Selective visible-light-driven oxygen reduction to hydrogen peroxide using BODIPY photosensitizers

Selective visible-light-driven O2 reduction to H2O2 was realized using BODIPY photosensitizers (PS) in the presence of ferrocene (Fc) as the reductant and acetic acid as the proton source. Mechanistic studies suggested that O2 could be activated by 3PS* through an energy transfer pathway to give singlet oxygen (1O2) in the absence of Fc. However, with Fc, 3PS* was first reductively quenched to PS˙−, which was able to reduce O2 to the superoxide radical form in a subsequent electron transfer step.