Mechanical twisting of a guest by a photoresponsive host
Mechanical twisting of a guest by a photoresponsive host
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DOI：
10.1038/nature04635
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发表时间：
2006-03-23
期刊：
影响因子：
64.8
通讯作者：
Aida, T
中科院分区：
文献类型：
--
作者：
Muraoka, T;Kinbara, K;Aida, T
各种机械装置的分子类似物，如梭子、制动器、单向转子和镊子已经被创造出来（1-11）。但是这些“分子机器”还没有被用来以可控和可逆的方式机械地操纵第二个分子。在这里，我们证明了光诱导的一个分子的剪刀状构象变化(5)可以引起非共价结合的客体分子的机械扭曲。为了实现这种分子运动的耦合，我们使用了先前设计的系统(5)：二茂铁片段与偶氮苯带，其两端连接到二茂铁单元的两个环戊二烯环中的一个，作为一个支点，使二茂铁环的光异构化旋转，从而也改变了两个“踏板”部分连接到二茂铁环的相对位置。我们将这种效应转化为分子间运动的耦合，通过赋予踏板结合位点，使宿主系统与双齿转子分子形成稳定的复合物。利用圆二色光谱，我们发现光诱导的宿主构象变化确实被传递并引起转子分子的机械扭曲。这一设计概念将成功的运动耦合大大扩展到合成变构受体所见的分子内水平之外（12），可能允许在更大的互锁分子系统中远程控制分子事件。
Molecular analogues of a variety of mechanical devices such as shuttles, brakes, unidirectional rotors and tweezers have been created(1-11). But these 'molecular machines' have not yet been used to mechanically manipulate a second molecule in a controlled and reversible manner. Here we show that light-induced scissor-like conformational changes of one molecule(5) can give rise to mechanical twisting of a non-covalently bound guest molecule. To realize this coupling of molecular motions, we use a previously designed system(5): a ferrocene moiety with an azobenzene strap, each end of which is attached to one of the two cyclopentadienyl rings of the ferrocene unit, acts as a pivot so that photoisomerization of the strap rotates the ferrocene rings relative to each other and thereby also changes the relative position of two 'pedal' moieties attached to the ferrocene rings. We translate this effect into intermolecular coupling of motion by endowing the pedals with binding sites, which allow the host system to form a stable complex with a bidentate rotor molecule. Using circular dichroism spectroscopy, we show that the photoinduced conformational changes of the host are indeed transmitted and induce mechanical twisting of the rotor molecule. This design concept, which significantly extends the successful coupling of motion beyond the intramolecular level seen in synthetic allosteric receptors(12), might allow for the remote control of molecular events in larger interlocked molecular systems.