A supramolecular analog of the photosynthetic special pair
A supramolecular analog of the photosynthetic special pair
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DOI：
10.1021/ja971473h
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发表时间：
1997-08-27
影响因子：
15
通讯作者：
Williams, DJ
中科院分区：
文献类型：
--
作者：
Feiters, MC;Fyfe, MCT;Williams, DJ
由于卟啉核具有非凡的电子和光催化性质，在最近的化学文献中出现了无数的合成类卟啉低聚物。产生这种类卟啉组合的主要驱动力之一是光合作用反应中心的解体，2在那里，两个细菌叶绿素的“特殊对”被ca. 3.2 Å以一种滑动的共面取向分开。我们推测，我们应该能够自组装一个相互交织的光合作用特殊对的相互交织的类似物，通过利用我们的程序方法来非共价合成相互交织的超分子笼。在这个过程中（方案1），两个具有卟啉核心的四聚四铵阳离子14+单元将与四个双位冠醚双对苯基-[34]冠-10 （BPP34C10）分子组装，产生六组分交织聚集体，其中四个冠醚标记将两个卟啉亚基以共面取向结合在一起。本文报道了在固态和溶液中[(BPP34C10) 4, -(1) 2] 8+超分子的非共价合成，并分别用x射线晶体学和EPR光谱进行了证明。当含有1,4pf6和4倍过量BPP34C10的MeCN溶液与i- pr2o分层时，对单晶进行x射线分析6，显示出根据我们的设计标准（方案1）自组装的六组分上层结构。以特征5的方式，将与ci相关的14+螯合物的二苄胺侧臂同时穿过四个循环处理的BPP34C10大环的空腔（图1）。除了卟啉核之间的传统π-π堆叠外（平均面间距为3.65 Å），超分子组合通过[N+稳定
On account of the porphyrin nucleus’ extraordinary electronic and photocatalytic properties, a myriad of synthetic porphyrinoid oligomers have surfaced1 in the recent chemical literature. One of the prime driving forces for the production of such porphyrinoid assemblages has been the unraveling of the photosynthetic reaction center, 2 where a “special pair” of two bacteriochlorophylls is held apart by ca. 3.2 Å with a slipped cofacial orientation. 3 We conjectured that we should be able to selfassemble4 an interwoven analog of the photosynthetic special pair by exploiting our programmed approach for the noncovalent synthesis of interwoven supramolecular cages. 5 In this procedure (Scheme 1), two units of the tetrafurcated tetrakisammonium cation 14+ spossessing a porphyrin coreswould assemble with four molecules of the ditopic crown ether bis-p-phenylene-[34] crown-10 (BPP34C10) to generate a six-component interwoven aggregate where the four crown ether macrorings would tie two porphyrin subunits together in a cofacial orientation. Here, we report the noncovalent synthesis of the [(BPP34C10) 4 ‚-(1) 2] 8+ supermolecule in the solid state, and in solution, as evidenced by X-ray crystallography and EPR spectroscopy, respectively.The X-ray analysis6 of a single crystalsobtained when a MeCN solution containing 1 ‚4PF6 and a 4-fold excess of BPP34C10 was layered with i-Pr2Osreveals a six-component superstructure that has self-assembled in accordance with our design criteria (Scheme 1). Pairs of Ci-related 14+ tetracations have their dibenzylammonium sidearms threaded simultaneously through the cavities of four cyclically-disposed BPP34C10 macrocycles (Figure 1) in characteristic5 fashion. In addition to conventional π-π stacking7 between the porphyrin nuclei (the mean interplanar separation is 3.65 Å), the supramolecular assemblage is stabilized Via [N+