Controlling the Molecular Shuttling of pH-Responsive 2Rotaxanes with Two Different Stations

摘要

A novel synthesis of degenerate [2]rotaxanes with two different amine stations is presented. Variable-temperature H-1 NMR and rotating-frame nuclear Overhauser effect correlation spectroscopy experiments revealed that the addition of trifluoroacetic acid initiates molecular shuttling. The activation barrier for the motion remained constant even when the amine in the outer station was changed. Conversely, the addition of camphorsulfonic acid caused a rotational motion, which was demonstrated by synthesizing a new [2]rotaxane without an outer station and examining its molecular behavior in the presence of acid.