Copper adatoms mediated adsorption of benzotriazole on a gold substrate

The adsorption of organic molecules on metal surfaces is often mediated by metal adatoms, however their effect on the geometry of the resulting supramolecular structure can be difficult to determine. Herein, the role played by reactive copper atoms in the adsorption chemistry of benzotriazole (BTAH), an organic corrosion inhibitor for copper well-known for forming adatom mediated supramolecular structures, on an inert substrate, Au(111), has been investigated in an ultra-high vacuum environment using a combination of complementary surface sensitive techniques and density functional theory calculations. Pseudo-ordered and hydrogen bonded flat-lying assemblies convert into ordered -[CuBTA]_n- flat-lying organometallic species of well-defined stoichiometry upon addition of copper atoms from the gas phase onto an Au(111) surface, which has been pre-dosed with BTAH. The formation and characterisation of these organometallic species are discussed in the light of the experimental results and computational modelling. The combination of complementary experimental and computational methods is crucial in order to obtain a thorough characterisation of such a complex system. The final supramolecular structure shows previously unseen BTAH phases, which are favoured by the adsorption distribution of copper adatoms on Au(111), and are stable up to 500 K.