Concentration dependent SERS study of a bioactive methylsulfonyl derivative

Abstract

Concentration dependent surface enhanced Raman scattering (SERS) studies of biologically active methylsulfonyl derivative (BMSP) are reported. Out of various concentrations, SERS at 10-3 M gives maximum enhancement. The experimental results are supported by theoretical investigations. BMSP exhibited selective micro molar activity against Staphylococcus aureus. The interaction of charge transfer between Ag and S atoms is confirmed by the enhanced bond length values. Reduction in ionization potential suggests that the BMSP-Ag6 system has stronger electron donating characteristics than BMSP. The electrophilicity index of the adsorbed system containing BMSP and silver cluster represent biological activity and the adsorption process is chemisorption. Presence of CH3 modes in the SERS spectrum suggest that the molecule adopts a tilted orientation, and that para-substituted phenyl ring is more slanted than poly-substituted phenyl ring. Presence of ring stretches, bending modes for all concentrations suggest that the BMSP molecule may tilt, resulting in an interaction with the metal surface and there is an orientation change for the molecule with respect to the metal surface as concentration changes.