Syntheses And Properties Of Proton Conductors And Their Composites Based On SiW₁₂O₄₀^4-,Cu²⁺ And Schiff Base

Because of their potential applications and intrinsic aesthetics value, the construction ofsupramolecular assemblies which are from organic and/or inorganic molecular building blocks hasdeveloped rapidly in many areas, such as coordination chemistry, crystal engineering and materials science,inorganic chemistry. In the construction of supramolecular compounds, polyoxometalates (POMs), whichare distinct metal oxide clusters with many properties and applications, are an excellent class of functionalinorganic building blocks. The properties of POMs can be modified depending on the structure, elementalcomposition and counteractions. Moreover, making the organic substituents anchor on the POM surfaceoffers the new possibility to harmonize the electronic character of the resulting complexes, such as thesolubility and proton conduction.In this paper, we have succeeded in constructing a new solid proton conductor (complex1):{[Cu3(L)2(H2O)4][Cu(DMF)4(SiW12O40)]·9H2O}n(L=N,Nˊ-bis[1-(2-methoxyphenol-6-yl)methylidene]hydrazine hydrate) by the controllable self-assembly of L, metal ions Cu2+and Keggin-anions(SiW4-12O40).Notably, X-ray single crystal structure analysis showed that the compound crystallized in the triclinic spacegroup Pī; Infrared analysis showed that the Keggin-type polyanion and the ligand molecule L were in thecompound; thermal gravimetric analysis result showed that its structure did not alter below100°C; watervapour adsorption isotherm test showed that it had water vapour absorption capacity in humid environment;AC impedance test results showed that it achieved good proton conductivities(10-4~10-3S·cm-1) in thetemperature100°C under relative humidity range35–98%, the activation energy is0.32eV; Analysis of X-ray powder diffraction data showed that the sample structure did not change before and after the protonconductivity measurement.Second, based on silica gel and SBA-15as the host materials and complex1as a guest material, wedesigned two composite materials:1–SG and1–SBA-15. They have been tested by infrared analysis,X-ray powder diffraction analysis, water vapour adsorption isotherm, thermal gravimetric analysis and theproton conducting performance. Infrared analysis proved that complex1and the host materials consistedin the composites; TG test represented that they had the loss of the majority of water in the temperature100°C; water vapour adsorption isotherm test showed that their bibulous abilities were very strong; ACimpedance test indicated that they had good proton conductivity; the X-ray powder diffraction analysisdata showed that their structures did not changed before and after the conductivity measurement.In addition, we also chosed the good proton conductive Keggin structure heteropoly acid(H3PMo12O40·6H2O and H3PW12O40·6H2O) and the ligand isonicotinic acid N-oxide(HINO) as rawmaterials, to successfully get two new proton conductors(complex2{[H3(H2O)11](HINO)4(PMo12O40)}nand complex3{[H3(H2O)11](HINO)4(PW12O40)}n) by the self assembly of molecular unit in thewater/acetonitrile solution at room temperature. At the same time, we made use of the sol-gel method toobtain several different ratios silica gel composites:2–SG1,2–SG2,3–SG1,3–SG2based on silicagel as the host material and the above complexes as the guest materials. They have been tested by infraredanalysis, X-ray powder diffraction analysis, water vapour adsorption isotherm, thermal gravimetricanalysis and the proton conducting performance.