Tautomerism of thymine on gold and silver nanoparticle surfaces: surface-enhanced Raman scattering and density functional theory calculation study

Tautomerism of thymine on gold and silver nanoparticle surfaces has been comparatively analyzed by means of surface-enhanced Raman scattering (SERS). The intensities of the ring breathing mode of thymine indicated that the N-3-deprotonated tautomer should be about 10 times more abundant than the N-1-deprotonated tautomer on Ag surfaces whereas almost no N-1-deprotonated tautorner was observed for An under our experimental condition. The density functional theory (DFT) calculation was performed at the levels of B3LYP and MP2 to estimate the energetic stability of the N-3 and N-1-deprotonated tautomers on the surfaces. The N-3-deprotonated tautomer was predicted to be more favorable on An than on Ag from the DFT calculation as consistent with our SERS spectra. (c) 2004 Elsevier B.V. All rights reserved.