The Experts below are selected from a list of 60 Experts worldwide ranked by ideXlab platform
Clare P Grey - One of the best experts on this subject based on the ideXlab platform.
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the role of ionic liquid breakdown in the electrochemical metallization of vo2 an NMR study of gating mechanisms and vo2 reduction
arXiv: Strongly Correlated Electrons, 2018Co-Authors: Michael A Hope, Kent J Griffith, Bin Cui, Fang Gao, Siân E Dutton, Stuart S P Parkin, Clare P GreyAbstract:Metallization of initially insulating VO2 via ionic liquid electrolytes (electrolyte gating) has recently been a topic of much interest. It is clear that the metallization takes place electrochemically and there has previously been extensive evidence for the removal of small amounts of oxygen during ionic liquid gating. Hydrogen intercalation has also been proposed, but the source of the hydrogen has remained unclear. In this work, Solid-State magic angle spinning NMR spectroscopy is used to investigate the thermal metal-insulator transition in VO2, before progressing to catalytically hydrogenated and electrochemically metallized VO2. Electrochemical metallization of bulk VO2 particles is shown to be associated with intercalation of hydrogen, the degree of which can be measured with quantitative 1H NMR spectroscopy. Possible sources of the hydrogen are explored, and by using a selectively deuterated ionic liquid, it is revealed that the hydrogenation is due to deprotonation of the ionic liquid; specifically, for the commonly used dialkylimidazolium based ionic liquids, it is the "carbene" proton that is responsible. Increasing the temperature of the electrochemistry is shown to increase the degree of hydrogenation, forming first a less hydrogenated metallic phase then a more hydrogenated insulating Curie-Weiss paramagnetic phase, both of which were also observed for catalytically hydrogenated VO2. The NMR results are supported by magnetic susceptibility measurements, which corroborate the degree of Pauli and Curie-Weiss paramagnetism. NMR spectroscopy is used to identify the presence of hydrogen in an electrolyte gated thin film of VO2, suggesting that electrolyte breakdown, proton intercalation and reactions with decomposition products within the electrolyte should not be ignored when interpreting the electronic and structural changes observed in electrochemical gating experiments.
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the role of ionic liquid breakdown in the electrochemical metallization of vo2 an NMR study of gating mechanisms and vo2 reduction
Journal of the American Chemical Society, 2018Co-Authors: Michael A Hope, Kent J Griffith, Bin Cui, Fang Gao, Siân E Dutton, Stuart S P Parkin, Clare P GreyAbstract:Metallization of initially insulating VO2 via ionic liquid electrolytes, otherwise known as electrolyte gating, has recently been a topic of much interest for possible applications such as Mott transistors and memory devices. It is clear that the metallization takes place electrochemically, and, in particular, there has previously been extensive evidence for the removal of small amounts of oxygen during ionic liquid gating. Hydrogen intercalation has also been proposed, but the source of the hydrogen has remained unclear. In this work, Solid-State magic angle spinning NMR spectroscopy (1H, 2H, 17O, and 51V) is used to investigate the thermal metal–insulator transition in VO2, before progressing to catalytically hydrogenated VO2 and electrochemically metallized VO2. In these experiments electrochemical metallization of bulk VO2 particles is shown to be associated with intercalation of hydrogen, the degree of which can be measured with quantitative 1H NMR spectroscopy. Possible sources of the hydrogen are e...
Hartmut Oschkinat - One of the best experts on this subject based on the ideXlab platform.
