Molecular machines operated by light have been recently shown to be able to produce oriented motion at the molecular scale1,2 as well as do macroscopic work when embedded in supramolecular structures3,4,5. However, any supramolecular movement irremediably ceases as soon as the concentration of the interconverting molecular motors or switches reaches a photo-stationary state6,7. To circumvent this limitation, researchers have typically relied on establishing oscillating illumination conditions—either by modulating the source intensity8,9 or by using bespoke illumination arrangements10,11,12,13. 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 diffusion14 of the chiral molecular motors creates continuous, regular and unidirectional rotation of the liquid crystal structure under non-equilibrium conditions.
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This research was supported financially by the H2020-MSCA-IF-2014 programme (Grant 661315 to T.O.), the Netherlands Organization for Scientific Research (FOM Grant 13PR3105 to F.L. and N.K.), and the European Research Council (Starting Grant 307784 to N.K.).
Captions for Supplementary Videos, Supplementary Figures 1–9; Supplementary Table 1; Supplementary Schemes 1–3.
Counter-clockwise rotation of a twisted topological structure with a diameter d ~ 45 µm.
Clockwise rotation of twisted topological structure with a diameter d ~ 45 µm.
Clockwise rotation of twisted topological structure with a diameter d ~ 50 µm.
Emergence of a twisted topological structure, when a cholesteric liquid crystal undergoes helix inversion under illumination.
Emergence of a twisted topological structure, when a cholesteric liquid crystal does not undergo helix inversion under illumination.
Orbital transport of a satellite cargo, along a clockwise trajectory.