Experimental and DFT investigations of SERS Profile of a Bioactive Hydroxybenzamide Derivative

Surface enhanced Raman scattering (SERS) experiments were used to evaluate the adsorption and orientation of 5-bromo-N-[4-bromo-3-(trifluoromethyl)phenyl]-2-hydroxybenzamide (BTB) adsorbed on silver colloid and the results were compared to normal Raman spectra of BTB. Density functional theory (DFT) analysis was used to theoretically validate the observed spectra of BTB. BTB and BTB-Ag6 molecular structures were optimized at first. The BTB molecule is adsorbed with the Ag6 with energy of −10.67 eV through atoms, O9, F22 and Br17 atoms. The charge transfer interaction between Ag6 clusters and BTB, which lead to BTB adsorption on Ag6 metal clusters, is confirmed by the Frontier Molecular Orbitals (FMOs) study. The BTB chemisorbed on silver with a tilted orientation, as confirmed by SERS spectral analysis and the accompanying results were theoretically justified.