Synthesis And Modification Of Inorganic Polyoxometalates

The development history of polyoxometalates(POMs) has more than 100 years. POMs belongs to inorganic oxo-metal clusters and constructed by two different structures MO6 octahedron and XO4 tetrahedron. Most POMs possess an extensive and reversible redox chemistry and some contain multiple unpaired d-electrons that make them useful in several fields. POMs are one of the most widely used inorganic components in a wide range of fields, such as catalysis, medicine, molecular magnetism or material science, owing to their extreme variability of composition, structure, electronic properties and applications.The thesis is focused on the synthesis and modification of polyoxometalates, the main research results are as follows:1. First, introduced the synthesis of modified precursor 4,5 - imidazole dicarboxylic acid, Na₃(PO₂NH)₃, and Na9PW9O34 preparation, and the structure of the three compounds were determined by IR, XRD, TGA.2. Second, explore different types of starting material, pH value and many other reaction conditions on the formation of the polyoxometalates's structure. Through hydrothermal methods we have successfully synthesised four compounds, namely: [Cu(en)₂][(en)₂][(H₆W₁₂O₄₂)].18H2O(1), {[Cu(en)₂(OH)]₂(en)[Cu(en)₂]}(P₂W₁₈O₆₂)].8H₂O(2),[Cu(en)₂(H₂O)]₂[Cu(en)₂]₂[CuV₂W₁₂O₄₆].3H₂O(3)å’Œ{[EMIM]₅(en)[(SiW₁₂O₄₀)1.5](4). compound 1 belongs to the hetero-polyoxometalates, the adjacent polyoxometalates anions were connected into a helical chain by [Cu(en)₂]²⁺, in every lattice, there exist eighteen nuclear water clusters and free en molecules, the existing hydrogen bonds lead the structure of compound 1 into a three-dimensional network; the polyanions in compound 2 can be classified to the Wells-Dawson structure, hydrogen bonds between the independent en molecules and polyanions connected the whole structure into a 3D supramolecular compounds in space; compound 3 is a 2D supramolecular compounds, the polyanion units in this structure belongs to the pesudo-keggin polyocometalates; compound 4 are connected by hydrogen bonds and electrostatic interaction into a 3D supramolecular compound.3. In the third part, utilied the synthesized Wells-Dawson type of polyanion as the structure precursor compound, use nitrogen ligand TPT and carboxylic acid molecules talked about the influence to the initial polyanions. Explore new functional photosensitive materials through group modifiction.