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I. V. Baklanova - One of the best experts on this subject based on the ideXlab platform.
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K_3VO_2(SO_4)_2: Formation conditions, crystal structure, and physicochemical properties
Russian Journal of Inorganic Chemistry, 2011Co-Authors: V. N. Krasil’nikov, A. P. Tyutyunnik, V. G. Zubkov, I. F. Berger, L. A. Perelyaeva, I. V. BaklanovaAbstract:Potassium oxosulfatovanadate(V) K_3VO_2(SO_4)_2 has been obtained by solid-phase synthesis from K_2SO_4, K_2S_2O_7, and V_2O_5 (2: 1: 1), and its formation conditions, crystal structure, and physiochemical properties have been studied. The conversions of K_3VO_2(SO_4)_2 in contact with potassium vanadates and other potassium oxosulfatovanadates(V) are considered in terms of phase relations in the K_2O-V_2O_5-SO_3 system, which models the active component of Vanadium catalysts for sulfur dioxide oxidation into sulfur trioxide. The X-ray diffraction pattern of K_3VO_2(SO_4)_2 is indexed in the monoclinic system (space group P 2_1) with unit cell parameters of a = 10.0408(1) Å, b = 7.2312(1) Å, c = 7.3821(1) Å, β = 104.457(1)°, Z = 2, and V = 519.02 Å^3. The crystal structure of K_3VO_2(SO_4)_2 is built from [VO_2(SO_4)_2]^3− complex anions, in which the Vanadium Atom is in an octahedral oxygen environment formed by two terminal oxygen Atoms (V-O(6) = 1.605(7) Å, V-O(10) = 1.619(7) Å and four oxygen Atoms of the two chelating sulfate anions. The vibrational spectra of K_3VO_2(SO_4)_2 are analyzed using these structural data.
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Synthesis, structure, and properties of M_3VO_2(SO_4)_2 (M = Rb, Cs)
Russian Journal of Inorganic Chemistry, 2010Co-Authors: V. N. Krasil’nikov, A. P. Tyutyunnik, V. G. Zubkov, I. F. Berger, L. A. Perelyaeva, I. V. BaklanovaAbstract:Vanadium(V) complexes of general composition M_3VO_2(SO_4)_2 (M = Rb, Cs) were synthesized by a solid-state route. The individuality of the synthesized compounds was proved by X-ray and neutron diffraction, vibrational spectroscopy, and microscopic analysis. The X-ray diffraction patterns of M_3VO_2(SO_4)_2 were indexed to fit the monoclinic system (space group P 2/ c, Z = 4) with the following unit cell parameters: a = 11.6487(2) Å, b = 8.4469(2) Å, c = 12.1110(2) Å, β = 109.483(1)°, V = 1123.43 Å^3 (Rb); a = 12.0546(3) Å b = 8.7706(2) Å, c = 12.6496(3) Å, β = 109.843(2)°, V = 1257.99 Å^3 (Cs). In the crystal structure of M_3VO_2(SO_4)_2, [VO_2(SO_4)_2]^3− complex anions can be discerned in which the Vanadium Atom is surrounded by five oxygen Atoms: two oxygen Atoms form short terminal V–O bonds, and three oxygen Atoms are from the two sulfato groups, one of which acts as a monodentate ligand and the other acts as a bidentate chelating ligand.
Themistoklis A. Kabanos - One of the best experts on this subject based on the ideXlab platform.
