Structural and supramolecular insights into crystalline multicomponent systems of 2,4-diamino-6-phenyl-1,3,5-triazine with various carboxylic acids

Three multicomponent systems, namely, 2,4-diamino-6-phenyl-1,3,5-triazine–nicotinic acid (DAPT–NA), C₉H₉N₅·C₆H₅NO₂, (I), 2,4-diamino-6-phenyl-1,3,5-triazin-1-ium hydrogen malonate (DAPT–MMA), C₉H₁₀N₅⁺·C₃H₃O₄⁻, (II), and 2,4-diamino-6-phenyl-1,3,5-triazin-1-ium hydrogen (+)-dibenzoyl-d-tartarate (DAPT–DBTA), C₉H₁₀N₅⁺·C₁₈H₁₃O₈⁻, (III), have been synthesized and characterized via single-crystal X-ray diffraction, and their supramolecular interactions have been analysed. The formation of cocrystal (I) and salts (II) and (III) was confirmed through the widening of the C—N—C bond angle of the triazine moiety of 2,4-diamino-6-phenyl-1,3,5-triazine and the difference in the C—O bond distances between the carboxyl and carboxylate groups of the respective carboxylic acids. Cocrystal (I) and salt (II) form robust homomeric and heteromeric R₂²(8) ring motifs through primary acid–base interactions and complementary base pairing. In cocrystal (I), the complementary base pair exists as wave-like supramolecular strands, whereas in salt (II), it exists as a discrete pair. Salt (II) exhibits DDDAAD sextuple and DADA quadruple hydrogen-bonded arrays (D is donor and A is acceptor) through acid–base interactions and generates a supramolecular rosette-like architecture. In salt (III), the presence of carboxyl–carboxylate interactions and acid–base interactions led to the development of a supramolecular sheet and tunnel-like architecture. Cocrystal (I) and salt (III) are stabilized through offset aromatic π–π stacking interactions and C—H…π interactions, and salts (II) and (III) are stabilized via weak carbonyl–π and C—H…O hydrogen bonds. Macrocyclic R₁₂¹²(64) and R₃³(24) motifs are present in salts (II) and (III), respectively. Hirshfeld surface analysis of (I)–(III) reinforces the fact that N…H/H…N, O…H/H…O and C…H/H…C interactions contribute to the crystal packing and stability.