Insights into the Difference Between Rotaxane and Pseudorotaxane

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• 作者：He-Lue Sun ; Dr. Heng-Yi Zhang ; Zhen Dai ; Xu Han and Prof. Dr. Yu Liu
• 刊名：Chemistry – An Asian Journal
• 出版年：2017
• 出版时间：January 17, 2017
• 年：2017
• 卷：12
• 期：2
• 页码：265-270
• 全文大小：1326K
• ISSN：1861-471X

文摘

Rotaxane and pseudorotaxane are two types of mechanically interlocked molecular architectures, and there is a clear topological difference and boundary between them. In this work, a “suggested [2]rotaxane 1⊂α-CD” was constructed based on axle molecule 1 bearing two terminal ferrocene groups and a wheel component α-cyclodextrin (α-CD), but the result obtained indicated that the ferrocene group cannot prevent α-CD dethreading under UV irradiation. That is, 1⊂α-CD is just a pseudo[2]rotaxane. Furthermore, the two ferrocene groups in 1⊂α-CD were encapsulated by two cucurbit[7]uril (CB[7]) units to obtain a heteropseudo[4]rotaxane 1⊂α-CD⋅2CB[7]. This heteropseudo[4]rotaxane displayed high stability towards harsh temperatures and the isomerization of azobenzene in 1, so it can be regarded as a [2]rotaxane. In this [2]rotaxane, the stoppers are not the bulky groups covalently bonded to the axle, but the cyclic CB[7] units connected through noncovalent interactions.