Robust Thiazole-Linked Covalent Organic Frameworks for Water Sensing with High Selectivity and Sensitivity
Kewei Wang,
Zhaoxia Wu,
Na Ji,
Tingxia Wang,
Yongxin Gu,
Zhixiang Zhao,
Yong Guo,
Xiaoyan Wang,
Zhifang Jia,
Bien Tan
Affiliations
Kewei Wang
Department of Chemistry and Chemical Engineering, Shanxi Datong University, Datong 037009, China
Zhaoxia Wu
Department of Chemistry and Chemical Engineering, Shanxi Datong University, Datong 037009, China
Na Ji
Department of Chemistry and Chemical Engineering, Shanxi Datong University, Datong 037009, China
Tingxia Wang
Department of Chemistry and Chemical Engineering, Shanxi Datong University, Datong 037009, China
Yongxin Gu
Department of Chemistry and Chemical Engineering, Shanxi Datong University, Datong 037009, China
Zhixiang Zhao
Department of Chemistry and Chemical Engineering, Shanxi Datong University, Datong 037009, China
Yong Guo
Department of Chemistry and Chemical Engineering, Shanxi Datong University, Datong 037009, China
Xiaoyan Wang
Key Laboratory of Material Chemistry for Energy Conversion and Storage, Ministry of Education, Hubei Key Laboratory of Material Chemistry and Service Failure, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
Zhifang Jia
Department of Chemistry and Chemical Engineering, Shanxi Datong University, Datong 037009, China
Bien Tan
Key Laboratory of Material Chemistry for Energy Conversion and Storage, Ministry of Education, Hubei Key Laboratory of Material Chemistry and Service Failure, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
The rational design of covalent organic frameworks (COFs) with hydrochromic properties is of significant value because of the facile and rapid detection of water in diverse fields. In this report, we present a thiazole-linked COF (TZ-COF-6) sensor with a large surface area, ultrahigh stability, and excellent crystallinity. The sensor was synthesized through a simple three-component reaction involving amine, aldehyde, and sulfur. The thiazole and methoxy groups confer strong basicity to TZ-COF-6 at the nitrogen sites, making them easily protonated reversibly by water. Therefore, TZ-COF-6 displayed color change visible to the naked eye from yellow to red when protonated, along with a red shift in absorption in the ultraviolet-visible diffuse reflectance spectra (UV-vis DRS) when exposed to water. Importantly, the water-sensing process was not affected by polar organic solvents, demonstrating greater selectivity and sensitivity compared to other COF sensors. Therefore, TZ-COF-6 was used to detect trace amounts of water in organic solvents. In strong polar solvents, such as N,N-dimethyl formamide (DMF) and ethanol (EtOH), the limit of detection (LOD) for water was as low as 0.06% and 0.53%, respectively. Even after 8 months of storage and 15 cycles, TZ-COF-6 retained its original crystallinity and detection efficiency, displaying high stability and excellent cycle performance.
