Five 3D supramolecular frameworks assembled from classical directional hydrogen-bonds and C[sbnd]H⋯O associations between carboxylic acids and bis-imidazoles

Abstract

Five crystalline organic acid–base adducts derived from bis(N-imidazolyl) and carboxylic acid (p-nitrobenzoic acid, m-nitrobenzoic acid, 3,5-dihydroxybenzoic acid, sebacic acid, and fumaric acid) were prepared and characterized by X-ray diffraction analysis, IR, mp, and elemental analysis. Of the five compounds three are organic salts (1, 3, and 5) and the other two (2, and 4) are cocrystals. In salts 1, and 5, the L1 are diprotonated, while in 3 the L1 is only monoprotonated.All supramolecular architectures of the adducts 1–5 involve extensive intermolecular NH⋯O, OH⋯O, and CH⋯O hydrogen bonds as well as other noncovalent interactions. The role of weak and strong noncovalent interactions in the crystal packing is ascertained. All the complexes displayed 3D framework structure for the synergistic effect of the various noncovalent interactions.The results presented herein indicate that the strength and directionality of the N+H⋯O−, OH⋯O, and OH⋯N hydrogen bonds between carboxylic acids and ditopic imidazoles are sufficient to bring about the formation of binary cocrystals or organic salts.