Spherical Crystallization of Carbamazepine/Saccharin Co-Crystals: Selective Agglomeration and Purification through Surface Interactions

Abstract

Spherical crystallization involves crystallization and simultaneous agglomeration of a crystalline particle using an immiscible phase, which has preferential affinity for the crystal surface. Here, we report application of a spherical crystallization technique to the field of co-crystallization. Carbamazepine/saccharin (CBZ/SAC) co-crystals were generated using reverse antisolvent addition and agglomerated using different bridging liquids. Two crystal forms of CBZ/SAC co-crystals were formed, depending on the levels of supersaturation achieved during processing. The selective agglomeration of co-crystal occurred during the agglomeration stage, depending on the relative interaction between bridging liquid and the crystal surfaces. The computational investigation of isosteric heats of adsorption of the bridging liquids at the prominent crystal surfaces proved to be a useful tool in understanding the surface interactions. The spherical crystallization technique shows opportunity to generate co-crystals and its purification through selective agglomeration.