Meng Linan, Xin Na, Wang Jinying, Xu Jiyu, Ren Shizhao, Yan Zhuang, Zhang Miao, Shen Cheng, Zhang Guangyu, Guo Xuefeng, Meng Sheng
Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, P. R. China.
University of Chinese Academy of Sciences, Beijing, 100049, P. R. China.
Angew Chem Int Ed Engl. 2021 May 25;60(22):12274-12278. doi: 10.1002/anie.202100168. Epub 2021 Apr 26.
Charge transport in a single-molecule junction is extraordinarily sensitive to both the internal electronic structure of a molecule and its microscopic environment. Two distinct conductance states of a prototype terphenyl molecule are observed, which correspond to the bistability of outer phenyl rings at each end. An azobenzene unit is intentionally introduced through atomically precise side-functionalization at the central ring of the terphenyl, which is reversibly isomerized between trans and cis forms by either electric or optical stimuli. Both experiment and theory demonstrate that the azobenzene side-group delicately modulates charge transport in the backbone via a single-molecule stereoelectronic effect. We reveal that the dihedral angle between the central and outer phenyl ring, as well as the corresponding rotation barrier, is subtly controlled by isomerization, while the behaviors of the phenyl ring away from the azobenzene are hardly affected. This tunability offers a new route to precisely engineer multiconfigurational single-molecule memories, switches, and sensors.
单分子结中的电荷传输对分子的内部电子结构及其微观环境都极为敏感。观察到一种原型三联苯分子的两种不同电导状态，这对应于两端外侧苯环的双稳态。通过在三联苯的中心环上进行原子精确的侧链功能化有意引入了一个偶氮苯单元，该单元可通过电刺激或光刺激在反式和顺式形式之间可逆异构化。实验和理论均表明，偶氮苯侧基通过单分子立体电子效应精细地调节主链中的电荷传输。我们发现，中心苯环和外侧苯环之间的二面角以及相应的旋转势垒受异构化的微妙控制，而远离偶氮苯的苯环行为几乎不受影响。这种可调性为精确设计多构型单分子存储器、开关和传感器提供了一条新途径。
