Synthesis of regioisomeric bacteriochlorophyll-d analogues possessing a hydroxy group at the 2(1)- or 3(1)-position: their chlorosome-like self-aggregation in solid films.
Zinc 2(1)- and 3(1)-hydroxy-13-carbonylhexaethylporphyrins 2 and 3 were synthesized by modifying easily available octaethylporphyrin, and the HPLC-separated regioisomers were fully characterized. The latter compound 3(1)-OH-13-C=O-3, which structurally resembled naturally self-aggregative bacteriochlorophyll-d (3(1)-OH/13-C=O), was preferable to make ordered J-aggregates in the solid film, compared to its regioisomeric 2(1)-OH-13-C=O-2. In contrast, more ordered oligomers were obtained by self-aggregation of zinc porphyrin 1 possessing the interactive moieties (3(1)-OH, Zn, 13-C=O) at the same positions, which was prepared by modifying natural chlorophyll-a molecule. The difference between self-aggregation of 1 and 3 was ascribable to the methyl and ethyl groups attached at the 2-position neighboring the 3(1)-OH group which is requisite for self-aggregation; the steric environment around the interactive OH group is important to make highly ordered supramolecules through strong molecular packings.
Kunieda
Michio
M
Department of Bioscience and Biotechnology, Faculty of Science and Engineering, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan.
Tamiaki
Hitoshi
H
D001419:Bacteria; D001429:Bacteriochlorophylls / Q000138:chemical synthesis* / Q000737:chemistry* / Q000378:metabolism; D032701:Biomimetics; D002851:Chromatography, High Pressure Liquid; D006878:Hydroxides / Q000737:chemistry*; D008968:Molecular Conformation; D010788:Photosynthesis; D013237:Stereoisomerism; D015032:Zinc / Q000737:chemistry
D001429:Bacteriochlorophylls; D006878:Hydroxides; C459779:bacteriochlorophyll d; C031356:hydroxide ion; D015032:Zinc