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structure of a protein determined by solid state magic angle spinning NMR spectroscopy
Nature, 2002Co-Authors: Federica Castellani, Barth Van Rossum, Annette Diehl, Mario Schubert, Kristina Rehbein, Hartmut OschkinatAbstract:The determination of a representative set of protein structures is a chief aim in structural genomics. Solid-State NMR may have a crucial role in structural investigations of those proteins that do not easily form crystals or are not accessible to solution NMR, such as amyloid systems1 or membrane proteins2,3,4. Here we present a protein structure determined by Solid-State Magic-Angle-Spinning (MAS) NMR. Almost complete 13C and 15N resonance assignments for a micro-crystalline preparation of the α-spectrin Src-homology 3 (SH3) domain5 formed the basis for the extraction of a set of distance restraints. These restraints were derived from proton-driven spin diffusion (PDSD) spectra of biosynthetically site-directed, labelled samples obtained from bacteria grown using [1,3-13C]glycerol or [2-13C]glycerol as carbon sources. This allowed the observation of long-range distance correlations up to ∼7 A. The calculated global fold of the α-spectrin SH3 domain is based on 286 inter-residue 13C–13C and six 15N–15N restraints, all self-consistently obtained by Solid-State MAS NMR. This MAS NMR procedure should be widely applicable to small membrane proteins that can be expressed in bacteria.
Michael A Hope - One of the best experts on this subject based on the ideXlab platform.
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the role of ionic liquid breakdown in the electrochemical metallization of vo2 an NMR study of gating mechanisms and vo2 reduction
arXiv: Strongly Correlated Electrons, 2018Co-Authors: Michael A Hope, Kent J Griffith, Bin Cui, Fang Gao, Siân E Dutton, Stuart S P Parkin, Clare P GreyAbstract:Metallization of initially insulating VO2 via ionic liquid electrolytes (electrolyte gating) has recently been a topic of much interest. It is clear that the metallization takes place electrochemically and there has previously been extensive evidence for the removal of small amounts of oxygen during ionic liquid gating. Hydrogen intercalation has also been proposed, but the source of the hydrogen has remained unclear. In this work, Solid-State magic angle spinning NMR spectroscopy is used to investigate the thermal metal-insulator transition in VO2, before progressing to catalytically hydrogenated and electrochemically metallized VO2. Electrochemical metallization of bulk VO2 particles is shown to be associated with intercalation of hydrogen, the degree of which can be measured with quantitative 1H NMR spectroscopy. Possible sources of the hydrogen are explored, and by using a selectively deuterated ionic liquid, it is revealed that the hydrogenation is due to deprotonation of the ionic liquid; specifically, for the commonly used dialkylimidazolium based ionic liquids, it is the "carbene" proton that is responsible. Increasing the temperature of the electrochemistry is shown to increase the degree of hydrogenation, forming first a less hydrogenated metallic phase then a more hydrogenated insulating Curie-Weiss paramagnetic phase, both of which were also observed for catalytically hydrogenated VO2. The NMR results are supported by magnetic susceptibility measurements, which corroborate the degree of Pauli and Curie-Weiss paramagnetism. NMR spectroscopy is used to identify the presence of hydrogen in an electrolyte gated thin film of VO2, suggesting that electrolyte breakdown, proton intercalation and reactions with decomposition products within the electrolyte should not be ignored when interpreting the electronic and structural changes observed in electrochemical gating experiments.
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the role of ionic liquid breakdown in the electrochemical metallization of vo2 an NMR study of gating mechanisms and vo2 reduction
Journal of the American Chemical Society, 2018Co-Authors: Michael A Hope, Kent J Griffith, Bin Cui, Fang Gao, Siân E Dutton, Stuart S P Parkin, Clare P GreyAbstract:Metallization of initially insulating VO2 via ionic liquid electrolytes, otherwise known as electrolyte gating, has recently been a topic of much interest for possible applications such as Mott transistors and memory devices. It is clear that the metallization takes place electrochemically, and, in particular, there has previously been extensive evidence for the removal of small amounts of oxygen during ionic liquid gating. Hydrogen intercalation has also been proposed, but the source of the hydrogen has remained unclear. In this work, Solid-State magic angle spinning NMR spectroscopy (1H, 2H, 17O, and 51V) is used to investigate the thermal metal–insulator transition in VO2, before progressing to catalytically hydrogenated VO2 and electrochemically metallized VO2. In these experiments electrochemical metallization of bulk VO2 particles is shown to be associated with intercalation of hydrogen, the degree of which can be measured with quantitative 1H NMR spectroscopy. Possible sources of the hydrogen are e...
