Hydrogen bonded supramolecular structures of eight organic salts based on 2,6-diaminopyridine, and organic acids

Here anhydrous and hydrated multi-component organic acid-base salts of 2,6-diaminopyridine have been prepared with the organic acids as trichloroacetic acid, 3,5-dinitrobenzoic acid, 5-nitrosalicylic acid, 3,5-dihydroxybenzoic acid, 5-sulfosalicylic acid, m-phthalic acid, naphthalene-1,5-disulfonic acid, and glutaric acid. The eight crystalline compounds were characterized by X-ray diffraction analysis, infrared (IR), melting point (mp), and elemental analysis. Except salt 4, all structures adopted the hetero R22(8) supramolecular synthon. There were extensive N–H···O/O–H···O/N–H···N/N–H···S hydrogen bonds as well as CH···O, CH–N, CH–π, NH–π, π–π, C–π, Cl–O, and O–O interactions in the supramolecular architectures. The combination of these weak and strong hydrogen bonding associations in the crystal packing led to the formation of the 2D/3D structures.