Artificial light-harvesting antennae: Singlet excitation energy transfer from zinc chlorin aggregate to bacteriochlorin in homogeneous hexane solution

Zinc chlorins possessing 3(1)-hydroxyl and 13(1)-carbonyl groups self-assem ble in nonpolar solvents, such as hexane, in a manner similar to bacterioch lorophyll c in the chlorosomes of green photosynthetic bacteria. Visible ab sorption and steady-state fluorescence measurements of zinc chlorin aggrega tes containing a small amount of the bacteriochlorin-zinc chlorin dyad mole cules showed that singlet excitation energy transfer from the zinc chlorin aggregate to the bacteriochlorin moiety of the coaggregated dyad occurs in the homogeneous solution. In the coaggregated dyad, the bacteriochlorin moi ety plays the role of an efficient energy trap and the chlorin moiety the r ole of an anchor to the donor aggregate, The artificial assembly thus mimic s the structure and function of natural chlorosomes and can be considered a s the first in vitro supramolecular light-harvesting antenna.