Electrogenerated chemiluminescence of (bis-bipyridyl)ruthenium(II) acetylacetonate complexes

The synthesis, electrochemistry, spectroscopy and electrogenerated chemiluminescence (ECL) of five bis-bipyridine ruthenium(II) complexes containing acetylacetonate complexes are reported. More specifically, (bpy)2Ru(BA)2(PF6) (bpy = 2,2′-bipyridine; BA = benzoylacetonate), (bpy)2Ru(TTFA)(PF6) (TTFA = thenoyltrifluoroacetonate), (bpy)2Ru(TFPB)(PF6) (TFPB = 4,4,4-trifluoro-1-phenyl-1,3-butanedionate), (bpy)2Ru(TFPD)(PF6) (TFPD = 1,1,1-trifluoro-2-4-pentanedionate), and (bpy)2Ru(DBM)(PF6) (DBM = dibenzoylmethide) display UV–Vis, photoluminescence, electrochemical and ECL properties characteristic of ruthenium bipyridyl complexes. All complexes display absorptions in the UV and visible regions of the spectra, with visible absorptions ranging from 350 to 700 nm, typical of metal-to-ligand charge transfer (MLCT) transitions. Photoluminescence emission maxima are also characteristic of MLCT transitions with wavelength maxima from 575 to 600 nm depending on the nature of the acetylacetonate ligand. ECL efficiencies for the complexes (ϕecl ∼ 0.013–0.051) are much lower than a standard (ϕecl = 1) with electron-withdrawing substituents resulting in lower efficiencies