studies confirm a hybrid bonding situation in [Bi9{Ru(cod)}2]3− with both localized and delocalized bonds. This cluster and [Tl2Bi6{Ru(cod)}]2− were obtained upon reaction of the binary Zintl anion (TlBi3)2− with [Ru(cod)(H2CC(Me)CH2)2]. Both clusters are rare examples of Zintl anions comprising Ru atoms and illustrate the electronic flexibility of Group 15 polyanions with (pseudo)atoms of other groups.
      PubDate: 2017-09-13T13:05:49.975701-05:
      DOI: 10.1002/anie.201707632
       
  • Intramolecular π–π Interactions in Flexibly Linked Partially
           Fluorinated Bisarenes in the Gas Phase
    • Authors: Sebastian Blomeyer; Marvin Linnemannstöns, Jan Hendrick Nissen, Jannik Paulus, Beate Neumann, Hans-Georg Stammler, Norbert W. Mitzel
      Pages: 13259 - 13263
      Abstract: Three compounds with phenyl and pentafluorophenyl rings bridged by (CH2)3 and (CH2)2SiMe2 units were synthesized by hydrosilylation and C−C coupling reactions. Their solid-state structures are dominated by intermolecular π stacking interactions, primarily leading to dimeric or chain-type aggregates. Analysis of free molecules in the gas phase by electron diffraction revealed the most abundant conformer to be significantly stabilized by intramolecular π–π interactions. For the silicon compounds, structures characterized by σ–π interactions between methyl and pentafluorophenyl groups are second lowest in energy and cannot be excluded completely by the gas electron diffraction experiments. C6H5(CH2)3C6F5, in contrast, is present as a single conformer. The gas-phase structures served as a reference for the evaluation of a series of (dispersion-corrected) quantum-chemical calculations.Undistorted structures of compounds with C6H5 and C6F5 groups linked by (CH2)3 and (CH2)2SiMe2 moieties show folding by intramolecular dispersion forces in the gas phase whereas in the solid state, extended conformers are adopted that interact intermolecularly. The experimental data served as a reference for the quality of quantum-chemical calculations.
      PubDate: 2017-09-19T08:10:41.731836-05:
      DOI: 10.1002/anie.201707716
       
  • Picomolar Traces of Americium(III) Introduce Drastic Changes in the
           Structural Chemistry of Terbium(III): A Break in the “Gadolinium
           Break”
    • Authors: Jan M. Welch; Danny Müller, Christian Knoll, Martin Wilkovitsch, Gerald Giester, Johannes Ofner, Bernhard Lendl, Peter Weinberger, Georg Steinhauser
      Pages: 13264 - 13269
      Abstract: The crystallization of terbium 5,5′-azobis[1H-tetrazol-1-ide] (ZT) in the presence of trace amounts (ca. 50 Bq, ca. 1.6 pmol) of americium results in 1) the accumulation of the americium tracer in the crystalline solid and 2) a material that adopts a different crystal structure to that formed in the absence of americium. Americium-doped [Tb(Am)(H2O)7ZT]2 ZT⋅10 H2O is isostructural to light lanthanide (Ce–Gd) 5,5′-azobis[1H-tetrazol-1-ide] compounds, rather than to the heavy lanthanide (Tb–Lu) 5,5′-azobis[1H-tetrazol-1-ide] (e.g., [Tb(H2O)8]2ZT3⋅6 H2O) derivatives. Traces of Am seem to force the Tb compound into a structure normally preferred by the lighter lanthanides, despite a 108-fold Tb excess. The americium-doped material was studied by single-crystal X-ray diffraction, vibrational spectroscopy, radiochemical neutron activation analysis, and scanning electron microcopy. In addition, the inclusion properties of terbium 5,5′-azobis[1H-tetrazol-1-ide] towards americium were quantified, and a model for the crystallization process is proposed.In trace amounts: The crystallization of terbium 5,5′-azobis[1H-tetrazol-1-ide] in the presence of trace amounts of americium results in the accumulation of the americium tracer in the crystalline solid and a material that adopts a different crystal structure to that formed in the absence of americium.
      PubDate: 2017-08-31T11:12:34.58186-05:0
      DOI: 10.1002/anie.201703971
       
  • α-Carbonyl Cations in Sulfoxide-Driven Oxidative Cyclizations
    • Authors: Tobias Stopka; Meike Niggemann, Nuno Maulide
      Pages: 13270 - 13274
      Abstract: The selective, metal-free generation of α-carbonyl cations from simple internal alkynes was accomplished by the addition of a sulfoxide to a densely substituted vinyl cation. The high reactivity of the α-carbonyl cations was found to efficiently induce hydrogen and even carbon shift reactions with unusual selecivities. Complex compounds with highly congested tertiary and all-carbon-substituted quartenary carbon centers can thus be accessed in a single step from simple precursors. Mechanistic analysis strongly supports the intermediacy of the title compounds and provides a simple predictive scheme for the migratory aptitude of different substituents.Combining forces enables the generation of α-carbonyl cations from vinyl cations in an acid-catalyzed process. These intermediates are highly reactive and thus undergo hydrogen and carbon shift reactions with unusual selectivities. Mechanistic analysis confirmed their intermediacy and provided a prediction scheme for the migratory aptitude of different substituents.
      PubDate: 2017-09-25T01:50:25.227495-05:
      DOI: 10.1002/anie.201705964
       
  • Radical Hydrodehalogenation of Aryl Bromides and Chlorides with Sodium
           Hydride and 1,4-Dioxane
    • Authors: Tobias Hokamp; Abhishek Dewanji, Maximilian Lübbesmeyer, Christian Mück-Lichtenfeld, Ernst-Ulrich Würthwein, Armido Studer
      Pages: 13275 - 13278
      Abstract: A practical method for radical chain reduction of various aryl bromides and chlorides is introduced. The thermal process uses NaH and 1,4-dioxane as reagents and 1,10-phenanthroline as an initiator. Hydrodehalogenation can be combined with typical cyclization reactions, proving the nature of the radical mechanism. These chain reactions proceed by electron catalysis. DFT calculations and mechanistic studies support the suggested mechanism.It is the combo! NaH in combination with 1,4-dioxane serves as the reagent for the radical chain reduction of various aryl halides. Hydrodehalogenation is initiated by 1,10-phenanthroline (phen) at elevated temperature and can be combined with a typical radical cyclization reaction. The reactions proceed via electron catalysis.
      PubDate: 2017-09-19T08:06:15.890358-05:
      DOI: 10.1002/anie.201706534
       
  • Solvation Accounts for the Counterintuitive Nucleophilicity Ordering of
           Peroxide Anions
    • Authors: Robert J. Mayer; Takahiro Tokuyasu, Peter Mayer, Jérôme Gomar, Stéphane Sabelle, Benedetta Mennucci, Herbert Mayr, Armin R. Ofial
      Pages: 13279 - 13282
      Abstract: The nucleophilic reactivities (N, sN) of peroxide anions (generated from aromatic and aliphatic peroxy acids or alkyl hydroperoxides) were investigated by following the kinetics of their reactions with a series of benzhydrylium ions (Ar2CH+) in alkaline aqueous solutions at 20 °C. The second-order rate constants revealed that deprotonated peroxy acids (RCO3−), although they are the considerably weaker Brønsted bases, react much faster than anions of aliphatic hydroperoxides (ROO−). Substitution of the rate constants of their reactions with benzhydrylium ions into the linear free energy relationship lg k=sN(N+E) furnished nucleophilicity parameters (N, sN) of peroxide anions, which were successfully applied to predict the rates of Weitz–Scheffer epoxidations. DFT calculations with inclusion of solvent effects by means of the Integral Equation Formalism version of the Polarizable Continuum Model were performed to rationalize the observed reactivities.Weak bases, but strong nucleophiles: Peroxybenzoate ions can be generated in aqueous solution under much less basic conditions than alkyl peroxide anions. Nevertheless, their nucleophilic reactivities exceed those of the alkyl peroxide anions significantly. Quantum chemical calculations reveal solvation to be the origin of the unexpected ordering of reactivity.
      PubDate: 2017-09-18T11:33:30.626286-05:
      DOI: 10.1002/anie.201707086
       
  • Octacyanidotungstate(IV) Coordination Chains Demonstrate a Light-Induced
           
    • Authors: Michał Magott; Olaf Stefańczyk, Barbara Sieklucka, Dawid Pinkowicz
      Pages: 13283 - 13287
      Abstract: A huge increase in the magnetization of two coordination chains based on tetravalent octacyanidometalates (WIV and MoIV) is observed on irradiation with 436 nm light, while no such behavior is observed for the NbIV analogue. A photomagnetic response based solely on [WIV(CN)8]4− is demonstrated for the first time. The observed behavior is attributed to the light-induced excited spin state trapping (LIESST) effect at the octacyanidometalate, and to the resulting magnetic exchange ON/OFF photoswitching between the MnII center and the photoinduced high-spin (S=1) WIV or MoIV centers.Let it shine! Octacyanidotungstate(IV) demonstrates a light-induced excited spin state trapping photomagnetic effect that can be used to produce very strong magnetic exchange photoswitching functionality in various bimetallic coordination polymers.
      PubDate: 2017-09-18T11:33:46.706192-05:
      DOI: 10.1002/anie.201703934
       
  • On the Role of Chirality in Guiding the Self-Assembly of Peptides
    • Authors: Shibaji Basak; Ishwar Singh, Annaleizle Ferranco, Jebreil Syed, Heinz-Bernhard Kraatz
      Pages: 13288 - 13292
      Abstract: Homochirality in peptides is crucial in sustaining “like–like” intermolecular interactions that allow the formation of assemblies and aggregates and is ultimately responsible for the resulting material properties. With the help of a series of stereoisomers of the tripeptide F–F–L, we demonstrate the critical role that peptide stereochemistry plays in the self-assembly of peptides, guided by molecular recognition, and for self-sorting. Homochiral self-assemblies are thermally and mechanically more robust compared to heterochiral self-assemblies. Morphological studies of the multicomponent peptide systems showed that aggregates formed from homochiral peptides possessed a uniform nano-fibrous structure, whereas heterochiral systems resulted in self-sorted systems with a heterogeneous morphology. In essence, homochiral peptides form the stronger aggregates, which may be one of reasons why homochirality is preferred in living systems.Explaining the handedness of life: Stereochemistry plays an important role in the self-assembly of peptides, guided by molecular recognition and self-sorting. Homochiral peptides form the stronger aggregates, which may be one of the reasons why homochirality is preferred in living systems.
      PubDate: 2017-09-21T08:51:03.90486-05:0
      DOI: 10.1002/anie.201706162
       
