Revolving supramolecular chiral structures powered by light in nanomotor-doped liquid crystals.

Molecular machines operated by light have been recently shown to be able to produce oriented motion at the molecular scale as well as do macroscopic work when embedded in supramolecular structures. However, any supramolecular movement irremediably ceases as soon as the concentration of the interconverting molecular motors or switches reaches a photo-stationary state. To circumvent this limitation, researchers have typically relied on establishing oscillating illumination conditions-either by modulating the source intensity or by using bespoke illumination arrangements. In contrast, here we report a supramolecular system in which the emergence of oscillating patterns is encoded at the molecular level. Our system comprises chiral liquid crystal structures that revolve continuously when illuminated, under the action of embedded light-driven molecular motors. The rotation at the supramolecular level is sustained by the diffusion of the motors away from a localized illumination area. Above a critical irradiation power, we observe a spontaneous symmetry breaking that dictates the directionality of the supramolecular rotation. The interplay between the twist of the supramolecular structure and the diffusion of the chiral molecular motors creates continuous, regular and unidirectional rotation of the liquid crystal structure under non-equilibrium conditions.