Surface confinement and its effects on the luminescence quenching of a ruthenium-containing metallopolymer.

Luminescence quenching of the metallopolymers Ru(bpy)(2)(PVP)(10) and Ru(bpy)(2)(PVP)(10)Os(bpy)(2), both in solution and as thin films, is reported, where bpy is 2,2'-bipyridyl and PVP is poly(4-vinylpyridine). When the metallopolymer is dissolved in ethanol, quenching of the ruthenium excited state, Ru(2+*), within Ru(bpy)(2)(PVP)(10) by Os(bpy)(3) proceeds by a dynamic quenching mechanism and the rate constant is (1.1 +/- 0.1) x 10(11) M(-1) s(-1). This quenching rate is nearly two orders of magnitude larger than that found for quenching of monomeric Ru(bpy)(3) under the same conditions. This observation is interpreted in terms of an energy transfer quenching mechanism in which the high local concentration of ruthenium luminophores leads to a single Os(bpy)(3) centre quenching the emission of several ruthenium luminophores. Amplifications of this kind will lead to the development of more sensitive sensors based on emission quenching. Quenching by both Os(bpy)(3) and molecular oxygen is significantly reduced within a thin film of the metallopolymer. Significantly, in both optically driven emission and electrogenerated chemiluminescence, emission is observed from both ruthenium and osmium centres within Ru(bpy)(2)(PVP)(10)Os(bpy)(2) films, i.e. the ruthenium emission is not quenched by the coordinated Os(bpy)(2) units. This observation opens up new possibilities in multi-analyte sensing since each luminophore can be used to detect separate analytes, e.g. guanine and oxoguanine.