  • Preorganization and Cooperation for Highly Efficient and Reversible
           Capture of Low-Concentration CO2 by Ionic Liquids
    • Authors: Yanjie Huang; Guokai Cui, Yuling Zhao, Huiyong Wang, Zhiyong Li, Sheng Dai, Jianji Wang
      Pages: 13293 - 13297
      Abstract: A novel strategy based on the concept of preorganization and cooperation has been designed for a superior capacity to capture low-concentration CO2 by imide-based ionic liquids. By using this strategy, for the first time, an extremely high gravimetric CO2 capacity of up to 22 wt % (1.65 mol mol−1) and excellent reversibility (16 cycles) have been achieved from 10 vol. % of CO2 in N2 when using an ionic liquid having a preorganized anion. Through a combination of quantum-chemical calculations and spectroscopic investigations, it is suggested that cooperative interactions between CO2 and multiple active sites in the preorganized anion are the driving force for the superior CO2 capacity and excellent reversibility.Two for one: A novel preorganization and cooperation strategy has been designed for a superior capacity (22 wt %, 1.65 mol mol−1) to capture low-concentration CO2 (10 vol. % CO2 in N2) by imide-based ionic liquids with excellent reversibility (16 cycles). Multiple-site cooperative interactions between CO2 and active sites in the preorganized anion are operative.
      PubDate: 2017-09-19T07:46:29.300997-05:
      DOI: 10.1002/anie.201706280
       
  • Iron-Catalyzed anti-Selective Carbosilylation of Internal Alkynes
    • Authors: Takahiro Iwamoto; Tatsushi Nishikori, Naohisa Nakagawa, Hikaru Takaya, Masaharu Nakamura
      Pages: 13298 - 13301
      Abstract: Reported is the anti-selective carbosilylation of internal alkynes with silylborane and alkyl halides using a FeBr2/DPPE catalyst system. The iron catalyst allows simultaneous introduction of a carbon electrophile and a silicon nucleophile to simple internal alkynes, including diaryl-, dialkyl-, and aryl/alkyl-substituted alkynes, in a highly stereoselective manner. Alkyl halides are applicable as the electrophiles, thereby enabling the synthesis of a variety of tetrasubstituted alkenylsilanes. In addition, syn-selective carbosilylation was achieved through stereoswitching, by using a silylborane having oxygen functionality on the silyl group. This novel iron-catalyzed carbosilylation is a useful tool for expedient synthesis of stereodefined multisubstituted olefins, a fundamental structural motif in organic chemistry.Pin on: anti-Selective carbosilylation of internal alkynes with PhMe2SiBpin and alkyl halides was achieved using a FeBr2/dppe catalyst system. The reaction exhibits high anti selectivity irrespective of the structure of the alkyne and electrophile. Additionally, syn-selective carbosilylation was achieved using Ph2(MeO)SiBpin. The oxygen functional group plays a key role in the syn selectivity.
      PubDate: 2017-09-19T08:06:03.184969-05:
      DOI: 10.1002/anie.201706333
       
  • Boosting the Catalytic Performance of Metal–Organic Frameworks for
           Steroid Transformations by Confinement within a Mesoporous Scaffold
    • Authors: Francisco G. Cirujano; Ignacio Luz, Mustapha Soukri, Cedric Van Goethem, Ivo F. J. Vankelecom, Marty Lail, Dirk E. De Vos
      Pages: 13302 - 13306
      Abstract: Solid-state crystallization achieves selective confinement of metal–organic framework (MOF) nanocrystals within mesoporous materials, thereby rendering active sites more accessible compared to the bulk-MOF and enhancing the chemical and mechanical stability of MOF nanocrystals. (Zr)UiO-66(NH2)/SiO2 hybrid materials were tested as efficient and reusable heterogeneous catalysts for the synthesis of steroid derivatives, outperforming the bulk (Zr)UiO-66(NH2) MOF. A clear correlation between the catalytic activity of the dispersed Zr sites present in the confined MOF, and the loading of the mesoporous SiO2, is demonstrated for steroid transformations.Sentenced to solitary: Confinement of UiO-66 metal–organic framework (MOF) nanocrystals inside the pores of SBA-15 mesoporous silica promotes MOF-catalyzed transformations of bulky steroids, while simultaneously enhancing the chemical and mechanical stability of the MOF.
      PubDate: 2017-09-25T11:14:12.974304-05:
      DOI: 10.1002/anie.201706721
       
  • Buchwald–Hartwig Amination of Nitroarenes
    • Authors: Fumiyoshi Inoue; Myuto Kashihara, M. Ramu Yadav, Yoshiaki Nakao
      Pages: 13307 - 13309
      Abstract: The Buchwald–Hartwig amination of nitroarenes was achieved for the first time by using palladium catalysts bearing dialkyl(biaryl)phosphine ligands. These cross-coupling reactions of nitroarenes with diarylamines, arylamines, and alkylamines afforded the corresponding substituted arylamines. A catalytic cycle involving the oxidative addition of the Ar−NO2 bond to palladium(0) followed by nitrite/amine exchange is proposed based on a stoichiometric reaction.Nitro to amino: The Buchwald–Hartwig amination of nitroarenes is catalyzed by a palladium complex bearing a dialkyl(biaryl)phosphine ligand. Nitroarenes were thus cross-coupled with diarylamines, arylamines, and alkylamines to afford the corresponding substituted arylamines.
      PubDate: 2017-09-22T02:21:13.343107-05:
      DOI: 10.1002/anie.201706982
       
  • Alkynyl Thioethers in Gold-Catalyzed Annulations To Form Oxazoles
    • Authors: Raju Jannapu Reddy; Matthew P. Ball-Jones, Paul W. Davies
      Pages: 13310 - 13313
      Abstract: Non-oxidative, regioselective, and convergent access to densely functionalized oxazoles is realized in a functional-group tolerant manner using alkynyl thioethers. Sulfur-terminated alkynes provide access to reactivity previously requiring strong donor-substituted alkynes such as ynamides. Sulfur does not act in an analogous donor fashion in this gold-catalyzed reaction, thus leading to complementary regioselective outcomes and addressing the limitations of using ynamides.Taking a different path: The first gold-catalyzed annulations with alkynyl thioethers are reported. This transformation provides ready and convergent access into densely functionalized 1,3-oxazole motifs. The sulfur substituent is integral to accessing the desired reactivity and provides a useful synthetic handle for later elaboration. In contrast with recent reports, the reaction does not follow a ketenethionium pathway.
      PubDate: 2017-09-19T08:06:27.186749-05:
      DOI: 10.1002/anie.201706850
       
  • Copper-Catalyzed Borylacylation of Activated Alkenes with Acid Chlorides
    • Authors: Yuan Huang; Kevin B. Smith, M. Kevin Brown
      Pages: 13314 - 13318
      Abstract: A method for the copper-catalyzed borylacylation of activated alkenes is presented. The reaction involves borylcupration of the alkene, followed by capture of the generated alkyl–copper intermediate with an acid chloride. The reactions operated with low catalyst loading and generally occurre within 15 min at room temperature for a range of activated alkenes. In the case of vinyl arenes, enantioselective borylacylation was possible.Give 'em the new one, two: A range of activated alkenes underwent rapid copper-catalyzed borylacylation at room temperature at low catalyst loadings (see scheme). The reaction involves borylcupration of the alkene and capture of the resulting alkyl–copper intermediate with an acid chloride. In the case of vinyl arenes, the transformation could be carried out in an enantioselective manner.
      PubDate: 2017-09-18T11:32:26.134404-05:
      DOI: 10.1002/anie.201707323
       
  • Catalytic Enantioselective Synthesis of Highly Functionalized
           Difluoromethylated Cyclopropanes
    • Authors: Maxence Bos; Wei-Sheng Huang, Thomas Poisson, Xavier Pannecoucke, André B. Charette, Philippe Jubault
      Pages: 13319 - 13323
      Abstract: The first catalytic asymmetric synthesis of highly functionalized difluoromethylated cyclopropanes is described. The method, based on a rhodium-catalyzed cyclopropanation of difluoromethylated olefins, gives access to a broad range of cyclopropanes bearing ester, ketone, or nitro functional groups. By using Rh2((S)-BTPCP)4 as a catalyst, the corresponding products were obtained in high yields and high diastereo- and enantioselectivities (up 20:1 d.r. and 99 % ee). This methodology allowed preparation of enantioenriched difluoromethylcyclopropanes for the first time.Small rings: The first catalytic asymmetric synthesis of difluorinated cyclopropanes is described. The methodology employs a rhodium catalyst and affords access to functionalized cyclopropanes in high yields with high diastereo- and enantioselectivities. PMP=para-methoxyphenyl.
      PubDate: 2017-09-18T11:39:39.13852-05:0
      DOI: 10.1002/anie.201707375
       
  • Copper-Catalyzed C(sp3)−H/C(sp3)−H Cross-Dehydrogenative Coupling with
           Internal Oxidants: Synthesis of 2-Trifluoromethyl-Substituted
           Dihydropyrrol-2-ols
    • Authors: Chuanle Zhu; Rui Zhu, Hao Zeng, Fulin Chen, Chi Liu, Wanqing Wu, Huanfeng Jiang
      Pages: 13324 - 13328
      Abstract: The first oxidative C(sp3)−H/C(sp3)−H cross-dehydrogenative coupling (CDC) reaction promoted by an internal oxidant is reported. This copper-catalyzed CDC reaction of oxime acetates and trifluoromethyl ketones provides a simple and efficient approach towards 2-trifluoromethyldihydropyrrol-2-ol derivatives in a highly diastereoselective manner by cascade C(sp3)−C(sp3) bond formation and cyclization. These products were further transformed into various significant and useful trifluoromethylated heterocyclic compounds, such as trifluoromethylated furan, thiophene, pyrrole, dihydropyridazine, and pyridazine derivatives. A trifluoromethylated analogue of an Aβ42 lowering agent was also synthesized smoothly. Preliminary mechanistic studies indicated that this reaction involves a copper(I)/copper(III) catalytic cycle with the oxime acetate acting as an internal oxidant.Internal solution: A copper-catalyzed oxidative C(sp3)−H/C(sp3)−H cross-dehydrogenative coupling reaction promoted by an internal oxidant gives rise to 2-trifluoromethyldihydropyrrol-2-ol derivatives in good yields and with high diastereoselectivity. These products were further transformed into various useful trifluoromethylated heterocycles.
      PubDate: 2017-09-22T02:45:37.094091-05:
      DOI: 10.1002/anie.201707719
       
