title: Photophysical characterization of the interactions among tris(2,2'-bipyridyl)ruthenium(II) complexes ion-exchanged within zirconium phosphate.
abstract: We studied the structures, luminescence, and self-quenching properties of tris(2,2'-bipyridyl)ruthenium(II) (Ru(bpy)(3)(2+)) two-dimensional arrangements within the layers of zirconium phosphate (ZrP). The intercalation of Ru(bpy)(3)(2+) was accomplished using a hydrated form of zirconium phosphate ZrP. Varying the Ru(bpy)(3)(2+)/ZrP intercalation ratio, different Ru(bpy)(3)(2+)-exchanged ZrP loading levels were achieved. The ion exchange of Ru(bpy)(3)(2+) within ZrP produces a red shift in the metal-to-ligand charge-transfer (MLCT) absorption band of the complex from 452 nm in aqueous solution to 460 nm in ZrP. Steady state luminescence spectra of the Ru(bpy)(3)(2+)-exchanged ZrP materials show an increase in the luminescence intensity with an increase in the Ru(bpy)(3)(2+) loading level until about 0.77 M, where subsequent increases in the loading level produce a decrease in the luminescence (self-quenching region). Time-resolved luminescence measurements are consistent with the steady state luminescence measurements. Analysis of the time domain luminescence measurements in loadings higher than 0.77 M leads to the determination of a collisional quenching rate constant of (1.67 +/- 0.05) x 10(6) M(-1) s(-1). Stern-Volmer analysis of the luminescence quantum yield of Ru(bpy)(3)(2+)-exchanged ZrP materials indicates that static quenching is also involved in the Ru(bpy)(3)(2+) self-quenching mechanism. The quantum yield data behavior might be explained by a model that takes into account collisional quenching and the quasi-static Perrin mechanism. The calculation yields a quenching sphere of action of 14.8 A, which is slightly larger than the collisional radii of two Ru(bpy)(3)(2+) ions (12.2 A), as predicted by the model.
authors.affiliation: Department of Chemistry, Rice University, 6100 S Main Street, MS-60, Houston, Texas 77005, USA.
authors.forename: Angel A
authors.initials: AA
authors.lastname: Martí
authors.forename: Jorge L
authors.initials: JL
authors.lastname: Colón
mesh_terms: D056831:Coordination Complexes; D008163:Luminescent Measurements; D009942:Organometallic Compounds / Q000737:chemistry*; D011789:Quantum Theory; D013057:Spectrum Analysis; D015040:Zirconium / Q000737:chemistry*; D017975:Ruthenium Compounds
chemical_list: D056831:Coordination Complexes; D009942:Organometallic Compounds; D015040:Zirconium; C547232:tris(2,2-bipyridine)-ruthenium(II); D017975:Ruthenium Compounds; C027006:zirconium phosphate