On the molecular origin of secondary relaxations in amorphous protic ionic conductor chlorpromazine hydrochloride — High pressure dielectric studies

Abstract In this paper, we report the study of sub-Tg dynamics of chlorpromazine hydrochloride. The substance is another pharmaceutical and glass-forming protic ionic conductor investigated by our group. We describe both ionic and dipolar behaviors and show the way in how to tell them apart. Mainly, we focus on the dynamics of the slower of the two secondary relaxation processes found. By means of the dielectric spectroscopy we study its behavior as a function of temperature and pressure. Moreover, on the basis of quantum-mechanical calculations, we designate the mechanism for faster secondary relaxation as the conformational change of the dimethylamine group. Finally, we compare the findings with data of lidocaine hydrochloride, procaine hydrochloride and procainamide hydrochloride to answer the question of which features are typical for the protic ionic glasses and which are associated with specific chemical structure.