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    33361 results match your criteria Angewandte Chemie International Edition [Journal]

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    Stable Oxindolyl-based Chichibabin's Hydrocarbon and Müller's Hydrocarbon Analogues.
    Angew Chem Int Ed Engl 2017 Sep 20. Epub 2017 Sep 20.
    National University of Singapore, 3 Science Drive 3, 117543, Singapore, SINGAPORE.
    Chichibabin's hydrocarbon and Müller's hydrocarbon are classical open-shell singlet diradicaloids but they are highly reactive. Herein we report the successful synthesis of their respective stable analogues, OxR-2 and OxR-3, based on the newly developed oxindolyl radical. X-ray crystallographic analysis on OxR-2 reveals a planar quinoidal backbone similar to Chichibabin's hydrocarbon, in accordance with its small diradical character (y0 = 11. Read More

    Olefin-Supported Rhenium(III) Terminal Oxo Complexes Generated by Nucleophilic Addition to a Cyclopentadienyl Ligand.
    Angew Chem Int Ed Engl 2017 Sep 19. Epub 2017 Sep 19.
    University of California, Berkeley, Department of Chemistry, Latimer Hall, 94720-1460, Berkeley, UNITED STATES.
    The reactivity of the oxo Re(V) β-diketiminate, OReCl2(BDI), with various cyclopentadienide (Cp) sources has been investigated. As a result, we have developed a route to a new class of terminal oxo complexes of Re(III) supported by olefin moieties of substituted cyclopentadienes. The success of this pathway is due to the electrophilic nature of the Cp ligand in the cation, [ORe(η5-Cp)(BDI)]+ (3+), which allows for nucleophilic attack by a variety of reagents under mild conditions. Read More

    Synthesis and Utilization of Nitroalkyne Equivalents in Batch and Continuous Flow.
    Angew Chem Int Ed Engl 2017 Sep 19. Epub 2017 Sep 19.
    Massachusetts Institute of Technology, Department of Chemistry, 77 Massachusetts Ave., 02139, Cambridge, UNITED STATES.
    We report a method for overcoming the low stability of nitroalkynes through the development of nitrated vinyl silyltriflate equivalents. Because of their instability, nitroalkynes have only rarely been utilized in synthesis. The reactivity of these silyltriflates, which are prepared in situ, is exemplified by dipolar cycloaddition reactions with nitrones to give highly substituted 4-nitro-4-isoxazolines in high yields. Read More

    Morphology Dependent Cell Imaging by a Self-assembled Diacetylene Peptide Amphiphile.
    Angew Chem Int Ed Engl 2017 Sep 20. Epub 2017 Sep 20.
    Universität Duisburg-Essen, Institut für Organische Chemie Fachbereich Chemie, Universitätsstraße 5, 45141, Essen, GERMANY.
    Herein, a novel cationic peptide gemini amphiphile containing diacetylene motifs (DA2P) is presented which self-assembles into novel tadpole- and bola-shaped nanostructures at low concentration and nanofibers at higher concentration, respectively. Interestingly, the DA2P assemblies can be polymerized to a fluorescent red phase but only during incubation with HeLa cells, most likely owing to the reorganization of the diacetylene chains of DA2P upon interaction with the cell membrane. The red-fluorescent polymerized DA2P assemblies can serve as a novel cell imaging probe. Read More

    One-pot, Three-Component Sulfonimidamide Synthesis exploiting the Sulfinylamine Reagent N-Sulfinyltritylamine, TrNSO.
    Angew Chem Int Ed Engl 2017 Sep 19. Epub 2017 Sep 19.
    University of Oxford, Organic Chemistry, Chemistry Research Laboratory, Mansfield Road, OX1 3TA, Oxford, UNITED KINGDOM.
    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. Read More

    (4+3)-Cycloaddition Reactions of N-Alkyl Oxidopyridinium Ions.
    Angew Chem Int Ed Engl 2017 Sep 19. Epub 2017 Sep 19.
    University of Missouri, Dept. of Chemistry, 123 Chemistry Building, 65211, Columbia, UNITED STATES.
    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 exhibited 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. Read More

