Structure of seven organic salts assembled from 2,6-diaminopyridine with monocarboxylic acids, dicarboxylic acids, and tetracarboxylic acids

• Seven organic salts have been prepared and structurally characterized.
• The interactions between 2,6-diaminopyridine and carboxylic acid have been ascertained.
• All structures adopted the hetero R22(8) supramolecular synthon.
• Hydrogen bonds are the primary intermolecular force in these salts.
• The secondary propagating interactions also play important roles in the packing of the compounds.

Studies concentrating on non-covalent interactions between the organic base of 2,6-diaminopyridine, and carboxylic acids have led to an increased understanding of the role 2,6-diaminopyridine in binding with carboxylic acid derivatives. Here anhydrous and hydrated multi-component organic acid-base salts of 2,6-diaminopyridine have been prepared with the carboxylic acids as nicotinic acid, o-chlorobenzoic acid, 1,3-benzodioxole-5-carboxylic acid, 3,5-dinitrosalicylic acid, 4-nitro-phthalic acid, 1,4-cyclohexanedicarboxylic acid, and butane-1,2,3,4-tetracarboxylic acid. The seven crystalline compounds were characterized by X-ray diffraction analysis, infrared (IR), melting point (mp), and elemental analysis. All structures adopted the hetero R22(8) supramolecular synthons. The supramolecular architectures bear extensive NH⋯N, OH⋯N, OH⋯O, NH⋯O, and CH⋯O associations as well as other nonbonding contacts as CHN, CH2O, π–π, C–π, O–π, Cl–π, ClO, and OO interactions. The role of weak and strong hydrogen bonding in the crystal packing is ascertained.