Two heterodyads were prepared from the chemical modification of naturally occurring (bacterio)chlorophyll-a and composed of a chlorin π-skeleton linked to a porphyrin or bacteriochlorin π-system. Zinc methyl pyropheophorbide-a, one of the chlorophyll-a derivatives, was covalently linked with its 17,18-didehydrogenated species (zinc methyl pyroprotopheophorbide-a) or its trans-7,8-dihydrogenated analog (zinc methyl pyrobacteriopheophorbide-a as one of the bacteriochlorophyll-a derivatives) through ethylene glycol diester at their 17-propionate residues. In benzene, the central zinc atoms of the synthetic conjugates were coordinated by two methanol molecules which were hydrogen-bonded with the 13-keto-carbonyl groups in a dyad molecule. The methanol locked, y-axis aligned, and slipped cofacial conformers showed two apparent Qy bands at longer wavelengths than those of the composite zinc complex monomers. The red-shifted Qy bands are ascribable to the exciton coupling of the two different π-systems in the folded heterodyad conformers. The synthetic heterodyads could be models of chlorophyll-a/c dimers in the light-harvesting antennas of chromophytes including fucoxanthin-chlorophyll proteins in diatoms and also chlorophyll-a species interacting with bacteriochlorophyll-a or g species in the charge-separating reaction centers of green sulfur bacteria or heliobacteria, respectively.

中文翻译：

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合成的叶绿素杂合体与不同π骨架的分子内相互作用。

通过对天然存在的（细菌）叶绿素-a进行化学修饰，制备了两个杂合体，它们由连接到卟啉或细菌绿素π系统的二氢卟酚π骨架组成。叶绿素-a衍生物之一的甲基甲基焦脱镁叶绿酸-a与它的17,18-二氢氢化物（锌甲基焦脱镁叶绿酸-a）或其反式7,8-二氢化类似物（锌甲基焦脱镁叶绿酸-a作为共价键）连接。的细菌叶绿素-a衍生物）在其17-丙酸酯残基处通过乙二醇二酯。在苯中，合成缀合物的中心锌原子由两个甲醇分子配位，这两个甲醇分子与二元分子中的13-酮羰基氢键合。甲醇锁定，y轴对齐，滑动的表面构象异构体在比复合锌络合物单体更长的波长处表现出两个明显的Qy带。红移的Qy带归因于折叠的杂合构象异构体中两个不同的π系统的激子耦合。合成杂合体可能是发色细胞光收集天线中叶绿素-a / c二聚体的模型，包括硅藻中的岩藻黄质-叶绿素蛋白，以及与细菌叶绿素-a或g物种在电荷分离反应中心相互作用的叶绿素-a物种。分别是绿色硫细菌或Heliobacteria。