Solvent Effect on the Behavior of Single Eosin Y Photoredox Catalyst.

Solvents are known to affect the product yield in photoredox catalysis. Previously, Efforts have been made to understand how solvents affect photoredox catalysis at the ensemble level. However, the underlying mechanism has not yet been fully elucidated. Here, we studied the behavior of single photoredox catalysts in a variety of solvents by using single-molecule fluorescence imaging. By analyzing the trajectories of single eosin Y (EY), we found that the solvent could affect photoredox catalysis both physically and chemically. Evidence of the long-lived triplet excited state of the photoredox catalyst and redox active impurities was found. These two factors may play important roles in photoredox catalysis and thus need to be given attention.