Supramolecular polymerization through rotation of light-driven molecular motors

Molecular motors are capable of acting on their environment through their unique capacity to generate nonreciprocal autonomous motions at the nanoscale. Although their operating principles are now well understood, artificial molecular motors have yet to demonstrate their general capacity to confer novel properties on (supra)molecular systems and materials. Here, we show that amphiphilic light-driven molecular motors can adsorb onto an air‒water interface and form Langmuir monolayers upon compression. Under UV-irradiation, the surface pressure isotherms of these films reveal a drastic shift toward smaller molecular areas as a consequence of motor activation. We explain this counterintuitive phenomenon by the rotation-induced supramolecular polymerization of amphiphilic motors through a non-thermal annealing process, which is limited by the maximal torque they can deliver (≈10 pN.nm) and leads to the formation of highly organized patterns. This serendipitous discovery highlights the opportunities offered by molecular motors to control supramolecular polymerization by motion-induced processes and to form active nanostructures for the design of innovative materials.