Structural, vibrational and electronic absorption characteristics of the monohydrate organic salt of 2-amino-5-bromo-6-methyl-4-pyrimidinol and 2,3-pyrazinedicarboxylic acid: A combined experimental and computational study

The monohydrate 1:2 organic salt of 2-Amino-5-bromo-6-methyl-4-pyrimidinol (ABMP), also known as 5-Bromo-6-methylisocytosine, with 2,3-pyrazinedicarboxylic acid (PDCA) has been synthesized by slow evaporation technique. The hydrated salt has been characterized by single crystal X-ray diffraction (SCXRD) and observed to crystallize in the orthorhombic space group P2(1)2(1)2(1). The infrared absorption spectroscopic technique combined with density functional theory (DFT) simulations have been employed to analyse the vibrational modes of the synthesized organic salt. Further, the FTIR spectra confirm that the salt formation from their unique spectroscopic feature as compared to its constituent molecules, PDCA and ABMP. The estimation of the optical band gap and maximum absorption wavelength of the hydrated organic salt have been performed using UV-Vis absorption spectroscopy. Degradation profile, as well as associated DTA peaks of the synthesized organic salt, have been critically analyzed by thermal gravimetric-differential thermal analysis (TG-DTA). Moreover, the Hirshfeld surface and associated fingerprint plot studies have been characterized the non-covalent interaction and their relative proportions to the present organic salt. The remaining important molecular properties like the frontier molecular orbital, nonlinear optical properties (NLO) and molecular electrostatic potential (MEP) map have also been studied for the above organic salt. (C) 2018 Elsevier B.V. All rights reserved.