  • Hydrosulfonylation Reaction with Arenesulfonyl Chlorides and
           Tetrahydrofuran: Conversion of Terminal Alkynes into Cyclopentylmethyl
           Sulfones
    • Authors: Christian Simon Gloor; Fabrice Dénès, Philippe Renaud
      Pages: 13329 - 13332
      Abstract: An efficient and simple radical chain reaction to convert terminal alkynes into arenesulfonylmethylcyclopentanes is described. The reaction involves a radical addition–translocation–cyclization process and necessitates solely the use of readily available arenesulfonyl chlorides in tetrahydrofuran. Interestingly, this radical-mediated C−H activation process took place with a high level of retention of configuration when an enantiomerically pure starting material was used.A solvent with style: A radical chain reaction was developed for the conversion of terminal alkynes into arenesulfonylmethylcyclopentanes. The radical addition–translocation–cyclization process simply requires the use of arenesulfonyl chlorides in tetrahydrofuran and provides products with a high level of retention of configuration (see scheme).
      PubDate: 2017-09-25T11:13:51.904772-05:
      DOI: 10.1002/anie.201707791
       
  • Practical Chemical Synthesis of Atypical Ubiquitin Chains by Using an
           Isopeptide-Linked Ub Isomer
    • Authors: Shan Tang; Lu-Jun Liang, Yan-Yan Si, Shuai Gao, Jia-Xing Wang, Jun Liang, Ziqing Mei, Ji-Shen Zheng, Lei Liu
      Pages: 13333 - 13337
      Abstract: Chemical ubiquitination is an effective approach for accessing structurally defined, atypical ubiquitin (Ub) chains that are difficult to prepare by other techniques. Herein, we describe a strategy that uses a readily accessible premade isopeptide-linked 76-mer (isoUb), which has an N-terminal Cys and a C-terminal hydrazide, as the key building block to assemble atypical Ub chains in a modular fashion. This method avoids the use of auxiliary-modified Lys and instead employs the canonical and therefore more robust Cys-based native chemical ligation technique. The efficiency and capacity of this isoUb-based strategy is exemplified by the cost-effective synthesis of several linkage- and length-defined atypical Ub chains, including K27-linked tetra-Ub and K11/K48-branched tri-, tetra-, penta-, and hexa-Ubs.All together now: Chemical protein synthesis enabled the generation of homogeneous atypical ubiquitin (Ub) chains that are difficult to prepare by other approaches. A ligation method mediated by an isopeptide-linked Ub isomer was developed to assemble the Ub chains. In this approach, a premade isopeptide-linked 76-mer (isoUb) bearing an N-terminal Cys and a C-terminal hydrazide is the key building block.
      PubDate: 2017-09-25T01:50:56.450926-05:
      DOI: 10.1002/anie.201708067
       
  • Enantioselective Direct Mannich-Type Reactions Catalyzed by Frustrated
           Lewis Acid/Brønsted Base Complexes
    • Authors: Ming Shang; Min Cao, Qifan Wang, Masayuki Wasa
      Pages: 13338 - 13341
      Abstract: An enantioselective direct Mannich-type reaction catalyzed by a sterically frustrated Lewis acid/Brønsted base complex is disclosed. Cooperative functioning of the chiral Lewis acid and achiral Brønsted base components gives rise to in situ enolate generation from monocarbonyl compounds. Subsequent reaction with hydrogen-bond-activated aldimines delivers β-aminocarbonyl compounds with high enantiomeric purity.Where no Mannich has gone before: A sterically “frustrated” chiral organoborane/achiral amine pair was found to serve as a potent cooperative acid/base catalyst for direct diastereo- and enantioselective Mannich-type reactions. An array of ketone, ester, and thioester pronucleophiles can be enolized to react with aldimines to afford β-aminocarbonyl compounds.
      PubDate: 2017-09-22T02:45:54.459591-05:
      DOI: 10.1002/anie.201708103
       
  • Stereoselective Synthesis of Z Fluoroalkenes through Copper-Catalyzed
           Hydrodefluorination of gem-Difluoroalkenes with Water
    • Authors: Jiefeng Hu; Xiaowei Han, Yu Yuan, Zhuangzhi Shi
      Pages: 13342 - 13346
      Abstract: A copper catalytic system was established for the stereoselective hydrodefluorination of gem-difluoroalkenes through C−F activation to synthesize various Z fluoroalkenes. H2O is used as the hydrogen source for the fluorine acceptor moiety. This mild catalytic system shows good-functional group compatibility, accepting a range of carbonyls as precursors to the gem-difluoroalkenes, including aliphatic, aromatic, and α,β-unsaturated aldehydes and even ketones. It serves as a powerful synthetic method for the late-stage modification of complex compounds.From A(ll) to Z: A copper catalytic system was established for the stereoselective hydrodefluorination of carbonyl-derived gem-difluoroalkenes with water through C−F activation. This route employs readily available aldehydes or ketones, cheap fluorine and hydrogen sources, and an earth-abundant metal as the catalyst, and it can be employed to construct Z fluoroalkenes without considering the Z/E configuration of the substrates or intermediates.
      PubDate: 2017-09-22T02:46:01.865247-05:
      DOI: 10.1002/anie.201708224
       
  • Pd-PEPPSI-IPent-SiO2: A Supported Catalyst for Challenging Negishi
           Coupling Reactions in Flow
    • Authors: Gregory A. Price; Abbas Hassan, Nalin Chandrasoma, Andrew R. Bogdan, Stevan W. Djuric, Michael G. Organ
      Pages: 13347 - 13350
      Abstract: A silica-supported precatalyst, Pd-PEPPSI-IPent-SiO2, has been prepared and evaluated for its proficiency in the Negishi cross-coupling of hindered and electronically deactivated coupling partners. The precatalyst Pd-PEPPSI-IPent loaded onto packed bed columns shows high catalytic activity for the room-temperature coupling of deactivated/hindered biaryl partners. Also for the first time, the flowed Csp3–Csp2 coupling of secondary alkylzinc reagents to (hetero)aromatics has been achieved with high selectivity with Pd-PEPPSI-IPent-SiO2. These couplings required residence times as short as 3 minutes to effect completion of these challenging transformations with excellent selectivity for the nonrearranged product.Scratching the surface: The Pd-PEPPSI-IPent precatalyst was attached to the surface of silica and loaded into packed-bed flow columns. The catalyst system displays extremely high reactivity for the room-temperature coupling of secondary alkylzinc reagents to heterocycles. The reactions feature fast residence times (ca. 3 to 20 min), high conversions, and excellent selectivity. The resulting products are undergoing evaluation in medicinal chemistry.
      PubDate: 2017-09-22T02:47:01.548268-05:
      DOI: 10.1002/anie.201708598
       
  • meta-Selective C−H Borylation of Benzylamine-, Phenethylamine-, and
           Phenylpropylamine-Derived Amides Enabled by a Single Anionic Ligand
    • Authors: Holly J. Davis; Georgi R. Genov, Robert J. Phipps
      Pages: 13351 - 13355
      Abstract: Selective functionalization at the meta position of arenes remains a significant challenge. In this work, we demonstrate that a single anionic bipyridine ligand bearing a remote sulfonate group enables selective iridium-catalyzed borylation of a range of common amine-containing aromatic molecules at the arene meta position. We propose that this selectivity is the result of a key hydrogen bonding interaction between the substrate and catalyst. The scope of this meta-selective borylation is demonstrated on amides derived from benzylamines, phenethylamines and phenylpropylamines; amine-containing building blocks of great utility in many applications.Clever positioning: A bipyridine ligand incorporating a remote anionic sulfonate group directs iridium-catalyzed borylation to the meta-position on a range of amide-containing arenes. It is proposed that this selectivity is a result of a hydrogen bonding interaction to correctly position the iridium metal centre in the crucial C−H activation.
      PubDate: 2017-09-19T07:40:40.295402-05:
      DOI: 10.1002/anie.201708967
       
  • In Vivo X-ray Imaging of Transport of Renal Clearable Gold
           Nanoparticles in the Kidneys
    • Authors: Jing Xu; Mengxiao Yu, Phoebe Carter, Elizabeth Hernandez, Andrew Dang, Payal Kapur, Jer-Tsong Hsieh, Jie Zheng
      Pages: 13356 - 13360
      Abstract: With more and more engineered nanoparticles (NPs) being designed renal clearable for clinical translation, fundamental understanding of their transport in the different compartments of kidneys becomes increasingly important. Here, we report noninvasive X-ray imaging of renal clearable gold NPs (AuNPs) in normal and nephropathic kidneys. By quantifying the transport kinetics of the AuNPs in cortex, medulla and pelvis of the normal and injured kidneys, we found that ureteral obstruction not just blocked the NP elimination through the ureter but also slowed down their transport from the medulla to pelvis and enhanced the cellular uptake. Moreover, the transport kinetics of the NPs and renal anatomic details can be precisely correlated with local pathological lesion. These findings not only advance our understandings of the nano-bio interactions in kidneys but also offer a new pathway to noninvasively image kidney dysfunction and local injuries at the anatomical level.Imaging of nanoparticle transport: High-contrast noninvasive X-ray imaging of the transport process of renal clearable gold nanoparticles makes it possible to quantitatively understand the interactions between the nanoparticles and both a normal and an injured kidney at the anatomical level. The transport kinetics of the nanoparticles and renal anatomic details can be precisely correlated with local pathological lesion.
      PubDate: 2017-09-25T11:13:23.366011-05:
      DOI: 10.1002/anie.201707819
       
