Coordination complexes grafted on metallic nanoparticles: towards synergy – COCOsMEN

COCOsMEN project deals with the synthesis and in depth study of hybrid nano-objects made from gold or silver nanoparticles, of various sizes and shapes, on which coordination complexes are grafted. Such architecture is proposed to enable synergy between the localized surface plasmon resonance of the nanoparticles and the optical or electronic properties of the grafted complexes. Innovative capping ligands will be used to anchor the coordination complexes to the nanoparticles. These heterotopic molecules will present the following features: a N-heterocyclic or mesoionic carbene group, able to yield a strong covalent bond with the gold or silver atoms at the surface of the nanoparticles, and a coordination site, based on phenanthroline, pyridyl or bipyridyl group, which can efficiently bind metallic complexes. Such design for the capping ligands should promote the energy or charge transfers at the hybrid interface, which are phenomena of prime importance in the foreseen synergy. The coordination sphere of the metallic centers will be completed by various multidentate terminal ligands, which could tune, through the ligand field, the optical or redox properties of the grafted complexes. The presence of long alkyl or poly(ethylene oxide) chains on the anchoring ligands should yield stable dispersions of these new nano-hybrid in various solvents, including water. Alternatively, the presence of two different capping ligands can also be envisaged: one to bind the coordination complexes and one for the stabilization of the nanoparticles.
Systems based on nickel (II) or iron (II or III) complexes will be investigated. With nickel, we will study the possibility of a near infrared emission (1000-1600 nm) when the nanoparticles plasmon band is excited. With iron, we will investigate the possibility to modify the nanoparticle plasmon resonance through the iron oxidation state. In depth chemical and structural characterizations of the complexes and hybrid nanoparticles will be performed to obtain a complete description of their composition and properties. Then, steady state absorption and photoluminescence measurements will be achieved to search for synergetic effects. Finally, to provide a better understanding of the energy or charge transfers involved and their kinetics, time resolved photoluminescence and absorption measurements will be carried out. Such innovative nano-hybrids could yield valuable applications in the fields of optical bioimaging, switchable plasmonic devices or sensing.
COCOsMEN is a basic research 42 months project gathering three academic partners with complementary expertise: The Laboratoire de Chimie de la Matière Condensée de Paris (UMR 7574) and the Institut Parisien de Chimie Moléculaire (UMR 8232), both at Sorbonne University (Paris) and the Laboratoire Ondes et Matière d'Aquitaine (UMR 5798) at Bordeaux University.