Speed Tuning of the Formation/Dissociation of a Metallorotaxane.

Switching between the formation/dissociation of rotaxanes is important to control the function of various types of rotaxane-based materials. We have developed a convenient and simple strategy, the so-called "accelerator addition", to make a static rotaxane dynamic without apparently affecting the chemical structure. As an interlocked molecule that enables tuning of the formation/dissociation speed, a metallorotaxane was quantitatively generated by the complexation of a triptycene-based dumbbell-shaped mononuclear complex, [PdL 2 ] 2+ (L=2,3-diaminotriptycene), with 27C9. As a result of the inertness of the Pd 2+ -based coordination structure, the metallorotaxane was slowly formed (the static state). This rotaxane formation was accelerated 27 times simply by adding Br - as an accelerator (the dynamic state). A similar drastic acceleration was also demonstrated during the dissociation process when Cs + was added to the metallorotaxane to form the free axle [PdL 2 ] 2+ and the 27C9-Cs + complex.