School of Chemistry and Environment , South China Normal University , Guangzhou 510006 , P. R. China.
The Molecular Foundry , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States.
ACS Appl Mater Interfaces. 2019 Apr 3;11(13):12830-12837. doi: 10.1021/acsami.9b02640. Epub 2019 Mar 22.
Two stable crystalline hydrazone-linked covalent organic frameworks (COFs) (Bth-Dha and Bth-Dma) containing functional O,N,O'-chelating sites have been designed and successfully synthesized by the Schiff-base condensation reactions between benzene-1,3,5-tricarbohydrazide (Bth) and 2,5-dihydroxyterephthalaldehyde (Dha) or 2,5-dimethoxyterephthal-aldehyde (Dma), respectively. Bth-Dma exhibits strong fluorescence in the solid state and in an aqueous dispersion, while no fluorescence can be observed for Bth-Dha. Interestingly, the as-synthesized Bth-Dma can be used as a turn-off fluorescence sensor for the Fe(III) ion in aqueous solution with outstanding selectivity and sensitivity. The recognition process can be attributed to the coordination interaction between Fe(III) ion and the O,N,O'-chelating sites in the pore wall of Bth-Dma COF, as verified by X-ray photoelectron spectroscopy and H NMR spectroscopy. To the best of our knowledge, this is the first report on the rational design of luminescent COF with predesigned O,N,O'-chelating sites as a fluorescence sensor for highly selective and sensitive metal ion detection. This work may pave the way for designing luminescent COF sensors with functional binding sites for detecting specific metal ions.
两个稳定的晶态腙键合共价有机框架（COFs）（Bth-Dha 和 Bth-Dma），含有功能的 O，N，O'-螯合位点，是通过苯-1,3,5-三腙（Bth）和 2,5-二羟基对苯二甲醛（Dha）或 2,5-二甲氧基对苯二甲醛（Dma）之间的席夫碱缩合反应，分别成功合成的。Bth-Dma 在固态和水分散体中表现出强荧光，而 Bth-Dha 则没有荧光。有趣的是，合成的 Bth-Dma 可以用作水溶液中 Fe(III)离子的关闭荧光传感器，具有出色的选择性和灵敏度。识别过程可以归因于 Fe(III)离子与 Bth-Dma COF 孔壁中 O，N，O'-螯合位点之间的配位相互作用，这通过 X 射线光电子能谱和 H NMR 光谱得到了验证。据我们所知，这是第一个关于具有预定 O，N，O'-螯合位点的发光 COF 的合理设计的报告，作为用于高选择性和灵敏金属离子检测的荧光传感器。这项工作可能为设计具有功能结合位点的发光 COF 传感器以检测特定金属离子铺平道路。