  • Photoredox Imino Functionalizations of Olefins
    • Authors: Jacob Davies; Nadeem S. Sheikh, Daniele Leonori
      Pages: 13361 - 13365
      Abstract: Shown herein is that polyfunctionalized nitrogen heterocycles can be easily prepared by a visible-light-mediated radical cascade process. This divergent strategy features the oxidative generation of iminyl radicals and subsequent cyclization/radical trapping, which allows the effective construction of highly functionalized heterocycles. The reactions proceed efficiently at room temperature, utilize an organic photocatalyst, use simple and readily available materials, and generate, in a single step, valuable building blocks that would be difficult to prepare by other methods.Light up: Polyfunctionalized nitrogen heterocycles can be easily prepared by a visible-light-mediated radical cascade process. This divergent strategy features the oxidative generation of iminyl radicals and subsequent cyclization/radical trapping, which allows the effective construction of highly functionalized heterocycles.
      PubDate: 2017-09-22T02:46:33.75356-05:0
      DOI: 10.1002/anie.201708497
       
  • Organic-Free Synthesis of a Highly Siliceous Faujasite Zeolite with
           Spatially Biased Q4(nAl) Si Speciation
    • Authors: Matthew D. Oleksiak; Koki Muraoka, Ming-Feng Hsieh, Marlon T. Conato, Atsushi Shimojima, Tatsuya Okubo, Watcharop Chaikittisilp, Jeffrey D. Rimer
      Pages: 13366 - 13371
      Abstract: We report the most siliceous FAU-type zeolite, HOU-3, prepared via a one-step organic-free synthesis route. Computational studies indicate that it is thermodynamically feasible to synthesize FAU with SAR=2–7, though kinetic factors seemingly impose a more restricted upper limit for HOU-3 (SAR≈3). Our findings suggest that a slow rate of crystallization and/or low concentration of Na+ ions in HOU-3 growth mixtures facilitate Si incorporation into the framework. Interestingly, Q4(nAl) Si speciation measured by solid-state NMR can only be modeled with a few combinations of Al positioning at tetrahedral sites in the crystal unit cell, indicating the distribution of Si(-O-Si)4−n(-O-Al)n species is spatially biased as opposed to being random. Achieving higher SAR is desirable for improved zeolite (hydro)thermal stability and enhanced catalytic performance, which we demonstrate in benchmark tests that show HOU-3 is superior to commercial zeolite Y.Biased position: Zeolite HOU-3 (FAU-type) is prepared with Si/Al≈3 via a one-step organic-free process. Combined experiments and modeling reveal that Al positioning in the framework is biased to achieve low energy configurations.
      PubDate: 2017-08-25T05:27:13.964409-05:
      DOI: 10.1002/anie.201702672
       
  • Protonation of Ferrocene: A Low-Temperature X-ray Diffraction Study of
           [Cp2FeH](PF6) Reveals an Iron-Bound Hydrido Ligand
    • Authors: Moritz Malischewski; Konrad Seppelt, Jörg Sutter, Frank W. Heinemann, Birger Dittrich, Karsten Meyer
      Pages: 13372 - 13376
      Abstract: Ferrocene, Cp2Fe, is quantitatively protonated in a mixture of liquid HF/PF5 to yield [Cp2FeH](PF6), which was characterized by 1H/13C NMR and 57Fe Mössbauer spectroscopy as well as single-crystal X-ray diffraction analysis. X-ray diffraction analysis at 100 K revealed a disordered, iron-coordinated hydrido ligand, which was unambiguously located by aspherical atom refinement at 100 K, and by analyzing the non-disordered crystal structure at 30 K, revealing a non-agostic structure.After more than 50 years, the mechanism of electrophilic substitutions on ferrocene was reinvestigated for the simplest electrophile, H+, and the potential intermediate [Cp2FeH]+ was isolated. Single crystals of [Cp2FeH](PF6) were obtained from an anhydrous HF/PF5 system. X-ray diffraction analysis revealed a non-agostic structure with an iron-bound hydrido ligand.
      PubDate: 2017-09-19T07:46:23.749197-05:
      DOI: 10.1002/anie.201704854
       
  • Catalytic Reductive Pinacol-Type Rearrangement of Unactivated 1,2-Diols
           through a Concerted, Stereoinvertive Mechanism
    • Authors: Nikolaos Drosos; Gui-Juan Cheng, Erhan Ozkal, Bastien Cacherat, Walter Thiel, Bill Morandi
      Pages: 13377 - 13381
      Abstract: A catalytic pinacol-type reductive rearrangement reaction of internal 1,2-diols is reported herein. Several scaffolds not usually amenable to pinacol-type reactions, such as aliphatic secondary–secondary diols, undergo the transformation well without the need for prefunctionalization. The reaction uses a simple boron catalyst and two silanes and proceeds through a concerted, stereoinvertive mechanism that enables the preparation of highly enantiomerically enriched products. Computational studies have been used to rationalize the preference for migration over direct deoxygenation.Opportunities for insiders: A catalytic pinacol-type reductive rearrangement of 1,2-internal diols was developed by the use of a simple boron catalyst and two silanes (see scheme). The reaction occurs through a concerted, stereoinvertive mechanism and is applicable to several substrate scaffolds not usually amenable to pinacol-type reactions, such as aliphatic secondary–secondary diols, without the need for prefunctionalization.
      PubDate: 2017-09-18T08:56:37.651555-05:
      DOI: 10.1002/anie.201704936
       
  • Assessing the Stability of Fluorescently Encoded Nanoparticles in
           Lysosomes by Using Complementary Methods
    • Authors: Ana M. Milosevic; Laura Rodriguez-Lorenzo, Sandor Balog, Christophe A. Monnier, Alke Petri-Fink, Barbara Rothen-Rutishauser
      Pages: 13382 - 13386
      Abstract: Nanoparticles (NPs) are promising tools in biomedical research. In vitro testing is still the first method for initial evaluation; however, NP colloidal behavior and integrity, in particular inside cells (that is, in lysosomes), are largely unknown and difficult to evaluate because of the complexity of the environment. Furthermore, while the majority of NPs are usually labeled with fluorescent dyes for tracking purposes, the effect of the lysosomal environment on the fluorophore properties, as well as the ensuing effects on data interpretation, is often only sparsely addressed. In this work, we have employed several complementary analytical methods to better understand the fate of fluorescently encoded NPs and identify potential pitfalls that may arise from focusing primary analysis on a single attribute, for example, fluorophore detection. Our study shows that in a lysosomal environment NPs can undergo significant changes resulting in dye quenching and distorted fluorescence signals.Unstable nanoparticles: The behavior and stability of fluorescently labeled gold nanoparticles after cellular internalization was investigated by several complementary analytical methods. It is shown that the lysosomal environment, that is, an acidic and confined space, can have an impact on polymer-grafted NPs with incorporated fluorophores resulting in a loss of fluorescence.
      PubDate: 2017-09-22T02:21:02.696816-05:
      DOI: 10.1002/anie.201705422
       
  • Divergent C–H Annulation for Multifused N-Heterocycles: Regio- and
           Stereospecific Cyclizations of N-Alkynylindoles
    • Authors: Khyarul Alam; Sung Won Hong, Kyung Hwan Oh, Jin Kyoon Park
      Pages: 13387 - 13391
      Abstract: N-Alkynylindoles were divergently cyclized for the synthesis of multifused N-heterocycles. An ortho-aryl palladium species was added to the α position of an ynamine to generate (Z)-6-alkylidene/benzylidene-6H-isoindolo[2,1-a]indoles, while Pt-catalyzed β-addition through π-activation gave 5-alkyl/arylindolo[2,1-a]isoquinolines. Double cyclizations using PdCl2 and oxidant afforded bright yellow benzo[7,8]indolizino[2,3,4,5-ija]quinolines, the synthesis of which was also demonstrated in a different synthetic route.A short fuse: N-Alkynylindoles were divergently cyclized to give multifused N-heterocycles. The Pd(OAc)2-catalyzed reaction with PPh3 led to 5-exo-dig cycloisomerization, while the PtCl2-catalyzed reaction led to 6-endo-dig cycloisomerization. With PdCl2 and oxidant, β-addition and tandem α-addition, followed by a second ring closure provided bright yellow benzo[7,8]indolizino[2,3,4,5-ija]quinoline, which was also synthesized by a different synthetic route.
      PubDate: 2017-09-18T08:57:14.994929-05:
      DOI: 10.1002/anie.201705514
       
  • Model for the Functional Active State of the TS Ribozyme from Molecular
           Simulation
    • Authors: Colin S. Gaines; Darrin M. York
      Pages: 13392 - 13395
      Abstract: Recently, a crystal structure has been reported of a new catalytic RNA, the TS ribozyme, that has been identified through comparative genomics and is believed to be a metalloribozyme having novel mechanistic features. Although this data provides invaluable structural information, analysis suggests a conformational change is required to arrive at a catalytically relevant state. We report results of molecular simulations that predict a spontaneous local rearrangement of the active site, leading to solution structures consistent with available functional data and providing competing mechanistic hypotheses that can be experimentally tested. The two competing hypotheses differ in the proposed identity of the catalytic general acid: either a water molecule coordinating a Mg2+ ion bound at the Watson–Crick edge of residue C7, or the N3 position of residue C7 itself.A new catalytic RNA, the TS ribozyme, is believed to be a metalloribozyme having novel mechanistic features. Molecular dynamics simulations predict a spontaneous local rearrangement of the active site, leading to solution structures consistent with available functional data and providing competing mechanistic hypotheses that can be experimentally tested.
      PubDate: 2017-09-08T04:41:37.431885-05:
      DOI: 10.1002/anie.201705608
       
