1,300 research outputs found

    “We Must be Able to Show How Science is Beneficial to Society”

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    Autonomous propulsion of carbon nanotubes powered by a multienzyme ensemble

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    Covalent attachment of the enzymes glucose oxidase and catalase to carbon nanotubes enables the tandem catalytic conversion of glucose and H2O2 formed to power autonomous movement of the nanotubes.

    Stereodivergent Anion Binding Catalysis with Molecular Motors

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    A photoresponsive chiral catalyst based on an oligotriazole-functionalized unidirectional molecular motor has been developed for stereodivergent anion binding catalysis. The motor function controls the helical chirality of supramolecular assemblies with chloride anions, which by means of chirality transfer enables the enantioselective addition of a silyl ketene acetal nucleophile to oxocarbenium cations. Reversal of stereoselectivity (up to 142 % Δee) was achieved through rotation of the motor core induced by photochemical and thermal isomerization steps

    Double strand DNA cleavage with a binuclear iron complex

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    Covalently linking two single strand DNA cleaving agents resulted in a new biomimetic binuclear iron complex capable of effecting oxidative double strand DNA cleavage.

    Straightforward Synthesis of α,β-Unsaturated Thioesters via Ruthenium-Catalyzed Olefin Cross-Metathesis with Thioacrylate

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    The cross-metathesis reaction of S-ethyl thioacrylate with a variety of olefins is effectively catalyzed by using a ruthenium benzylidene olefin metathesis catalyst. This reaction provides a convenient and versatile route to substituted α,β-unsaturated thioesters, key building blocks in organic synthesis.

    Unclicking of thioureas:Base catalyzed elimination of anilines and isothiocyanates from thioureas

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    Bisaromatic thioureas are widely used in e.g. asymmetric organocatalysis and considered to be robust compounds. Herein we show, in strong contrast to common notion, that thioureas dissociate to amines and isothiocyanates in a base catalyzed reaction under mild conditions. This 'unclicking' process can occur in the presence of weak organic bases even at moderate temperatures. The influence of the substituents at the aromatic rings of the thiourea on the regioselectivity of this unclicking process is also shown. (C) 2019 Published by Elsevier Ltd

    Photoswitchable catalysis based on the isomerisation of double bonds

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    Photoswitchable catalysis is a young but rapidly evolving field that offers great potential for non-invasive dynamic control of both activity and selectivity in catalysis. Within this context, the E/Z photoisomerisation of double bonds in molecular switches and motors is one of the most popular tools to control the catalytic activity essentially due to its reversible nature, the large concomitant geometrical changes, and the high tunability of such photochromic entities. This Feature Article summarises the key developments accomplished over the past years through the incorporation of photoswitchable double bonds into the structure of catalytically competent molecules and shows some perspectives on the remaining challenges and possibilities arising from this, yet still somehow immature, exciting area of research

    Synthesis of Optically Active Bifunctional Building Blocks through Enantioselective Copper-Catalyzed Allylic Alkylation Using Grignard Reagents

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    Enantioselective copper-catalyzed allylic alkylations were performed on allylic bromides with a protected hydroxyl or amine functional group using several Grignard reagents and Taniaphos L1 as a ligand. The terminal olefin moiety in the products was transformed into various functional groups without racemization, providing facile access to a variety of versatile bifunctional chiral building blocks.
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