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During present work, the crystal of the organic salt (SA−.AHMP+) between salicylic acid and 2-amino-4- hydroxy-6-methylpyrimidine (AHMP) has been characterized using powder X-ray diffraction (PXRD), and FT-Raman. Then after, UV-Vis spectrum of SA−.AHMP+ is employed to estimate optical band gap using Tauc’s relation. The crystal structures and phase of the crystal have been investigated by combined analysis PXRD and Rietveld refinement. From PXRD analysis, cell parameters suggest that the SA−.AHMP+ belongs to orthorhombic structure. The vibrational signatures of the SA−.AHMP+ complex have been studied with the help of the Raman spectrum and DFT computation. The corrections in the vibrational frequencies at anharmonic oscillator approximation are made using the generalized second-order vibrational perturbation theory (GVPT2) at B3LYP/6-31G(d,p) level of theory. Moreover, nonlinear optical (NLO) properties of the SA−.AHMP+ complex are also studied at the same level of theory. [ABSTRACT FROM AUTHOR]

DFT and TD-DFT studies of o-phenylenediamine (PDA), 3,5-dinitrosalicylic acid (DNSA) and their charge transfer complex have been carried out at B3LYP/6-311G(d,p) level of theory. Molecular geometry and various other molecular properties like natural atomic charges, ionization potential, electron affinity, band gap, natural bond orbital (NBO) and frontier molecular analysis have been presented at same level of theory. Frontier molecular orbital and natural bond orbital analysis show the charge delocalization from PDA to DNSA. [ABSTRACT FROM AUTHOR]

The charge transfer (CT) complex of the 2-amino-4-hydroxy-6-methylpyrimidine and 2,3 pyrazinedicarboxylic acid (PDCA-.AHMP+) was synthesized and its single crystal was grown by solution method. The structure of the crystalline complex has been investigated by single crystal X-ray diffraction (SCXRD). The vibrational features of the complex have been studied with the help of FTIR spectra and DFT computation. The anharmonic corrections in vibrational frequencies are made using the GVPT2 method at B3LYP/6-311++G(d,p) level of theory. The frontier molecular orbitals and global chemical reactivity have been calculated to understand the pharmacological aspect of the synthesized crystal. Furthermore, Hirshfeld electrostatic potential (ESP) surface, void space in the crystal structure and natural as well as Mulliken atomic charges are studied. [ABSTRACT FROM AUTHOR]