Département de chimie moléculaire

Authors report the synthesis of original osmium(II) complexes bearing chelating N-heterocyclic (NHC) and bipyridine ligands. The pincer ligand 1,1'-dimethyl-3,3'-methylenediimidazole-2,2'-diylidene was used to tune the redox properties of osmium complexes. Bipyridine ligands modified with pyrene groups were chosen to study the electrosynthesis of OsII-NHC-based metallopolymers as well as the noncovalent immobilization of these complexes on carbon-nanotube (CNT) electrodes. Poly-[OsII-NHC] polypyrene polymer was electrogenerated on a GC electrode, whereas the pyrene-modified [OsII-NHC] could interact with the CNTs' sidewalls through $π$-$π$ interactions, allowing the immobilization of the NHC complexes at the surface of $π$-extended nanostructured electrodes. Furthermore, an OsII-NHC complex was studied in water, showing electron transfer mediation with multicopper enzymes. UV-visible and electrochem. expts. demonstrate that redox properties of the OsII-NHC complex provide sufficient driving force for electron transfer with bilirubin oxidase from Myrothecium verrucaria while achieving high potential electroenzymic oxygen redn. at E = +0.45 V vs. Ag/AgCl at pH 6.5. [on SciFinder(R)]