Elucidation of Structure and Function of Photosynthetic Antenna by Model Study

Synthesis of Novel Chlorophyllous PigmentsNovel3 I D11个D 1-hydroxy-13个D 11个D 1-oxo-chlorins possessing various substituents at 3个D 11个D 1-，7-，8-，13个I D12个D 1-，17个I D 14个D 1-and 20-positions and their metal complexes were prepared by modification of naturally occurring chlorophylls.2.Preparation of Artificial ChlorosomesSynthetic metal-chlorins self-aggregated to give any oligomers in non-polar organic solvents.Aqueous organic solution，aqueous solutions of detergents，solid thin films and solid powders.Supramolecular structures of the resulting oligomers were investigated by several spectroscopic techniques，indicating that a linear orientation among the hydroxy，keto groups and central metal along the Qy-axis in the molecule is requisite for formation of highly ordered supramolecules and also that magnesium，zinc and cadmium as the central metal were effective for the self-aggregation。Peripheral substituents affected slightly the supramolecular structures of the oligomers，but did not change the framework.In an aqueous solution of a detergent，synthetic pigments self-aggregated at the hydrophobic sphere in the micelle。When a chromophore of a bacteriochlorin moiety was added to the aqueous solution，photoexcited energy of the oligomers was transferred to the added bacteriochlorin，indicating the in vitro self-aggregates are good functional model for natural chlorosomes.Comparison of Natural Chlorosomes with Artificial ChlorosomesNatural chlorophyllous pigments are consisted of several the homologues.It is not unclear how the homologues self-aggregate in the natural systems.体外self-aggregation of synthetic pigments gave any information for the mechanism of in vivo self-aggregation.

Synthesis of Novel Chlorophyllous PigmentsNovel 3ィイD11ィエD1-hydroxy-13ィイD11ィエD1-oxo-chlorins possessing various substituents at 3ィイD11ィエD1-,7-,8-,13ィイD12ィエD1-,17ィイD14ィエD1-and 20-positions and their metal complexes were prepared by modification of naturally occurring chlorophylls.2. Preparation of Artificial ChlorosomesSynthetic metal-chlorins self-aggregated to give any oligomers in non-polar organic solvents. aqueous organic solution, aqueous solutions of detergents, solid thin films and solid powders. Supramolecular structures of the resulting oligomers were investigated by several spectroscopic techniques, indicating that a linear orientation among the hydroxy, keto groups and central metal along the Qy-axis in the molecule is requisite for formation of highly ordered supramolecules and also that magnesium, zinc and cadmium as the central metal were effective for the self-aggregation.All the self-aggregates were built-up mainly by 13-C=・・・H(3-CHR)O・・・M and π-πinteraction of the chlorin chromophores, which are good structural models for natural chlorosomes, extramembranous antennae of photosynthetic green bacteria. Peripheral substituents affected slightly the supramolecular structures of the oligomers, but did not change the framework.In an aqueous solution of a detergent, synthetic pigments self-aggregated at the hydrophobic sphere in the micelle. When a chromophore of a bacteriochlorin moiety was added to the aqueous solution, photoexcited energy of the oligomers was transferred to the added bacteriochlorin, indicating the in vitro self-aggregates are good functional model for natural chlorosomes.Comparison of Natural Chlorosomes with Artificial ChlorosomesNatural chlorophyllous pigments are consisted of several the homologues. It is not unclear how the homologues self-aggregate in the natural systems. In vitro self-aggregation of synthetic pigments gave any information for the mechanism of in vivo self-aggregation.