Chemiluminescence reactions with cationic, neutral, and anionic ruthenium(II) complexes containing 2,2′-bipyridine and bathophenanthroline disulfonate ligands

Ruthenium complexes containing 4,7-diphenyl-1,10-phenanthroline disulfonate (bathophenanthroline disulfonate; BPS) ligands, Ru(BPS)34−, Ru(BPS)2(bipy)2− and Ru(BPS)(bipy)2, were compared to tris(2,2′-bipyridine)ruthenium(II) (Ru(bipy)32+), including examination of the wavelengths of maximum absorption and corrected emission intensity, photoluminescence quantum yield, stability of their oxidised ruthenium(III) form, and relative chemiluminescence intensities and signal-to-blank ratios with cerium(IV) sulfate and six analytes (codeine, morphine cocaine, potassium oxalate, furosemide and hydrochlorothiazide) in acidic aqueous solution. The presence of BPS ligands in the complex increased the photoluminescence quantum yield, but decreased the stability of the oxidised form of the reagent. In contrast to previous evidence showing much greater electrochemiluminescence intensities using Ru(BPS)2(bipy)2− and Ru(BPS)(bipy)2, these complexes did not provide superior chemiluminescence signals than their homoleptic analogues.