    Total Synthesis of (+)-Gracilamine Based on Oxidative Phenolic Coupling Reaction and Determination of its Absolute Configuration.
    Angew Chem Int Ed Engl 2017 Sep 19. Epub 2017 Sep 19.
    Tokyo University of Agriculture and Technology, JAPAN.
    The Amaryllidaceae alkaloid (+)-gracilamine (1), isolated from Galanthus gracilis, contains a characteristic pentacyclic ring system with seven consecutive stereogenic centers, including an all-carbon quaternary stereocenter. Herein, we report the first enantioselective total synthesis of (+)-gracilamine (1), featuring a diastereoselective phenolic coupling reaction followed by a regioselective intramolecular aza-Michael reaction to construct the ABCE ring system. The stereochemistry at C3a in 1 is controlled by the stereocenter at C9a, which was selectively generated (91% ee) by utilizing an organocatalytic enantioselective aza-Friedel-Crafts reaction developed by our group. Read More

    High-Temperature Formed Protective Film at Cathode/Electrolyte Interface: A Functional Layer in Lithium-Sulfur Batteries.
    Angew Chem Int Ed Engl 2017 Sep 20. Epub 2017 Sep 20.
    Institute of Chemistry, Chinese Academy of Sciences, Key Laboratory of Molecular Nanostructure and Nanotechnology, 2, North 1st Street, Zhongguancun, 100190, Beijing, CHINA.
    Lithium-sulfur (Li-S) batteries have been attracting wide attention due to their promising high specific capacity. Deep understanding of Li-S interfacial mechanism including the temperature (T) effect is increasingly required to meet the burgeoning demands for battery modification and systematic researches. Herein, interfacial behavior during discharge/charge is investigated at high temperature (HT) of 60 ̊C in electrolyte based on lithium bis(fluorosulfonyl) imide (LiFSI). Read More

    High thermoelectric performance of new rhombohedral phase of GeSe stabilized via alloying with AgSbSe2.
    Angew Chem Int Ed Engl 2017 Sep 20. Epub 2017 Sep 20.
    Dalian Institute of Chemical Physics, State Key Laboratory of Catalysis, 457 Zhongshan Road, 116023, Dalian, CHINA.
    GeSe is a IV-VI semiconductor, like the excellent thermoelectric materials PbTe and SnSe. Orthorhombic GeSe has been predicted theoretically to have good thermoelectric performance but is difficult to dope experimentally. Like PbTe, rhombohedral GeTe has a multivalley band structure, which is ideal for thermoelectrics and also promotes the formation of Ge vacancies to provide enough carriers for electrical transport. Read More

    Alkynylation of sp2 C(O)-H Bonds Enabled by Photoredox-Mediated Hydrogen Atom Transfer.
    Angew Chem Int Ed Engl 2017 Sep 19. Epub 2017 Sep 19.
    WWU Münster, Organisch-Chemisches Institut, Corrensstrasse 40, 48149, Münster, GERMANY.
    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 protocol for the efficient synthesis of ynones, ynamides and ynoates with high regio- and chemoselectivity by direct functionalization of sp2 C(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. Read More

    Covalent Triazine Frameworks via a Low Temperature Polycondensation Approach.
    Angew Chem Int Ed Engl 2017 Sep 19. Epub 2017 Sep 19.
    Huazhong University of Science and Technology, School of Chemisry & Chemical Engineering, 1037 Luoyu Road, 430074, Wuhan, CHINA.
    Covalent triazine frameworks (CTFs) are normally synthesized by ionothermal methods. The harsh synthetic conditions and associated limited structural diversity do not benefit for further development and practical large-scale synthesis of CTFs. Herein we report a new strategy to construct CTFs (CTF-HUSTs) via a polycondensation approach, which allows the synthesis of CTFs under mild conditions from a wide array of building blocks. Read More

    Asymmetric Total Syntheses of Communesin F and a Putative Member of the Communesin Family.
    Angew Chem Int Ed Engl 2017 Sep 19. Epub 2017 Sep 19.
    Seoul National University, Department of Chemistry, Gwanak-1 Gwanak-ro,, Gwanak-gu,, 151-742, Seoul, KOREA, REPUBLIC OF.
    Here we report asymmetric total syntheses of communesin F and a putative member of the communesin family of bis-aminal alkaloid natural products. The successful strategy featured the invention of an asymmetric organocatalytic reaction to unify two oxindole subunits, a Ti(OiPr)4-mediated dehydrative skeletal rearrangement, and a late-stage Pd(OAc)2-catalyzed directed CH-alkenylation reaction. Collectively, the synthetic technologies disclosed herein enabled the preparation of a late-stage polycyclic intermediate catered for the synthesis of both naturally occurring and designed communesins. Read More

