Molecular conformational stability and spectroscopic analysis of n-((3-bromo-1-(phenylsulfonyl)-1h-indol-2-yl)methyl)acetamide with experimental and quantum chemical calculations

The complete vibration analysis of the fundamental modes of N-((3-Bromo-1-(phenylsulfonyl) -1H-indol-2-yl) methyl) acetamide (N3BP2MA) was carried out using the experimental FTIR and FT-Raman data and quantum chemical studies. The observed vibrational data were compared with the wavenumbers derived theoretically from the optimized geometry of the compound from the DFT–B3LYP gradient calculations employing 6-31G (2d, 3p) and 6-311++G (2d, 3p) basis sets. Thermodynamic properties like entropy, heat capacity and enthalpy were calculated for the molecule and the HOMO–LUMO energy gap was calculated. The intramolecular contacts had been interpreted using natural bond orbital (NBO) and natural localized molecular orbital (NLMO) analysis. Important non-linear properties such as electric dipole moment and first hyperpolarizability of N3BP2MA were computed using B3LYP quantum chemical calculations. Finally, the Mulliken population analysis on atomic charges of the title compound were calculated.