The effect of diffusive solvent relaxation on ultrafast electron transfer within the methyl viologen-hexacyanoferrate complex in trehalose–water glass

Electron transfer rate were measured for methyl viologen-hexacyanoferrate and methyl viologen-hydroquinone complexes in solution and in trehalose–water glass matrices. Rates measured in the glass were a factor of 2.5–3 smaller than those observed in aqueous solution, whereas linear absorption spectra were shifted by less than 300 cm−1 with only minor differences in line shape. Our data in the trehalose–water glass are consistent with a predominantly aqueous local environment. Electron transfer rate data are modeled by allowing 10% of the solvent reorganization in the glass to proceed diffusively.