Hydrogen bonded supramolecular framework in organic acid–base adducts: Crystal structures of five cocrystals/salts assembled from 2-methylquinoline with monocarboxylic acid, dicarboxylic acid, and tricarboxylic acid

Studies concentrating on noncovalent weak interactions between the organic base of 2-methylquinoline, and carboxylic acid derivatives have led to an increased understanding of the role 2-methylquinoline has in binding with carboxylic acid derivatives. Here anhydrous and hydrous multicomponent organic acid–base adducts of 2-methylquinoline have been prepared with carboxylic acids that ranged from monocarboxylic acid to tricarboxylic acid such as 3,5-dinitrobenzoic acid, 3-hydroxy-2-naphthoic acid, oxalic acid, fumaric acid, and citric acid.The five crystalline complexes were characterized by X-ray diffraction analysis, IR, mp, and elemental analysis. These structures adopted homo or heterosupramolecular synthons or both. Analysis of the crystal packing of 1–5 suggests that there are NH⋯O, OH⋯N, and OH⋯O hydrogen bonds (charge assisted or neutral) between acid and base components in the studied compounds. Except the classical hydrogen bonding interactions, the secondary propagating interactions also play an important role in structure extension. These weak interactions are responsible for the formation of 1D–3D frameworks.

► Five organic acid-base adducts assembled from 2-methylquinoline with carboxylic acid derivatives have been prepared. ► The five compounds are characterized by XRD, IR, mp, and elemental analysis. ► The classical hydrogen bond interaction modes in the compounds have been ascertained. ► The secondary propagating interactions are also analyzed.