Solid-state electrogenerated chemiluminescence from gel-entrapped ruthenium(II) tris(bipyridine) and tripropylamine

A navel approach for the electrogeneration of stable light emission in a so lid host; structure under room conditions is. described. In this work, the chemiluminescent precursors, ruthenium(II) tris(bipyridine) (Ru(bpy)(3)(2+) ) and tripropylamine (TPA), were trapped in a porous silicate host matrix a long with an electrode assembly. When the electrode potential was scanned o r stepped to a potential sufficient to oxidize gel-entrapped TPA and RU(bpy )(3)(2+), electrochemiluminescence (ECL) was observed. The solid-state ECL spectrum was identical to the fluorescence spectrum of gel-entrapped Ru(bpy )(3)(2+). The intensity of the emission depends on the amount of TPA and RU (bpy)(3)(2+) in the gel as well as the size of the electrode. When an ultra microelectrode (microband or microdisk) was used to generate the ECL, the r esultant emission was found to be remarkably stable. Little drop in intensi ty was observed upon continuous application of ca. 1.2 V for 2-12 h. In dir ect contrast, the ECL dropped significantly at a large electrode (e.g., r = 1.1 mm) in a relatively short period of time. The improved stability of th e ECL at ultramicroelectrodes can be attributed not only to their small siz e, which results in a decreased consumption of TPA, but also to the steady- state flux of reagents to the electrode surface.