Preparation, Construction And Properties Researches Of The Metal-substituted Keggin-type Polyoxotungstate

At high pH conditions，Keggin-type polytungstate or lacunary Keggin-type polytungstatetodegrade to be abuilding units, and then thosesbuilding unit will be linked by transition metalions to be TM-substituted POMS. The design and synthesis of TM-substituted POMs have beenaroused broad interest, as they exhibit a variety of structural features and properties includingcatalysis, magnetism and photochemistry. In this paper, we make use of the conventional aqueoussolution methods to obtain extended structure constructed from lacunary polyoxotungstates,then we investigate the structures and proerties of these compounds. Extended structuresconstructed from TM-substituted polyoxotungstates. were characterized by elemental analyses,XPS, IR, TG, UV-vis and magnetic,et al.1、Two new compounds1and2, based lacunary Keggin-type polytungstate,and transitionmetal ions，have been synthesized：K₇Na₆[{DyIIIMn^Ш4（μ₃-O）₂（μ₂-OH）₂（H₂O）（CO₃）}(β-SiW₈O₃₁)₂]·21H₂O （1）K₉Na₆[{KMn^Ш4（μ₃-O）₂（μ₂-OH）₂（CO₃）}(β-SiW₈O₃₁)₂]·22H₂O （2）The heterometallic appended {MMn^III₄}(M=Dy³⁺and K⁺) cubanes were firstly trapped bytwo diamagnetic POM shells, which were robust enough to construct the inorganic crystallinetubular materials.2、A pure inorganic porous framework3based on the tungstoferrate [FeW₁₂O₄₀]5-, wasobtained by the conventional aqueous solution method,Fe（H₂O）₆H[Na6FeW₁₂O₄₀]₂·44H₂O （3）.compound3is composed of a porous inorganic framework [Na6FeW₁₂O₄₀]n with two kindsof pores A and B, accommodating Fe（H₂O）₆units in pore A, which was observed rarely in thepure inorganic framework..