Design and synthesis of rotaxanes aimed at the development of actuating and locomotional functions

Rotaxanes are mechanically interlocked molecules, in which an axle is threaded into a wheel and trapped with bulky stopper groups at the termini. Bistable rotaxanes possessing two or more station moieties have attracted particular interests, because they can switch on/off and change the molecular lengths in response to external stimuli. In addition to the molecular-level properties of these molecules in solution, properties in nano-, micro-, and macroscale of the molecular-integrated systems recently have attracted attentions. This review highlights the development in the design and synthesis of bistable rotaxanes to integrate from molecules to the systems to show actuation and locomotion.