An artificial photosynthetic antenna-reaction center complex

A model photosynthetic antenna consisting of four covalently linked zinc te traarylporphyrins, (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 emissio n studies, excitation of any peripheral zinc porphyrin moiety (P-ZP) in 2-m ethyltetrahydrofuran solution is followed by singlet-singlet energy transfe r to the central zinc porphyrin to give (P-ZP)(3)-P-1(ZC)-P-C-60 With a tim e constant of similar to 50 ps. The excitation is passed on to the free bas e porphyrin in 240 ps to produce (P-ZP)(3)-P-ZC-P-1-C-60, which decays by e lectron 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 1 330 ps, and is generated with a quantum yield of 0.70 based on light absorb ed by the zinc porphyrin antenna. The complex thus mimics the basic functio ns of natural photosynthetic antenna systems and reaction center complexes.