The implications of various molecular interactions on the dielectric behavior of cimetidine and cimetidine hydrochloride

Herein, we employed broadband dielectric spectroscopy to characterize the molecular dynamics of the two related materials, cimetidine base and cimetidine hydrochloride, with similar structural skeletons but involving different molecular interactions (ionic vs. non-ionic). BDS experiments performed at ambient and elevated pressures, combined with rheology and temperature-modulated calorimetry studies, revealed significant discrepancies in the supercooled dynamics of both samples. The strong electrostatic interactions resulted in slower dynamics of the ionic counterparts, manifested by a higher Tg value. However, the samples exhibited some similarities in the glassy dynamics. The dielectric response of cimetidine hydrochloride revealed features similar to those previously observed for the other molten hydrochloride salts, wherein decoupling between the timescales of the structural and ionic displacements affirms the universal character of the behavior presented herein.