Switchable Synthetic Smiles Rearrangement Small
Molecule Walkers

Abstract

Natural protein walkers, such as kinesin or dynein, found in biological systems are able to walk along a cytoskeletal polymer track whilst carrying out complex cellular functions. Synthetic small molecule walkers are developed to emulate the walking motion using dynamic covalent chemistry, in sizes hundreds of times smaller than proteins. Although varies levels of success have been achieved, the challenge still remains to design a synthetic walker system that could operate efficiently and be adaptable to a wide range of conditions, environments and designs.
In this research, we have designed and synthesised a series of acid/base switchable Smiles Rearrangement small molecule walkers and through in-situ switching walking experiments monitored using 1H NMR spectroscopy we demonstrated that we could transport a walking unit along amino-alcohol tracks via consecutive Smiles Rearrangements operated in a wide range of solvents. The walkers were proved to be capable of carrying out repetitive walking and are also processive, progressive, autonomous, and in one case directional. The structures of three of our walker species were confirmed with X-ray crystallography. Our results show that the Smiles Rearrangements walkers could be robust, highly switchable and adaptable, offering high degrees of control. This research has contributed to the current library of synthetic small molecule walkers, while deepening our understanding of the mechanistic of the Smiles Rearrangements, this work demonstrated clear potentials for the application of the Rearrangement in the design of other future functional walkers.