Highly Efficient Electrochemiluminescence of Functionalized Tris(2,2′‐bipyridyl)ruthenium(II) and Selective Concentration Enrichment of Its Coreactants

Abstract An enhanced electrochemiluminescence (ECL) efficiency is obtained from the ruthenium complex tris(2,2′‐bipyridyl)ruthenium(II) (Ru(bpy)₃²⁺) by introduction of an ionic liquid (IL) 1‐butyl‐3‐methylimidazolium tetrafluoroborate (BMImBF₄). Upon addition of 1 % (v/v) BMImBF₄ to 0.1 mM Ru(bpy)₃²⁺ solution, a maximum increase in ECL intensity is obtained both at an indium tin oxide (ITO) electrode (15‐fold) and at a glassy carbon (GC) electrode (5‐ to 6‐fold). Furthermore, upon addition of 1 % (v/v) BMImBF₄ to 5 μM Ru(bpy)₃²⁺/100 mM co‐reactant systems at a GC electrode, IL adsorption occurs at the electrode surface, which results in a change of the polarity of the electrode surface. Such functionalization greatly improves the functions of both Ru(bpy)₃²⁺ and ionic liquids, as is demonstrated in the sensitive and selective concentration enrichment of the Ru(bpy)₃²⁺ co‐reactants.