Rhodamine 3B(+)ClO(4)(-) in water : toluene mixtures - Evidence of water cluster formation

Rhodamine 3B perchlorate coexists solubilized in mixtures of water:toluene as a distribution of ion pair (74%) and cation (26%). The quantum yield var iation shows that the fluorescence quenching process of the ion pair is dif fusion controlled with a rate constant oscillating within the limits of sli p and stick boundary conditions. The driving force for the excited-state co nversion is the unbalance of electrostatic forces and changes in inter-ioni c distances in the water cluster solvation sphere created around the ion pa ir by dielectric enrichment. (C) 1999 Elsevier Science B.V. All rights rese rved.