Assembly Chemistry Of Polyoxometalates Decorated By The D-and F-metals

The aim of this thesis is the synthesis of a variety of new polyoxometalate-based compounds with high-dimension and porous by using the d/f single metal or d-f mixed metals, supplemented by organic ligands, through covalent, ionic and metal bonds or intermolecular interactions. Their relationship between structures and properties is also carried out.Seventeen new single d/f metal modified polyoxometalate compounds and three d-f heterometallic modified polyoxometalate compounds have been synthesized by hydrothermal technique and/or aqueous synthesis, characterized by elemental analyses, IR, XRPD, TG and single crystal X-ray diffractions. The magnetic properties, thermal stabilities, electrochemical properties and photoluminescence properties of these compounds have been studied.1. By using the d metals Cu or Ag and tuning coordination modes, length and flexibility of the organic ligands step by step, ten d metal-modified compounds based on different polyoxometalates have been synthesized under hydrothermal conditions, and structurally characterized. [Ag(phen)₂]₇{Ag[Ag(phen)(VW10V2O₄₀)]₂} (1) {[Cu^II(DF)₃]₂GeW₁₂O₄₀} (2) {[CuI₂(DF)₂H₂O]₂SiMo₁₂O₄₀} (3) {[CuI₂(DF)₂H₂O]₂SiW₁₂O₄₀}·2H₂O (4) {[CuI₂(DF)₂H₂O]₂GeMo₁₂O₄₀}·2H₂O (5) [CuI(bipy)]₂[H₂SiW₁₂O₄₀]·2H₂O (6) [Ag(bipy)]₂[Ag(bipy)(Hbipy)][P₂W₁₈O₆₂]·[H₂bipy] (7) {[CuI(bipy)]₂[Mo₂^VMo₆^VIO₂₄]}·H₂O (8) [CuI(bpp)₂][H₂PW₁₂O₄₀]·2H₂O (9) [Cu(bimb)]₂[HPW₁₂O₄₀]·3H₂O (10)phen = 1,10-phenaanthroline DF = 4,5-diazafluoren-9-one bipy = 4,4'-bipy bimb = 1,4-bis(imidazol-1-ylmethyl)biphenyl bpp = 1,3-bis(4-pyridyl)propaneCompound 1 represents the first V-centre tungstovanadate grafted by transition metal coordination polymers. Compound 1 consists of five-silver oligomer connected together via Ag…Ag interactions and the Ag capped Keggin structure. These structural features of 1 are all unusual in POM chemistry. Compounds 2-5 are composed of DF ligand, Cu atoms, Keggin cluster. The coordination modes of DF ligand can be affected by changing the valence of Cu atoms: when Cu atoms are in the +II oxidation state, the DF ligands adopt a common chelating coordination mode, bonding only one Cu atom (see compound 2); When Cu atoms are in the +I oxidation state, the DF ligands adopt unusual bidentate coordination mode coordinating to two Cu atoms forming a copper-dimer (see compounds 3-5). As a result, compound 2 shows low dimensional structure, while, compounds 3-5 possess extended dimensional structures. Compounds 4 and 5 are networks with the left- and right-handed helical chains.Compounds 6-8 were based on the different POMs modified by Cu-bipy/Ag-bipy coordination polymeric chains: compound 6 represents 1D chain based on bi-track Cu-bipy coordination polymeric chains modifying Keggin POMs; Compound 7 shows a 3D network based on hexa-track Cu-bipy coordination polymeric chains modifying Wells-Dawson POMs; Compound 8 exhibits a 3D framework consisting of an infinite track Cu-bipy coordination polymeric chain and a new molybdenum oxide chain; Compound 9 shows a 1D chain constructed by flexible ligand bpp, Cu and PW₁₂ clusters. Compound 10 represents a unique POM-encapsulated metal–organic (pseudo-)rotaxane framework with nano-scale porous structure constructed by flexible ligand bimb, Cu and PW₁₂ clusters.2. By the utilities of pre-synthesized H4[SiW₁₂O40]·14H₂O, H4[SiMo₁₂O40]·13H₂O and (NH4)6[H₂W₁₂O40]·3H₂O, lanthanide ions and pyridine-4-carboxyl ligands, we have successfully synthesized seven new polyoxotungstate-based rare earth compounds in aqueous solution. [Ce(H₂O)₃(HL)_<sub>2(H₂L)]₂[SiW₁₂O₄₀]₂·10H₂O (11)[Ce(H₂O)₃(HL)₃]₂[HSiMo₁₂O₄₀]₂[HL]·7H₂O (12)[La(H₂O)₃(HL)₂]₂[H₂W₁₂O₄₀]·5H₂O (13)[Ce(H₂O)₃(HL)₂]₂[H₂W₁₂O₄₀]·7H₂O (14)[Ce(H₂O)₅(HL)]₂[H₂W₁₂O₄₀]·7H₂O (15)[Pr(H₂O)₅(HL)]₂ [H₂W₁₂O₄₀]·7H₂O (16)[Nd(H₂O)₅(HL)]₂[H₂W₁₂O₄₀]·6H₂O (17)HL = Pyridine-4-carboxylateBoth compounds 11 and 12 are composed of Ce2-Ln and Keggin ions. Further, the 3D supramolecular frameworks are formed via H-bonds between Ce2-Ln and Keggin ions. In the framework of 11, there exits 1D channels along a axis, while in the framework of 12, there exits a novel water chain constructed by the linkages of (H₂O)12 clusters. Different from compounds 11 and 12, compounds 13-17 are constructed by [H₂W₁₂O40]^6- and Ln-L coordination complexes possessing extended structures: the isostructural compounds 13 and 14 exhibit 1D zig-zag chains, while the isostructural compounds show a 2D structure with left- and right-handed helical chains. By comparing the structures of compounds 11-17, we found that: the high charge density [H₂W₁₂O40]^6- cluster possesses higher coordination tendency than [SiW₁₂O40]^4- and [SiMo₁₂O40]^4- clusters. In addition, the pH of the reaction system plays a key role in forming the final structures.3. By the utilities of pre-synthesized (NH4)6[H₂W₁₂O40]·3H₂O and H4[SiW₁₂O40]·14H₂O, lanthanide and transition ions, we have synthesized three new POM-based d-f heterometallic compounds in aqueous solution. [{Ag₃(H₂O)₂}{Ce₂(H₂O)₁₂}H5{H₂W₁₁Ce(H₂O)₄O₃₉}₂]·8H₂O (18)[Ag{Ag₂(H₂O)₄}{Ce (H₂O)₆}₂ H{SiW₁₁Ce(H₂O)₄O₃₉}₂]·12H₂O (19)[Ag{Ag₂(H₂O)₄}{Pr (H₂O)₆}₂H{SiW₁₁Pr(H₂O)₄O₃₉}₂]·10H₂O (20)Compounds 18-20 show three-dimensional pure inorganic porous frameworks. Compound 18 is composed of [H₂W₁₁O₃₉]^10-, Ce³⁺ and Ag⁺, while compounds 19 and 20 are composed of [SiW₁₁O₃₉]^8-, Ce³⁺/Pr³⁺ and Ag⁺. Compound 18 exhibits reversible water sorption capability. The magnetic susceptibilities of compounds 19 and 20 have been studied, indicating the existence of anti-ferromagnetic responses.