Self-Assembly of M24L48 Polyhedra Based on Empirical Prediction
Self-Assembly of M24L48 Polyhedra Based on Empirical Prediction
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DOI：
10.1002/anie.201108731
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发表时间：
2012-01-01
影响因子：
16.6
通讯作者：
Fujita, Makoto
中科院分区：
文献类型：
--
作者：
Bunzen, Jens;Iwasa, Junji;Fujita, Makoto
由金属离子和桥联配体组成的巨型配位多面体的自组装是当前化学研究的热点之一。[1-3]理论上，通过对金属配位几何结构和配体桥联角度的分析，可以预测多面体的结构。然而，在现实中，由于分子组分比预期的要灵活得多，金属中心会允许配位角发生相当大的偏差，所以经常会出现不可预测的结构。最近，M12L24立方八面体[7]和M24L48菱形双八面体[8]分别由非常相似的配体1和5与PdII离子络合而成(图1)。这两种结构的理论预测是不可能的，但当混合配体(1+5)进行金属络合时，我们观察到当混合比例为1：5=8：2%7：3时，生成的结构从M12L24到M24L48的临界开关，其中配体的平均弯曲角从131到1348变化。[8]我们假设控制得到的结构的最重要参数是配体的弯曲角Q，并预测如果对弯曲角进行化学调制，临界结构开关将发生在Q=131-1348左右(图1b)。在这里，我们表明这个简单的经验预测适用于配体2-4的自组装。通过将这些配体的弯曲角参考图1b中的经验尺度，我们预测了迄今已知的最大配位多面体M24L48从这些配体2-4自组装。
Self-assembly of giant coordination polyhedra from metal ions and bridging ligands is one of the intriguing topics in current chemistry.[1–3] In theory, the structures of the polyhedra can be predicted based on the analysis of the coordination geometry at the metal and the bridging angles of the ligands.[4] In reality, however, unpredicted structures often appear because molecular components are much more flexible than expected and metal centers can permit considerable deviation in their coordination angles.[5, 6] In particular, when the number of the components is considerably large (more than about 50), the prediction of self-assembled structures becomes increasingly difficult or impossible. Recently, an M12L24 cuboctahedron [7] and an M24L48 rhombicuboctahedron [8] were constructed from very similar ligands 1 and 5, respectively, upon complexation with PdII ions (Figure 1). The prediction of these two structures by theory was not possible, but when mixed ligands (1+ 5) were subjected to metal complexation, we observed the critical switch of the resultant structures from M12L24 to M24L48 at the mixing ratios of 1: 5= 8: 2% 7: 3, where the averaged ligand bend angle varies from 131 to 1348.[8] We assumed that the most important parameter that controls the resultant structures was the bend angle q of the ligands and predicted that the critical structural switch would occur at around q= 131–1348 if the bend angle was chemically modulated (Figure 1 b). Herein, we show that this simple empirical prediction is applicable for self-assembly from ligands 2–4. By referring the bend angles of these ligands to the empirical scale in Figure1b, we predicted the self-assembly of M24L48, the largest hitherto known coordination polyhedron, from these ligands 2–4.