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