Structure, proton conductivity and molecular dynamics of guanidine zinc sulfate

The role of molecular and proton dynamics in the electrolyte system, guanidinium zinc sulfate, is studied using the solid state NMR technique in combination with detailed analysis of impedance spectra and X-ray results. Single crystals of guanidinium zinc sulfate, [C(NH2)3]2Zn(SO4)2, were grown and the crystal structure was characterized at 150 K and re-determined at room temperature (295 K) using single-crystal X-ray diffraction. The dynamics of protons in the ordered and disordered crystalline phases was characterized by 1H NMR spectra analysis, whereas complex impedance studies yielded information on the temperature characteristics of the electric conductivity and activation energy of proton diffusion in the bulk of the crystal. The obtained results give a clear picture of the electrical conductivity process (chemical exchange of protons and proton diffusion within the hydrogen bonds in the bulk of the crystal) in relation to the crystal molecular dynamics studied.