Benzylic Amide Rotaxanes: A Versatile Architecture

Rotaxanes are currently seen as one of the most promising components in artificial molecular machines. In the last few decades, much effort has been dedicated to the developing of such interlocked architectures, which can be subjected to different types of submolecular motion. The field of Rotaxanes has evolved to stimuli-responsive molecular shuttle, capable of responding to several different external stimuli. The interest in molecular shuttles arises from the possibility of achieving controlled submolecular motion of their components with respect to one another. Here, we present an overview of benzylic amide rotaxanes, smart molecules able to function as electrochemically switchable molecular shuttles, both in solution and on surfaces. Transposing working systems from the solution phase onto surfaces and into the solid state is fundamental for their applicability in different technological fields including electromechanical switches and molecular electronic devices. The synthesis of benzylic amide rotaxanes is based on template effects mediated by hydrogen bonds, which play a key role also in the shuttling process. Given the electrostatic nature of hydrogen bonds, their interactions can be modulated through injection of electrons. Electrochemistry seems to be a powerful reagent-free tool to operate stimulus and characterize the molecular level motion across different environments, necessary from the point of view of future integration with current technologies.