Spectroscopic and quantum chemical computation on molecular structure, AIM, ELF, RDG, NCI, and NLO activity of 4-VINYL benzoic acid: A DFT approach

Vibrational spectral analysis was carried out for 4-Vinyl Benzoic acid (4VBA) by using Fourier transform infrared (FT-IR) and FT-Raman spectroscopy in the range of 40 0-40 0 0 and 50-350 0 cm -1 respectively. The optimized geometrical parameters were computationally obtained at the DFT/B3LYP level of theory. The distribution of the vibrational bands was carried out with the help of normal coordinate analysis (NCA). The resulting harmonic wavenumbers were scaled by using NCA method. 13 C and 1 H NMR spectra were recorded and 13 C and 1 H nuclear magnetic resonance chemical shifts of the molecule were calculated using the gauge independent atomic orbital (GIAO) method. Topological analysis, such as Electron localization function (ELF), natural bond orbital analysis (NBO), reduced density gradient (RDG) and atoms in molecule (AIM) analysis, molecular electrostatic potential (MEP) have been used to evaluate the intermolecular interaction, especially the hydrogen bonds. UV-visible spectrum of the compound was recorded in the region 20 0-90 0 nm and the electronic properties and HOMO-LUMO energies were calculated by time dependent density functional theory approach.