Remotely Photocontrolled Microrobots based on Photomechanical Molecular Crystals

Creating nano-to-macroscopic-sized artificial actuators in response to light has been a challenging issue. Herein, we describe the design, synthesis, and operation of a photomechanical molecular crystal (PMMC) that exhibits well-controlled multiple photo-driven motions, including translation, rotation, and jumping, by adjusting the irradiation sites. Theoretical calculation discloses that conversion of light energy into macroscopic motion occurs through a molecular conformation change between the excited and ground states mediated by ultrafast conical internal conversion, making the photomechanical/recovery responses a rapid cycle. Therefore, our PMMCs can complete the directional and continuous motions using only one laser beam. We also demonstrated the actuated rotation of a cross-shaped sample by rotating the polarization of the laser beam at a rate of >2 Hz, like a dancer under a spotlight. This finding could lead to remote-controlled micrometer-sized vehicles and valves on solid substrates.