Investigation of molecular structure, vibrational, electronic, NMR and NBO analysis of 5-chloro-1-methyl-4-nitro-1H-imidazole (CMNI) using ab initio HF and DFT calculations

This study represents the vibrational, electronic, NMR, NLO and structural aspects of 5-chloro-1-methyl-4-nitro-1H-imidazole (CMNI). A detailed interpretation of the FT-IR, FT-Raman, UV and NMR spectra were reported. Theoretical calculations were performed by ab initio HF and density functional theory (DFT)/B3LYP method using 6-311+G(d,p) basis sets. The electronic properties was also studied and the most prominent transition corresponds to π → π∗. The lower frontier orbital gap of CMNI explains the eventual charge transfer interaction taking place within the molecule. The stability and charge delocalization of the molecule was studied by natural bond orbital (NBO) analysis. CMNI exhibited good nonlinear optical activity and was 11 times greater than that of urea. In addition, a molecular electrostatic potential map (MEP) of the title compound was studied for predicting the reactive sites.