Cocrystallization of 2,3-dimethylquinoxaline with 3,5-dinitrobenzoic acid: Crystal structure, Hirshfeld surface, spectroscopic features and DFT studies

A new cocrystal (DMQNB) of 2,3-dimethylquinoxaline with 3,5-dinitrobenzoic acid has been grown by slow evaporation method and its crystal structure is characterized by single crystal X-ray diffraction analysis (SCXRD). The structure is found to be monoclinic with space group P21/n and lattice parameters (a = 15.55 Å, b = 5.82 Å, c = 18.64 Å). Hirshfeld surface and its associated fingerprint plots were used to investigate the intermolecular close contact and their percentage contribution in the crystal structure. The characteristics of the functional groups present in the crystal are explored by the FTIR, FT-Raman and FT-NMR spectral analysis as well as density functional theory (DFT) calculations. Using UV–Vis absorption spectrum, the maximum absorption wavelength, excitation energy and optical energy band gap have been evaluated. The thermal behaviour of the crystal has been investigated by TG/DSC analysis. Beside this, others molecular properties like frontier molecular orbital and nonlinear optical (NLO) properties are also reported.