Surface enhanced Raman spectroscopy of self-assembled monolayers of 2-mercaptopyridine on a gold electrode

Surface enhanced Raman spectroscopy (SERS) was used to investigate the structure of self-assembled monolayers of 2-mercaptopyridine (2Mpy) adsorbed on the surface of a roughened polycrystalline gold electrode from either water or 0.1 M aqueous H2SO4 at different electrode potential values in 0.5 M aqueous H2SO4. A band in the range 215 to 245 cm(-1) assigned to a gold-sulfur stretching mode indicates formation of a sulfur-bonded adsorbate of 2Mpy. There is also evidence that 2Mpy is bonded through the nitrogen atom of the pyridine ring forming a chelate-like structure. Results suggest a perpendicular orientation of 2Mpy on the gold surface.