Femtosecond electron solvation in micellar solutions: Application to one-electron transfer kinetic in the univalent reduction of a coenzyme

Femtosecond UV pulses are used to generate solvated electrons and then initiate the univalent reduction of an oxidized coenzyme (βNAD+). These phenomena are monitored, at the same femtosecond level, by time-resolved absorption spectroscopy techniques. These experiments show that the subpicosecond dynamics of electron solvation in the polar water bulk of micellar solutions is strongly dependent on the nature and the type of micelles forming the surfactant. In deoxygenated aqueous micelles, the charged micellar surface prevents the reverse electron transfer with cationic radical (PTH+) entrapped in the nonpolar inner core. Univalent reduction of oxidized nicotinamide adenine dinucleotide (βNAD+). by one-electron transfer reaction with a time constant of 270 ps has been observed implying that this coenzyme has retained its ability to mediate electron transfer when solubilized in the semirigid environment of the polar water bulk of aqueous micelles.