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.