Modification of the Supramolecular Hydrogen-Bonding Patterns of Acetazolamide in the Presence of Different Cocrystal Formers: 3:1, 2:1, 1:1, and 1:2 Cocrystals from Screening with the Structural Isomers of Hydroxybenzoic Acids, Aminobenzoic Acids, Hydroxybenzamides, Aminobenzamides, Nicotinic Acids, Nicotinamides, and 2,3-Dihydroxybenzoic Acids

Abstract

Acetazolamide (ACZ) has been combined via liquid-assisted grinding in water with a library of cocrystal formers derived from benzoic and nicotinic acid, which provided novel cocrystals with 2-hydroxybenzamide, 2-aminobenzamide, picolinamide, and 2,3-dihydroxybenzoic acid. The cocrystalline phases were identified first by XRPD analysis and then structurally characterized by IR spectroscopy and single-crystal X-ray diffraction analysis. These cocrystals and the previously reported cocrystalline phases obtained from 4-hydroxybenzoic acid and nicotinamide constitute a series of six cocrystals of varied stoichiometric ratios (3:1, 2:1, 1:1, and 1:2), which allowed for a profound analysis of the structural and chemical factors that govern their formation. The structural analysis has shown that the ACZ molecules participate in the dominant hydrogen-bonding patterns within the crystal structures: three cocrystal structures exhibit extended supramolecular aggregates of ACZ having channels, pores, or semispherical voids, in which the cocrystal formers are included as guest molecules, and can, therefore, be described as inclusion or clathrate complexes. One cocrystal can be considered as a pillared or intercalation compound, and the remaining two cocrystals are true two-component 2D or 3D networks. In addition, a variety of alternative preparative methods (liquid-assisted grinding, neat grinding, reaction crystallization, solution-mediated phase transformation, and solution crystallization) have been employed, showing that four of the six cocrystals required the presence of water for successful cocrystal formation