Molecular Structure, Vibrational Spectral Investigations (FT-IR and FT-Raman), NLO, NBO, HOMO-LUMO, MEP Analysis of (E)-2-(3-pentyl-2,6-diphenylpiperidin-4-ylidene)-N-phenylhydrazinecarbothioamide Based on DFT and Molecular Docking Studies

Abstract

The molecular spectroscopic investigations of (E)-2-(3-pentyl-2,6-diphenylpiperidin-4-ylidene)-N-phenylhydrazine carbothioamide (3-PDPPPHC) are studied. The FT-IR and FT-Raman experimental spectra of the molecule have been recorded in the range of 4000–400 cm−1 and 4000–50 cm−1, respectively. The molecular structure, fundamental vibrational frequencies, and intensities of the vibrational bands were interpreted to aid structure optimizations based on the density functional theory (DFT) method with B3LYP/6-311++G(d,p) level of basis set. The complete vibrational assignments of wavenumbers were made based on total energy distribution (TED). The calculations' results were applied to the title compound's simulated spectra, which show good agreement with observed spectra. The dipole moment, polarizability, and first hyperpolarizability values were also computed. The stability of the molecule analyzing from hyper-conjugative interaction and charge delocalization of the title compounds were studied by NBO analysis. Frontier molecular orbitals (FMOs), molecular electrostatic potential (MEP), and thermodynamic properties were performed. Mulliken charges of the title molecule were also calculated and interpreted. The thermodynamic properties such as heat capacity, entropy, and enthalpy of the title compound were calculated at different gas-phase temperatures. To establish information about the interactions between protein and this novel compound theoretically, docking studies were carried out in detail.