Synthesizing [2]Rotaxanes and [2]Catenanes through Na(+)-Templated Clipping of Macrocycles around Oligo(ethylene glycol) Units.

Di-, tri-, and tetra(ethylene glycol) units in both dumbbell-shaped and macrocyclic molecules can be used as primary recognition units for the clipping of macrocycles in the presence of templating Na(+) ions to form corresponding [2]rotaxanes and [2]catenanes. One such tri(ethylene glycol)-containing [2]catenane behaves as a Na(+) ion-controllable molecular switch.