  • Recognition and Extraction of Cesium Hydroxide and Carbonate by Using a
           Neutral Multitopic Ion-Pair Receptor
    • Authors: Qing He; Gretchen Marie Peters, Vincent M. Lynch, Jonathan L. Sessler
      Pages: 13396 - 13400
      Abstract: Current approaches to lowering the pH of basic media rely on the addition of a proton source. An alternative approach is described herein that involves the liquid–liquid extraction-based removal of cesium salts, specifically CsOH and Cs2CO3, from highly basic media. A multitopic ion-pair receptor (2) is used that can recognize and extract the hydroxide and carbonate anions as their cesium salts, as confirmed by 1H NMR spectroscopic titrations, ICP-MS, single-crystal structural analyses, and theoretical calculations. A sharp increase in the pH and cesium concentrations in the receiving phase is observed when receptor 2 is employed as a carrier in U-tube experiments involving the transport of CsOH through an intervening chloroform layer. The pH of the source phase likewise decreases.Less is less: Lowering pH by extraction. The elusive inorganic hydroxide and carbonate anions are captured in the form of their cesium salts by a metal-free multitopic ion-pair receptor consisting of a hemispherand-strapped calix[4]pyrrole. Direct liquid–liquid extraction and transport studies reveal that it is possible to lower the pH of a highly basic aqueous phase through the removal of the hydroxide anion instead of the addition of protons.
      PubDate: 2017-08-09T01:37:03.169194-05:
      DOI: 10.1002/anie.201705788
       
  • Regio- and Stereoselective Chlorocyanation of Alkynes
    • Authors: Alejandro G. Barrado; Adam Zieliński, Richard Goddard, Manuel Alcarazo
      Pages: 13401 - 13405
      Abstract: A variety of terminal and internal alkynes were converted regio- and stereoselectively into (Z)-3-chloroacrylonitriles by treatment with BCl3 in the presence of stoichiometric amounts of imidazolium thiocyanates. These products could be readily functionalized to provide useful building blocks, thus demonstrating the synthetic value of the method. Preliminary mechanistic studies suggest initial activation of the cationic thiocyanate by the Lewis acid, followed by electrophilic attack of the alkyne. The syn addition of a chloride to the vinyl cation intermediate and final elimination of the thiourea unit afford the desired chloroacrylonitriles.Ready, willing, able: Alkynes were converted into (Z)-3-chloroacrylonitriles by the use of imidazolium thiocyanates as electrophilic cyanating reagents in a transformation found to be efficient (fast at room temperature), versatile (24 examples, internal and terminal alkynes), and selective (excellent regio- and stereoselectivity; see scheme). The products could be readily functionalized to provide useful building blocks.
      PubDate: 2017-09-21T08:45:48.768555-05:
      DOI: 10.1002/anie.201705851
       
  • Selective C−H Bond Cleavage in Methane by Small Gold Clusters
    • Authors: Sandra M. Lang; Thorsten M. Bernhardt, Valeriy Chernyy, Joost M. Bakker, Robert N. Barnett, Uzi Landman
      Pages: 13406 - 13410
      Abstract: Methane represents the major constituent of natural gas. It is primarily used only as a source of energy by means of combustion, but could also serve as an abundant hydrocarbon feedstock for high quality chemicals. One of the major challenges in catalysis research nowadays is therefore the development of materials that selectively cleave one of the four C−H bonds of methane and thus make it amenable for further chemical conversion into valuable compounds. By employing infrared spectroscopy and first-principles calculations it is uncovered herein that the interaction of methane with small gold cluster cations leads to selective C−H bond dissociation and the formation of hydrido methyl complexes, H-Aux+-CH3. The distinctive selectivity offered by these gold clusters originates from a fine interplay between the closed-shell nature of the d states and relativistic effects in gold. Such fine balance in fundamental interactions could prove to be a tunable feature in the rational design of a catalyst.Selection by gold: Vibrational spectroscopy in conjunction with first-principle calculations demonstrate that small gold clusters can mediate the selective dissociation of one of the four C−H bonds of methane, which thus represents the first step towards its conversion into higher-quality chemicals. The distinct selectivity of these gold clusters originates from their finely balanced electronic structure. Au yellow, C gray, H white.
      PubDate: 2017-09-22T06:05:24.819662-05:
      DOI: 10.1002/anie.201706009
       
  • Peroxidyme-Amplified Radical Chain Reaction (PARCR): Visible Detection of
           a Catalytic Reporter
    • Authors: John P. Goertz; Ian M. White
      Pages: 13411 - 13415
      Abstract: Peroxidyme Amplified Radical Chain Reaction (PARCR), a novel enzyme-free system that achieves exponential amplification of a visible signal, is presented. Typical enzyme-free amplification systems that produce a visible readout suffer from long reaction times, low sensitivity, and narrow dynamic range. PARCR employs photocatalyzed nonlinear signal generation, enabling unprecedented one-pot, naked-eye detection of a catalytic reporter from 1 μm down to 100 pm. In this reaction, hemin-binding peroxidase-mimicking DNAzymes (“peroxidymes”) mediate the NADH-driven oxidation of a colorless, nonfluorescent phenoxazine dye (Amplex Red) to a brightly colored, strongly fluorescent product (resorufin); illumination with green light initiates multiple radical-forming positive-feedback loops, rapidly producing visible levels of resorufin. Collectively, these results demonstrate the potential of PARCR as an easy-to-use readout for a range of detection schemes, including aptamer labels, hybridization assays, and nucleic acid amplification.A weakness becomes an asset: The oxidative activity of catalytic nucleic acids in tandem with the much-maligned photosensitivity of the phenoxazine dye Amplex Red is leveraged to engineer an exponentially propagating reaction that creates a visible readout via multiple positive-feedback loops. This novel assay enables visible detection of the catalytic reporter from 1 μm to 100 pm.
      PubDate: 2017-09-19T00:31:18.980587-05:
      DOI: 10.1002/anie.201706163
       
  • “Isolated” DyO+ Embedded in a Ceramic Apatite Matrix Featuring
           Single-Molecule Magnet Behavior with a High Energy Barrier for
           Magnetization Relaxation
    • Authors: Pavel E. Kazin; Mikhail A. Zykin, Valentina V. Utochnikova, Oxana V. Magdysyuk, Alexander V. Vasiliev, Yan V. Zubavichus, Walter Schnelle, Claudia Felser, Martin Jansen
      Pages: 13416 - 13420
      Abstract: Meeting the challenges of Moore's Law, predicting ambitious miniaturization rates of integrated circuits, requires to go beyond the traditional top-down approaches, and to employ synthetic chemistry methods, to use bottom-up techniques. During the recent decades, it has been shown that open-shell coordination compounds may exhibit intramolecular spontaneous magnetization, thus offering promising prospects for storage and processing of digital information. Against this background we regarded it rewarding to implement similar magnetic centers into a ceramic material, which would provide better long-term mechanical and chemical durability. Here we present new robust inorganic compounds containing separate DyO+ ions in an apatite matrix, which behave like single-molecule magnets. The materials exhibit a blocking temperature of 11 K and an energy barrier for spin reversal of a thousand inverse centimeters which is among the highest values ever achieved.Dy2O3-doped apatites show low-temperature hysteresis magnetization with a blocking temperature of up to 11 K and slow relaxation of magnetization with an energy barrier (Ueff) of up to 1043 cm−1. The barrier was determined by an electron spin tunneling through the third and fourth excited Kramers doublet for calcium and strontium compounds, respectively.
      PubDate: 2017-09-18T08:57:21.023596-05:
      DOI: 10.1002/anie.201706391
       
  • Colossal Stability of Gas-Phase Trianions: Super-Pnictogens
    • Authors: Tianshan Zhao; Jian Zhou, Qian Wang, Puru Jena
      Pages: 13421 - 13425
      Abstract: Multiply charged negative ions are ubiquitous in nature. They are stable as crystals because of charge compensating cations; while in solutions, solvent molecules protect them. However, they are rarely stable in the gas phase because of strong electrostatic repulsion between the extra electrons. Therefore, understanding their stability without the influence of the environment has been of great interest to scientists for decades. While much of the past work has focused on dianions, work on triply charged negative ions is sparse and the search for the smallest trianion that is stable against spontaneous electron emission or fragmentation continues. Stability of BeB11(X)123− (X=CN, SCN, BO) trianions is demonstrated in the gas phase, with BeB11(CN)123− exhibiting colossal stability against electron emission by 2.65 eV and against its neutral adduct by 15.85 eV. The unusual stability of these trianions opens the door to a new class of super-pnictogens with potential applications in aluminum-ion batteries.The unusually stable trianions BeB11(CN)123−, BeB11(BO)123−, and BeB11(SCN)123− were synthesized using the octet and Wade–Mingos electron counting rules simultaneously. In the gas phase, the trianions are stable against spontaneous electron emission by 2.65, 1.30, and 0.59 eV, respectively. The chemistry of the stable trianions mimics that of Group 15 elements.
      PubDate: 2017-08-16T09:00:40.751324-05:
      DOI: 10.1002/anie.201706764
       
  • Carboxylation of Aromatic and Aliphatic Bromides and Triflates with CO2 by
           Dual Visible-Light–Nickel Catalysis
    • Authors: Qing-Yuan Meng; Shun Wang, Burkhard König
      Pages: 13426 - 13430
      Abstract: We report the efficient carboxylation of bromides and triflates with K2CO3 as the source of CO2 in the presence of an organic photocatalyst in combination with a nickel complex under visible light irradiation at room temperature. The reaction is compatible with a variety of functional groups and has been successfully applied to the synthesis and derivatization of biologically active molecules. In particular, the carboxylation of unactivated cyclic alkyl bromides proceeded well with our protocol, thus extending the scope of this transformation. Spectroscopic and spectroelectrochemical investigations indicated the generation of a Ni0 species as a catalytic reactive intermediate.Not only good for plants, CO2 (formed in situ from K2CO3) and light enabled the efficient and mild carboxylation of bromides and triflates in the presence of an organic fluorophore and a nickel complex (see scheme). A variety of functional groups were tolerated, and non-activated cyclic alkyl bromides reacted well. The synthesis and derivatization of biologically active molecules demonstrated the applicability of the method in multistep synthesis.
      PubDate: 2017-09-18T08:57:34.880472-05:
      DOI: 10.1002/anie.201706724
       
