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.

The first two-fold interpenetrating polyoxometalate-based coordination polymer with helical channels: structure and catalytic activities

Abstract: A polyoxometalate-based coordination polymer with a [helix + interpenetration] double configuration feature, Na[Ag4(pyttz-I)2][H2PMo12O40] (POMCP-1), was isolated and structurally characterized. POMCP-1 exhibits a 3D structure with open 3D tunnels along the [10−1], [111] and [1−11] axes. The large void space in the single net induces the interpenetration of two identical 3D frameworks, resulting in the formation of a highly ordered two-fold interpenetrating aggregate. To the best of our knowledge, this represents the first example of two-fold interpenetrating POMCPs with helical channels. In particular, POMCP-1 was found to display efficient catalytic activities for the esterification reaction and the photodecomposition of Rhodamine-B.

Synthesis and photo-/electro-catalytic properties of a 3D POMOF material based on an interpenetrated copper coordination polymer linked by in situ dual ligands and Dawson-type phosphotungstates.

Abstract: A novel 3D polyoxometalate metal organic framework (POMOF), [{CuII6CuI10 (H2O)5(pzc)10(pz)6}{P2W18O62}2]·4H2O (1) (Hpzc = pyrazine-2-carboxylic acid, pz = pyrazine) has been hydrothermally synthesized and characterized by IR, TG, XRD, UV-vis and elemental analyses. In compound 1, the pzc and pz ligands are generated through in situ transformation from pyrazine-2,3-dicarboxylic acid (pzdc) to remove one or two CO2 molecules. The ligands with four coordination modes connect nine crystallographically independent Cu atoms to form a super-big circle unit. Each ring unit is connected to the adjacent six rings via an edge-sharing way to form a 2-D Cu/pz/pzc MOF layer, which is further extended along two spatial directions by two kinds of insert modes to generate an interpenetrating and staggered 3-D metal organic network. The {P2W18} clusters as nine-node inorganic guest molecules are grafted on the Cu/pz/pzc framework forming a complex 3D POMOF with a new topology {4·6·83·10}2 {4·6·8}2 {4·62·82·10}2{4·63·82}2{4·85}2{42·62·82}2{42·63·8}{43·67·813·1010·123}2 {4}6{6·82}2{62·8}2 {64·8·10}{6}2{8}4. Additionally, compound 1 exhibits good electrocatalytic activity for the reduction of H2O2 and effective photocatalytic degradation ability for three azo dyes under UV irradiation.

Polyoxomolybdate‐Stabilized Ru0 Nanoparticles Deposited on Mesoporous Silica as Catalysts for Aromatic Hydrogenation

Abstract: We use polyoxometalates as precursors for the preparation of heterogeneous catalysts. In the starting molecular precursor [{Ru(C6Me6)}2Mo5O18{Ru(C6Me6)(H2O)}], three ruthenium arene fragments are supported on a formally lacunary Lindqvist-type polyoxomolybdate. This species was introduced by incipient wetness impregnation into the porosity of a SBA-15-type mesoporous silica. The evolution of the system under reducing atmosphere is followed by several methods, such as temperature-programmed reduction (TPR), Raman, and X-ray absorption spectroscopy (XAS). The results indicate that the polyoxometalate structure is retained after grafting on silica and allows the stabilization of Ru0 nanoparticles after reduction. The resulting system exhibits interesting catalytic activity in benzene hydrogenation.

Ionic liquid-enhanced photooxidation of water using the polyoxometalate anion [P2W18O62](6-) as the sensitizer.

Abstract: Simple polyoxometalate anions are known to be photoreduced in molecular solvents in the presence of 2-propanol or benzyl alcohol. The use of ionic liquids (ILs) as the solvent is now reported to also allow the photooxidation of water to be achieved. In particular, the photochemistry of the classic Dawson polyoxometalate salt K6[P2W18O62] has been studied in detail when water is present in the aprotic IL, 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4]) and the protic IL, diethanolamine hydrogen sulfate (DEAS). In these and other ILs, irradiation with white light (wavelength 275–750 nm) or UV light (wavelength 275–320 nm) leads to overall reduction of the [P2W18O62]6– anion to [P2W18O62]7– and concomitant oxidation of water to dioxygen and protons. The modified structure of bulk water present in ILs appears to facilitate its oxidation. Analogous results were obtained in aqueous solutions containing the protic IL as an electrolyte. The photoproducts (reduced polyoxometalate anion, dioxygen, and p...

Inorganic–Organic Heteropolyacid–Gold(I) Hybrids: Structures and Catalytic Applications

Abstract: Gold(I)-polyoxometalate hybrid complexes 1-4 ((PPh3AuMeCN)xH4xSiW12O40, x = 1-4) were synthesized and characterized. The structure of the primary gold(I)- polyoxometalate 1 (x = 1) was fully ascertained by XRD, FTIR, 31 P and 29 Si magic-angle spinning (MAS) NMR, mass spectroscopy, and SEM-energy dispersive X-ray spectros- copy (EDX) techniques. Moreover, this complex exhibited better catalytic activity and selectivity compared with standard, homogeneous, gold catalysts in the new re- arrangement of propargylic gem-diesters. Polyoxometalates (POMs) are oxygen-bridged, anionic, metal clusters with unique structural characteristics and a wide diver- sity in structures. The properties lead to various applications in different fields, especially in catalysis, medicine, biology, elec- trochromism, magnetism, and material science. (1) Recent years have thus witnessed the development of POM-based molecu- lar and composite materials. (2)