An antipsychotic drug: Spectroscopic identification, structural features, DFT computations and molecular docking studies on 4-(methylamino)-3-nitrobenzoic acid

Abstract

Spectral features of 4-(methylamino)-3-nitrobenzoic acid (MNA) have been probed by the techniques of Fourier transform infrared, Raman and UV–visible combined with density functional theory calculations at the B3LYP level with 6–311++G(d,p) basis set. By using potential energy distribution the detailed interpretation of vibrational spectral assignments has been carried out. Geometrical parameters reveal that the bioactive conformer of MNA molecule is in a planar position. The red-shifted N–H stretching wavenumber describes the N–H⋯O intramolecular hydrogen bonding evidenced by the vibrational analysis. Natural orbital and natural population analysis support this result. The strongest vibrational modes contributing to the bioactivity effect from the simultaneous infrared and Raman activities of the benzene ring CC, C–C stretching modes have been identified and analyzed clearly. The influence of electronic effects including back-donation and induction on the C–H stretching vibrations of methyl group causing the decrease of stretching wavenumbers has been extensively investigated. The antipsychotic activity of substituents is available which target amino acids as evidenced from molecular docking study. Frontier molecular orbital, the molecular electrostatic potential analysis was also analyzed.