Photostimulus‐Responsive Large‐Area Two‐Dimensional Covalent Organic Framework Films

• Published in: Angewandte Chemie International Edition Vol. 58; no. 45; pp. 16101 - 16104
• Main Authors: Yu, Fei, Liu, Wenbo, Li, Bang, Tian, Dan, Zuo, Jing‐Lin, Zhang, Qichun
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 04.11.2019
• Edition: International ed. in English
• Subjects: Circuits; covalent organic frameworks; Cyclopentene; Electrical conductivity; Electrical resistivity; electrical switching; Electronic properties; Electronic structure; external stimuli; Irradiation; Light emitting diodes; photostimulus; Pollution monitoring; Reaction kinetics; Ultraviolet radiation; external stimuli; covalent organic frameworks; electrical switching; photostimulus
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201909613

Using an external stimulus to modulate the electronic structure of covalent organic frameworks (COFs) is very important because such a response will endow them with additional functions. A two‐dimensional (2D) COF, constructed from a photo‐responsive unit (1,2‐bis(5‐formyl‐2‐methylthien‐3‐yl)cyclopentene), can reversibly switch its electrical conductivity 200 times from low state (the open form) to high state (the closed form) upon irradiation with UV light and reversible with visible light. This reversible phenomenon can be monitored through a circuit containing a light‐emitting diode (LED). Photoinduced ring‐closing/opening reactions do not destroy the integrity of the frameworks, and both processes follow logarithmic carrier generation with time. Moreover, the correlation between COFs electronic properties and changes in photoinduced kinetics and absorption curves has been demonstrated. Two‐dimensional COFs that are photostimulus‐responsive exhibit a change of electrical conductivity as a function of the photon energy. The modulation of electronic structures of COFs, associated with ring closing and opening, is visualized by the on/off of a light‐emitting diode (LED) owing to the corresponding variation in electrical conductivity.