Synthesis、Structure And Property Study Of The Keggin-type Polyoxometalates-based Inorganic-organic Hybrid Materials

Inorganic-organic hybrid materials relied on POMs have attracted wide attention, owingto their interesting structure skeleton as well as superior applications in catalysis, adsorption,conductivity, magnetic and photochemical. The functionality of organic-inorganic hybridmaterials based on POMs can be multiplied by incorporation of coordination polymers intothe POMs, resulting in numerous novel structures and properties due to the interplay andsynergistic effects of organic and inorganic motifs.In this paper, using saturated Keggin type polyoxometalates, nitrogen–embodyingligands and transition metal salt, five new inorganic-organic hybrids materials have beensynthesized by covalent bonds or supramolecular under hydrothermal synthesis method.Compounds1and2have been characterized through single crystal X-ray diffraction,elemental analysis, infrared spectroscopy and thermal analysis. Compounds3-5have beencharacterized through infrared spectroscopy.The electrical conductivity and photocatalyticproperty of the compounds1and2have been studied preliminarily.1. We chose two classic Keggin type polyoxometalates (12-phosphomolybdic acid and12-phosphptungstic acid), Cu-bis(triazole) complexes, two novel inorganic-organic hybridcompounds have been synthesized under hydrothermal conditions, namely[Cu3(L1)3(PMo12O40)2]·9H2O(1),[Cu3(L1)3(PW12O40)2]·9H2O(2)[L1=1,4-bis(1,2,4-triazol-1-ylmethyl)-benzene].The materials of the compounds1and2are the identical in addition to Keggin typepolyanions. Single-crystal X-ray diffraction analysis reveals that compounds1and2areisostructural. In these structures, Cu ion is connected by bis(triazole) ligands in the equatorialpositions into a2D puckered sheet which have two types of meshes(One is trigonal and theother is circular), Keggin anions are attached to the2D layered skeleton through Cu-Ointeractions in a mutual anti orientation. Compounds1and2represent rare2D structuralexamples with POM clusters as pendants. In addition, the diffuse reflectivity spectra of thesetwo compounds show that they can be regarded as a wide gap semiconductor. Thephotocatalytic experiments indicate that both1and2exhibit high catalytic activity forphotodegradation of Rho-damine B (RhB) with UV irradiation.2. Under hydrothermal synthesis method, tree new inorganic-organic hybrid compounds havebeen successfully prepared based on the Keggin-type polyoxometalates and transition metal-organic nitrogen assemblies, namelyL1[(CuIL1)2(PMo12O40)]·H2O(L1=1,4-bis(1,2,4-triazol-1-ylmethyl)benzene)(3),[Zn2(H2O)2(L2)3][PMoVI11MoVO40](L2=4,4’-bis(1,2,4-triazol-1-ylmethyl)biphenyl)(4), [Cu(L3)2]{[Cu(L3)2]4[(PWVI10WV2O40)2}·2H2O(L3=2,2’-biimidazole)(5).In compound3, Cu+and L1ligand form a helical one-dimensional chain and Kegginanions are alternately connected with a one-dimensional chain by Cu-O bond in a mutual antiorientation. These chains are expanded into a two-dimensional layer, and the adjacent spiralone-dimensional chains are in mirror symmetry. In compound4, Zn2+connected with a synconformation, an anti conformation ligands and a water molecule respectively into aone-dimensional chain with a chair-shaped cavity, and Keggin polyanion has been wrappedinto the cavity of metal-organic complexes through supramolecular interactions. One Moatom of PMo12is reduced to+V. Compound5is composed of {[Cu (L3)2]4[(PWVI10WV2O40)]}where the PW12cluster is supported by two [Cu(bim)2]2+fragments and [Cu(L3)2] cation, andtwo W atoms of PW12were reduced to+V.