Supramolecular light-harvesting antenna system by co-aggregates of zinc (bacterio)chlorophyll-a derivatives with biomimetic chlorosomal self-assemblies

Light-harvesting (LH) antennas are one of the most important apparatuses for photosynthetic organisms to utilize solar energy. The main LH apparatuses in photosynthetic green bacteria are chlorosomes containing baseplate proteins. A chlorosome possesses a large number of bacteriochlorophyll(BChl)-c-f molecules. These BChls are chemically programmed pigments for J-aggregation, which self-assemble in a hydrophobic environment. The BChl-c-f self-assemblies in a chlorosome are primary energy donors, which absorb sunlight, migrate the excitation energy, and transfer it to energy acceptor BChl-a pigments in a baseplate protein. To develop such chlorosomal LH antenna in artificial systems, self-assemblies of synthetic BChl-d analogs and BChl-a derivatives have been used for the energy donors and acceptors, respectively. In this study, we report the co-aggregation of zinc chlorophyll derivatives with chlorosomal self-assemblies. The present system showed singlet excitation energy transfer from energetically donating chlorosomal self-assemblies to energetically accepting zinc chlorophyll derivatives in the solution and solid states.