Self-Healing of a Copper(I) [2]Rotaxane Shuttle Monitored by Fluorescence.

We demonstrate self-healing of the shuttling dynamics of a molecular machine operating by negative feedback. When zinc(II) was added to the copper(I)-loaded [2]rotaxane shuttle [Cu( R )] + , copper(I) was replaced, thereby generating the static zinc(II)-loaded [2]rotaxane [Zn( R )] 2+ . Loss of the dynamics was accompanied by a fluorescence enhancement at λ = 364 nm. Notably, the released copper(I) ions catalyzed the formation of a bis-triazole ligand, which selectively captured zinc(II). As a result, the copper(I) was restored in the rotaxane, and the dynamic shuttling motion of [Cu( R )] + was regained. The healing was conveniently followed by diagnostic fluorescence changes.