Journal of Photochemistry and Photobiology A: Chemistry ( IF 4.3 ) Pub Date : 2020-04-18 , DOI: 10.1016/j.jphotochem.2020.112554 Airi Katayama , Hitoshi Tamiaki
Zinc methyl 3-hydroxymethyl-131-deoxo-pyropheophorbides-a possessing a variety of O-substituted oxime moieties at the 13-position were prepared as models of bacteriochlorophyll-d, which could be found in the main light-harvesting system of green photosynthetic bacteria by chemical modification of naturally occurring chlorophyll-a. The E/Z-stereoisomers of the synthetic O-substituted oximes were successfully separated by silica gel column chromatography. Most of these zinc bacteriochlorophyll-d analogs formed J-type self-aggregates in an aqueous Triton X-100 micelle solution, affording large oligomers whose Soret and Qy bands were red-shifted, compared with those of their monomers in tetrahydrofuran. The self-aggregation was dependent on their E/Z-stereochemistry. Thus, the E-stereoisomers showed the red-shifted electronic absorption bands, which were similar to those of the original bacteriochlorophyll-d bearing the 131-oxo group. On the other hand, the Z-stereoisomers exhibited the less red-shifted absorption bands than did the E-stereoisomers, to give different self-aggregates. In addition, the self-aggregation could be controlled by the size of the O-substituents in the oxime moiety.
中文翻译:
锌细菌叶绿素d类似物的立体选择性自聚集在13位上具有一个O取代的肟部分
锌甲基-3-羟甲基- 13 1 -deoxo-pyropheophorbides-一个具有各种直径: -取代的肟基部分在13位上制备成bacteriochlorophyll-的模型d,这可能在绿色的主要的光收集系统中找到通过化学修饰天然存在的叶绿素a的光合细菌。合成的O-取代的肟的E / Z-立体异构体通过硅胶柱色谱法成功分离。大多数这些锌bacteriochlorophyll-的d类似物形成Ĵ型Triton X-100胶束溶液中的自聚集型,与四氢呋喃中的单体相比,提供了其Soret和Qy带发生红移的大的低聚物。自聚集取决于它们的E / Z-立体化学。因此,Ë -立体异构体显示出红移电子吸收带,其中的那些相似的原始bacteriochlorophyll-的d轴承13 1 -氧代基团。另一方面,Z-立体异构体显示出比E-立体异构体更少的红移吸收带,从而给出不同的自聚集体。此外,可以通过肟部分中的O-取代基。