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-C60, 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))3-1P(ZC)-P- C60 with a time constant of ~50 ps. The excitation is passed on to the free base porphyrin in 240 ps to produce (P(ZP))3-P(ZC)-1P-C60, which decays by electron transfer to the fullerene with a time constant of 3 ps. The (P(ZP))3-P(ZC)-P(·)+-C60(·)- 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.
ASJC Scopus subject areas