(Invited) Metal-Assisted Formation of an Extremely Long–Lived Charge-Separated State in a Porphyrin–Flavin Dyad

A long-lived charge-separated (CS) state formed by photoinduced electron transfer (ET) is indispensable to convert absorbed light energy into other energies as observed in photosynthesis, solar cells, photocatalysts for material production. 1 Porphyrins have been linked to various kinds of electron acceptors including fullerenes and quinones to provide donor-acceptor dyads forming CS states upon photo-excitation. 1,2 Recently, oxidized forms of flavin derivatives have been demonstrated to act as electron acceptors in photoinduced ET to afford longlived CS states due to their small reorganization energy (λ) in ET reactions. 3 Herein, we synthesized a porphyrin– flavin-linked dyad and its zinc and palladium complexes (MPor–Fl, 1-M, M = 2H, Zn, Pd; Figure 1) and investigated their photodynamics of intramolecular photoinduced ET to form long-lived CS states.