Ruthenium nitrosyl complexes with NO release capability: the use of fluorene as an antenna.

A ruthenium nitrosyl complex of formula [Ru II (fluorene(C6)CH 2 O-terpy)(bipy)(NO)] 3+ (AC) in which fluorene(C6) is the 9,9-dihexylfluorene, terpy the 2,2';6',2''-terpyridine, and bipy the 2,2'-bipyridine is presented with its related [Ru II (MeO-terpy)(bipy)(NO)] 3+ (C) and 9,9-dihexylfluorene 2-hydroxymethylfluorene (A) building blocks. The reference complex C undergoes NO release capabilities under irradiation at λ = 365 nm. The effect of the introduction of the fluorescent A antenna within the resulting AC complex is discussed both experimentally and theoretically. The importance of the encaging parameter defined as ϕ AC· I AC, in which I AC is the quantity of light absorbed by AC and ϕ AC the quantum yield of NO release is evidenced and found to be concentration dependent. The conditions of optimization of the antenna approach to maximize ϕ AC· I AC are discussed. The crystal structure of [Ru II (fluorene(C6)CH 2 O-terpy)(bipy)(NO 2 )](PF 6 ), the last intermediate in the synthesis of AC is also presented.