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Light‐Powered Autonomous Flagella‐Like Motion of Molecular Crystal Microwires
Author(s) -
Tong Fei,
Kitagawa Daichi,
Bushnak Ibraheem,
AlKaysi Rabih O.,
Bardeen Christopher J.
Publication year - 2021
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.202012417
Subject(s) - photoisomerization , rotation around a fixed axis , materials science , chemical physics , dipole , liquid crystal , torque , rotation (mathematics) , polarization (electrochemistry) , polymer , optics , molecular physics , optoelectronics , physics , chemistry , classical mechanics , composite material , biochemistry , geometry , mathematics , isomerization , thermodynamics , catalysis , quantum mechanics
The ability to exhibit life‐like oscillatory motion fueled by light represents a new capability for stimuli‐responsive materials. Although this capability has been demonstrated in soft materials like polymers, it has never been observed in molecular crystals, which are not generally regarded as dynamic objects. In this work, it is shown that molecular crystalline microwires composed of (Z)‐2‐(3‐(anthracen‐9‐yl)allylidene)malononitrile ((Z)‐ DVAM ) can be continuously actuated when exposed to a combination of ultraviolet and visible light. The photo‐induced motion mimics the oscillatory behavior of biological flagella and enables propagation of microwires across a surface and through liquids, with translational speeds up to 7 μm s −1 . This is the first example of molecular crystals that show complex oscillatory behavior under continuous irradiation. A model that relates the rotation of the transition dipole moment between reversible E→Z photoisomerization to the microscopic torque can qualitatively reproduce how the rotational frequency depends on light intensity and polarization.