    Synthesis of a Metallo-Iminosilane via a Silanone-Metal π-Complex.
    Angew Chem Int Ed Engl 2017 Sep 19. Epub 2017 Sep 19.
    Technische Universität Berlin, Chemie, Strasse des 17. Juni 135, Sekr. C2, 10623, Berlin, GERMANY.
    Facile oxygenation of the acyclic amido chlorosilylene-bis(N-heterocyclic carbene) Ni0 complex 1, [{N(Dipp)(SiMe3)ClSi:→Ni(NHC)2] (Dipp = 2,6-Pri2C6H4; N-heterocyclic carbene = C[(Pri)NC(Me)]2) with N2O furnishes the first Si-metallo-iminosilane complex, [DippN=Si(OSiMe3)Ni(Cl)(NHC)2] 3, in a cascade of rearrangement reactions. Markedly, the formation of 3 ensues via a silanone (Si=O)-Ni pi-complex 2 as the initial product, which has been predicted by DFT calculations and could be observed spectroscopically. Both the Si=O and Si=N moieties in 2 and 3, respectively, undergo hydroboration, a reaction which typically requires a catalyst for the C=O and C=N analogues. Read More

    Cobalt versus osmium: control of both trans and cis selectivity in construction of the EFG rings of pectenotoxin 4.
    Angew Chem Int Ed Engl 2017 Sep 19. Epub 2017 Sep 19.
    University of Oxford, Department of Chemistry Chemistry Research Laboratory, Mansfield Road, OX1 3TA, Oxford, UNITED KINGDOM.
    Catalytic oxidative cyclisation reactions have been employed for the synthesis of the E and F rings of the complex natural product target pectenotoxin 4. The choice of metal catalyst (cobalt or osmium based) allowed for the formation of THF rings with either trans or cis stereoselectivity. Fragment union using a modified Julia reaction then enabled the synthesis of an advanced synthetic intermediate containing the EF and G rings of the target. Read More

    Hydrogen Transfer-Mediated a-Functionalization of 1,8-Naphthyridines by a Strategy Overcoming the Over-Hydrogenation Barrier.
    Angew Chem Int Ed Engl 2017 Sep 19. Epub 2017 Sep 19.
    South China University of Technology, School of Chemistry & Chemical Engineering, 381 Wushan Rd, Guangzhou 510641, People's Republic of China, 510641, Guangzhou, CHINA.
    By a hydrogen transfer-mediated activation mode for non-activated pyridyl nucleus, a general catalytic hydrogen transfer-mediated -functionalization of 1,8-naphthyridines is reported for the first time. Its -site selectively couples with the C8-site of various tetrahydroquinolines (THQs) to afford novel -functionalized tetrahydro 1,8-naphthyridines, a class of synthetically useful building blocks and potential candidates for the discovery of therapeutic and bio-active products. The utilization of THQs as inactive hydrogen donors (HDs) appears to be a key strategy to overcome the over-hydrogenation barrier and address the chemo-selectivity issue. Read More

    Solution Structure of AlMe2F and its Reactivity with Metallocenes: Mimicking Cation-Anion Interactions in Metallocenium-MAO Inner-Sphere Ion Pairs.
    Angew Chem Int Ed Engl 2017 Sep 19. Epub 2017 Sep 19.
    Università di perugia, Chimica, Biologia e Biotecnologie, via Elce di Sotto 8, 06132, Perugia, ITALY.
    The solution structure of AlMe2F and its reactivity with a prototypical ansa-metallocene have been investigated by advanced NMR techniques, in an attempt to indirectly shed some light on the "structure and working principles" of methylalumoxane (MAO) mixtures in olefin polymerization. In solution, AlMe2F leads to a complex equilibrium of oligomeric species, including a heterocubane [(Me2Al)4F4] tetramer, resembling the behavior of MAO. Such a complex mixture reacts with the prototypical ansa-zirconocene (ETH)ZrMe2 affording [(ETH)ZrMeδ+(μ-F)(AlMe2F)nAlMe3δ-] inner-sphere ion pairs through the successive insertions/deinsertion of AlMe2F units into the Zr…(μ-F) bond. Read More

