Photoreduction by visible light of 1,l '-dimethyl-4,4'-bipyri- dinium salts (paraquat, PQ”) into the corresponding cation radical PQ*+ which is a mild reducing agent, is currently achieved in the presence of a photosensitizer such as R~(bpy),~+ or Zn(TPP) (bpy = 2,2'-bipyridine; TPP = tetraphenylporphyrin) and an irreversible electron donor. This system has been used extensively for photoredox catalysis, especially for the photoreduction of water? We report here a new ...