  • Divergent Reactivity of a Dinuclear (NHC)Nickel(I) Catalyst versus
           Nickel(0) Enables Chemoselective Trifluoromethylselenolation
    • Authors: Alexander B. Dürr; Henry C. Fisher, Indrek Kalvet, Khai-Nghi Truong, Franziska Schoenebeck
      Pages: 13431 - 13435
      Abstract: We herein showcase the ability of NHC-coordinated dinuclear NiI–NiI complexes to override fundamental reactivity limits of mononuclear (NHC)Ni0 catalysts in cross-couplings. This is demonstrated with the development of a chemoselective trifluoromethylselenolation of aryl iodides catalyzed by a NiI dimer. A novel SeCF3-bridged NiI dimer was isolated and shown to selectively react with Ar−I bonds. Our computational and experimental reactivity data suggest dinuclear NiI catalysis to be operative. The corresponding Ni0 species, on the other hand, suffers from preferred reaction with the product, ArSeCF3, over productive cross-coupling and is hence inactive.A nickel(I) dimer catalyzes the chemoselective trifluoromethylselenolation of aryl iodides, and computational and experimental reactivity data suggest dinuclear NiI catalysis to be operative. The corresponding Ni0 species, on the other hand, suffers from preferred reaction with the product, ArSeCF3, over productive cross-coupling and is hence inactive.
      PubDate: 2017-09-14T04:05:44.075307-05:
      DOI: 10.1002/anie.201706423
       
  • A Rewritable, Reprogrammable, Dual Light-Responsive Polymer Actuator
    • Authors: Anne Helene Gelebart; Dirk J. Mulder, Ghislaine Vantomme, Albertus P. H. J. Schenning, Dirk J. Broer
      Pages: 13436 - 13439
      Abstract: We report on the fabrication of a rewritable and reprogrammable dual-photoresponsive liquid crystalline-based actuator containing an azomerocyanine dye that can be locally converted into the hydroxyazopyridinium form by acid treatment. Each dye absorbs at a different wavelength giving access to programmable actuators, the folding of which can be controlled by using different colors of light. The acidic patterning is reversible and allows the erasing and rewriting of patterns in the polymer film, giving access to reusable, adjustable soft actuators.Bending patterns: Rewritable and reprogrammable actuators can be obtained by using the local activation of an initially chemically homogenous film. The locally activated material is exposed to UV light, which results in the precise folding of the actuator. By switching the wavelength, a different shape can be obtained. Furthermore, the pattern can be erased and a new one can be written, giving access to a multitude of actuated shapes.
      PubDate: 2017-09-22T02:21:17.260731-05:
      DOI: 10.1002/anie.201706793
       
  • Tuning Crystallization Pathways through the Mesoscale Assembly of
           Biomacromolecular Nanocrystals
    • Authors: Fei Tao; Qian Han, Kaiqiang Liu, Peng Yang
      Pages: 13440 - 13444
      Abstract: Macromolecular crystallization has many implications in biological and materials science. Similar to the crystallization of other molecules, macromolecular crystallization conventionally considers a critical nucleus, followed by crystallographic packing of macromolecules to drive further crystal growth. Herein, we discover a distinctive macromolecular crystallization pathway by developing the concept of a macromolecular mesocrystal. This nonclassical polymer crystallization occurs through the mesoscale self-assembly of (bio)macromolecular nanocrystals. The new concept for macromolecular crystallization presented herein is fundamental and relevant to many fields, including materials science, chemistry, biomimetics, nanoscience, and structural biology.Designable macromolecular crystals! The concept of a macromolecular mesocrystal is developed and applied to the discovery of a distinctive macromolecular crystallization pathway. By using the programmed mesoscale assembly and fusion of core–shell architectures, flexible crystalline macromolecular materials with complex forms and hierarchies can be facilely manipulated.
      PubDate: 2017-09-21T09:00:52.921756-05:
      DOI: 10.1002/anie.201706843
       
  • Optimizing Optical Absorption, Exciton Dissociation, and Charge Transfer
           of a Polymeric Carbon Nitride with Ultrahigh Solar Hydrogen Production
           Activity
    • Authors: Guigang Zhang; Guosheng Li, Zhi-An Lan, Lihua Lin, Aleksandr Savateev, Tobias Heil, Spiros Zafeiratos, Xinchen Wang, Markus Antonietti
      Pages: 13445 - 13449
      Abstract: Polymeric or organic semiconductors are promising candidates for photocatalysis but mostly only show moderate activity owing to strongly bound excitons and insufficient optical absorption. Herein, we report a facile bottom-up strategy to improve the activity of a carbon nitride to a level in which a majority of photons are really used to drive photoredox chemistry. Co-condensation of urea and oxamide followed by post-calcination in molten salt is shown to result in highly crystalline species with a maximum π–π layer stacking distance of heptazine units of 0.292 nm, which improves lateral charge transport and interlayer exciton dissociation. The addition of oxamide decreases the optical band gap from 2.74 to 2.56 eV, which enables efficient photochemistry also with green light. The apparent quantum yield (AQY) for H2 evolution of optimal samples reaches 57 % and 10 % at 420 nm and 525 nm, respectively, which is significantly higher than in most previous experiments.Free to dissociate: The simultaneous modification of the electronic band structures, layer-stacking geometry, and crystallinity of carbon nitride polymers enables the liberation of Frenkel exciton dissociation and magnification of the hot-charges yield, which dramatically enhances the visible-light photocatalytic activities.
      PubDate: 2017-09-18T11:33:33.725104-05:
      DOI: 10.1002/anie.201706870
       
  • Electro-kinetic Separation of Rare Earth Elements Using a Redox-Active
           Ligand
    • Authors: Huayi Fang; Bren E. Cole, Yusen Qiao, Justin A. Bogart, Thibault Cheisson, Brian C. Manor, Patrick J. Carroll, Eric J. Schelter
      Pages: 13450 - 13454
      Abstract: Purification of rare earth elements is challenging due to their chemical similarities. All of the deployed separation methods rely on thermodynamic properties, such as distribution equilibria in solvent extraction. Rare-earth-metal separations based on kinetic differences have not been examined. Herein, we demonstrate a new approach for rare-earth-element separations by exploiting differences in the oxidation rates within a series of rare earth compounds containing the redox-active ligand [{2-(tBuN(O))C6H4CH2}3N]3−. Using this method, a single-step separation factor up to 261 was obtained for the separation of a 50:50 yttrium–lutetium mixture.Let′s go kinetic: The separation of rare earth elements not by thermodynamic but by kinetic methods is feasible based on the difference of the oxidation rates of [RE(TriNOx)thf]/[RE(TriNOx)] upon oxidation with [Cp2Fe][BArF]. TriNOx3−=[{2-(tBuN(O))C6H4CH2}3N]3−; BArF=tetra[3,5-bis(trifluoromethyl)phenyl]borate.
      PubDate: 2017-09-25T01:51:14.4424-05:00
      DOI: 10.1002/anie.201706894
       
  • Conjugated Polymer with Intrinsic Alkyne Units for Synergistically
           Enhanced Raman Imaging in Living Cells
    • Authors: Shengliang Li; Tao Chen, Yunxia Wang, Libing Liu, Fengting Lv, Zhiliang Li, Yanyi Huang, Kirk S. Schanze, Shu Wang
      Pages: 13455 - 13458
      Abstract: Development of Raman-active materials with enhanced and distinctive Raman vibrations in the Raman-silent region (1800–2800 cm−1) is highly required for specific molecular imaging of living cells with high spatial resolution. Herein, water-soluble cationic conjugated polymers (CCPs), poly(phenylene ethynylene) (PPE) derivatives, are explored for use as alkyne-state-dependent Raman probes for living cell imaging due to synergetic enhancement effect of alkyne vibrations in Raman-silent region compared to alkyne-containing small molecules. The enhanced alkyne signals result from the integration of alkyne groups into the rigid backbone and the delocalized π-conjugated structure. PPE-based conjugated polymer nanoparticles (CPNs) were also prepared as Raman-responsive nanomaterials for distinct imaging application. This work opens a new way into the development of conjugated polymer materials for enhanced Raman imaging.Cell watching: Cationic poly(phenylene ethynylene) (PPE) derivatives are explored for use as Raman probes for living cell imaging due to a synergetic-enhancement effect of alkyne vibrations in Raman-silent regions. The enhanced alkyne signals result from the integration of alkyne groups into the rigid polymer backbone. PPE-based conjugated polymer nanoparticles were also prepared as Raman-responsive nanomaterials for distinct imaging application.
      PubDate: 2017-09-19T00:30:58.147896-05:
      DOI: 10.1002/anie.201707042
       
  • Molecular Design of Bisphosphonates To Adjust Their Reactivity toward
           Metal Sources for the Surfactant-Assisted Synthesis of Mesoporous Films
    • Authors: Tatsuo Kimura
      Pages: 13459 - 13463
      Abstract: The precise control of primary reactions in solutions is one of the most significant steps for the nanoscale design of inorganic solids in multidisciplinary fields. However, further growth of the inorganic species to give bulkier species disturbs such designs. The surfactant-assisted synthesis of mesoporous materials is a good strategy for addressing such concerns because pores formed by supramolecularly mediated processes are surrounded by nanometer-sized continuous frameworks. Many experiments are generally conducted to optimize the reaction conditions for the synthesis of highly ordered mesostructures. Herein, to minimize such trial-and-error efforts, a new and practical concept is proposed for the precise design of porous materials. By adjusting the reactivity between bisphosphonates and metal sources through molecular design of the starting bisphosphonate compound, it was possible to synthesize mesoporous films with unique compositions by a surfactant-assisted approach.Do away with trial and error: Usually many experiments are required to optimize the reaction conditions for the synthesis of highly ordered mesostructures. However, by adjusting the reactivity between bisphosphonates and a metal source through molecular design of the bisphosphonate, it was possible to synthesize precisely designed mesoporous films with unique compositions by a surfactant-assisted approach (see picture).
      PubDate: 2017-09-22T02:45:42.798911-05:
      DOI: 10.1002/anie.201707225
       
