Adsorption and Dissociation of -Methyl -Tolyl Sulfoxide on Au(111).

Sulfur-based molecules producing self-assembled monolayers on gold surfaces have long since become relevant functional molecular materials with many applications in biosensing, electronics, and nanotechnology. Among the various sulfur-containing molecules, the possibility to anchor a chiral sulfoxide to a metal surface has been scarcely investigated, despite this class of molecules being of great importance as ligands and catalysts. In this work, ()-(+)-methyl -tolyl sulfoxide was deposited on Au(111) and investigated by means of photoelectron spectroscopy and density functional theory calculations. The interaction with Au(111) leads to a partial dissociation of the adsorbate due to S-CH bond cleavage. The observed kinetics support the hypotheses that ()-(+)-methyl -tolyl sulfoxide adsorbs on Au(111) in two different adsorption arrangements endowed with different adsorption and reaction activation energies. The kinetic parameters related to the adsorption/desorption and reaction of the molecule on the Au(111) surface have been estimated.