Solid-state studies of the triclinic (Z' = 2) antiprotozoal drug ternidazole.

The solid-state properties of antiprotozoal ternidazole (3-(2-methyl-5-nitroimidazol-1-yl)-propan-1-ol) have been studied. Crystals are triclinic in the temperature interval between 100 and 333 K (melting point) with two different molecular conformations present in the asymmetric unit (Z' = 2) and two of each conformer make up a tetramer held together by hydrogen bonding. Its melting enthalpy at 333 K is 25.65 (± 1.29) kJ · mol(-1). Linear plots were obtained for the melting temperature versus pressure (dP/dT = 5.67 (± 0.08) MPa · K(-1)] and the glass transition versus pressure [dP/dT = 7.73 (±1.76) MPa · K(-1)]. No crystalline polymorphism could be detected; thus, the single-crystal structure that has been found is most likely the stable one.