Origins of Bound-Probe Fluorescence Decay Heterogeneity in the Distribution of Binding Sites on Silica Surfaces
Year: 1995
Type: article
Abstract: Inhomogeneous fluorescence decay kinetics have been observed from 3-(1-pyrenyl)-propyldimethylsilane (3PPS) covalently bound to silica surface. The excited-state decay kinetics were found to follow a discrete biexponential model rather than a continuous lifetime distribution model and were attributed to the specific site heterogeneity on the silica surface. The existence of two distinguisable silanol sites on silica surface was further supported by the difference in fluorescence decays when a chlorosilane versus a hydroxysilane reagent is used to bind pyrene to the surface. It was also found, for chlorosilane-bound pyrene, that the decay kinetics became more heterogeneous with increasing reaction time or upon exposure of the derivatized sample to water. These results can be explained by a selective reaction between the hydroxysilane and a small population of active silanols, while chlorosilane reacts indiscriminately with the surface under kinetic control. Furthermore, fluorescence quenching studies of surface-immobilized pyrene by iodine were also conducted; enhanced quenching rates for the shorter-lived excited-state population were observed and attributed to the adsorption of quencher molecules to active silanol sites which also caused a faster decay rate of the surface-bound pyrene probe.
DOI: 10.1021/j100046a028
Authors: Haibo Wang, Joel M. Harris
Institution: University of Utah
Language: English
Subfield: Physical and Theoretical Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: green
Funder: U.S. Department of Energy
OpenAlex ID: W2051923245