Molecular Dynamics Simulation of Benzenethiolate and Benzyl Mercaptide on Au(111)

Abstract

We report the results of theoretical studies on the self-assembled monolayers of benzenethiolate (BT) and benzyl mercaptide (BZM) on a Au(111) surface. A few relevant potential energy parameters were determined. We have performed annealing type molecular dynamics simulations where the minimized initial configurations are heated to 1000 K and then cooled to room temperature, assuming two types of unit cells: √3 × √3R30° and 2 × 2. The results of the simulations showed that BZM formed a nearly perfect herringbone structure, while the apparent herringbone type structure of BT was somewhat disordered in the √3 × √3R30° unit cell. For the 2 × 2 unit cell with larger area per molecule, both monolayers did not form well-ordered structures, but the BZM showed some local ordering with herringbone structure. In both cases, the molecules of BZM are found to be nearly vertical to the surface, while those of BT are tilted from the surface normal. All these theoretical results are consistent with recent experimental findings. The role of a flexible methylene unit near the sulfur headgroup in discriminating stable packing structures of the self-assembled monolayers is discussed.

Effect of immersion temperature on structure of the self-assembled monolayer of 1,2-diphenyldiselenide on gold surface

“…Several earlier studies found that benzenethiol do not form an ordered structure on gold surface [42,70,71]. Formation of small ordered domains was also reported for benzenethiol SAMs [72]. In a different study, the ( ffiffiffiffiffiffi 13 p  ffiffiffiffiffiffi 13 p Þ structure was also reported [73].…”

Effect of Ring Substitution Position on the Structural Conformation of Mercaptobenzoic Acid Self-Assembled Monolayers on Au(111)

“…Within these monolayers, the biphenyl based monomers adopt more upright than prostrate orientations on the underlying Au [46] and, importantly, exhibit closely comparable molecular tilt angles to 4-MBA. Molecular dynamics simulations conducted by Jung et al [47] illustrate that molecules of benzyl mercaptan adsorbed on Au(111) in herringbone-like SAM arrangements would also have similar tilt angles to 4-MBA. Hence, it is probable that monolayers of 4-MBA adopt a herringbone-like packing scheme.…”

Adsorption of 1,4-Benzenedithiol on Gold and Silver Surfaces: Surface-Enhanced Raman Scattering Study

“…• unit cells (18). Guided by the above implications, we examined the adsorption behavior of 1,4-benzenedithiol (1,4-BDT) on gold and silver sol surfaces by means of surface-enhanced Raman scattering (SERS).…”