FTIR, FT-Raman spectra and DFT analysis of 3-methyl-4-nitrophenol

Abstract

The FTIR and FT-Raman spectra of 3-methyl-4-nitrophenol (MNP) have been recorded in the regions 4000-400 cm^-1 and 3500-50 cm^-1, respectively. Utilizing the observed FTIR and FT-Raman data, a complete vibrational assignment and analysis of the fundamental modes of the compound were carried out. The optimum molecular geometry, harmonic vibrational frequencies, infrared intensities and Raman scattering activities, were calculated by density functional theory (DFT/B3LYP) method using 6-31+G(d,p) and 6-311++G(d,p) basis sets. The difference between the observed and scaled wavenumber values of most of the fundamentals is very small. A detailed interpretation of the infrared and Raman spectra of MNP is also reported based on total energy distribution (TED). The calculated HOMO and LUMO energies shows that the charge transfers occur within the molecule.