Luminescence quenching of Ru(bpy)(3)(2+) by nitrophenols in silicate thin films

摘要

The luminescence quenching of ruthenium(II)-tris-12-bipyridine ion (Ru(bpy)(3)(2+)) included in methyltriethoxysilane-derived films by 2-, 3- and 4-nitrophenol was investigated. Sol-gel technology was used to prepare the "sol". Coating thin films were obtained from the "sol" by spin-coating on glass slide. A blue shift in the Ru(bpy)(3)(2+) emission spectrum included in the films with respect to the aqueous solution was observed. Ru(bpy)(3)(2+) luminescence quenching experiments were carried out with the quencher in aerated aqueous solution at pH 2 in contact with the film. The quenching plots obtained from either steady-state or time-resolved luminescence intensity measurements showed a downward curvature. Both plots were fitted satisfactorily by a sum of two terms of Stern-Volmer with quenching constants K-sv1 and K-sv2 values and the corresponding fractions of the total emission f(1)(0) and f(2)(0) for both sites suggest that only a low percentage of the probe is accessible to the quencher and that the K-sv in homogeneous aqueous solution. A dynamic process of electron transfer was suggested for the luminescence quenching of Ru(bpy)(3)(2+) in the film by nitrophenols in aqueous solution. (c) 2005 Published by Elsevier B.V.