A fluorescent bistable [2]rotaxane molecular switch on SiO₂ nanoparticles.

A fluorescent bistable [2]rotaxane terminated with an alkyne functional group was constructed and immobilized onto the surface of SiO2 nanoparticles through click reaction. The shuttling motion of the macrocycle component between two different stations was driven by external acid-base stimuli both in solution and on SiO2 nanoparticles, accompanied by visual fluorescence changes.