Photoinduced electron transfer across reverse micelle interfaces using anthracene and ferric cyanide

CHED 1018

Sheneve Butler, and Ruth E. Riter, Department of Chemistry, Agnes Scott College, 141 East College Avenue, Decatur, GA 30030
We have studied the photoinduced electron transfer (PET) across Aerosol-OT (AOT) and Sodium Dodecyl Sulfate (SDS) reverse micelles using anthracene as the electron donor and ferric cyanide as the electron acceptor. Reverse micelles are made up of surfactant aggregates solvating nanosized water droplets in nonpolar solvents. The time-resolved fluorescence of anthracene shows two decay constants when ferric cyanide is present. Since anthracene is preferentially dissolved in the nonpolar solvent and ferric cyanide in the water, we attribute the faster decay constant to PET across the reverse micelle interface. For AOT reverse micelle systems, the time-resolved fluorescence exhibited 1.60.05ns(40%) and 3.80.05ns(60%). The 3.8-ns time constant is consistent with the fluorescence decay of anthracene. For SDS reverse micelle solutions with pentanol as the cosurfactant, the decay constants were 1.50.07ns(50%) and 4.20.04ns(50%). These results are similar to previous studies with methyl viologen as the electron acceptor, suggesting that the electron acceptor solvated inside the reverse micelle lies close to the micelle interface regardless of its charge, the reverse micelle size or cosurfactant.