Construction of Supercryptand Structures and Specific Molecular Recognition

以双列Claisen重排法制备的大环化合物（crown - phanes）为原料，建立了一种共价键合成轮烷的新途径。研究了该方法构建的[2]轮烷及其基于分子间能量传递现象的传感功能。研究发现，这些轮烷类化合物与锂离子具有选择性络合作用，转子分子与轴分子协同作用捕捉离子，并且只有在锂离子存在时才会出现荧光强度的特定增加并伴有能量转移现象。此外，我们的方法成功合成了[1]和[3]轮烷，迄今为止还没有通过形成共价键的合成方法合成它们的报道。经核磁共振和质谱分析证实，所制备的轮烷类化合物在碱金属离子中特异地与锂离子形成络合物，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（超隐型结构），导致锂离子以高选择性进入腔内。我们的方法还制备了[3]轮烷，其中一种与铯离子形成1:1的三明治状配合物。因此，本项目开发了一种新的轮烷合成方法，并对其功能进行了阐述。也就是说，我们的合成方法不仅可以用于[2]轮烷的合成，还可以用于[1]和[3]轮烷的合成，并在荧光光谱中观察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.