Synthesis And Characterization Of Organic-inorganic Hybrid Compound Constructed From Polyoxometalate And Nitrogen Organic Components

Three new type polyoxometalates were successfully synthesized by hydrothermal method and natural evaporation method with the saturated Keggin or lacunary type polyoxometalate and transition metal ions as the inorganic building blocks,and salicylidence thiosemicarbazone?H₂L?as the organic building blocks.Their crystal structures have been determined by X?ray single?crystal diffraction,elemental analyses,IR spectra,and thermo gravimetric analyses.the assorptive property,thermal stability and electrochemical properties of the compounds were also investigated by adsorption experiments,TG?DSC,CV and the other methods.1.A novel compound modified by 1,3,4?thiasiazole was synthesized with salicylidene thiosemicarbazone and polyoxometalates of Keggin type:[C₈H₇N₃OS]₄{[C₈H₈N₃OS]₂[HPW₁₂O₄₀]}·7H₂O?1? Salicylidene thiosemicarbazone reacted in?situ cyclization reaction to generate the 1,3,4?thiasiazole,and combination with polyoxoanion by H?bond and???stacking formed a 3D supramolecular compound.The compound 1 crystallized in a triclinic crystal system,with space group P?1?2?.The cyclic voltammogram indicated that three couples redox waves were observed on the compound.2.The polyoxometalate compound modified by metal?organic framework has been obtained with salicylidene thiosemicarbazone,H₃PW₁₂O₄₀·xH₂O and CH₃OH,DMF assolvent under natural evaporation method:[Co^II?C₈H₈N₃OS?₂]₂[HPW₁₂O₄₀]·4DMF?2? In this compound,polyoxoanion contact with six?coordinated complexes formed by Co²⁺and salicylidene thiosemicarbazone through H?bond and electrostatic attraction,constituted a three?dimensional open?framework.The compound 2 crystallized in a monoclinic crystal system,with space group P2?1?.3.A new polyoxometalate compound which is heteroatom replace by Ni was synthesized with H₄SiW₁₂O₄₀·xH₂O and Ni?NO₃?₂:[Ni^III?C₈H₈N₃OS?₂]₂[Ni^IIW₁₂O₄₀]·2H₂O?3? In this compound,polyoxoanion contact with six?coordinated complexes formed by Ni³⁺and salicylidene thiosemicarbazone through H?bond and electrostatic, constituted a two?dimensional layered structure.The compound 3 crystallized in a triclinic crystal system,with space group P-1.The cyclic voltammogram indicated that three couples redox waves were observed on the compound.4.In the above two kinds of organic?inorganic hybrid materials?compound 2 and 3?as the adsorbent,the effects of adsorbent,initial concentration and reaction time on the decolorization were studied.The maximum adsorption capacities of compound 2 on methylene blue were 16.67 mg/g,the maximum adsorption capacities of compound 3 on rhodamine B were 17.86 mg/g.The optimum reaction time was 30 min.Both of them were more likely to fit the secondary dynamic model,and the adsorption process was chemisorption.