Crystal structure analysis of the biologically active drug mol-ecule riluzole and riluzolium chloride.

ABSTRACT: This study is an investigation into the crystal structure of the biologically active drug mol-ecule riluzole [RZ, 6-(tri-fluoro-meth-oxy)-1,3-benzo-thia-zol-2-amine], C₈H₅F₃N₂OS, and its derivative, the riluzolium chloride salt [RZHCl, 2-amino-6-(tri-fluoro-meth-oxy)-1,3-benzo-thia-zol-3-ium chloride], C₈H₆F₃N₂OS⁺·Cl^-. In spite of repeated efforts to crystallize the drug, its crystal structure has not been reported to date, hence the current study provides a method for obtaining crystals of both riluzole and its corresponding salt, riluzolium hydro-chloride. The salt was obtained by grinding HCl with the drug and crystallizing the obtained solid from di-chloro-methane. The crystals of riluzole were obtained in the presence of l-glutamic acid and d-glutamic acid in separate experiments. In the crystal structure of RZHCl, the -OCF₃ moiety is perpendicular to the mol-ecular plane containing the riluzolium ion, as can be seen by the torsion angle of 107.4?(3)°. In the case of riluzole, the torsion angles of the four different mol-ecules in the asymmetric unit show that in three cases the tri-fluoro-meth-oxy group is perpendicular to the riluzole mol-ecular plane and only in one mol-ecule does the -OCF₃ group lie in the same mol-ecular plane. The crystal structure of riluzole primarily consists of strong N-H?N hydrogen bonds along with weak C-H?F, C-H?S, F?F, C?C and C?S inter-actions, while that of its salt is stabilized by strong [N-H]⁺?Cl^- and weak C-H?Cl^-, N-H?S, C-H?F, C?C, S?N and S?Cl^- inter-actions.

SUBMITTER: Mondal PK 

PROVIDER: S-EPMC6690469 | biostudies-literature | 2019 Aug

REPOSITORIES: biostudies-literature