Stoichiometric Variation of the Components in the Crystals Derived from Squaric Acid and Benzimidazole by Solvent Mediated Crystallization

The stoichiometric ratio of the components in the crystals based on squaric acid (SQ) and benzimidazole (BIMD) was altered by the solvent used in crystallization. Crystallization of a 1:1 mixture of SQ and BIMD in water, DMF, and an equal volumetric mixture of acetonitrile and water resulted in the formation of salts with 5:6, 1:2, and 1:1 stoichiometries of squarate anion to benzimidazolium cation, respectively. On the other hand, crystallizing 3:1 and 2:1 stoichiometries of the starting materials in water afforded 3:2 and 2:1 salt-cocrystals, respectively. This study reports the highest number of organic salt crystals prepared by using the same chemical components with different stoichiometric ratios. The solubility of the components and the salts in the solvent and the mixture of solvents used for crystallization played an important role in the stoichiometric variation of the components.