pH-Controlled Multiple Interconversion between Cucurbit[7]uril-Based Molecular Shuttle, [3]Pseudorotaxane and [2]Pseudorotaxane

摘要

An axle molecule 1(2+) containing one viologen nucleus and two identical p-toluic acid sides was synthesized. The sequential binding of the Q[7] wheels to the 1(2+) axle leads to the formation of a molecular shuttle and then a homowheel, [3]pseudorotaxane. The [3]pseudorotaxane can reversibly transform to [2]pseudorotaxane by acid-base control. On the other hand, the initially formed molecular shuttle can also transform to [2]pseudorotaxane directly and reversibly under pH control. As a whole, a molecular shuttle and [3]/[2]pseudorotaxanes constructed a pH-controlled multiple interconvertible system.