Title
Self-aggregation of synthetic chlorophyll-c derivative and effect of C17-acrylate residue on bridging green gap in chlorosomal model
Author
Shogo Matsubara, Sunao Shoji, Hitoshi Tamiaki
Year
2017
Journal
Journal of Photochemistry and Photobiology A: Chemistry
Abstract
A zinc bacteriochlorophyll-d analog possessing a fully π-conjugated porphyrin skeleton and an acrylate residue at the 17-position was prepared by chemical modification of an accessory photosynthetic pigment, chlorophyll-c1 from a diatom Chaetoceros species. The synthetic zinc chlorophyll-c1 derivative self-aggregated in a less polar organic solvent and in a solid film to give a red-shifted and broadened visible absorption spectrum, which is similar to that of the main light-harvesting antenna of a green photosynthetic bacterium, where magnesium chlorins with the 17-propionate residue including bacteriochlorophyll-d aggregate in a J-type fashion to form large oligomers. The resulting self-aggregates showed specific and intense absorption bands at around 500 and 600 nm due to the π-extension along the molecular x-axis, which could bridge the “green gap” observed in the above natural antenna system. Visible and infrared absorption spectral analyses revealed that the supramolecular structure of self-aggregates of the zinc chlorophyll-c1 derivative are comparable to those of the natural antenna, in spite of double dehydrogenation at the 17,18- and 171,172-positions in the molecule.
Instrument
J-720
Keywords
Circular dichroism, Stereochemistry, Inorganic chemistry, Biochemistry