Noncovalent-bonded 2D-3D supramolecular adducts from 6-methylpyridine-3-carboxamide and carboxylic acids

Abstract

Cocrystallization of 6-methylpyridine-3-carboxamide, with mono- to dicarboxylic acids coformers afforded a total of six novel adducts including three co-crystals (2, and 5–6) and two salts (1, and 3–4). They have been featured by SCXRD, IR and EA, their m.p. were also measured. Their structural and supramolecular facets are fully inspected. The result tells that in all salts the aryl N in 6-methylpyridine-3-carboxamide is the only protonated position. The crystal packing is woven by the strong NH···O, OH···N and OH···O H-bonds. The CONH2 dimers were made in 1 and 6 by a pair of NH···O H-bonds. Deep view of the crystal packing uncovered that different sets of subsidiary CH···O/CH3···O, O···I, I···I, O···π, π···C, CH···π and π···π contacts contribute to the stabilization and expansion of the final 2D-3D structures. For the delicate balance of the various non-covalent bonds these structures contained homo/hetero supramolecular synthons or both, the common R22(8) graph set has been enclosed in all for the cooperation of H-bonds and non-covalent contacts.