Department of Chemistry, University of California, Riverside, 501 Big Springs Road, Riverside, CA, 92521, USA.
Current Address: Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering, Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, Institute of Fine Chemicals, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai, 200237, China.
Angew Chem Int Ed Engl. 2021 Feb 1;60(5):2414-2423. doi: 10.1002/anie.202012417. Epub 2020 Dec 23.
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 . 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.
能够展示由光驱动的类似生命的振荡运动代表了对刺激响应材料的新能力。尽管这种能力已经在聚合物等软材料中得到了证明，但在通常不被视为动态物体的分子晶体中从未观察到过。在这项工作中，已经表明由(Z)-2-(3-(蒽-9-基)烯丙基)丙二腈((Z)-DVAM)组成的分子晶须可以在暴露于紫外线和可见光的组合时连续运动。光诱导运动模拟了生物鞭毛的振荡行为，并能够使晶须在表面和液体中传播，平移速度高达 7μm/s。这是第一个在连续照射下表现出复杂振荡行为的分子晶体的例子。一个将过渡偶极矩在可逆 E→Z 光致异构化之间的旋转与微观扭矩相关联的模型，可以定性地再现旋转频率如何取决于光强度和偏振。
