Effects of electron withdrawing and donating groups on the efficiency of tris(2,2′-bipyridyl)ruthenium(ii)/tri-n-propylamine electrochemiluminescence

Abstract

The effects of electron withdrawing and electron donating groups on the electrochemiluminescent (ECL) properties of tris(2,2'-bipyridyl)ruthenium(II) (Ru(bpy)3(2+) where bpy = 2,2'-pyridine) are reported. The electrochemistry, photophysics and ECL of (bpy)2Ru(DC-bpy)2+, and (bpy)2Ru(DM-bpy)2+ (DC = 4,4'-dicarboxy-2,2'-bipyridine; DM = 4,4'-dimethyl-2,2'-bipyridine) have been studied relative to Ru(bpy)3(2+) in 50:50 (v/v) acetonitrile(CH3CN):H2O (0.1 M KH2PO4), and aqueous solutions. Furthermore, the effects of Triton X-100 (polyethylene glycol tert-octylphenyl ether) on the electrochemical, spectroscopic and ECL properties of these compounds are reported. The anodic oxidation of Ru(bpy)3(2+), (bpy)2Ru(DC-bpy)2+, and (bpy)2Ru(DM-bpy)2+ produces ECL in the presence of tri-n-propylamine (TPrA) in all solvent systems. ECL efficiencies (phi(ecl), photons produced per redox event) of 0.73 and 0.84 for (bpy)2Ru(DC-bpy)2+, and (bpy)2Ru(DM-bpy)2+ were obtained in aqueous buffered solution, using Ru(bpy)3(2+) as a relative standard (phi(ecl) = 1.0). Addition of 0.4 mM Triton X-100 results in a greater than 2-fold increase in ECL efficiences (i.e., 3.8, 2.4 and 2.3 for Ru(bpy)3(2+), (bpy)2Ru(DC-bpy)2+, and (bpy)2Ru(DM-bpy)2+, respectively) using aqueous Ru(bpy)3(2+) containing no surfactant as standard (phi(ecl) = 1.0). ECL efficiencies of 27.4, 16.5 and 26.1 were found in 50:50 (v/v) CH3CN:H2O (0.1 M KH2PO4) for Ru(bpy)3(2+), (bpy)2Ru(DC-bpy)2+, and (bpy)2Ru(DM-bpy)2+, respectively, using aqueous Ru(bpy)3(2+) containing no surfactant as standard (phi(ecl) = 1.0). Detailed studies support adsorption of surfactant on the electrode surface, thus facilitating TPrA and ruthenium oxidation.

The Factors Affecting the Electrochemiluminescence of Tris(2,2′‐bipyridyl)Ruthenium(II)/Tertiary Amines

“…The results indicated that the different Ru(bpy) 3 2þ derivatives could not lead to dramatic increase or decrease in ECL efficiency but the adsorption of TPA or other factors contribute to the surfactants effect [15]. In the present work, the difference in solubility between TPA and TMBA results in their different responses to the added surfactants.…”

“…Bruce et al [15] gave a novel protocol to validate the effects of surfactant on ECL emission. Various carboxyland methyl-groups were attached to the bipyridyl group of Ru(bpy) 3 2þ , and therefore, changed the hydrophobicity of Ru(bpy) 3…”

Electrochemiluminescence of Tris(2,2′‐bipyridine)ruthenium with Various Co‐reactants under Ultrasound Irradiation

“…Ru(bpy) 3 2+ based ECL system can emit light at room temperature in both aqueous and non-aqueous solutions with relatively higher ECL efficiency. The ECL reaction of Ru(bpy) 3 2+ with TPA has been well investigated by many workers [3,12,13]. Scheme 1 describes the general ECL mechanism where the oxidation of TPA generates a strongly reducing specie of TPA･ [3].…”

Electrochemiluminescence Sensor Based on Multiwalled Carbon Nanotubes Doped Polyvinyl Butyral Film Containing Ru(bpy)$\rm{ {_{3}^{2+}}}$ as Chemiluminescence Reagent

“…The principle and reaction mechanism of Ru(bpy) 2þ 3 with TPA have been studied in many works [3,19,20] …”