    Highly 2,3-Selective Polymerization of Phenylallene and Derivatives with Rare-Earth Metal Catalyst: from Amorphous to Crystalline Products.
    Angew Chem Int Ed Engl 2017 Sep 19. Epub 2017 Sep 19.
    Chinese Academy of Sciences, State Key Laboratory of Polymer Physics and Chemistry, Renmin Street 5625, 130022, Changchun, CHINA.
    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 firstly 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. Read More

    Stereospecific Reaction of Donor-Acceptor Cyclopropanes with Thioketones: A Novel Access to Highly Substituted Tetrahydrothiophenes.
    Angew Chem Int Ed Engl 2017 Sep 19. Epub 2017 Sep 19.
    TU Braunschweig, Institut für Organische Chemie, Hagenring 30, 38102, Braunschweig, GERMANY.
    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 using AlCl3 as Lewis acid. Moreover, an intramolecular approach was successfully implemented to gain access to sulfur-bridged [n. Read More

    A Simple and Broadly Applicable C-N Bond Forming Dearomatization Protocol Enabled by Bifunctional Amino-Reagents.
    Angew Chem Int Ed Engl 2017 Sep 19. Epub 2017 Sep 19.
    University of Bristol, School of Chemistry, Cantock's Close, BS8 1TS, Bristol, UNITED KINGDOM.
    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. Read More

    Polyamine-Mediated Stoichiometric Assembly of Ribonucleoproteins for Enhanced mRNA Delivery.
    Angew Chem Int Ed Engl 2017 Sep 19. Epub 2017 Sep 19.
    Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
    Messenger RNA (mRNA) represents a promising class of nucleic acid drugs. Although numerous carriers have been developed for mRNA delivery, the inefficient mRNA expression inside cells remains a major challenge. Inspired by the dependence of mRNA on 3'-terminal polyadenosine nucleotides (poly A) and poly A binding proteins (PABPs) for optimal expression, we complexed synthetic mRNA containing a poly A tail with PABPs in a stoichiometric manner and stabilized the ribonucleoproteins (RNPs) with a family of polypeptides bearing different arrangements of cationic side groups. Read More

    Organocatalytic Enantioselective Protonation for Photoreduction of Activated Ketones and Ketimines Induced by Visible Light.
    Angew Chem Int Ed Engl 2017 Sep 19. Epub 2017 Sep 19.
    Henan University, Key Laboratory of Natural Medicine and Immuno-Engineering of Henan Province, Jinming Campus, 475004, Kaifeng, CHINA.
    The first catalytic asymmetric photoreduction of 1,2-diketones and α-keto ketimines under visible light irradiation is reported. A transition-metal-free synergistic catalysis platform harnessing dicyanopyrazine-derived chromophore (DPZ) as the photoredox catalyst and a non-covalent chiral organocatalyst is effective for these transformations. With the flexible use of a chiral Brønsted acid or base in H+ transfer interchange to control the elusive enantioselective protonation, a variety of chiral α-hydroxy ketones and α-amino ketones were obtained with high yields and enantioselectivities. Read More

    Enhanced Photoactivity from Single-crystalline SrTaO2N Nanoplates Synthesized by Topotactic Nitridation.
    Angew Chem Int Ed Engl 2017 Sep 18. Epub 2017 Sep 18.
    Indiana University - Bloomington, Chemistry, 800 E. Kirkwood Ave., 47405, Bloomington, UNITED STATES.
    There are few methods yielding oxynitride crystals with defined shape, yet shape-controlled crystals often render enhanced photoactivity. Here, single-crystalline SrTaO2N nanoplates and polyhedra are achieved selectively. Central to these synthetic advances is the crystallization pathways used, where single-crystalline SrTaO2N nanoplates form by topotactic nitridation of aerosol-prepared Sr2Ta2O7 nanoplates and SrTaO2N polyhedra form by flux-assisted nitridation of the nanoplates. Read More

    Structure and mechanism of the monoterpene cyclolavandulyl diphosphate synthase that catalyses consecutive condensation and cyclisation.
    Angew Chem Int Ed Engl 2017 Sep 18. Epub 2017 Sep 18.
    The University of Tokyo, Biotechnology Research Center, 1-1-1 Yayoi, Bunkyo-ku, 113-8657, Tokyo, JAPAN.
    Here, we report the three-dimensional structure of cyclolavandulyl diphosphate (CLPP) synthase (CLDS), which consecutively catalyses the condensation of two molecules of dimethylallyl diphosphate (DMAPP) followed by cyclisation 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. Read More

