Conformational polymorphs of 3-cyclopropyl-5-(3-methyl-[1,2,4]triazolo[4,3-a]pyridin-7-yl)-1,2,4-oxadiazole

The dipharmacophore compound 3-cyclopropyl-5-(3-methyl-[1,2,4]triazolo[4,3-a]pyridin-7-yl)-1,2,4-oxadiazole, C12H11N5O, was studied on the assumption of its potential biological activity. Two polymorphic forms differ in both their molecular and crystal structures. The monoclinic polymorphic form was crystallized from more volatile solvents and contains a conformer with a higher relative energy. The basic molecule forms an abundance of interactions with relatively close energies. The orthorhombic polymorph was crystallized very slowly from isoamyl alcohol and contains a conformer with a much lower energy. The basic molecule forms two strong interactions and a large number of weak interactions. Stacking interactions of the 'head-to-head' type in the monoclinic structure and of the `head-to-tail' type in the orthorhombic structure proved to be the strongest and form stacked columns in the two polymorphs. The main structural motif of the monoclinic structure is a double column where two stacked columns interact through weak C-H center dot center dot center dot N hydrogen bonds and dispersive interactions. In the orthorhombic structure, a single stacked column is the main structural motif. Periodic calculations confirmed that the orthorhombic structure obtained by slow evaporation has a lower lattice energy (0.97 kcal mol(-1)) compared to the monoclinic structure.

Automated summary

The study on a dipharmacophore compound revealed two polymorphic forms with different molecular and crystal structures, varying in conformers and energy levels. The monoclinic form showed an abundance of interactions with close energies, while the orthorhombic form had fewer but stronger interactions. Stacking interactions differed between the two forms, with the monoclinic structure having 'head-to-head' type interactions and the orthorhombic structure having 'head-to-tail' type interactions, leading to stacked columns. Periodic calculations confirmed the lower lattice energy of the orthorhombic structure compared to the monoclinic structure.