Nanodevices based on metallic nanoparticles and metallic complexes are of particular interest considering the synergy expected between the intrinsic electronic and optical properties of the two components of these nanocomposites. The realization of such nanosystems in which the metallic nanoparticle and the metallic complex are in direct interaction could open new perspectives in several domains such as catalysis and biology. Cédric Mayer, from the Institut Lavoisier of Versailles in France, and colleagues have managed to synthesize nanocomposites of this type, in which ruthenium complexes bearing various terminal pendant groups (phenanthroline, pyridine, thiophene) are used to directly stabilize and functionalize gold and silver nanoparticles. 

"The originality of this work lies in the direct interaction between the ruthenium complex and the metallic nanoparticle through a fully conjugated system and the ability to stabilize these nanocomposites in aqueous and non aqueous media", Mayer says. 
Preliminary electrochemical and luminescence measurements have shown the influence of the metallic nanoparticle on the properties of the ruthenium complex. These original results are currently used in order to develop new nanocomposites. 

Mayer is confident that this work will open new routes to future developments: "Our systems offer various interesting perspectives. The ability to easily tune the nature of the metallic complex, modifying for example the nature of the metallic centre, the nature of the pendant group ensuring the connection with the metallic nanoparticle, the length of the rigid conjugated system, and therefore the distance between the two components of our nanocomposites, will be used to develop nanosystems with specific properties. The grafting of polymetallic systems on the surface of metallic nanoparticles is currently developed together with the use of multifunctional metallic complexes in order to generate 1D-, 2D- and 3D-assemblies of metallic nanoparticles".

According to Mayer, a crucial challenge will be to manage to control the electronic and optical properties of these nanocomposites. The presence of a tunable connection (rigid fully conjugated system or aliphatic chains) between the metallic centre and the nanoparticle will be very helpful in discriminating the energy and electronic transfers that explain the fluorescence enhancement / quenching observed with such nanosystems or to generate new nanodevices with specific electrochemical properties.