Ionic cocrystals can be obtained when organic molecules, including APIs, are cocrystallized with inorganic salts. In ionic cocrystals (ICCs) the dominant interactions have an electrostatic nature, with the possible additional contribution of hydrogen bonds between common donor and acceptors (OH, NH, O, N, etc.) and between HB donors and anions (OH···Cl−, NH···Br−, etc.). Because of the strong Coulombic interactions, the change in physicochemical properties with respect to those of the organic molecule associated with ICC formation is expectedly more dramatic than with most molecular cocrystals. Moreover, since some inorganic salts are admitted by the pharmacopoeias, they are suitable coformers.
Co-crystallization with inorganic salts also offers a viable route to the resolution of racemic mixtures by using enantiopure coformers.
Prof. Dario Braga, Prof. Fabrizia Grepioni, Dr. Oleksii (Alex) Shemchuk.