    Asymmetric Iron-Catalyzed C-H Alkylation Enabled by Remote Ligand meta-Substitution.
    Angew Chem Int Ed Engl 2017 Sep 18. Epub 2017 Sep 18.
    Georg-August-Universitaet Goettingen, Institut fuer Organische und Biomolekulare Chemie, Tammannstr. 2, 37077, Goettingen, GERMANY.
    Highly enantioselective iron-catalyzed C-H alkylations by inner-sphere C-H activation were accomplished with ample scope. High levels of enantiocontrol proved viable through a novel ligand design that exploits a remote meta-substitution on N-heterocyclic carbenes within a facile LLHT C-H cleavage. Read More

    Structural characterization of a covalent monolayer sheet obtained by two-dimensional polymerization at an air/water interface.
    Angew Chem Int Ed Engl 2017 Sep 18. Epub 2017 Sep 18.
    ETH Zürich Hönggerberg, Swiss Federal Institute of Technology Department of Materials Institute of Pol, Vladimir-Prelog-Weg 5, HCI J 541, 8093, Zürich, SWITZERLAND.
    This work describes a two-dimensional polymerization at an air/water interface and provides, for the first time, direct spectroscopic evidence for the kind of cross-links formed and for the conversion reached in a covalently bonded monolayer sheet. This is achieved by a combination of a variety of monolayer characterization techniques before and after transfer onto solid substrates in particular by tip-enhanced Raman spectroscopy (TERS) and TERS mapping after transfer of both the monomer and polymer monolayer onto Au(111). This is a major advance for the field of 2D polymers synthesized at the air/water interface as it in principle allows to estimate crystallinity via percolation theory and to locate regions with defects. Read More

    Encapsulation of Isolated Luminophores within Supramolecular Cages.
    Angew Chem Int Ed Engl 2017 Sep 18. Epub 2017 Sep 18.
    Department of Chemistry and Molecular Design Institute, New York University, 100 Washington Square East, New York, NY, 10003-6688, USA.
    The sequestration of luminophores within supramolecular polyhedral compartments of a crystalline zeolite-like hydrogen-bonded framework illustrates a unique approach to limiting the self-quenching ordinarily exhibited at the high concentrations achievable in this framework. A range of differently sized luminescent guests, namely coumarin 1, coumarin 4, fluorescein, [Ru(bpy)3 ]Cl2 , and rhodamine B, can be encapsulated in amounts of up to one molecule per cage, equivalent to a concentration of 0.175 m, which is significantly higher than the concentration at which aggregation-induced quenching occurs in other media. Read More

    Enantioselective [2,3]-Sigmatropic Rearrangements: Metal-Bound or Free Ylides as Reaction Intermediates?
    Angew Chem Int Ed Engl 2017 Sep 18. Epub 2017 Sep 18.
    Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074, Aachen, Germany.
    Out of bounds: Enantioselective rearrangement reactions are a long-standing challenge in organic synthesis. Recent advances are highlighted that led to the development of the first enantioselective Doyle-Kirmse reaction and enantioselective rearrangement reactions of iodonium ylides. Read More

    An Active and Robust Bifunctional Oxygen Electrocatalyst through Carbon-Free Hierarchical Functionalization.
    Angew Chem Int Ed Engl 2017 Sep 18. Epub 2017 Sep 18.
    Department of Mechanical Engineering, University of South Carolina, Columbia, SC, 29201, USA.
    A hierarchically functionalized hybrid electrode for Zn-air batteries is discussed that requires no carbon. Instead, an oxygen evolution reaction (OER)-active, porous, conductive, and corrosion-resistant nitride Ni3 FeN is used as a support for oxygen reduction reaction (ORR)-active ordered intermetallic Fe3 Pt NPs. The porosity in the Ni3 FeN substrate is an important enabling factor for the high OER activity. Read More

