Synthesis and Characterization of Co-Crystallization of Pyridine 2, 6- Dicarboxylic Acid with Different Bases

Abstract

Three novel co-crystals of pyridine-2,6-dicarboxylic acid were successfully synthesized with nicotinamide, 2-amino-6-chlorobenzothiazole, and caffeine in a stoichiometric ratio of 1:2. The synthesis was carried out using a suitable solvent evaporation technique, resulting in the formation of stable crystalline products with appreciable yield. These co-crystals were structurally characterized through various analytical techniques, including UV–visible spectroscopy and Fourier Transform Infrared (FT-IR) spectroscopy, to confirm the formation of intermolecular interactions and functional group involvement. In addition, melting point determination and solubility studies were performed to evaluate their physicochemical properties. The spectroscopic analysis revealed significant shifts in characteristic absorption bands, indicating the formation of hydrogen bonding and other non-covalent interactions between the carboxylic acid groups of pyridine-2,6-dicarboxylic acid and the functional groups of the co-formers. The presence of carboxylate groups (C=O and C–O) plays a crucial role in facilitating these bonding interactions, contributing to the stability of the co-crystals. Furthermore, variations in melting points compared to the pure components confirmed the successful formation of new crystalline phases. Overall, all synthesized co-crystals exhibited good yield and enhanced physicochemical characteristics, suggesting their potential applicability in pharmaceutical and material science fields, particularly in improving solubility and stability of active compounds.

Keywords: Co-crystals synthesis, Pyridine-2,6-dicarboxylic acid, FT-IR spectroscopy, Hydrogen bonding interactions, Cocrystal characterization