Time-resolved EPR observation of blue-light-induced radical ion pairs in a flavin-Trp dyad.

A dyad of flavin and Trp bridged by a p -phenylamide linker was synthesized as an artificial model system to investigate molecular-based magnetic-field sensors relevant to blue-light photoreceptor proteins. The results demonstrated that intramolecular electron transfer generates a radical pair, only the triplet-born one of which has a microsecond lifetime at room temperature.