Spectroscopic and SERS investigations of (E)-3-[(3-methoxybenzylidene) amino]rhodanine – Experimental, DFT and MD analyses in solvents

Abstract

Studying the interfacial characteristics of nanoparticles and adsorption behavior of molecules on silver colloids requires application of surface enhanced Raman scattering (SERS) and density functional theory (DFT). In this research the effects of (E)-3-[(3-methoxybenzylidene)amino]-2-thioxothiazolidin-4-one (MAT) adsorption at various concentrations on silver colloids were investigated. It was shown that the MAT molecule interacted with silver through the oxygen, nitrogen and methyl groups. The computed wavenumbers for the MAT molecule were in agreement with experimental values, proving that DFT approach may be used to assign wavenumbers. It is important to note that when MAT is adsorbed on Ag and MAT is chemisorbed on the metal cluster, the electron density is reallocated and the charge is transferred from molecule to silver atoms. A variation in orientation of MAT molecule with regard to silver colloid changes the nature of adsorption as concentration changes as well. Higher fluctuation during molecular dynamics (MD) simulation gives molecular instability, while smaller fluctuation denotes a biological system that is noticeably stable. Solvent-accessible surface area (SASA) plots showed certain shrinkage for MAT and MAT-Ag6 complexes solvent accessible areas in methanol, while a certain increase of the solvent accessible regions was observed in water for both.