Adsorption-induced conformational transition in 2,2 '-bipyridine on silversurfaces: a surface-enhanced Raman scattering study

Surface-enhanced Raman spectra of 2,2'-bipyridine molecules adsorbed on rou gh silver surfaces were obtained. The spectra are interpreted in terms of t wo adsorbed species, one of which closely resembles the classical [Ag(bipy) (2)](+) complex. The spectral features of the second adsorbate indicate the existence of 2,2'-bipyridine in the cis conformation oriented orthogonally to the surface. A thiol self-assembled monolayer, preadsorbed on the activ e surface, was used as a nanometric spacer to avoid the direct interaction of the molecules with silver. The same spectral features of the cis conform er are present even in this last case. The results are in agreement with an adsorption-induced transition of the thermodynamically stable trans confor mation of the 2,2'-bipyridine molecule. Copyright (C) 1999 John Whey & Sons , Ltd.