Ion-Mediated Electron Transfer in a Supramolecular Donor-Acceptor Ensemble
Ion-Mediated Electron Transfer in a Supramolecular Donor-Acceptor Ensemble
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DOI：
10.1126/science.1192044
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发表时间：
2010-09-10
期刊：
影响因子：
56.9
通讯作者：
Sessler, Jonathan L.
中科院分区：
文献类型：
--
作者：
Park, Jung Su;Karnas, Elizabeth;Sessler, Jonathan L.
离子结合通常作为辅因子策略介导生物系统中的电子传递，无论是作为启动子还是作为抑制剂。然而，它很少（如果有的话）被用于合成主客体组装。我们在这里报告，强结合的特定阴离子（氯离子，溴离子和甲基硫酸根，但不是四氟硼酸根或六氟磷酸根）的四硫富瓦烯杯[4]吡咯（TTF-C4 P）供体强制执行主机构象，有利于电子转移到bisimidazolium醌（BIQ（2+））客体受体。相比之下，在TTF-C4 P腔中比BIQ（2+）客体更有效结合的四乙基铵阳离子的添加导致背电子转移，恢复供体和受体对的初始氧化态。通过光谱学和X射线晶体学对这些过程的产物进行了表征。
Ion binding often mediates electron transfer in biological systems as a cofactor strategy, either as a promoter or as an inhibitor. However, it has rarely, if ever, been exploited for that purpose in synthetic host-guest assemblies. We report here that strong binding of specific anions (chloride, bromide, and methylsulfate but not tetrafluoroborate or hexafluorophosphate) to a tetrathiafulvalene calix[4]pyrrole (TTF-C4P) donor enforces a host conformation that favors electron transfer to a bisimidazolium quinone (BIQ(2+)) guest acceptor. In contrast, the addition of a tetraethylammonium cation, which binds more effectively than the BIQ(2+) guest in the TTF-C4P cavity, leads to back electron transfer, restoring the initial oxidation states of the donor and acceptor pair. The products of these processes were characterized via spectroscopy and x-ray crystallography.