Syntheses And Properties Of Polyoxometalates Based Materials Modified By Transition Metals-azolate Derivative Ligands

The aim of this thesis is to design and synthesize polyoxometalate-based material based on Keggin or Dawson Polyanions,which are modified by transition metals(Cu⁺、Co²⁺、Zn²⁺、Ni²⁺、Ag+) and imidazole/pyrazole ligands, respectively.Eighteen material based on polyoxometalates have been obtained by hydrothermal technique. And they have been characterized by single crystal X-ray diffraction, IR,powder X-ray diffraction, elemental analysis, XPS, etc. The photoluminescence properties, electrochemical properties of parts of compounds have been studied. The study on 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, which improve the theoretical and experimental data for directional synthesis of Polyoxometalate-based hybrid materials.1. Keggin POM modified by transition metallic copper and pyrazol/triazole derivative ligands. We choose two kinds of different reaction system（Cu⁺bpmb,Cu⁺bbtz）, and four new hybrid compounds based on polyoxometalates with distinct architectures have been synthesized, except for alternation of the polyoxoanions under the identical reaction conditions. By introducing different polyoxomolybdates（[PMo12O40]3-, PMo12）,（[PW12O40]3-, PW12） and（[Si W12O40]4-, Si W12） into the Cu⁺bpmb system, compounds 1-3 were synthesized, respectively. Compounds 1 and2 have the similar structures. Compounds 1 and 2 are a POM-templated 3D supermolecular structure. In compound 3, the meso chain is formed by bpmb and Cu⁺,and the neighbouring meso chains formed cavity with 13.2 ? × 15.2 ? windows by hydrogen bonding. Si W12 in the form template filling in the cavity. Adopting Cu/bbtz as the reaction system by introducing（[BW12O40]5-, BW12）, we obtain compound 4with 3D porous supramolecular structure.The electrocatalytic properties of compounds 1-4 are investigated. Compared to compounds 1, 3 and 4, compound 2 has the best electrocatalytic efficiency towards the reduction of iodate. The photoluminescence properties of compounds 2 are investigated. The may be good candidate for potential solid-state luminescent material.2. Wells-Dawson POM modified by transition metal-imidazole derivative ligands. By introducing different transition metal ions(Zn²⁺,Cu⁺,Ni²⁺,Co²⁺) into the{（[P2W18O62]6-, P2W18）+bimb} system, and four new material based on polyoxometalates with distinct architectures have been synthesized. Compound 5shows a 2D supermolecular structure. Compound 6 is 1D rail chain structure.Compound 7 is a Dawson POM-double templated 2D layer structure. Compound 8exhibits a rare 2D+2D�'3D interdigitated architecture.The photoluminescence properties and electrocatalytic properties of compounds5-8 are investigated. They may be good candidates for potential solid-state luminescent materials. Compounds 6 and 8 have the better electrocatalytic efficiency towards the reduction of iodate than compounds 5 and 7.3. Keggin POM modified by transition metal-imidazole derivative ligands. Four POM-based material with distinct architectures have been hydrothermally synthesized composed of M/bimb（M = CuI, ZnII, AgI） segments. Compound 9 is 3D supramolecular structure composed of Cu-bimb ligand and BW12 polyanion.Compound 10 shows a 2D layers. Compounds 11 and 12 have the similar structures.A structural feature in compounds 11 and 12 shows a POM-pillared POMOF. By introducing different Keggin polyanion {（[BW12O40]5-, BW12）;（[Ge W12O40]4-, Ge W12）;（[H2W12O40]6-, W12） and（[VW12O40]4-, VW12）} into the（CoII+bimb） system, and four new hybrid compounds based on polyoxometalates with distinct architectures have been synthesized. Compounds 13-16 have the similar structures. There is a 3D honeycomb MOF with hexagonal metal-organic nanotubes（MONT）.The electrocatalytic properties of compounds 9, 10, 12, 13, 14 and 16 have also been investigated toward reduction iodate（IO3-）. Compounds 12, 14 and 16 have a good electrocatalytic effect toward the reduction of IO3-.4. Two new compounds with different new types of entanglement networks have been synthesized under 160 °C hydrothermal system. Compound 17 exhibitsinterdigitated architectures with 1D+2D�'3D topological features. Compound 18 is a（6,4,3）-connected self-penetrating net that is assembled from bimb pillared two-fold interpenetrating sheets.They may be good candidates for potential solid-state luminescent materials.Compounds 17 and 18 have the best electrocatalytic efficiency towards the reduction of iodate.