Syntheses,Catalytic Properties And Proton Conduction Of Polymolybdate(polytungsdate) With Extended Structures

A series of novel functional extended structures based on polyoxomolybdate and polyoxotungstate are obtained by modified with different transition metals,rare-earth metals and organic ligands under hydrothermal condition in this thesis.The optimum synthetic conditions for these compounds are determined by the exploration of reaction conditions.All of these compounds are characterized by single crystal X-ray diffraction analysis,powder X-ray diffraction analysis and thermogravimetric analysis.The magnetic,catalytic and proton conduction properties of these compounds are discussed on the basis of their compositions and structures.The main research results are included as follows:1.A bifunctional catalyst with Lewis acid catalysis and visible-light photocatalysis has been successfully synthesized under hydrothermal condition.Compound 1 is a novel 3D POMs-based trinuclear-copper coordination polymer with[?-Mo₅O₁₈]^6-anion as template.Each trinuclear-copper unit of 1 has coordination water site and could be used as Lewis acid catalytic site after thermal activated.1 possesses good Lewis acid catalytic activity for cyclohexanone ketal reaction.The band gap of 1 is 2.34 eV,which is calculated by UV-vis diffuse reflectance spectra?UV-vis DRS?,and 1 is an effective photocatalyst for photodecomposition of RhB under visible light.In addition,Cu²⁺ions of trinuclear-copper unit exit antiferromagnetic interactions.{H₂[Cu₃?H₂O??trz?₃??₃-OH?]₂[?-Mo₅O₁₈]}·3H₂O?1?2.A chain polymer based on[?-Mo₈O₂₆]^4-has been synthesized by hydrothermal synthesis method.Each[?-Mo₈O₂₆]^4-unit is linked by terminal oxygen and formed 1D chain polymer based on[?-Mo₈O₂₆]^4-.The 2D supramolecular layer and 3D supramolecular network formed by N/O-H···O hydrogen bond interactions between the adjacent{[?-Mo₈O₂₆]_n}^4n-chains,2D supramolecular layer and TEDA.The band gap of compound 2 is calculated by UV-vis DRS.2is an effectively photocatalyst for visible-light decomposing RhB.In addition,2 is a kind of good proton conductive material with proton conductivity of 4.18×10^-4 s cm^-1 at 85 ^oC and 97%relative humidity.{H₄[TEDA][?-Mo₈O₂₆]}·3H₂O?2?3.A 3D supramolecular structure has been synthesized under hydrothermal condition.Compound 3 is composed of 1,2,4-triazole,piperazine and[PMo₁₂O₄₀]^3-anions.N-H···O hydrogen bond interactions between 1,2,4-triazole and[PMo₁₂O₄₀]^3-,which form 3D supramolecular network of 3.The free proton H⁺,1,2,4-triazole and[PMo₁₂O₄₀]^3-unit in the structure form anhydrous hydrogen bonding pathway for high temperature proton conduction.The band gap of 3 is 1.32 eV,and the photodecomposition rate of RhB of 3 is 99.2%under visible light.H₆?pip??trz?₅[PMo₁₂O₄₀]₂?3?4.Two Ln-POMs compounds with pure inorganic framework have been synthesized by self-assembly of rare-earth metals substituted POMs under hydrothermal condition.Dimer{[Nd^??H₂O?(GeW₁₁O₃₉)]₂}^10-and[Na?H₂O?₂]⁺units form the 2D plane structure of compound4.The adjacent 2D plane form the 3D network structure through the O-H···O hydrogen bond interaction of crystalline water,coordination water and O atoms of{[Nd^??H₂O?(GeW₁₁O₃₉)]₂}^10-.Compound 5 is composed of two[Ce?H₂O?₅]³⁺and a[Ce^??H₂O?₃(As₂W₁₇O₆₁)]^7-units,the structure of 5 is a 3D pure inorganic framework.Proton H⁺,crystalline water and coordination water make 4 and 5 candidates for proton conduction materials,their proton conductivities were 1.28×10^-3 S cm^-11 and 4.59×10^-3 S cm^-1 at 75 ^oC and 97%RH,respectively.In addition,antiferromagnetic interactions exist in two Nd³⁺centers of compound 4 and three Ce³⁺centers of compound 5.{H₅[Co?2,2'-bpy?₃]₂[Na?H₂O?][Nd^??H₂O?(GeW₁₁O₃₉)]₂}·10H₂O?4?{H[Ce^??H₂O?₅]₂[Ce^??H₂O?₃(As₂W₁₇O₆₁)]}·6H₂O?5?5.A modified sandwich germanium tungstate based on[Co₄?H₂O?₂(GeW₉O₃₄)₂]^12-has been successfully synthesized by hydrothermal method.Compound 6 exhibits excellent Lewis acid activity for cyclohexanone ketal reaction due to four coordination water active sites formed after loss of coordination water.The band gap calculated by UV-vis DRS is 1.67 eV,and 6shows good photodegcomposition of RhB under visible light.The antiferromagnetic interactions exist between Co²⁺ions in 6.{[H₂[Co?2,2'-bpy?₃][Co?2,2'-bpy?]₂[Co?2,2'-bpy?₂?H₂O?]₂-[Co₄?H₂O?₂(GeW₉O₃₄)₂]}·4H₂O?6?6.Two Keggin-type POMs-based organic-inorganic hybrid materials have been synthesized under hydrothermal condition.[PW₁₂O₄₀]^3-and[GeW₁₂O₄₀]^4-as inorganic nodes form 2D plane structures in 7 and 8.The adjacent 2D plane structures form 3D supramolecular structures through the C-H···O hydrogen bond interactions between the organic ligand 2,2'-bpy,4,4'-bpy and O atom of POMs in 7 and 8.Band gap of 7 and 8 are 2.59 eV and 2.78 eV,respectively.7 and 8 exhibit excellent photocatalytic activity for decomposition of RhB under visible light.In addition,antiferromagnetic interactions between Co²⁺ion in 7.H[Co^??2,2'-bpy?₂][PW₁₂O₄₀]?7?[Cu₄^I?4,4'-bpy?₈][GeW₁₂O₄₀]?8?...