Topic
Polyoxometalate
About: Polyoxometalate is a research topic. Over the lifetime, 3493 publications have been published within this topic receiving 94123 citations. The topic is also known as: POM.
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TL;DR: In this paper, the multiproton-multielectron electrochemical reduction of CO2 in homogeneous solution by using (TOA)6[α-SiW11O39Co) polyoxometalate as an electrocatalyst was reported.
Abstract: We report here on the multiproton-multielectron electrochemical reduction of CO2 in homogeneous solution by using (TOA)6[α-SiW11O39Co(_)] (TOA = tetraoctyl ammonium; _ = vacant position in the coordination sphere of Co) as an electrocatalyst. First, the electrochemical behavior of (TOA)6[α-SiW11O39Co(_)] was analyzed in detail by cyclic voltammetry in dichloromethane, studying the influence of the presence of protons and/or CO2. These preliminary results were further used to optimize the conditions of electrolysis in terms of reduction potentials. Analysis of the electrolysis products in the gas and liquid phases show the formation of CO and HCHO without formation of H2. Our results tend to show that the (TOA)6[α-SiW11O39Co(_)] polyoxometalate is a catalyst for CO2 electroreduction, with unique selectivity.
34 citations
TL;DR: In this article, it was shown that substituting the Lewis basic BiIII into the terminal position of the polyoxometalate structure leads to an apparent umpolung of the peroxoxide species and formation of a nucleophilic peroxo intermediate.
Abstract: The epoxidation of alkenes with peroxides by WVI, MoVI, VV, and TiIV compounds is well established, and it is well accepted that the active intermediate peroxo species are electrophilic toward nucleophilic substrates. Polyoxotungstates, for example, those of the “sandwich” structure, [WZn(TM–L)2(ZnW9O34)2]q− in which TM = transition metal and L = H2O, have in the past been found to be excellent epoxidation catalysts. It has now been found that substituting the Lewis basic BiIII into the terminal position of the “sandwich” polyoxometalate structure to yield [Zn2BiIII2(ZnW9O34)2]14– leads to an apparent umpolung of the peroxo species and formation of a nucleophilic peroxo intermediate. There are two lines of evidence that support the formation of a reactive nucleophilic peroxo intermediate: (1) More electrophilic sulfoxides are more reactive than more nucleophilic sulfides, and (2) nonfunctionalized aliphatic alkenes and dienes showed ene type reactivity rather than epoxidation pointing toward “dark” format...
34 citations
TL;DR: In this article, the crystal structure of a Ti-substituted Dawson-type polyoxotungstate K 19 H 9 [P 4 W 32 Ti 6 O 132 ] has been determined in the presence of coordinated oxalate anions.
Abstract: The crystal structure of a Ti-substituted Dawson-type polyoxotungstate K 19 H 9 [P 4 W 32 Ti 6 O 132 ] has been determined in the presence of coordinated oxalate anions. The K + salt is water soluble and the [ n -Bu 4 N] + salt is soluble in acetonitrile and acetone. The anion exists as a dimer of two [P 2 W 16 Ti 2 O 62 ] 10− units connected via two external TiO 6 octahedra. The photocatalytic activity of the [ n -Bu 4 N] + salt toward the oxidation of cyclohexanol, 1-hexanol, and 2-hexanol gave pseudo first-order rate constants of 0.03 h −1 , 0.01 h −1 , and 0.01 h −1 , respectively. The relative photocatalytic activities for the oxidation of cyclohexanol by ( n -Bu 4 N) 9 H 19 [P 4 W 32 Ti 6 O 132 ] and various polyoxotungstates of similar structure are compared.
34 citations
TL;DR: In this paper, a 3D polyoxometalate-based 3D framework was synthesized in moderate yields and the enthalpy of adsorption and DFT calculation indicated that the materials strongly interact with CO2, but weakly interact with CH4, due to electrostatic interactions between the materials and molecules.
Abstract: Polyoxometalate-based 3D frameworks, Na1.5H11.4[ZnMo12O40{Zn2}]·5.5H2O and (NH4)1.5H8.5[ZnMo12O40{Zn2}]·6H2O, are synthesized in moderate yields. Rotation of the reactor under hydrothermal conditions is essential to improve the yield. The materials show zeolite-like selective molecule adsorption properties. Depending on the micropore aperture size of the materials, small molecules can be adsorbed in the materials, while large molecules cannot. The enthalpy of adsorption and DFT calculation indicate that the materials strongly interact with CO2, but weakly interact with CH4, due to electrostatic interactions between the materials and molecules. CO2/CH4 co-sorption experiments show that the materials can selectively adsorb CO2, and CO2 adsorption selectivity of the material with sodium cations is higher than that of the material with ammonium cations. The material with sodium ions can be utilized for gas chromatographic separation of CH4 and CO2.
34 citations
TL;DR: In this paper, the effect of the transition metal on the catalytic activity was investigated in the order, Zn, Fe, Ni, Cr, Mn, Co, and Cu.
Abstract: Various organic–inorganic hybrid compounds, [bmim] x [PW11MO39] · 3H2O {(bmim: 1-n-butyl-3-methylimidazolium) and [M = V(IV), Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II)]}, were prepared and characterized by elemental analysis, UV-Vis, FT-IR, and TGA. The synthesized hybrid compounds were used as catalysts in oxidation of various alcohols with hydrogen peroxide in acetonitrile. The effect of the transition metal on the catalytic activity was in the order, Zn > Fe > Ni > Cr > Co > V > Mn > Cu. In this catalytic system, the effects of other parameters such as the type of solvent, amount of oxidant and catalyst, and the temperature were also investigated. [bmim]5[PW11ZnO39] · 3H2O was reused several times without loss of catalytic activity.
33 citations