Experimental Raman, FTIR and UV-vis spectra, DFT studies of molecular structures and barrier heights, thermodynamic functions and bioactivity of kaempferol

Abstract

Molecular structures and vibrational parameters for the all the four possible conformers of kaempferol were investigated using Gaussian 09 and GAR2PED software. Raman and FTIR spectra of kaempferol were recorded in the regions 50–4000 cm−1 and 400–4000 cm−1, respectively and interpreted in the light of the computed quantities. Some of the modes were found to have conformer dependent frequencies, IR and Raman intensities and depolarisation ratios. The complex, broad and intense IR band in the range 2900–3500 cm−1 is explained to arise due to the four OH stretching and an overtone modes. The barrier heights for the OH tops against internal rotations have been determined. The UV–vis absorption spectrum was measured in the range 220–800 nm. MEP and HOMO-LUMO energies were computed for all the four conformers and NBO analysis was carried out. Thermodynamic functions of title compound have been carried out. Different bioactivity scores for this molecule were computed.