    Catalytic Enantioselective Carbopalladation/C-H Functionalization with Statistical Amplification of Product Enantiopurity: A Convertible Linker Approach.
    Angew Chem Int Ed Engl 2017 Sep 18. Epub 2017 Sep 18.
    Ecole Polytechnique Federale de Lausanne, Institute of Chemical Sciences and Chemical Engineering, EPFL-SB-ISIC-LSPN, BCH5304, CH-1015, Lausanne, SWITZERLAND.
    We demonstrated that combining a catalytic enantioselective reaction with dimerization in a single operation is an efficient way to upgrade the enantiomeric excesses (ee) of the product. Palladium-catalyzed reaction of N-(2-iodophenyl)-N-methyl methacrylamide derivatives with oxadiazole afforded, via a double enantioselective carbopalladation/intermolecular direct heteroarene C-H alkylation cascade, homodimers in good yields with excellent ee. The dimer was subsequently elaborated to the monomer in which the linker (oxadiazole) was incorporated into the target product. Read More

    Redox Modulatory Mn3O4 Nanozyme with Multi-enzyme Activity Provides Efficient Cytoprotection to Human Cells in Parkinson's Disease Model.
    Angew Chem Int Ed Engl 2017 Sep 18. Epub 2017 Sep 18.
    Indian Institute of Science, Bangalore, INDIA.
    Nanomaterials with enzyme-like activities (nanozymes) attracts significant interest due to their therapeutic potential for the treatment of various diseases. Herein, we report that a Mn3O4 nanozyme functionally mimic three major antioxidant enzymes, i.e. Read More

    Stoichiometric Reactions of CO2 and Indium-Silylamides and Catalytic Synthesis of Ureas.
    Angew Chem Int Ed Engl 2017 Sep 18. Epub 2017 Sep 18.
    University of Toronto, Chemistry, 80 St George St, M5S3H6, Toronto, CANADA.
    The indium compounds In(N(SiMe3)2)2Cl*THF (2) and In(N(SiMe3)2)Cl2*(THF)n¬ (3) were shown to react with CO2 to give [(Me3Si)2N)InX(-OSiMe3)]2 (X = N(SiMe3)2 4, Cl 5). 0.05-2. Read More

    A Space-Charge Treatment of the Increased Concentration of Reactive Species at the Surface of a Ceria Solid Solution.
    Angew Chem Int Ed Engl 2017 Sep 18. Epub 2017 Sep 18.
    RWTH Aachen University, GERMANY.
    We apply a space-charge theory applicable to concentrated solid solutions-Poisson-Cahn theory-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. Read More

    Borane-Stabilized Isomeric Dimers of the Phosphaethynolate Anion.
    Angew Chem Int Ed Engl 2017 Sep 18. Epub 2017 Sep 18.
    University of Toronto, Chemistry, 80 St George St, M5S3H6, Toronto, CANADA.
    The reactions of the phosphaethynolate anion ([PCO]-) with a range of boranes were explored. BPh3 and [PCO]- form a dimeric anion featuring P-B bonds and is prone to dissociation at room temperature. The more Lewis acidic borane B(C6F5)3 yields a less symmetric dimer of [PCO]- with P-B and P-O bonds. Read More

    Mass Production and Pore Size Control of Holey Carbon Microcages.
    Angew Chem Int Ed Engl 2017 Sep 18. Epub 2017 Sep 18.
    Huazhong University of Science and Technology, School of Materials Science and Engineering, 1030 Luoyu Road, 430074, Wuhan, CHINA.
    Architectural control of porous solids, such as porous carbon cages, has received considerable attention for versatile applications because of their attractive ability to interact with liquids and gases not only at the surface, but throughout the bulk. Here we report a scalable, facile spray-pyrolysis route to synthesize holey carbon microcages with mosquito-net-like shells. Using the surfaces of water droplets as the growth templates, styrene-butadiene rubber macromolecules are controllably cross-linked, and size-tunable holes on the carbon shells are generated. Read More

    The Quest for Mononuclear Gold(II) and its Potential Role in Photocatalysis and Drug Action.
    Angew Chem Int Ed Engl 2017 Sep 18. Epub 2017 Sep 18.
    Johannes Gutenberg-University Mainz, Institute of Inorganic and Analytical Chemistry, Duesbergweg 10-14, 55128, Mainz, GERMANY.
    The chemistry of gold strongly focuses on the ubiquitous oxidation states +I and +III. The intermediate oxidation state +II is generally avoided in mononuclear gold species. In recent years, gold(II) has been increasingly suggested as key intermediate in artificial photosynthesis systems with gold(III) moieties as electron acceptors or in gold-catalyzed photoredox catalysis and radical chemistry. Read More