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Model investigations for Vanadium-protein interactions: Vanadium(III) compounds with dipeptides and their oxoVanadium(IV) analogues
JBIC Journal of Biological Inorganic Chemistry, 2002Co-Authors: Anastasios J. Tasiopoulos, Evangelos J. Tolis, John M. Tsangaris, Angelos Evangelou, Derek J. Woollins, Alexandra M. Slawin, João Pessoa, Isabel Correia, Themistoklis A. KabanosAbstract:The reaction of VCl_3 with 1,10-phenanthroline and a series of dipeptides (H_2dip), having aliphatic as well as aromatic side chains, in methyl alcohol and in the presence of triethylamine affords Vanadium(III) compounds of the general formula [V^III(dip)(MeOH)(phen)]Cl. Aerial oxidation/hydrolysis of the Vanadium(III) species gives their oxoVanadium(IV) analogues of the general formula [V^IVO(dip)(phen)]. X-ray crystallographic characterization of the [V^IVO(dip)(phen)] compounds (where dip^2–=Gly- L -Ala, Gly- L -Val and Gly- L -Phe) revealed that the Vanadium Atom possesses a severely distorted octahedral coordination and is ligated to a tridentate dip^2– ligand at the N_amine Atom, the deprotonated N_peptide Atom and one of the O_carboxylate Atoms, as well as an oxo group and two phenanthroline nitrogen Atoms. Circular dichroism characterization of the V^III/V^IVO^2+-dipeptide compounds revealed a strong signal for the V^IVO^2+ species in the visible range of the spectrum, with a characteristic pattern which may be exploited to identify the N_am, N_pep and O_car ligation of a peptide or a protein to V^IVO^2+ center, and a weak Cotton effect of opposite sign to their Vanadium(III) analogues. The visible spectra of the V^III-dipeptide compounds revealed two d-d bands with high intensity, thus indicating that the covalency of the metal-donor Atoms is significant, i.e. the Vanadium d orbitals are significantly mixed with the ligand orbitals, and this is confirmed by the low values of their Racah B parameters. The high-intensity band of the V^IVO^2+-dipeptide compounds at ~460 nm implies also a strong covalency of the metal with the equatorial donor Atoms and this was supported by the EPR spectra of these compounds. Moreover, the V^III/V^IVO^2+-dipeptide complexes were characterized by EPR and IR spectroscopies as well as conductivity and magnetic susceptibility measurements.
Won-sub Yoon - One of the best experts on this subject based on the ideXlab platform.
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Porous V2O5/RGO/CNT hierarchical architecture as a cathode material: Emphasis on the contribution of surface lithium storage
Scientific Reports, 2016Co-Authors: Kumaran Palanisamy, Mihee Jeong, Ji Hyun Um, Won-sub YoonAbstract:A three dimensional Vanadium pentoxide/reduced graphene oxide/carbon nanotube (3D V2O5/RGO/CNT) composite is synthesized by microwave-assisted hydrothermal method. The combination of 2D RGO and 1D CNT establishes continuous 3D conductive network, and most notably, the 1D CNT is designed to form hierarchically porous structure by penetrating into V2O5 microsphere assembly constituted of numerous V2O5 nanoparticles. The highly porous V2O5 microsphere enhances electrolyte contact and shortens Li(+) diffusion path as a consequence of its developed surface area and mesoporosity. The successive phase transformations of 3D V2O5/RGO/CNT from α-phase to ε-, δ-, γ-, and ω-phase and its structural reversibility upon Li(+) intercalation/de-intercalation are investigated by in situ XRD analysis, and the electronic and local structure reversibility around Vanadium Atom in 3D V2O5/RGO/CNT is observed by in situ XANES analysis. The 3D V2O5/RGO/CNT achieves a high capacity of 220 mAh g(-1) at 1 C after 80 cycles and an excellent rate capability of 100 mAh g(-1) even at a considerably high rate of 20 C. The porous 3D V2O5/RGO/CNT structure not only provides facile Li(+) diffusion into bulk but contributes to surface Li(+) storage as well, which enables the design of 3D V2O5/RGO/CNT composite to become a promising cathode architecture for high performance LIBs.
J.a. Dumesic - One of the best experts on this subject based on the ideXlab platform.
