Stabilization of terpyridine covered gold nanoparticles by metal ions complexation

The introduction of 1, a thiol presenting a terpyridine ligand, on the surface of weakly stabilized nanoparticles leads, at high concentration of this capping agent, to the aggregation of the gold clusters. This behaviour is due to the weak, but not negligible interaction of the terpyridine moiety with the metal surface, an interaction that becomes relevant at high concentrations of 1 on the surface, when several units can cooperate in interlinking the nanoparticles. To avoid this effect, we have investigated the complexation of zinc by the terpyridine derivative bound to gold nanoclusters, in excess of metal ion and in the presence of coordinating anions, as a powerful tool for the stabilization of gold nanoparticles. In this context, anions, such as bromide, showed to play an important role in this processes; the use of anions containing desired functions can than be a very versatile strategy to obtain new enriched nanoparticles.