Two-dimensional self-assembly of benzotriazole on an inert substrate

The ultra-high vacuum (UHV) room temperature adsorption of benzotriazole (BTAH), a well-known corrosion inhibitor for copper, has been investigated on the pristine Au(111) surface using a combination of surface sensitive techniques. The dimensionality of the molecule is reduced from the 3D crystal structure to a 2-dimensional surface confinement, which induces the formation of hydrogen bonded 1-dimensional molecular chains consisting of alternating pro-S and pro-R enantiomers mainly. The 0-dimensional system is characteristic of gas-phase BTAH, which undergoes a tautomeric equilibrium, with consequences for the resulting adsorbed species. The balance between hydrogen bonding, inter-chain van der Waals interactions and surface-molecule interactions, and the correlation with the dimensionality of the system, are discussed in light of the experimental results and a computational description of the observed features. Fine tuning of experimental conditions allows dimensional control of benzotriazole species adsorbed on Au(111), revealing a subtle interplay between H-bonding, vdW inter-adsorbate and surface-adsorbate interactions, as highlighted both experimentally and theoretically.