Stepwise formation of ruthenium(II) complexes by direct reaction on organized assemblies of thiol-terpyridine species on gold

Surface-confined polypyridinebased metal complexes are of importance in several applications such as solar energy conversion, luminescent sensors and molecular electronics[1]. Anchoring of complexes on metal surfaces can be obtained, among others, via an intermediate step involving the preparation of a self-assembled monolayer (SAM) with suitable functional tail groups. The SAM can then be used for binding the metal complex, by a stepwise procedure involving coordination chemistry reactions, directly at the surface. However, the known synthetic routes for bulk preparation of metal complexes, such as polypyridine complexes of ruthenium, osmium and iridium (among the most interesting polypyridine metal complexes, because of their outstanding photophysical and redox properties)[2] are based on reaction conditions that could be incompatible with the properties (e.g. thermal stability) of the monolayer that acts as one of the reactants. Indeed, whereas for example, surface-confined iron or cobalt polypyridine complexes have been prepared by a stepwise procedure based on suitably-derivatized surfaces,[3] analogous ruthenium systems have been elusive up to now, in spite of the large interest of these latter species.