The competition between cocrystallization and separated crystallization based on crystallization from solution

Abstract

The competition between cocrystallization and separated crystallization in a solvent was explored via X-ray diffraction and high-performance liquid chromatography methods in different solvents and by considering the solvent evaporation rate. The results revealed that the solvent system and solvent evaporation rate can affect the nucleation order of the cocrystal and coformers in the solution. In fact, solubility tests in different solvents confirmed that the solubility plays a key role in the cocrystal formation process. Furthermore, the width of the metastable zone influenced the solute nucleation order and was a decisive factor in the cocrystal formation process when the solvent evaporation rate was varied. Cocrystals could therefore be obtained by adjusting the solvents and solvent evaporation rate. The preparation of kinetic 2,4,6,8,10,12-hexanitrohexaazaisowurtzitane–2,4,6-trinitrophenol cocrystals via rapid solvent evaporation proves the practicability of this theory.