Controlled photoinduced electron transfer via triplet in polymer matrix using electrostatic interactions

Abstract

Drawing inspiration from highly efficient natural photosynthetic systems, we developed an artificial photoinduced electron transfer (PET) system within a poly(N-methyl-4-vinylpyridinium) (P4VPMe) polymer matrix. This system features 5,10,15,20-tetrakis-(4-sulfonatophenyl) porphyrin (TPPS) and its zinc complex (ZnTPPS) as electron donors and methylviologen (MV2+) as the electron acceptor. In the presence of an excess of P4VPMe, ZnTPPS exists as individual molecules rather than self-aggregating, favoring PET. Under these conditions, P4VPMe inhibits the formation of ground-state charge-transfer complex between ZnTPPS and MV2+. This shifts the main PET process from singlet to triplet states. ZnTPPS in an excess of P4VPMe demonstrates over a tenfold increase in catalytic activity for the photoinduced oxidation of MV2+ compared to ZnTPPS alone.