Polymorphism observed in dapsone–flavone cocrystals that present pronounced differences in solubility and stability

Abstract

Four dapsone–flavone cocrystals were synthesized, including three polymorphic 1 : 1 cocrystals and a 1 : 2 cocrystal. Single crystal structures were disclosed, and the differences in H-bonding interactions were illustrated by comparison of the crystal structures and Hirshfeld surface analysis. The various cocrystals were fully characterized by X-ray powder diffraction, FTIR and thermal analysis. The solubilities, dissolution rates and form transformations in solution were determined. The phase transformation experiments revealed complex phase transformations among the cocrystals. Solid-state transformations among different stoichiometries were also observed in the dapsone–flavone system.