Two novel organic-inorganic heteropolyoxometalate compounds [{Cu（1,10-phen）OH}2]2[V2WaO199]·6H2O （1） and [Co（1,10-phen）3]2[V2WaO19]·5H2O （2） （1,10-phen = 1,10-phenanthroline） were hydrothermally sy...Two novel organic-inorganic heteropolyoxometalate compounds [{Cu（1,10-phen）OH}2]2[V2WaO199]·6H2O （1） and [Co（1,10-phen）3]2[V2WaO19]·5H2O （2） （1,10-phen = 1,10-phenanthroline） were hydrothermally synthesized and characterized by elemental analysis, IR spectra and single-crystal X-ray diffraction. Compound 1 contains a di-V substituted classical Lindqvist-type polyanion [V2W4O19]^4-, two dinuclear copper cations [ {Cu（1,10-phen）OH} 2]^2＋ and six water molecules of crystallization. Two dinuclear copper cations [{Cu（1,10-phen）OH}2]^2＋ con-sist of four transition metal coordination cations {Cu（1,10-phen）}^2＋, bridged by four hydroxyl groups. Meanwhile, both two dinuclear cations are grafted on the Lindqvist polyanion [V2W4O19]^4- through two terminal oxygen （0（9）） and two μ2-0xygen （O（6）） atoms. Such an unusual linking fashion is unique in the polyoxometalate chemistry. The basic framework of 2 is similar to that of 1 and contains one Lindqvist-type polyanion [V2W4O19]^4-, two six-coordinated cobalt cations [Co（1, 10-phen）3]^2＋ and five free water molecules.展开更多
The electronic properties and stabilities of five [Nb2W4O18OCH3]3-isomers have been investigated using a density functional theory method.The results show that the isomer with the methoxy group occupying a bridging po...The electronic properties and stabilities of five [Nb2W4O18OCH3]3-isomers have been investigated using a density functional theory method.The results show that the isomer with the methoxy group occupying a bridging position between two tungsten atoms(two tungsten atoms in the plane that contains two niobium atoms) in the [Nb2W4O18OCH3]3-framework is the most stable isomer in acetonitrile.The stability of the one-electron-reduced isomers changes little.The most stable one-electron-reduced isomer has the methoxy group occupying a bridging position between niobium atoms in the [Nb2W4O18OCH3]4-framework.The M-Ob(M = Nb,W;b denotes bridging) bond lengths in anions in which the metal atoms are connected by a methoxy group are longer than those in [Nb2W4O19]4-.The highest occupied molecular orbitals(HOMO) in [Nb2W4O19]4-mainly delocalize over the bridging oxygen atoms of two niobium atoms and two tungsten atoms located in the equatorial plane,and the bridging oxygen atoms on the axial surface.The lowest unoccupied molecular orbitals(LUMO) of [Nb2W4O19]4-are mainly concentrated on the tungsten atoms and antibonding oxygen atoms.Methoxy substitution modifies the electronic properties of the [Nb2W4O18OCH3]3-isomers.The HOMOs in the five isomers formally delocalize over the bridging oxygen atoms,which are distant from the surface containing the methoxy group and four metal atoms.The LUMOs delocalize over the d-shells of the four metal atoms that are close to the methoxy group,and the p-orbitals of oxygen.One-electron reduction occurred at the tungsten atoms,not the niobium atoms.展开更多
An integrated approach combining the development of an innovative catalyst and the research of a set of adequate operating conditions for the propane oxidative dehydrogenation （ODH） is described.The experimental set...An integrated approach combining the development of an innovative catalyst and the research of a set of adequate operating conditions for the propane oxidative dehydrogenation （ODH） is described.The experimental set-up,specially designed for steady-state and transient studies is presented.The preparation method,the characterization and the performances in steady-state and transient regimes of catalysts based on V2W4O194-Lindqvist isopolyanion used as a precursor and supported on alumina are reported.The influence of the preparation method of the catalyst and the role of water in the feed gas are more particularly discussed.展开更多
The Lindqvist method is adopted to estimate the ice resistance for an icebreaker.The accuracy of the method is evaluated in a comparison of the calculated results with model test results.In addition to the estimation ...The Lindqvist method is adopted to estimate the ice resistance for an icebreaker.The accuracy of the method is evaluated in a comparison of the calculated results with model test results.In addition to the estimation of ice resistance,a sensitivity analysis based on the Lindqvist method is carried out.A full parametric model developed using CAESES software allows the convenient construction of many new hull lines.The primary factors relevant to ice resistance are embedded as design parameters in the full parametric model.Meanwhile,response surface methodology is adopted to give better insight into new hull lines.Results show that the ice resistance is more sensitive to the rake angle and waterline entrance angle.The aim of the present study is to improve the techniques of designing the hull forms of icebreakers.展开更多
