Reactivity of Nitroxide Spin Probes toward Photochemically Generated Benzyl Radicals in Clay Mineral Suspensions

摘要

The ESR spectra of three nitroxide probes in laponite (synthetic hectorite)/cyclohexane slurries show up to three components assigned to probes dissolved in solution, bound to the surface, and aggregated near the surface. Addition of dibenzly ketone (DBK) to the probe/clay suspensions results in partial probe desorption. Upon ultraviolet irradiation of these mixtures, the component of the ESR spectra assigned to bound probe changes to a lesser extent than corresponding to solubilized probe, which disappears as benzyl radicals react with the nitroxide. With the probe aggregates, irradiation of samples sharpening of the peaks. This paper demonstrates a novel use of nitroxide traps for unstable radicals as structural probes of heterogenous systems.