Novel solid form of prothioconazole and its crystallographic analysis

Abstract Prothioconazole is a broad spectrum anti-fungal agent of triazolinthione family; it has been widely used in crop protection especially in cereals. To date, only the crystal structure of form II and p-xylene solvates were reported, as per our knowledge, there are no other crystallographic reports in the literature. Here we report the dioxane solvate of prothioconazole with improved solubility. The novel form is completely characterized by powder XRD, DSC, TGA and finally by single-crystal XRD. In the present investigation, we compared the arrangement of molecules and hydrogen bonding interactions in prothioconazole form II, p-xylene solvate and novel 1,4−dioxane solvate. The crystal structure analysis revealed that prothioconazole form II crystallized in monoclinic crystal system with P21/n space group and molecules are held together by N···Cl interactions and N–H⋯O hydrogen bonding interactions. The p-xylene solvate crystallized in P21 space group and molecules are held together by N–H⋯N and C–S⋯Cl interactions. Whereas the novel solid form crystallized in the triclinic crystal system with P−1 space group and molecules are held together by N⋯O interactions. The novel solid form has shown improved solubility compared to reference drug.