Surface-enhanced Raman scattering study of the surface coordination of porphyrins adsorbed on silver

Abstract

Surface coordination of porphyries meso-tetrakis(4-sulfonatophenyl)porphyrin (TSPP) and meso-tetrakis(4acetoxyphenyl)porphyrin (TAOP) has been studied with surface-enhanced Raman scattering (SERS). When HNO₃-roughened Ag foils were dipped into porphyrin solutions, the porphyrin molecules could easily coordinate with surface atoms and form silver-porphyrin complexes. TAOP molecules showed different orientations on the metal surface when the samples were prepared under different deposition conditions. Dipping Ag foils into a normal neutral TAOP solution produced a perpendicular orientation of phenyl groups, whereas in acidic solution a ‘lying-flat’ orientation was adopted.