Electrochemiluminescence of Tris(2,2‘-bipyridine)ruthenium in Water at Carbon Microelectrodes

Abstract

Electrochemiluminescence (ECL) of Ru(bpy)(3)(2+) in water only, without any added electrolyte or reducing agents, has been obtained at carbon interdigitated microelectrode arrays (C-IDAs) of 2 μm width and spacing. In a generation/collection biasing mode, ECL can be clearly seen with the naked eye in normal room lighting at concentrations greater than 1 mM. Using a conventional photomultiplier tube (PMT), a detection limit of 10(-)(7) M Ru(bpy)(3)(2+) has been achieved for an electrode area of 0.25 mm(2). In comparison, the ECL intensity produced at Pt-IDA of the same geometry, under identical experimental conditions, was more than 300 times less. The ECL obtained at C-IDAs is attributed to the annihilation reaction of the reduced and oxidized forms of the Ru(bpy)(3)(2+) made possible due to the small electrode spacing.

Chemiluminescent investigation of tris(2,2'-bipyridyl)ruthenium(II) immobilized on a cationic ion-exchange resin and its application to analysis

“…1-3. Indeed, the CL emission of the electronically generated Ru(bpy) 3 3+ in water has been reported by Fiaccabrino et al [26] recently and they declared that it was the first discovery, but the CL reaction mechanism was not described clearly in their report. To our knowledge, there were two explanations for this phenomenon.…”

Cathodic electrochemiluminescence of Ru(bpy)/Nafion coated on graphite oxide electrode in purely aqueous solution

“…Several mechanisms are involved in the ECL of Ru(bpy) 3 2+ . The annihilation reaction of Ru(bpy) 3 3+ and Ru(bpy) 3 + in organic solvents generates the excited state Ru(bpy) 3 2+ *, resulting in a strong orange emission (λ max = 610 nm).…”

“…Several mechanisms are involved in the ECL of Ru(bpy) 3 2+ . The annihilation reaction of Ru(bpy) 3 3+ and Ru(bpy) 3 + in organic solvents generates the excited state Ru(bpy) 3 2+ *, resulting in a strong orange emission (λ max = 610 nm). The reduction to Ru(bpy) 3 + at a more negative potential is problematic in purely aqueous solutions due to hydrogen evolution.…”

“…Oxalate or tripropylamine (TPA) is generally used as the reducing co-reactant, whereas peroxidisulphate (S 2 O 8 2− ) serves as the oxidative co-reactant. However, few studies have been carried out on the ECL of Ru(bpy) 3 2+ in purely aqueous solution without the addition of a reducing agent. Fiaccabrino et al (3) reported on the ECL of Ru(bpy) 3 2+ in water at carbon interdigitated microelectrode arrays, without any added electrolytes or reducing agents.…”

Electrochemiluminescence of the Ru(bpy)32+/S2O82- System in Purely Aqueous Solution at Carbon Paste Electrode

“…The oxidative-reduction type ECL of Ru(bpy) 2 3 in aqueous solutions is well documented and has resulted in the recent development of highly sensitive detection schemes for many analytes [7±12]. Recently the ECL reaction involved in the annihilation of Ru(bpy) 3 and Ru(bpy) 3 3 has been obtained in water at carbon interdigitated micrelectrode arrays [13]. However, ECL reactions in aqueous solutions have not been reported at normal sized electrodes for the last two types, because Ru(bpy) 3 is unstable andaor the quenching of Ru(bpy) 2 3 * by S 2 O 2À 8 is very quick in fully aqueous solution [6].…”