Nitric oxide photo-release from a ruthenium nitrosyl complex with a 4,4′-bisfluorenyl-2,2′-bipyridine ligand

Abstract A ruthenium nitrosyl complex of formula [Ru II (terpy)(F2B)(NO)](PF 6 ) 3 , where terpy stands for 2,2′:6′,2″-terpyridine and F2B for 4,4′-bis(9,9′-dibutyl-9H-fluoren-2-yl)-2,2′-bipyridine, is presented and fully characterized. The X-ray crystal structure of F2B is reported. The electronic properties of the complex are compared to those of related [Ru II (terpy)(bpy)(NO)] 3+ complexes having a bipyridine (bpy) free of fluorene or bearing a fluorene on the terpyridine ligand. DFT computations are provided to support the experimental data. [Ru II (terpy)(F2B)(NO)](PF 6 ) 3 releases NO under irradiation at 405 nm with a quantum yield ( ϕ NO ) equal to 0.033. Additionally, the two-photon absorption cross-section investigated at 800 nm by the Z-scan technics is equal to 156 ± 23 GM, which indicates that the complex can release NO under irradiation in the therapeutic window.