    Iridium-catalyzed direct C-H amidation polymerization: step-growth polymerization by C-N bond formation via C-H activation to give fluorescent polysulfonamides.
    Angew Chem Int Ed Engl 2017 Sep 15. Epub 2017 Sep 15.
    We report a powerful strategy for activation of C-H bonds to produce polysulfonamides by an atom-economical and green method using iridium-catalyzed direct C-H amidation polymerization (DCAP). After screening various directing groups, additives, silver salts, concentrations, and temperatures to optimize DCAP, high molecular-weight (up to 149 kDa) and defect-free polysulfonamides were synthesized from various bis-sulfonyl azides. Although these polymers do not have conventional fluorescent conjugated cores, they emit blue light with large Stokes shifts and high quantum yields upon photoexcitation, due to excited-state intramolecular proton transfer process. Read More

    Construction and Crystal Structure Analysis of Heme Acquisition Protein HasA Containing Iron(III)-5,15-Diphenylporphyrin and Derivatives Thereof as an Artificial Prosthetic Group.
    Angew Chem Int Ed Engl 2017 Sep 15. Epub 2017 Sep 15.
    Nagoya University, Graduate School of Science, Furo, Chikusa,, 464-8602, Nagoya , JAPAN.
    Iron(III)-5,15-diphenylporphyrin (1) and its derivatives (2-7) were accommodated by the heme acquisition protein HasA secreted by Pseudomonas aeruginosa, despite possessing bulky substituents at the meso-position of the porphyrin. Crystal structure analysis revealed that the two phenyl groups at the meso-positions of porphyrin extend outside HasA. It was shown that growth of P. Read More

    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.
    Angew Chem Int Ed Engl 2017 Sep 17. Epub 2017 Sep 17.
    Boreskov Institute of Catalysis, Siberian Branch of Russian Academy of Sciences, GERMANY.
    We present the first deuteron quadrupole coupling constants (DQCC) for selected protic ionic liquids (PILs) measured by solid-state NMR spectroscopy. The experimental data are supported by dispersion-corrected density functional theory (DFT-D3) calculations and molecular dynamics (MD) simulations. The DQCCs of the N-D bond in the triethylammonium cations are the lowest reported for deuterons in PILs indicating strong doubly ionic hydrogen bonds. Read More

    Doubly N-Confused [36]Octaphyrin( Isomerization, Bis-Metal Coordination, and Topological Chirality.
    Angew Chem Int Ed Engl 2017 Sep 18. Epub 2017 Sep 18.
    Kyushu University, Dept. of Chemistry and Biochemistry, Grad School Engineering, 744 Motooka, Nishi-ku, 819-0395, Fukuoka, JAPAN.
    A novel [36]octaphyrin analogue embedding two N-confused pyrrole units demonstrated unique prototropy-coupled isomerization between the figure-of-eight and dumbbell conformers. Upon bis-metal coordination, fixation of fully π-conjugated figure-of-eight structures were achieved as referred from the X-ray crystal structure. Chirogenesis of the helical enantiomers was proved by intense circular dichroism (CD) response in the near infrared (NIR) region. Read More

    Enzymatic synthesis, amplification, and application of DNA with a functionalized backbone.
    Angew Chem Int Ed Engl 2017 Sep 15. Epub 2017 Sep 15.
    The Scripps Research Institute, Chemistry, 10550 North Torrey Pines Rd, CB262R, 92037, La Jolla, UNITED STATES.
    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. Read More

    A Catalytic Microwave Process for Superfast Preparation of High Quality Reduced Graphene Oxide.
    Angew Chem Int Ed Engl 2017 Sep 15. Epub 2017 Sep 15.
    Fudan University, Macromolecular Science, 220 Handan Road, 200433, Shanghai, CHINA.
    Herein we report that a small amount of graphite can unexpectedly act as the catalyst to greatly promote the microwave exfoliation and reduction of graphite oxide in ambient air. The reaction can be finished in a few seconds in contrast to more than ten minutes without catalyst. Meanwhile, the catalytic microwave exfoliated graphite oxide (CMEGO) shows much better quality than the traditional microwave exfoliated graphite oxide, including a much higher exfoliation degree with thinner graphene sheets and higher specific surface area (886 m2/g vs 466 m2/g), a much larger C/O ratio (19. Read More

