Highly efficient synthesis of a tristable molecular shuttle and its controlled motion under chemical stimuli

Abstract

According to the threading-followed-by-stoppering approach, a tristable molecular shuttle could be efficiently synthesized in 76% yield using a K⁺ ion template and a bulky isocyanate stopper. This high yield was reasoned from the combination of the powerful template effect and highly effective stoppering reaction. Through detailed studies of the ¹H NMR, HSQC and 2D-ROESY NMR spectra, it was proved that the shuttling of the triptycene-derived macrocycle between the three stations of pyromellitic diimide (PmI), anthraquinone (AQ) and N-methyltriazolium (MtA) could be unambiguously achieved in a chemical way. The three distinct stable states of the molecular shuttle could be further evidenced by analyzing the high-resolution electrospray ionization (HR-ESI) mass spectra and UV-Vis spectra.