Coreactant electrogenerated chemiluminescence of ruthenium porphyrins

The coreactant electrogenerated chemiluminescence (ECL) of 5,10,15,20-tetraphenyl-21H ,23H -porphine ruthenium(II) carbonyl (Ru(TPP)(CO))), and 2,3,7,8,12,13,17, 18-octaethyl-21H ,23H -porphine ruthenium(II) carbonyl (Ru(OEP)(CO)) in acetonitrile is reported. Both complexes have absorption maxima in the visible region of the spectrum and emit in fluid solution at room temperature around 650 nm in acetonitrile. Photoluminescence efficiencies (ϕ em) were between 1.5 × 10−4 and 4.0 × 10−4 when compared to View the MathML sourceRu(bpy)32+ (bpy = 2,2′-bipyridine) with ϕ em = 0.042. The complexes show two-electrochemically reversible oxidations via cyclic voltammetry. ECL was generated using tri-n -propylamine (TPrA) as an oxidative–reductive coreactant and the ECL peaks at a potential corresponding to oxidation of both the TPrA and both of the porphyrin oxidations. ECL efficiencies (ϕ ecl) were 0.65 for Ru(TPP)(CO) and 0.58 for Ru(OEP)(CO) when compared to View the MathML sourceRu(bpy)32+ (ϕecl = 1). Also, qualitative studies using transmission filters suggest that both complexes emit ECL in approximately the same region as their photoluminescence, indicating that the same excited state is formed in both experiments.