Remote Control of the Synthesis of a [2]Rotaxane and its Shuttling via Metal-Ion Translocation

Remote control in an eight-component network commanded both the synthesis and shuttling of a 2]rotaxane via metal-ion translocation, the latter being easily monitored by distinct colorimetric and fluorimetric signals. Addition of zinc(II) ions to the red colored copper-ion relay station rapidly liberated copper(I) ions and afforded the corresponding zinc complex that was visualized by a bright sky blue fluorescence at 460 nm. In a mixture of all eight components of the network, the liberated copper(I) ions were translocated to a macrocycle that catalyzed formation of a rotaxane by a double-click reaction of acetylenic and diazide compounds. The shuttling frequency in the copper-loaded 2]rotaxane was determined to k₂₉₈=30 kHz (ΔH^≠=62.3±0.6 kJ mol^?1, ΔS^≠=50.1±5.1 J mol^?1 K^?1, ΔG^≠₂₉₈=47.4 kJ mol^?1). Removal of zinc(II) ions from the mixture reversed the system back generating the metal-free rotaxane. Further alternate addition and removal of Zn²⁺ reversibly controlled the shuttling mode of the rotaxane in this eight-component network where the ion translocation status was monitored by the naked eye.