Design, Structural Elucidation, and Dynamics of a Dual-Station [2]Rotaxane Featuring Z/E Configuration Inversion

Mechanically interlocked molecules (MIMs), in special, rotaxanes, represent a prominent class of artificial molecular machines capable of controlled translational and rotational dynamics driven by molecular interactions.1,2 Herein, we report the multi-step synthesis of a novel dual-station [2]rotaxane to investigate whether macrocycle entrapment promotes Z→E double-bond isomerization. The linear thread was constructed from maleic anhydride precursors through nucleophilic additions and S_N2 substitutions to incorporate amide and ester stations, capped with bulky benzylamine stoppers, and joined via CuAAC (Copper-catalyzed azide- alkyne cycloaddition) click chemistry. The target architecture was assembled using a multicomponent macrocyclic clipping methodology. Solution ¹H and ¹³C NMR spectroscopy and single-crystal X-ray diffraction revealed that macrocycle encapsulation selectively induces Z→E isomerization exclusively at the amide station, whereas the ester station retains its Z-configuration. Variable-temperature NMR experiments confirmed controlled shuttling and rotational dynamics, establishing a robust platform for functional molecular switches.