Construction of Supercryptand Structures and Specific Molecular Recognition

以Claisen重排反应制备的冠芳大环化合物为原料，通过共价键合成轮烷。利用该方法构建了[2]轮烷类化合物，并研究了其基于分子间能量转移现象的传感等功能。结果表明，这些轮烷与锂离子具有选择性络合作用，在络合过程中，轮烷分子与轴分子协同捕获锂离子，只有在锂离子存在时才能观察到荧光强度的特异性增强，并伴有能量转移现象。而迄今为止还没有通过共价键形成的合成方法报道它们的合成。[1]在NMR和质谱中证实所制备的轮烷与碱金属离子中的锂离子特异性地形成络合物，并观察到能量转移现象。结果表明，大环部分和轴部分形成了三维结构（超穴状结构），从而使锂离子以高选择性进入空穴。本课题还合成了[3]轮烷类化合物，其中一种与铯离子形成1：1的类铯离子配合物，从而为轮烷类化合物的合成提供了一种新的方法，并阐明了其功能。也就是说，我们的合成方法不仅可以应用于[2]轮烷的合成，还可以应用于[1]和[3]轮烷的合成，并且在荧光光谱中观察到了对阳离子的特定能量转移行为。

A new route for rotaxane synthesis via covatent bond formation was developed from macrocyclic compounds (crownophanes) prepared by tandem Claisen rearrangement. The construction of [2]rotaxanes by this method and their functions such as sensing based on the energy transfer phenomenon between molecules were investigated. It was found that these rotaxanes can exhibit the selective complexation with lithium ion, where the roter and axle molecules work cooperatively to catch the ion, and the specific increase of fluorescent intensity was observed only in the presence of lithium ion accompanying with energy transfer phenomenon.In addition, [1]and [3]rotaxanes were successfully synthesized by our method, while their synthesi has not been reported by a synthetic method via covalent bond formation so far. [1]Rotaxanes prepared were confirmed to make complex with lithium ion specifically among alkali metal ions in the NMR and Mass spectra and observed the energy transfer phenomenon. It is concluded that the macrocyclic part and axle part form three dimensional structure (supercryptand structure) to result in the incorporation of lithium ion with high selectivity into the cavity. By our method, [3]rotaxanes were also prepared, and one of them forms 1:1 complex with cesium ion in the manner of sandwich-like structure.Thus, in this project, a novel synthetic method for rotaxanes has been developed and and the functions have been elucidated. That is, our synthetic method can be applied to the synthesis not only of [2]rotaxanes but also of [1]and [3]rotaxanes, and the specific energy transfer behaviors toward cations were observed in the fluorescence spectrum.