An artificial photosynthetic antenna-reaction center complex

A model photosynthetic antenna consisting of four covalently linked zinc tetraarylporphyrins, (P-ZP)(3)-P-ZC, has been joined to a free base porphyrin-fullerene artificial photosynthetic reaction center, P-C-60, to form a (P-ZP)(3)-P-ZC-PC60 hexad. As revealed by time-resolved absorption and emission studies, excitation of any peripheral zinc porphyrin moiety (P-ZP) in 2-methyltetrahydrofuran solution is followed by singlet-singlet energy transfer to the central zinc porphyrin to give (P-ZP)(3)-P-1(ZC)-P-C-60 With a time constant of similar to 50 ps. The excitation is passed on to the free base porphyrin in 240 ps to produce (P-ZP)(3)-P-ZC-P-1-C-60, which decays by electron transfer to the fullerene with a time constant of 3 ps. The (P-ZP)(3)-P-ZC-P.+-C-60(.-) charge-separated state thus formed has a lifetime of 1330 ps, and is generated with a quantum yield of 0.70 based on light absorbed by the zinc porphyrin antenna. The complex thus mimics the basic functions of natural photosynthetic antenna systems and reaction center complexes.