DFT study of cysteine adsorption on Au(111)

Rosa Di Felice, Annabella Selloni, Elisa Molinari

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192 Scopus citations

Abstract

The adsorption of the cysteine amino acid (H-SCβH2-CαH-NH2-COOH) on the (111) surface of gold is studied by means of periodic density functional calculations. Results for different adsorption sites and molecular configurations show that chemisorption involving S(thiolate)-Au bonds on Au(111) is favored by starting with either cysteine or cysteine gas-phase molecular precursors. In the most stable adsorption configuration, the sulfur headgroup sits at the bridge site between two surface Au atoms, and the S-Cβ bond is tilted by 57° with respect to the surface normal, whereas the in-plane orientation of the molecular backbone plays a secondary role. The analysis of the electronic properties shows that the hybridization of the p-like S states with the d-like Au states produces both bonding and antibonding occupied orbitals, and the process is well described by a model for the interaction of localized orbitals with narrow-band dispersive electron states. The bonding orbitals well below the Fermi level contribute to the strong chemisorption of cysteine on gold. The calculated sulfur-projected density of states allows us to locate the cysteine molecular orbitals with respect to the system Fermi level, which gives a measure of the injection barrier at the molecule/electrode junction.

Original languageEnglish (US)
Pages (from-to)1151-1156
Number of pages6
JournalJournal of Physical Chemistry B
Volume107
Issue number5
DOIs
StatePublished - Feb 6 2003

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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