407 research outputs found

    Mesoporous Silica Nanoparticles Loaded with Surfactant: Low Temperature Magic Angle Spinning 13C and 29Si NMR Enhanced by Dynamic Nuclear Polarization

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    We show that dynamic nuclear polarization (DNP) can be used to enhance NMR signals of13C and 29Si nuclei located in mesoporous organic/inorganic hybrid materials, at several hundreds of nanometers from stable radicals (TOTAPOL) trapped in the surrounding frozen disordered water. The approach is demonstrated using mesoporous silica nanoparticles (MSN), functionalized with 3-(N-phenylureido)propyl (PUP) groups, filled with the surfactant cetyltrimethylammonium bromide (CTAB). The DNP-enhanced proton magnetization is transported into the mesopores via 1H–1H spin diffusion and transferred to rare spins by cross-polarization, yielding signal enhancements Δon/off of around 8. When the CTAB molecules are extracted, so that the radicals can enter the mesopores, the enhancements increase to Δon/off ≈ 30 for both nuclei. A quantitative analysis of the signal enhancements in MSN with and without surfactant is based on a one-dimensional proton spin diffusion model. The effect of solvent deuteration is also investigated

    Catalysing sustainable fuel and chemical synthesis

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    Concerns over the economics of proven fossil fuel reserves, in concert with government and public acceptance of the anthropogenic origin of rising CO2 emissions and associated climate change from such combustible carbon, are driving academic and commercial research into new sustainable routes to fuel and chemicals. The quest for such sustainable resources to meet the demands of a rapidly rising global population represents one of this century’s grand challenges. Here, we discuss catalytic solutions to the clean synthesis of biodiesel, the most readily implemented and low cost, alternative source of transportation fuels, and oxygenated organic molecules for the manufacture of fine and speciality chemicals to meet future societal demands

    Hydrogen-transfer catalysis with Cp*Ir<sup>III</sup> complexes:The influence of the ancillary ligands

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    Fourteen Cp*IrIII complexes, bearing various combinations of N- and C-spectator ligands, are assayed in hydrogen-transfer catalysis from isopropyl alcohol to acetophenone under various conditions to investigate ligand effects in this widely used reaction. The new cationic complexes bearing monodentate pyridine and N-heterocyclic carbene (NHC) ligands were characterized crystallographically and by variable-temperature nuclear magnetic resonance (VT-NMR). Control experiments and mercury poisoning tests showed that iridium(0) nanoparticles, although active in the reaction, are not responsible for the high activity observed for the most active precatalyst [Cp*Ir(IMe) 2Cl]BF4 (6). For efficient catalysis, it was found necessary to have both NHCs in monodentate form; tying them together in a bis-NHC chelate ligand gave greatly reduced activity. The kinetics of the base-assisted reaction showed induction periods as well as deactivation processes, and H/D scrambling experiments cast some doubt on the classical monohydride mechanism. © 2013 American Chemical Society

    Pure and multi metal oxide nanoparticles: synthesis, antibacterial and cytotoxic properties

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    Dual Optimization Approach to Bimetallic Nanoparticle Catalysis: Impact of M 1

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    Editorial preface: A special issue on themes (i) Nano-energy / Environmental for a better Society and (iii) Nano-catalysis for Green technology

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    The contributors to this special issue are from early carrier researchers to experts in their relative areas from across the world and represent a current and up to date research overview on functional nanomaterials in energy / environmental for a better society and nano-catalysis for green technology. The topics were the two important themes in our 1st International symposium entitled Functional Nanomaterials in Industrial Applications: Academic - Industry Meet (29-31 March 2016), University of Central Lancashire, Preston, United Kingdom. A special focus issue on theme 2 (Nanomedicine for Health and Diagnostics) will be published in the journal "Nanomedicine" by Future Medicine in November 2016
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