Theoretical and experimental spectroscopic studies of monomeric and dimeric structures of 4-hydroxybenzamide

Abstract

4-Hydroxybenzamide (4HBM) molecule was optimized geometrically and vibrational spectral analyses of monomer and dimer structures have been reported by DFT calculations using B3LYP/6–311++G(d,p) level of theory. The molecular structural parameters of the title compound have been observed experimentally and compared with the theoretical (monomer and dimer) data. The experimental FT-IR and FT-Raman vibrational spectral data have been compared with the computational data. The experimental NMR (1H and 13C) chemical shifts have been compared with the calculated chemical shifts that obtained by GIAO (Gauge–Independent Atomic Orbital) theoretical method. The experimental UV–Visible spectrum and vertical electron transition energies were compared with values that found by TD–DFT approach. The electron charge transition by Frontier molecular orbitals theory (HOMO–LUMO energy gap), important chemical reactivity and electron–hole charge transitions have also been studied. Furthermore, the intermolecular interactions have been interpreted using NHO, NLMO, and NBO analyses. The antibacterial and antifungal activities of 4HBM were studied using molecular docking program and the values are compared with the experimental results. The formative role played by the chemical and biological parameters are calculated using spectroscopic and DFT methods and correlated with antibacterial and fungal inhibitory activities which were done by Quantitative Structure-Activity Relationship(QSAR) study.