Quantum mechanical study of the structure and spectroscopic (FTIR, FT-Raman), first-order hyperpolarizability and NBO analysis of 1,2-benzoxazol-3-ylmenthane sulfonamide

•The vibrational assignment and spectroscopic analysis have been carried out.•NBO analysis has been carried out to explain the interaction between donors and acceptors.•NLO behaviors were computed.•The HOMO and LUMO energy gap were theoretically predicated.•The molecular orbital contributions were studied.

Fourier transform infrared (FTIR) and FT-Raman spectra of 1,2-benzoxazol-3-ylmenthane sulfonamide in the solid phase were recorded and analyzed. The molecular geometry, vibrational frequencies, infrared intensities, Raman activities and atomic charges were calculated using HF and density functional theory calculation (B3LYP) with standard 6-31G(d, p) basis set. Complete vibrational assignment and analysis of the fundamental modes of the compound were carried out using the observed FTIR and FT-Raman spectra. The thermodynamic functions of the title compound were also performed. Stability of the molecule arising from hyper-conjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. The dipole moment (μ), polarizability (α) and the hyperpolarizability (β) values of the molecule has been computed. Potential Energy Distribution (PED) were computed for the assignment of unambiguous vibrational fundamental modes. UV–vis spectrum of the compound was also recorded. The theoretical electronic absorption spectra have been calculated by TD-DFT/B3LYP using 6-31G(d,p) basis set. The HOMO and LUMO energy gap reveals that the chemical activity of the molecule. The molecular orbital contributions were studied by density of energy states (DOSs). Thermodynamic properties (heat capacity, entropy and enthalpy) of the title compound at different temperatures were calculated. Finally, simulated FTIR and FT-Raman spectra of 1,2-benzoxazol-3-ylmenthane sulfonamide showed good agreement with the observed spectra.

Graphical abstract1,2-Benzoxazol-3-ylmenthane sulfonamide is used for adjunctive treatment of partial seizures in adults and neuropathic pain. It is chemically called as 1,2-benzoxazol-3-ylmenthane sulfonamide. An extensive work has been carried out on the title compound and its derivatives in recent year. At present, vibrational spectroscopy is used not only for functional group identification of organic compounds, but also to investigate the molecular conformation, reaction kinetics.Figure optionsDownload full-size imageDownload as PowerPoint slide