  • Biphasic Synergistic Gel Materials with Switchable Mechanics and
           Self-Healing Capacity
    • Authors: Ziguang Zhao; Yuxia Liu, Kangjun Zhang, Shuyun Zhuo, Ruochen Fang, Jianqi Zhang, Lei Jiang, Mingjie Liu
      Pages: 13464 - 13469
      Abstract: A fabrication strategy for biphasic gels is reported, which incorporates high-internal-phase emulsions. Closely packed micro-inclusions within the elastic hydrogel matrix greatly improve the mechanical properties of the materials. The materials exhibit excellent switchable mechanics and shape-memory performance because of the switchable micro- inclusions that are incorporated into the hydrogel matrix. The produced materials demonstrated a self-healing capacity that originates from the noncovalent effect of the biphasic heteronetwork. The aforementioned characteristics suggest that the biphasic gels may serve as ideal composite gel materials with validity in a variety of applications, such as soft actuators, flexible devices, and biological materials.It's morphin’ time: Closely packed switchable micro-inclusions in a hydrogel matrix produce biphasic synergistic gel materials with switchable mechanics, self-healing capacity, and shape-memory properties.
      PubDate: 2017-09-18T11:33:03.120757-05:
      DOI: 10.1002/anie.201707239
       
  • Trichalcogenasumanene ortho-Quinones: Synthesis, Properties, and
           Transformation into Various Heteropolycycles
    • Authors: Yantao Sun; Xuexiang Li, Chunlin Sun, Hongguang Shen, Xueqing Hou, Dongxu Lin, Hao-Li Zhang, Chong-an Di, Daoben Zhu, Xiangfeng Shao
      Pages: 13470 - 13474
      Abstract: The regioselective transformation of heterobuckybowl trichalcogenasumanenes 1 a,b at peripheral butoxy groups afforded trichalcogenasumanene ortho-quinones 2 a,b. Compounds 2 a,b are distinct from 1 a,b in terms of their molecular geometry and electronic state; that is, they have a shallower bowl depth and show absorbance in the NIR region. The reaction of 2 a,b with diamines resulted in a variety of heteropolycycles, including molecular spoon 3 a–6 a, planar π-systems 3 b–6 b, and highly twisted [7-6-6]-fused systems 7 a,b. These new heteropolycycles had different optical/electrical properties: 4 a,b showed hole mobility of approximately 0.002 cm2 V−1 s−1, 6 a displayed red emission in both solution and the solid state, and 7 a,b formed tight stacks of the curved π-surface.Bowls and spoons: Trichalcogenasumanene ortho-quinones, synthesized by the regioselective transformation of heterobuckybowl trichalcogenasumanenes, showed NIR absorption and ON/OFF fluorescence in response to electrochemical stimuli. Molecular engineering of these compounds resulted in various heteropolycycles, such as molecular spoons with semiconducting behavior and/or solid-state emission (see scheme) and a [7-6-6]-fused curved π-system.
      PubDate: 2017-09-21T08:47:05.774629-05:
      DOI: 10.1002/anie.201707397
       
  • CIT-9: A Fault-Free Gmelinite Zeolite
    • Authors: Michiel Dusselier; Jong Hun Kang, Dan Xie, Mark E. Davis
      Pages: 13475 - 13478
      Abstract: A synthetic, fault-free gmelinite (GME) zeolite is prepared using a specific organic structure-directing agent (OSDA), cis-3,5-dimethylpiperidinium. The cis-isomers align in the main 12-membered ring (MR) channel of GME. Trans-isomer OSDA leads to the small-pore zeolite SSZ-39 with the OSDA in its cages. Data from N2-physisorption and rotation electron diffraction provide evidence for the openness of the 12 MR channel in the GME 12×8×8 pore architecture and the absence of stacking faults, respectively. CIT-9 is hydrothermally stable when K+-exchanged, while in the absence of exchange, the material transforms into an aluminous AFI-zeolite. The process of this phase-change was followed by in situ variable temperature powder X-ray diffraction. CIT-9 has the highest Si/Al ratio reported for GME, and along with its good porosity, opens the possibility of using GME in a variety of applications including catalysis.A 40-year search for a truly porous gmelinite zeolite (GME) is brought to an end with the discovery of CIT-9, thus allowing final benchmarking of GME for important hydrocarbon chemistries. The synthesis is exceptionally sensitive to the concentration of the organic structure serving as the directing agent, and its cis to trans isomerism, the latter of which was confirmed by molecular modelling.
      PubDate: 2017-09-21T08:45:39.596034-05:
      DOI: 10.1002/anie.201707452
       
  • Osmium-Mediated Transformation of 4-Thiouridine to Cytidine as Key To
           Study RNA Dynamics by Sequencing
    • Authors: Christian Riml; Thomas Amort, Dietmar Rieder, Catherina Gasser, Alexandra Lusser, Ronald Micura
      Pages: 13479 - 13483
      Abstract: To understand the functional roles of RNA in the cell, it is essential to elucidate the dynamics of their production, processing and decay. A recent method for assessing mRNA dynamics is metabolic labeling with 4-thiouridine (4sU), followed by thio-selective attachment of affinity tags. Detection of labeled transcripts by affinity purification and hybridization to microarrays or by deep sequencing then reveals RNA expression levels. Here, we present a novel sequencing method (TUC-seq) that eliminates affinity purification and allows for direct assessment of 4sU-labeled RNA. It employs an OsO4-mediated transformation to convert 4sU into cytosine. We exemplify the utility of the new method for verification of endogenous 4sU in tRNAs and for the detection of pulse-labeled mRNA of seven selected genes in mammalian cells to determine the relative abundance of the new transcripts. The results prove TUC-seq as a straight-forward and highly versatile method for studies of cellular RNA dynamics.RNA modification: The osmium-mediated conversion of thiouridine (4sU) to cytidine (C) is a so far disregarded reaction with great potential for comparative sequencing approaches.
      PubDate: 2017-09-18T11:39:12.37625-05:0
      DOI: 10.1002/anie.201707465
       
  • Conformationally Flexible Bis(9-fluorenylidene)porphyrin Diradicaloids
    • Authors: Hejian Zhang; Hoa Phan, Tun Seng Herng, Tullimilli Y. Gopalakrishna, Wangdong Zeng, Jun Ding, Jishan Wu
      Pages: 13484 - 13488
      Abstract: A stable 5,10-bis(9-fluorenylidene)porphyrin (Por-Fl) diradicaloid was synthesized. It shows a quinoidal, saddle-shaped geometry in the single crystal but can be thermally populated to a triplet diradical both in solution and in the solid state. Coordination with the Ni2+ ion (Por-Fl-Ni) does not significantly change the contorted conformation but reduces the singlet–triplet gap. Heat-induced geometric change can explain the observed paramagnetic properties as well as unusual hysteresis in SQUID measurements. On the other hand, protonation (Por-Fl-2H+) dramatically changes the conformation while maintains the closed-shell electronic structure. Our studies demonstrate how heat, coordination, and protonation affect the geometry, diradical character, and physical properties of conformationally flexible open-shell singlet diradicaloids.Protonation with a twist! A quinoidal bis(9-fluorenylidene)porphyrin and its NiII complex showed closed-shell saddle-shaped geometry in the crystalline state but they can be thermally populated to paramagnetic triplet species through geometric change. Protonation also dramatically changes the conformation and physical properties.
      PubDate: 2017-09-18T11:39:00.080679-05:
      DOI: 10.1002/anie.201707480
       
  • Platinum Nanoparticle Impacts at a Liquid Liquid Interface
    • Authors: T. Jane Stockmann; Léo Angelé, Vitor Brasiliense, Catherine Combellas, Frédéric Kanoufi
      Pages: 13493 - 13497
      Abstract: Single nanoparticle (NP) electrochemistry detection at a micro liquid liquid interface (LLI) is exploited using the catalyzed oxygen reduction reaction (ORR). In this way, current spikes reminiscent of nanoimpacts were recorded, which corresponded to electrocatalytic enhancement of the ORR by Pt NPs. The nature of the LLI allows exploration of new phenomena in single NP electrochemistry. The recorded impacts result from a bipolar reaction occurring at the Pt NP straddling the LLI. O2 reduction takes place in the aqueous phase, while ferrocene hydride (Fc-H+; a complex generated upon facilitated interfacial proton transfer by Fc) is oxidized in the organic phase. Ultimately, the role of reactant partitioning, NP bouncing, or the ability of NPs to induce Marangoni effects, is demonstrated.Pitter-patter of tiny Pt: Platinum nanoparticles (NPs) were electrochemically recorded in the form of stochastic impact events at a micro liquid liquid interface by platinum-catalyzed oxygen reduction. The findings expand metal single NP detection to soft interfaces and provide insight into NP interactions and their mechanistic/physicochemical processes at liquid liquid interfaces.
      PubDate: 2017-09-22T02:45:23.688644-05:
      DOI: 10.1002/anie.201707589
       
  • Discovery of Key Physicochemical, Structural, and Spatial Properties of
           RNA-Targeted Bioactive Ligands
    • Authors: Brittany S. Morgan; Jordan E. Forte, Rebecca N. Culver, Yuqi Zhang, Amanda E. Hargrove
      Pages: 13498 - 13502
      Abstract: While a myriad non-coding RNAs are known to be essential in cellular processes and misregulated in diseases, the development of RNA-targeted small molecule probes has met with limited success. To elucidate the guiding principles for selective small molecule/RNA recognition, we analyzed cheminformatic and shape-based descriptors for 104 RNA-targeted ligands with demonstrated biological activity (RNA-targeted BIoactive ligaNd Database, R-BIND). We then compared R-BIND to both FDA-approved small molecule drugs and RNA ligands without reported bioactivity. Several striking trends emerged for bioactive RNA ligands, including: 1) Compliance to medicinal chemistry rules, 2) distinctive structural features, and 3) enrichment in rod-like shapes over others. This work provides unique insights that directly facilitate the selection and synthesis of RNA-targeted libraries with the goal of efficiently identifying selective small molecule ligands for therapeutically relevant RNAs.A space for RNA: The curation and analysis of the RNA-targeted BIoactive ligaNd Database (R-BIND) uncovered distinguishing 2D and 3D molecular properties that support the existence of an RNA-privileged chemical space. These guiding principles can facilitate the future design of selective ligands targeted toward therapeutically relevant RNAs.
      PubDate: 2017-09-18T11:37:58.014707-05:
      DOI: 10.1002/anie.201707641
       