Carmela Aprile - One of the best experts on this subject based on the ideXlab platform.
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mesoporous methyl functionalized sn silicates generated by the aerosol process for the sustainable production of ethyl lactate
ACS Sustainable Chemistry & Engineering, 2018Co-Authors: Alvise Vivian, Luca Fusaro, Damien P Debecker, Carmela AprileAbstract:The aerosol-assisted sol–gel process was used to synthesize in a straightforward one-pot procedure a series of methyl-functionalized tin silicates with different degrees of methylation. The successful incorporation of isolated Sn as single site within the silica framework was confirmed via 119Sn Solid-State NMR measurements, while 29Si and 13C Solid-State Magic-Angle-Spinning NMR experiments revealed a degree of methylation close to the theoretical value, hence proving the efficacy of the adopted cosynthetic approach. These materials were tested as catalysts in the synthesis of ethyl lactate from dihydroxyacetone and ethanol. The methylated solids display enhanced performances in terms of both activity and selectivity compared to the nonmethylated analogues, highlighting a strong beneficial role of surface hydrophobicity. Under proper conditions a total conversion and a selectivity higher than 95% were achieved. Moreover, the efficient separation and reuse of the heterogeneous catalyst as well as the poss...
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Mesoporous Methyl-Functionalized Sn-Silicates Generated by the Aerosol Process for the Sustainable Production of Ethyl Lactate
2018Co-Authors: Alvise Vivian, Luca Fusaro, Damien P Debecker, Carmela AprileAbstract:The aerosol-assisted sol–gel process was used to synthesize in a straightforward one-pot procedure a series of methyl-functionalized tin silicates with different degrees of methylation. The successful incorporation of isolated Sn as single site within the silica framework was confirmed via 119Sn Solid-State NMR measurements, while 29Si and 13C Solid-State Magic-Angle-Spinning NMR experiments revealed a degree of methylation close to the theoretical value, hence proving the efficacy of the adopted cosynthetic approach. These materials were tested as catalysts in the synthesis of ethyl lactate from dihydroxyacetone and ethanol. The methylated solids display enhanced performances in terms of both activity and selectivity compared to the nonmethylated analogues, highlighting a strong beneficial role of surface hydrophobicity. Under proper conditions a total conversion and a selectivity higher than 95% were achieved. Moreover, the efficient separation and reuse of the heterogeneous catalyst as well as the possibility of an easily recover of the reaction solvent result in a very low waste production protocol with an exceptionally low E-factor
Federica Castellani - One of the best experts on this subject based on the ideXlab platform.
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structure of a protein determined by solid state magic angle spinning NMR spectroscopy
Nature, 2002Co-Authors: Federica Castellani, Barth Van Rossum, Annette Diehl, Mario Schubert, Kristina Rehbein, Hartmut OschkinatAbstract:The determination of a representative set of protein structures is a chief aim in structural genomics. Solid-State NMR may have a crucial role in structural investigations of those proteins that do not easily form crystals or are not accessible to solution NMR, such as amyloid systems1 or membrane proteins2,3,4. Here we present a protein structure determined by Solid-State Magic-Angle-Spinning (MAS) NMR. Almost complete 13C and 15N resonance assignments for a micro-crystalline preparation of the α-spectrin Src-homology 3 (SH3) domain5 formed the basis for the extraction of a set of distance restraints. These restraints were derived from proton-driven spin diffusion (PDSD) spectra of biosynthetically site-directed, labelled samples obtained from bacteria grown using [1,3-13C]glycerol or [2-13C]glycerol as carbon sources. This allowed the observation of long-range distance correlations up to ∼7 A. The calculated global fold of the α-spectrin SH3 domain is based on 286 inter-residue 13C–13C and six 15N–15N restraints, all self-consistently obtained by Solid-State MAS NMR. This MAS NMR procedure should be widely applicable to small membrane proteins that can be expressed in bacteria.