Adsorption of amine compounds on the Au(111) surface: A density functional study

A Density Functional Theory study of the adsorption energetics of various amine compounds on the gold(111) surface revealed that preferential binding occurs in under-coordinated sites. The largest binding energy is obtained when a gold adatom is placed in the fee position and the amine positioned with the nitrogen above the adatom. The results are compared with previous calculations for thiols, phosphines, and ethynylbenzene molecules to provide a meaningful comparison within a consistent computational framework. The systematic increase in binding energy with methyl group substitution previously observed for phosphine compounds is not observed for the amine analogues. The binding energy of the amines is considerably lower than that for thiols and binding is indicated for only the adatom geometry-a result consistent with experimental data.