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Raman, FTIR and Theoretical Evidence for Dynamic Structural Rearrangements of Vanadia/Titania DeNOx Catalysts
Catalysis Letters, 2001Co-Authors: Nan-yu Topsøe, Mark Anstrom, J.a. DumesicAbstract:Insight into the selective catalytic reduction (SCR) of NO by NH_3 over vanadia/titania catalysts is obtained from a combination of Raman and FTIR spectroscopic investigations and density functional theory (DFT) calculations. Studies of the V–OH and V=O functional groups under different conditions coupled with calculations of the stability and mobility of H Atoms provide evidence that dynamic structural rearrangements may occur during the SCR reaction. Hydrogen Atoms are bonded more strongly to oxygen Atoms that are coordinated to a single Vanadium Atom (V=O species), compared to bonding at oxygen Atoms that are coordinated to multiple Vanadium Atoms ( e.g. , V–O–V species); and, activation energy barriers for hydrogen transfer from a V=O species to another V=O species and to a V–O–V species are estimated from DFT calculations to be 60 and 130 kJ/mol, respectively. This dynamic nature of hydrogen transfer between oxygen Atoms having different coordination environments also appears to explain some of the spectroscopic changes observed for vanadia/titania catalysts having different vanadia loadings.
V. N. Krasil’nikov - One of the best experts on this subject based on the ideXlab platform.
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K_3VO_2(SO_4)_2: Formation conditions, crystal structure, and physicochemical properties
Russian Journal of Inorganic Chemistry, 2011Co-Authors: V. N. Krasil’nikov, A. P. Tyutyunnik, V. G. Zubkov, I. F. Berger, L. A. Perelyaeva, I. V. BaklanovaAbstract:Potassium oxosulfatovanadate(V) K_3VO_2(SO_4)_2 has been obtained by solid-phase synthesis from K_2SO_4, K_2S_2O_7, and V_2O_5 (2: 1: 1), and its formation conditions, crystal structure, and physiochemical properties have been studied. The conversions of K_3VO_2(SO_4)_2 in contact with potassium vanadates and other potassium oxosulfatovanadates(V) are considered in terms of phase relations in the K_2O-V_2O_5-SO_3 system, which models the active component of Vanadium catalysts for sulfur dioxide oxidation into sulfur trioxide. The X-ray diffraction pattern of K_3VO_2(SO_4)_2 is indexed in the monoclinic system (space group P 2_1) with unit cell parameters of a = 10.0408(1) Å, b = 7.2312(1) Å, c = 7.3821(1) Å, β = 104.457(1)°, Z = 2, and V = 519.02 Å^3. The crystal structure of K_3VO_2(SO_4)_2 is built from [VO_2(SO_4)_2]^3− complex anions, in which the Vanadium Atom is in an octahedral oxygen environment formed by two terminal oxygen Atoms (V-O(6) = 1.605(7) Å, V-O(10) = 1.619(7) Å and four oxygen Atoms of the two chelating sulfate anions. The vibrational spectra of K_3VO_2(SO_4)_2 are analyzed using these structural data.
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Synthesis, structure, and properties of M_3VO_2(SO_4)_2 (M = Rb, Cs)
Russian Journal of Inorganic Chemistry, 2010Co-Authors: V. N. Krasil’nikov, A. P. Tyutyunnik, V. G. Zubkov, I. F. Berger, L. A. Perelyaeva, I. V. BaklanovaAbstract:Vanadium(V) complexes of general composition M_3VO_2(SO_4)_2 (M = Rb, Cs) were synthesized by a solid-state route. The individuality of the synthesized compounds was proved by X-ray and neutron diffraction, vibrational spectroscopy, and microscopic analysis. The X-ray diffraction patterns of M_3VO_2(SO_4)_2 were indexed to fit the monoclinic system (space group P 2/ c, Z = 4) with the following unit cell parameters: a = 11.6487(2) Å, b = 8.4469(2) Å, c = 12.1110(2) Å, β = 109.483(1)°, V = 1123.43 Å^3 (Rb); a = 12.0546(3) Å b = 8.7706(2) Å, c = 12.6496(3) Å, β = 109.843(2)°, V = 1257.99 Å^3 (Cs). In the crystal structure of M_3VO_2(SO_4)_2, [VO_2(SO_4)_2]^3− complex anions can be discerned in which the Vanadium Atom is surrounded by five oxygen Atoms: two oxygen Atoms form short terminal V–O bonds, and three oxygen Atoms are from the two sulfato groups, one of which acts as a monodentate ligand and the other acts as a bidentate chelating ligand.
