Spectroscopic (FT-IR, FT-Raman, FT-NMR and UV–Vis) investigation on benzil dioxime using quantum computational methods

Abstract

The spectral analysis of benzil dioxime is carried out using the FTIR, FT Raman, FT NMR and UV–Vis spectra of the compound with the help of quantum computations by density functional theories. The FT-IR (4000 – 400 cm−1) and FT-Raman (4000–100 cm−1) spectra are recorded in solid phase, the 1H and 13C NMR spectra in DMSO phase and the UV spectrum (200–400 nm) in ethanol phase. The different conformers of the compound and their minimum energies are studied by potential energy surface scan, using semi-empirical method PM6. The computed wavenumbers from different methods are scaled so as to agree with the experimental values and the scaling factors are reported. All the fundamental modes have been assigned based on the potential energy distribution (PED) values and the structure the molecule is analyzed interms of parameters like bond length, bond angle and dihedral angles predicted byB3LYP and CAM-B3LYP methods with cc-pVDZ basis sets. The values of dipole moment (μ), polarizability (α) and hyperpolarizability (β) of the molecule are reported, using which the non -linear optical property of the molecule is discussed. The HOMO-LUMO mappings are reported which reveals the different charge transfer possibilities within the molecule. The isotropic chemical shifts predicted for 1H and 13C atoms using gauge invariant atomic orbital (GIAO) theory show good agreement with experimental shifts and the same is discussed in comparison with atomic charges, predicted by Mullikan and APT charge analysis. NBO analysis is carried out to picture the probable electronic transitions in the molecule.