title: Surface confinement and its effects on the luminescence quenching of a ruthenium-containing metallopolymer.
abstract: Luminescence quenching of the metallopolymers [Ru(bpy)(2)(PVP)(10)](2+) and [Ru(bpy)(2)(PVP)(10)Os(bpy)(2)](4+), 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)](2+) by [Os(bpy)(3)](2+) 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)](2+) 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)](2+) 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)](2+) 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)](4+) films, i.e. the ruthenium emission is not quenched by the coordinated [Os(bpy)(2)](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.
authors.affiliation: Biomedical Diagnostics Institute National Centre for Sensor Research School of Chemical Sciences Dublin City University, Dublin 9, Ireland. Lynn.Dennany@dcu.ie
authors.forename: Lynn
authors.initials: L
authors.lastname: Dennany
authors.forename: Tia E
authors.initials: TE
authors.lastname: Keyes
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Forster
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000032:analysis*; D006801:Humans; D049449:Luminescence; D053768:Metal Nanoparticles; D009992:Osmium; D010777:Photochemistry / Q000379:methods*; D012428:Ruthenium
chemical_list: D015415:Biomarkers; D009992:Osmium; D012428:Ruthenium