Is Soret-excited ZnTPP quenched by electron transfer in chlorinated solvents?

The title question is addressed by careful steady state and fs fluorescence upconversion measurements. Changes in S2 population decay times and S2–S0 fluorescence intensities of ZnTPP observed when solvents like benzene are replaced by potentially electron-accepting solvents like CH2Cl2 can be interpreted quantitatively in terms of variations in the solvent’s refractive index. Contrary to literature reports, no evidence of a major electron-transfer decay route is found for Soret-excited ZnTPP in chlorinated solvents, although ZnTPP+ radical cations are formed in very low yield. The answer to the title question is therefore, yes, but only with low quantum efficiency.