Dynamic force spectroscopy of synthetic oligorotaxane foldamers

Significance Donor–acceptor oligorotaxane foldamers are a class of molecular switches elegantly incorporating mechanical bonds in a folded molecular architecture. Such examples of foldamers are very rare, leaving the question wide open regarding what might emerge from a synergistic combination of mechanically interlocked molecules and foldamers. Here, using atomic-force-microscopy-based dynamic single-molecule force spectroscopy, we mechanically drive oligorotaxanes out of equilibrium at a wide range of loading rates and observe their exceptional refolding capabilities and the very fast dynamics of the process. The near-equilibrium pulling–relaxing cycles were exploited to determine the energy required to break one single donor–acceptor interaction from the distribution of work trajectories using fluctuation theorems. Our findings highlight the importance of molecular design on the performance of artificial molecular machines.