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

Abstract

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.