Eleven supramolecular adducts of 5,7-dimethyl-1,8-naphthyridine-2-amine and organic acids assembled by classical hydrogen bonds and other noncovalent intermolecular interactions

This article demonstrates 5,7-dimethyl-1,8-naphthyridine-2-amine based supramolecular adducts formation in eleven crystalline solids 1-11, in which the acidic moiety have been integrated. Addition of equivalents of the acid to the solution of 5,7-dimethyl-1,8-naphthyridine-2-amine generates the corresponding supramolecular assemblies. Except 8, all the compounds crystallize as their organic salts with the acidic proton at the organic acids transferred to the aromatic nitrogen of the 5,7-dimethyl-1,8-naphthyridine-2-amine moiety. All adducts have been characterized through IR, mp, elemental analysis and X-ray single crystal diffraction technique. The major driving force in the adducts 1-11 is attributed to the classical hydrogen-bonds arising from 5,7-dimethyl-1,8-naphthyridine-2-amine and the acids. The other extensive non-covalent interactions also play great functions in space association of the molecular counterparts in relevant crystals. The homo or hetero supramolecular synthons or both were found at these adducts. The common R22(8) graph set has been observed in all of the adducts due to the H-bonds and the non-covalent associations. For the synergistic interactions of the classical H-bonds and the various non-covalent associations, these adducts displayed 2D/3D structures.