Synthesis, physico-chemical characterization and quantum chemical studies of 2, 3-dimethyl quinoxalinium-5-sulphosalicylate crystal

2,3-dimethylquinoxalinum-5-sulphosalicylate (MQSA) was synthesized and grown into single crystals by slowly evaporating the solvent in methanol at room temperature. According to the lattice parame-ters found by the SCXRD analysis method ( a = 8.8031 (17) A, b = 17.768(3) A, c = 10.7979(16) and alpha = gamma = 90 degrees, beta = 90.611 (7) degrees), the crystal belongs to monoclinic crystal system with the P21/n space group. Moreover, powder X-ray diffraction investigation supported the crystalline nature. The compound's UV-Vis spectra exhibited a CT-band with a wavelength maximum of 372 nm, as well as its NIR spectra revealed good optical transmittance in the visible region with a low cut-off wavelength of 376 nm and an optical band gap of 5.12 eV. Dual emission bands at 418 and 484 nm are observed in the PL emis-sion spectra. The synthesized crystal was examined using FT-IR, FT-Raman, and NMR spectral methods. The crystal is thermally stable up to 274 degrees C, furthermore, TG-DTA and DSC methods were employed to study the degradation process. The second and third-order NLO efficiencies of the crystal was analyzed by Kurtz-Perry powder and Z-scan methods, respectively. The single crystal of MQSA is further studied through Hirshfeld surface analysis, fingerprint plots, and crystal voids analysis to understand the inter-moleculiar interactions and individual atomic arrangements inside the crystal. The H...H and O...H/H...O interactions are greatly aided by crystal structure. Additionally, the quantum computational methods were used to assess several molecular level electronic properties, including molecular orbitals, molecular elec-trostatic potentials maps, linear polarizability and static third-order nonlinear optical (NLO) polarizability, which is a molecular-level NLO response property. The isotropic linear polarizability and NLO polarizabil-ity of MQSA are 29.99 x 10 -24 esu and 28.45 x 10 -36 esu, respectively, in the M06-2X/6-311G* method, which demonstrates the decent potential of the synthesized crystal for its use as NLO materials. Further-more, the frontier molecular orbitals, molecular electrostatic potentials, and UV-Visible spectrum were calculated and discussed. (c) 2023 Elsevier B.V. All rights reserved.