Abstract:

A new heteropolyacidorganic charge transfer salt (C3H5N2)3[PMo12O40] was synthesized from phosphomolybdic acid and imidazole, and characterized by means of elemental analysis, infrared spectrum(IR), diffuse reflectance spectrum(DRS), electron spin resonance(ESR) and thermal analysis techniques(TG). The decomposition mechanism and nonisothermal kinetic parameters of the salt were obtained from an analysis of the TG-DTG curves obtained by means of the single scanning methods(the Achar method and CoatsRedfern method). For the first step of the thermal decomposition reaction, the possible reaction mechanism was suggested to be a threedimensional diffusion. Its kinetic equation with parameters is dα/dt=1.58×108[1-(1-α)1/3]-1(1-α)2/3exp(-40 931.0/T), with E=34030 kJ/mol and A=1.05×108 s-1. The salt shows photochromism under ultraviolet light, and its photochromic reaction was studied with solid diffuse reflectance spectra and found to exhibit firstorder or pseudofirstorder kinetics with a rate constant k=9.80×10-5 s-1.

Key words: phosphomolybdic acid,imidazole,chargetransfer salt,thermal decomposition,photochromism,kinetics