• benzylpenicillin;
  • DFT calculation;
  • SERS


Raman spectroscopic investigations in combination with density-functional theory (DFT) calculations were performed on the potassium benzylpenicillin (KBP) molecule. The theoretical values of the geometrical parameters and the vibrational wavenumbers were compared with the experimental X-ray diffraction and Raman data and a fairly good agreement was obtained. The SER spectrum of the KBP molecule on silver colloid at pH value of 6 was recorded and analyzed. The adsorbed molecule is bonded to the silver surface through the carboxylate group. The comparison between KBP aqueous solution Raman spectrum and SERS data demonstrates that benzene, beta-lactam, and thiazolidine rings are situated at a relatively large distance to the silver surface and for these rings the electromagnetic mechanism of enhancement can be implied. Copyright © 2006 John Wiley & Sons, Ltd.