Surface-Enhanced Raman Study of Benzylpenicillin

Abstract

The surface-enhanced Raman spectra (SERS) of benzylpenicillin on electrochemically roughened Ag electrodes were investigated. Spectral assignments were carried out. Comparison with powder Raman spectra demonstrated that the benzene ring is in a vertical position relative to the surface. The molecule is bonded to the silver surface through the carboxylate group and the tertiary nitrogen of the beta-lactam ring, resulting in formation of a bidentate surface complex. Evidence of partial benzylpenicillin hydrolysis into 6-aminopenicillanic acid and phenylacetic acid on the surface of the electrode is presented. No indication of electrochemical reactions was observed in the potential range from −1.2 to +0.3 V.