New supramolecular cocrystal of 2-amino-5-chloropyridine with 3-methylbenzoic acids: Syntheses, structural characterization, Hirshfeld surfaces and quantum chemical investigations

Abstract 2-amino-5-chloropyridine: 3-methylbenzoic acid [(2A5CP) (3MBA)] ( I ) cocrystal was synthesized and its single crystal was grown by slow evaporation technique. The structure of the grown crystal was elucidated by using single crystal X-ray diffraction technique. The cocrystal belongs to the monoclinic crystallographic system with space group P2 1 /c, Z = 4, and a = 13.3155 (5) A, b = 5.5980 (2) A, c = 18.3787 (7) A, β = 110.045 (2)°. The crystal structure is stabilized by N pyridine -H∙∙∙O C, C O–H∙∙∙N pyridine and C–H⋯O type hydrogen bonding interactions. The presence of unionized –COOH functional group in the cocrystal was identified both by spectral methods and X-ray structural analysis. The experimental studies obtained by using the methods of single crystal X-ray analysis, powder X-ray diffraction (PXRD) analysis, FTIR, 1 H NMR and 13 C NMR spectroscopies confirmed the predicted cocrystal. The supramolecular assembly of the cocrystal was analyzed and discussed. The molecular geometry, vibrational frequencies of the compound in the ground state were calculated by using the density functional theory (DFT) method with 6–311++G (d,p) basis set and were compared with the experimental data. Additionally, HOMO–LUMO energy gap, natural bond orbital (NBO) analysis and nonlinear optical (NLO) properties of the compound were performed at B3LYP/6–311++G (d,p) level. Hirshfeld surfaces were used to confirm the existence of inter-molecular interactions in the compound.