The Preparation And Property Study Of Crystalline Fuctional Materials Based On Tungstate

Polyoxometalates are a subset of inorganic materials, comprising a large diversity of structures, and have an almost unmatched and tunable range of physical and chemical properties, such as high negative charge, remarkable redox characteristics, adjustable acidity and nanosize etc., which display extensive and long-term application prospects in catalysis, medicine and magnetic. The reasonable design and assembly of novel POM-based crystalline materials with unique functionalities by introducing specific polyoxometalates as inorganic building blocks, has become a key emerging area and hotspot in POM chemistry.Thirteen novel POM-based crystalline materials have been obtained through selecting different types of tungstates as building blocks based on the point of molecular design, self-assembly and surface modification. The synthetic rules and the relationships between structures and properties for these materials have been studied. The thermal stabilities, magnetic properties, electrochemical properties, catalytic properties and proton conductivities have also been investigated carefully.1. By acidifying the solution of Na2WO4 and then refluxing the mixture in the presence of [Mn12(CH3COO)16(H2O)4O12]·2CH3COOH·4H2O({Mn12}), a unique δ-Dawson-type cluster has been synthesized, which represents the first example of inserting Mn into the δ-type POMs.(CH3NH2CH3)6[H6(WO5)3W14MnIII2O44Cl2]·4H2O(1)The central [WO5], two belt [WO5] as well as the [Mn O4Cl] square pyramids make it different from the classic Wells-Dawson polyoxoanion. It has been structurally characterized by single crystal X-ray diffraction, TG, UV-vis, IR, XPS. Besides, the stability, electrochemical property, magnetic property and photocatalytic H2 evolution activity have been studied. Compared with traditional {P2W18}, 1 shows higher photocatalytic activity towards H2 evolution.2. Three high nuclear inorganic frameworks have been successfully synthesized based on the superlacunary {P2W12}/{P8W48} heteropolyanion and {Co2+} linkers via control of reaction conditions and crystallisation procedure.Na8Li8Co5[Co5.5(H2O)19P8W48.5O184]·60H2O(2)K2Na4Li11Co5[Co7(H2O)28P8W48O184]Cl·59H2O(3)K2Na4Li Co11[Co8(H2O)32P8W48O184](CH3COO)4Cl·47H2O(4)The experimental results show that relatively small changes in p H values could also lead to different crystalline compounds with different cobalt ions content and/or different distribution among inner and outer coordination sites. In 2 and 3, each {P8W48} fragment is linked to four others by means of Co–O–W linkages, generating 2D networks. In 4, {Co8P8W48} fragment is joined with twelve others to construct a 12-connected 3D network. 4 contains the largest-ever number of cobalt ions in the {P8W48}-based POMs and {P8W48} unit shows the highest number of connections.3. Seven organic-inorganic hybrid compounds built by Keggin and Wells-Dawson polyometalates with TM-trz complexes were obtained at different p H values under hydrothermal conditions, which exhibit 0D dimer, 1D chain, 2D planar network and 3D framework, respectively. The photocatalytic performances have been investigated with photodegradation of organic dyes under UV irradiation.[Cd(Htrz)3]2[Si W12O40]·2H2O(5)[Co2(H2O)2(Htrz)5][Si W12O40]·2.5H2O(6)[Zn5(Htrz)8(trz)2(H2O)8][Si W12O40]2·10H2O(7)[CuI2CuII4(Htrz)4(trz)4Cl2][Ge W12O40]·15H2O(8)[CuI2CuII4(Htrz)4(trz)4Cl2][Si W12O40]·15H2O(9)K2Na2(H2O)2[Co11(trz)14(H2O)14][P2W18O62]2·29H2O(10)[Cu12(trz)10(Htrz)2(OH)4(SO4)2(H2O)6][P2W18O62]·28H2O(11)Htrz = 1,2,4-triazole4. Two unique porous polyoxometalate-based metal-organic frameworks have been successfully constructed by introducting polyoxometalates with different charges and structures as building blocks, and two simple rigid ligands Hatz and Hmim.[Cu3(μ3-OH)(H2O)3(atz)3]3[P2W18O62]·14H2O(12)(H2mim)[NiIII(Hmim)4][H2Si W11NiIIO39(Hmim)]·3H2O(13)Hatz = 3-amino-1,2,4-triazolateHmim = 2-methylimidazoleCompound 12 consists of infinite single-walled metal–organic nanotubes, which are held together by Dawson-type cluster {P2W18}, leading to the unique nanotubular arrays. Compound 13 reveals a honeycomb-like structure with 1D channels along the c axis and the 1D channels have an aperture with a diameter of approximately 18.83 ?. These two compounds show excellent thermal stabilities.