  • Constructing a Strongly Absorbing Low-Bandgap Polymer Acceptor for
           High-Performance All-Polymer Solar Cells
    • Authors: Zhi-Guo Zhang; Yankang Yang, Jia Yao, Lingwei Xue, Shanshan Chen, Xiaojun Li, William Morrison, Changduk Yang, Yongfang Li
      Pages: 13503 - 13507
      Abstract: All-polymer solar cells (all-PSCs) offer unique morphology stability for the application as flexible devices, but the lack of high-performance polymer acceptors limits their power conversion efficiency (PCE) to a value lower than those of the PSCs based on fullerene derivative or organic small molecule acceptors. We herein demonstrate a strategy to synthesize a high-performance polymer acceptor PZ1 by embedding an acceptor–donor–acceptor building block into the polymer main chain. PZ1 possesses broad absorption with a low band gap of 1.55 eV and high absorption coefficient (1.3×105 cm−1). The all-PSCs with the wide-band-gap polymer PBDB-T as donor and PZ1 as acceptor showed a record-high PCE of 9.19 % for the all-PSCs. The success of our polymerization strategy can provide a new way to develop efficient polymer acceptors for all-PSCs.Energy conversion: Embedding an acceptor–donor–acceptor-structured organic semiconductor building block into a polymer main chain creates an excellent low-band-gap polymer acceptor with red-shifted absorption and a high absorption coefficient. The polymer acceptor provides a record-high power conversion efficiency of 9.19 % for all-polymer solar cells.
      PubDate: 2017-09-19T00:35:47.184736-05:
      DOI: 10.1002/anie.201707678
       
  • Mesoporous Semimetallic Conductors: Structural and Electronic Properties
           of Cobalt Phosphide Systems
    • Authors: Malay Pramanik; Satoshi Tominaka, Zhong-Li Wang, Toshiaki Takei, Yusuke Yamauchi
      Pages: 13508 - 13512
      Abstract: Mesoporous cobalt phosphide (meso-CoP) was prepared by the phosphorization of ordered mesoporous cobalt oxide (meso-Co3O4). The electrical conductivity of meso-CoP is 37 times higher than that of nonporous CoP, and it displays semimetallic behavior with a negligibly small activation energy of 26 meV at temperatures below 296 K. Above this temperature, only materials with mesopores underwent a change in conductivity from semimetallic to semiconducting behavior. These properties were attributed to the coexistence of nanocrystalline Co2P phases. The poor crystallinity of mesoporous materials has often been considered to be a problem but this example clearly shows its positive aspects. The concept introduced here should thus lead to new routes for the synthesis of materials with high electronic conductivity.Phosphorization of ordered mesoporous cobalt oxide generates mesoporous cobalt phosphide. Its electrical conductivity is 37 times higher than that of nonporous CoP, and it displays semimetallic behavior with a negligibly small activation energy of 26 meV at temperatures below 296 K. These properties were attributed to the coexistence of nanocrystalline Co2P phases.
      PubDate: 2017-09-22T06:26:09.128165-05:
      DOI: 10.1002/anie.201707878
       
  • Tree-Bark-Shaped N-Doped Porous Carbon Anode for Hydrazine Fuel Cells
    • Authors: Jaehoon Jeong; Myounghoon Choun, Jaeyoung Lee
      Pages: 13513 - 13516
      Abstract: Metal-free N-doped porous carbon has great potential as a catalyst for hydrazine oxidation in direct hydrazine fuel cells (DHFCs). However, previous studies have reported only half-cell characterization, and the effect of the pore size distribution has not been intensively investigated. Herein, we report the synthesis of highly active, metal-free N-doped carbon (NDC) by controlling the pore size distribution, and for the first time, the effect of the pore size distribution on the anode performance in a DHFC is investigated. As a result, tree-bark-shaped NDC with meso/macroporous (>10 nm) structures exhibit a remarkable power density of 127.5 mW cm−2 in a DHFC.Barking up the right tree: A tree-bark-shaped N-doped porous carbon nanofiber acts as a highly active, metal-free catalyst for hydrazine oxidation in hydrazine fuel cells.
      PubDate: 2017-09-22T02:45:48.357273-05:
      DOI: 10.1002/anie.201707880
       
  • Light-Activated Active Colloid Ribbons
    • Authors: Zhihua Lin; Tieyan Si, Zhiguang Wu, Changyong Gao, Xiankun Lin, Qiang He
      Pages: 13517 - 13520
      Abstract: We report a dynamic self-organization of self-propelled peanut-shaped hematite motors from non-equilibrium driving forces where the propulsion can be triggered by blue light. They result in one-dimensional, active colloid ribbons with a positive phototactic characteristic. The motion of colloid motors is ascribed to the diffusion-osmotic flow in a chemical gradient by the photocatalytic decomposition of hydrogen peroxide fuel. We show that self-propelled peanut-shaped colloids readily form one-dimensional, slithering ribbon structures under the out-of-equilibrium collisions. This self-organization intrinsically results from the competition among the osmotically driven motion, the phoretic attraction and the inherent magnetic moments. The giant size number fluctuation in colloid ribbons is observed above a critical point 4.1 % of the surface density of colloid motors. Such phototactic colloid ribbons may provide a model system to understand the emergence of function in biological systems and have potential to construct bioinspired active materials based on different active building blocks.Dynamic assembly: Peanut-shaped hematite colloid motors activated by light can readily be organized into one-dimensional colloid ribbons, which exhibit a positive phototactic behavior. The direction, speed, and size of as-formed active colloid ribbons can be modulated by using light and surface fraction of colloidal suspensions.
      PubDate: 2017-09-25T11:13:11.910885-05:
      DOI: 10.1002/anie.201708155
       
  • Evolution of the Ligand Shell Morphology during Ligand Exchange Reactions
           on Gold Nanoparticles
    • Authors: Zhi Luo; Jing Hou, Laure Menin, Quy Khac Ong, Francesco Stellacci
      Pages: 13521 - 13525
      Abstract: Ligand exchange reactions are used to achieve nanoparticles coated with a mixture of ligand molecules. Currently, nothing is known on the evolution of the morphology of the ligand shell during the reaction. Here, we use a recently developed method (based on MALDI-TOF) to follow the evolution of the ligand shell composition and morphology during the reaction. We observe the expected evolution in composition and we find that the ligand shell starts as a random mixture and gradually evolves towards a patchy morphology. When the composition has reached a plateau (i.e. when the reaction is generally assumed to be finished), the ligand shell morphology keeps evolving for days, slowly approaching its equilibrium configuration.Patchy ligand distributions: The evolution of the ligand shell morphology during ligand exchange reactions on surfaces of nanoparticles is elucidated for the first time. Kinetics and thermodynamics both play important roles in the formation of patchy domains at different reaction stages.
      PubDate: 2017-09-14T04:02:54.090413-05:
      DOI: 10.1002/anie.201708190
       
  • Reversible S0/MgSx Redox Chemistry in a MgTFSI2/MgCl2/DME Electrolyte for
           Rechargeable Mg/S Batteries
    • Authors: Tao Gao; Singyuk Hou, Fei Wang, Zhaohui Ma, Xiaogang Li, Kang Xu, Chunsheng Wang
      Pages: 13526 - 13530
      Abstract: The redox chemistry of magnesium and its application in rechargeable Mg batteries has received increasing attention owing to the unique benefits of Mg metal electrodes, namely high reversibility without dendrite formation, low reduction potentials, and high specific capacities. The Mg/S couple is of particular interest owing to its high energy density and low cost. Previous reports have confirmed the feasibility of a rechargeable Mg/S battery; however, only limited cycling stability was achieved, and the complicated procedure for the preparation of the electrolytes has significantly compromised the benefits of Mg/S chemistry and hindered the development of Mg/S batteries. Herein, we report the development of the first rechargeable Mg/S battery with a MgTFSI2/MgCl2/DME electrolyte (DME=1,2-dimethoxyethane, TFSI=bis(trifluoromethanesulfonyl)imide) and realize the best cycling stability among all reported Mg/S batteries by suppressing polysulfide dissolution. Mechanistic studies show that the battery works via S0/MgSx redox processes and that the large voltage hysteresis is mainly due to the Mg anode overpotential.Three components: A MgTFSI2/MgCl2/DME mixture (DME=1,2-dimethoxyethane, TFSI=bis(trifluoromethanesulfonyl)imide) was used as a silylamide-free, easy-to-prepare electrolyte for a rechargeable Mg/S battery that functions by S0/MgSx redox chemistry. By suppressing the dissolution of polysulfide with concentrated electrolyte (1 m), the best cycling stability thus far was achieved for such systems.
      PubDate: 2017-09-22T02:46:05.983777-05:
      DOI: 10.1002/anie.201708241
       
  • Inside Back Cover: Recognition and Extraction of Cesium Hydroxide and
           Carbonate by Using a Neutral Multitopic Ion-Pair Receptor (Angew. Chem.
           Int. Ed. 43/2017)
    • Authors: Qing He; Gretchen Marie Peters, Vincent M. Lynch, Jonathan L. Sessler
      Pages: 13531 - 13531
      Abstract: Capturing basic anions by liquid–liquid extraction is a new approach to lowering the pH value through the removal of ion pairs, rather than the addition of protons. This could be advantageous in applications in which maintaining or reducing the volumes of basic solutions is critical. In their Communication on page 13396 ff., J. L. Sessler et al. demonstrate this approach using a calixpyrrole-based ion pair extractant and cesium carbonate and cesium hydroxide as test salts.
      PubDate: 2017-08-23T12:28:52.341004-05:
      DOI: 10.1002/anie.201708377
       
  • Back Cover: Organic-Free Synthesis of a Highly Siliceous Faujasite Zeolite
           with Spatially Biased Q4(nAl) Si Speciation (Angew. Chem. Int. Ed.
           43/2017)
    • Authors: Matthew D. Oleksiak; Koki Muraoka, Ming-Feng Hsieh, Marlon T. Conato, Atsushi Shimojima, Tatsuya Okubo, Watcharop Chaikittisilp, Jeffrey D. Rimer
      Pages: 13532 - 13532
      Abstract: Designing zeolites with tunable composition and acid siting is a significant challenge for applications in adsorption and catalysis. In their Communication on page 13366 ff., W. Chaikittisilp, J. D. Rimer, and co-workers report on the synthesis of high-silica faujasite (HOU-3) with a Si/Al ratio of 3 and show that the Al locations within the structure are biased and not random.
      PubDate: 2017-09-05T06:33:02.29674-05:0
      DOI: 10.1002/anie.201708471
       
 
 
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