| The aim of this thesis is to reported a series of new polyoxometalates (POMs) based on Keggin and Pseudo-Keggin type polyoxoanions by exploiting appropriate metal cations or organic ligands as linkers on the basis of sodium tungstate, sodium molybdate, vanadium pentoxide and phosphotungstic acid etc. The study on the synthetic conditions and rules for these new compounds and the exploration of relationships between structures and properties for these new compounds are also carried out.Nine new POM-based compounds have been synthesized via common organic solvents and hydrothermal methods. These POM-based compounds have also been structurally characterized by single crystal X-ray diffractions, XPS, IR, TG, cyclic voltammetry and so on.1 . Based on Keggin-type polyoxoanions as building blocks and bpp (1,3-Di (4-pyridyl)propane) as bridging cations, two new 3D POM-based supramolecular compounds have been gained via conventional aqueous and hydrothermal method, respectively.[H3(bpp)2][PMo12O40]·3DMF (1)[H3(bpp)2]2[PMo9V3(VO)2O40]2 (2)2. Based on Keggin-type polyoxoanions with the centre of vanadium and M-phen (M = Ni, Zn, Co) subunits, three novel POM-based supramolecular compounds have been synthesized via hydrothermal methods:[Ni(phen)3]2HN(CH3)2[VW8V4(VO)2O40]·6H2O(3)[Zn(phen)3]2HN(CH3)2[VW8V4(VO)2O40]·6H2O (4)[Co(phen)3]3[VW12O40]·12H2O (5)Three 3D supramolecular compounds are constructed via intermolecular hydrogen bond andπ-πinteractions occurred among POM anions and M-phen cations. Compounds 3 and 4 are isostructural which contain bicapped-Keggin-type polyoxoanions with the centre of vanadium while compound 5 is constituted by classic Keggin-type [VW12O40]6-polyoxoanion .3 . Three new 1D POM-based covalently compounds containing the V-centered Keggin-type clusters have been synthesized on the basis of hydrothermal technique:[Cu(2,4'-bpy)]2[Cu3(2,4'-bpy)4][Cu(2,4'-bpy)2(H2O)2][VW12O40] (6) [Cu(en)2]2[Cu(en)2(H2O)]2[V4.08W8 92O40(VO)4]·3H2O (7)[(VO4)W6.4V5 6Sb2V2O37]·2DMF·6H2O (8)All three structures exhibit one-dimensional structures. Compound 6 contains a classic V-centered Keggin-type anion, linked each other by Cu-bpy subunits. Compounds 7 and 8 both contain tetracapped pseudo-Keggin-type polyoxoanions. Compound 8 represents an unusual mixed tetracaped-Keggin structure: two {V=O} and two {Sb} caps.4. A new POM compound has been hydrothermally synthesized based on vanadium clusters and second metal-ligand groups (SMGs) Ni-mbpy (mbpy = 4,4'-Dimethyl-2,2'bipyridyl):[(Nimbpy)2V8O21] (9)...
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