| Two new insoluble silver salts of Keggin-type heteropolyanions, Ag3PW12O40·13H2O （1） and Ag4H3PTi2W10O40·16H2O （2） were synthesized with saturatedKeggin-type polyoxometalate and silver acetate by ion-changed reaction. Compound1is based on [PW12O40]3-polyoxometalate, and characterized by ICP analysis,infrared spectrum （IR）, thermogravimetric analysis （TGA）, and solid diffusereflectance spectrum to determine its composition. And compound2is a newthree-dimensional polyoxometalate compound based on [H3PTi2W10O40]4-, and itsstructure was determined by single crystal X-ray diffraction, it composition wasdetermined by ICP analysis and TGA, and its properties were characterized by IR andsolid diffuse reflectance spectrum （DRS）.The crystal structure of compound2contains one [H3PTi2W10O40]4-polyanion,four Ag+and16H2O. In compound2, the Ag+coordinated with the oxygen atoms ofpolyanion to form {AgO6} units, and {AgO6} units bridge [H3PTi2W10O40]4-leadingto the formation of a two-dimensional layer structure paralleling to ab-plane. Thetwo-dimensional layer can be further extended to three-dimensional networkstructure.DRS analysis indicates that the absorption band of compound1and2shiftedtowards visible light area after compared with crude material, can absorb visible light,and may be an excellent photocatalytic material.The two compounds are both insoluble silver polyoxometalate. Therefore, wedetermined the solubility product of1and2by spectrophotometry at25oC andcalculated the standard electrode potential of Ag4H3PTi2W10O40/Ag with the results ofsolubility product by Nernst equation. The solubility product of1and2weredetermined by spectrophotometry at25oC, the results were1.92×10-10and7.22×10-12,respectively. On that basis, the standard electrode potential of Ag4H3PTi2W10O40/Agwere also worked out by Nernst equation, results were0.6079å'Œ0.6345V. And thedata can provide the theory basis for the further physicochemical characterization andapplication of the compounds. |
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