    Fluorine Effects on Guiding Group Migration via Rh(V) Nitrenoid Intermediate.
    Angew Chem Int Ed Engl 2017 Sep 15. Epub 2017 Sep 15.
    Nanjing Tech University, Department of Applied Chemistry, NO.30 Puzhu Road(S), 210009, Nanjing, CHINA.
    An unprecedented Rh(III)-catalyzed hydroarylation of α,α-difluoromethylene alkynes with N-pivaloxyl aroylamides through sequential C-H activation and aryl migration was detailed herein. A large array of α,α-difluoromethylene alkynes and N-pivaloxyl aroylamides were well amenable to this transformation, thus providing a novel synthetic protocol for the construction of difluorinated 2-alkenylaniline derivatives in both high yields and excellent regioselectivity. Also of note, the unique fluorine effects were uncovered to underlie the thus unconventional reaction manifold. Read More

    The thermodynamic basis of the fuzzy interaction of an intrinsically disordered protein.
    Angew Chem Int Ed Engl 2017 Sep 15. Epub 2017 Sep 15.
    Faculty of Chemistry and Chemical Technology, University of Ljubljana, Physical Chemistry, Vecna pot 113, 1000, Ljubljana, SLOVENIA.
    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. Here we introduce a thermodynamic framework, based on analysis of ITC and CD spectroscopy data, that provides experimental description of IDP association in terms of folding and binding contributions which can be predicted using sequence folding propensities and molecular modeling. Read More

    Wireless electrochemical actuation of conducting polymers.
    Angew Chem Int Ed Engl 2017 Sep 15. Epub 2017 Sep 15.
    Bordeaux INP, Chemistry, ENSCBP 16 avenue Pey Berland, 33607, Pessac, FRANCE.
    Electrochemical actuation of conducting polymers usually requires a direct connection to an electric power supply. In this contribution, we suggest to overcome this issue by using the concept of bipolar electrochemistry. This allows changing the oxidation state of the polymer in a gradual and wireless way. Read More

    A Freestanding SeS2 Cathode Based on CoS2-decorated Multichannel Carbon Fibers with Enhanced Lithium Storage Performance.
    Angew Chem Int Ed Engl 2017 Sep 15. Epub 2017 Sep 15.
    Nanyang Technological University, School of Chemical and Biomedical Eng, 62 Nanyang Drive, #N1.2-B1-09, 637459, Singapore, SINGAPORE.
    SeS2 shows attractive advantages beyond bare S and Se as a cathode material for lithium storage. Here, a freestanding lotus root-like carbon fiber network decorated with CoS2 nanoparticles (denoted as CoS2@LRC) has been designed and prepared as the SeS2 host for enhancing the lithium storage performance. The integrated electrode is constructed by three-dimensional interconnected multichannel carbon fibers, which can not only accommodate high content of SeS2 (70 wt. Read More

    Ethers on Si(001): A prime example for the common ground between surface science and molecular organic chemistry.
    Angew Chem Int Ed Engl 2017 Sep 15. Epub 2017 Sep 15.
    Philipps-Universität Marburg, Fachbereich Chemie, Hans-Meerwein-Straße 4, 35032, Marburg, GERMANY.
    Using computational chemistry, we show that the adsorption of ether molecules on Si(001) under ultra-high vacuum conditions can be understood with textbook organic chemistry. The two-step reaction mechanism of (1) dative bond formation between the ether oxygen and a Lewis acidic surface atom and (2) a nucleophilic attack of a nearby Lewis basic surface atom is analysed in detail and found to mirror the acid-catalysed ether cleavage in solution. The O-Si dative bond is found to be the strongest of its kind and reactivity from this state defies the Bell-Evans-Polanyi principle. Read More

    Selective electrochemical reduction of CO2 to ethanol on B and N codoped nanodiamond.
    Angew Chem Int Ed Engl 2017 Sep 15. Epub 2017 Sep 15.
    Dalian University of Technology, School of Environmental Science and Technology, Linggong Road 2#, 116024, Dalian, CHINA.
    Electrochemical reduction of CO2 to ethanol, a clean and renewable liquid fuel with high heating value, is an attractive strategy for global warming mitigation and resource utilization. However, converting CO2 to ethanol remains great challenge due to the low activity, poor product selectivity and stability of electrocatalysts. Here, B and N codoped nanodiamond (BND) was reported as an efficient and stable electrode for selective reduction of CO2 to ethanol. Read More

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