基金supported by the Foundation of Education Department of Henan Province
文摘Two novel organic-inorganic heteropolyoxometalate compounds [{Cu（1,10-phen）OH}2]2[V2WaO199]·6H2O （1） and [Co（1,10-phen）3]2[V2WaO19]·5H2O （2） （1,10-phen = 1,10-phenanthroline） were hydrothermally synthesized and characterized by elemental analysis, IR spectra and single-crystal X-ray diffraction. Compound 1 contains a di-V substituted classical Lindqvist-type polyanion [V2W4O19]^4-, two dinuclear copper cations [ {Cu（1,10-phen）OH} 2]^2＋ and six water molecules of crystallization. Two dinuclear copper cations [{Cu（1,10-phen）OH}2]^2＋ con-sist of four transition metal coordination cations {Cu（1,10-phen）}^2＋, bridged by four hydroxyl groups. Meanwhile, both two dinuclear cations are grafted on the Lindqvist polyanion [V2W4O19]^4- through two terminal oxygen （0（9）） and two μ2-0xygen （O（6）） atoms. Such an unusual linking fashion is unique in the polyoxometalate chemistry. The basic framework of 2 is similar to that of 1 and contains one Lindqvist-type polyanion [V2W4O19]^4-, two six-coordinated cobalt cations [Co（1, 10-phen）3]^2＋ and five free water molecules.
基金supported by the National Natural Science foundation of China (20971020, 21073030 and 21131001)the Doctoral Fund of the Ministry of Education of China (20100043120007)the Science and Technology Development Planning of Jilin Province (20100104)
文摘The electronic properties and stabilities of five [Nb2W4O18OCH3]3-isomers have been investigated using a density functional theory method.The results show that the isomer with the methoxy group occupying a bridging position between two tungsten atoms(two tungsten atoms in the plane that contains two niobium atoms) in the [Nb2W4O18OCH3]3-framework is the most stable isomer in acetonitrile.The stability of the one-electron-reduced isomers changes little.The most stable one-electron-reduced isomer has the methoxy group occupying a bridging position between niobium atoms in the [Nb2W4O18OCH3]4-framework.The M-Ob(M = Nb,W;b denotes bridging) bond lengths in anions in which the metal atoms are connected by a methoxy group are longer than those in [Nb2W4O19]4-.The highest occupied molecular orbitals(HOMO) in [Nb2W4O19]4-mainly delocalize over the bridging oxygen atoms of two niobium atoms and two tungsten atoms located in the equatorial plane,and the bridging oxygen atoms on the axial surface.The lowest unoccupied molecular orbitals(LUMO) of [Nb2W4O19]4-are mainly concentrated on the tungsten atoms and antibonding oxygen atoms.Methoxy substitution modifies the electronic properties of the [Nb2W4O18OCH3]3-isomers.The HOMOs in the five isomers formally delocalize over the bridging oxygen atoms,which are distant from the surface containing the methoxy group and four metal atoms.The LUMOs delocalize over the d-shells of the four metal atoms that are close to the methoxy group,and the p-orbitals of oxygen.One-electron reduction occurred at the tungsten atoms,not the niobium atoms.
基金supported by CNRS standing for Centre National de la Recherche Scientifique (France),CAPES standing for Coordenao de Aperfeioamento de Pessoal de Nível Superior (Brazil),CNPq standing for Conselho Nacional de Desenvolvimento Científico e Tecnológico (Brazil) and FINEP standing for Financiadora de Estudos e Projetos (Brazil)
文摘An integrated approach combining the development of an innovative catalyst and the research of a set of adequate operating conditions for the propane oxidative dehydrogenation （ODH） is described.The experimental set-up,specially designed for steady-state and transient studies is presented.The preparation method,the characterization and the performances in steady-state and transient regimes of catalysts based on V2W4O194-Lindqvist isopolyanion used as a precursor and supported on alumina are reported.The influence of the preparation method of the catalyst and the role of water in the feed gas are more particularly discussed.
文摘The Lindqvist method is adopted to estimate the ice resistance for an icebreaker.The accuracy of the method is evaluated in a comparison of the calculated results with model test results.In addition to the estimation of ice resistance,a sensitivity analysis based on the Lindqvist method is carried out.A full parametric model developed using CAESES software allows the convenient construction of many new hull lines.The primary factors relevant to ice resistance are embedded as design parameters in the full parametric model.Meanwhile,response surface methodology is adopted to give better insight into new hull lines.Results show that the ice resistance is more sensitive to the rake angle and waterline entrance angle.The aim of the present study is to improve the techniques of designing the hull forms of icebreakers.
