Structure, vibrational, electronic, NBO and NMR analyses of 4-amino-N-[2-pyridinyl] benzene sulfonamide (sulfapyridine) by experimental and theoretical approach

•FT-IR and FT-Raman spectra of APBSA in the solid phase were recorded and analyzed.•The conformational analysis was examined through PES scan studies.•Tautomerism and the effect of solvent on the tautomeric equilibria were analyzed.•The sulfonyl and amino groups of APBSA would be the most reactive site.•NMR chemical shifts were calculated by GIAO method.

The optimized molecular structure, vibrational wavenumbers, atomic charges, molecular electrostatic potential, NBO, electronic properties, NLO, 1H NMR and 13C NMR chemical shifts of 4-amino-N-[2-pyridinyl] benzene sulfonamide (APBSA) have been studied in this investigation. Theoretical calculations were performed by density functional theory (DFT) method using B3LYP and B3PW91 with 6-311++G(d,p) basis sets. The conformational analysis was examined through PES scan studies. Tautomerism and the effect of solvent on the tautomeric equilibria in the gas phase and in different solvents were investigated. Molecular electrostatic potential (MEP) map of the title compound has been analyzed for predicting the reactive sites. The reactivity of the compound of interest was described by low HOMO–LUMO energy gap. The electronic properties were also discussed and the most prominent transition corresponds to π → π*. The APBSA exhibited good nonlinear optical property and nine times greater than that of urea. In addition, the thermodynamic properties of the title compound were calculated at different temperatures and corresponding relations between the properties and temperature were also studied.

Graphical abstractVibrational, electronic, NMR, reactivity and structural aspects of 4-amino-N-[2-pyridinyl] benzene sulfonamide (sulfapyridine) were studied in detail using DFT method and the results were also compared with the experimental values.Figure optionsDownload full-size imageDownload as PowerPoint slide