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Porosity-Induced Selective Sensing of Iodide in Aqueous Solution by a Fluorescent Imidazolium-Based Ionic Porous Framework
journal contributionposted on 2020-02-21, 16:05 authored by Zixu Chen, Ruixue Sun, Shengyu Feng, Dengxu Wang, Hongzhi Liu
Developing a chemosensor for rapid, sensitive, and visual detection of iodide (I–) by a simple synthetic strategy is still challenging. Herein, we report a highly efficient iodide sensor by simply introducing ionic imidazolium groups into the porous network. This sensor, that is, a fluorescent ionic porous framework (IPF), was prepared by the quaternization reaction of octa((benzylchloride)ethenyl)silsesquioxane and 1,4-bis(1H-imidazole-1-yl)benzene and exhibited moderate porosity with a Brunauer–Emmett–Teller surface area of 379 m2 g–1 and blue fluorescence when excited by UV light. The IPF suspension in water can detect I– with high sensitivity and selectivity among various anions and quick response by fluorescence quenching. In contrast to no response toward I– by the linear model compound and the enhanced sensing performance with an increment of porosity, this finding indicates that the porosity of IPF is important for the detection of I– and an inducement of the sensing process. A fluorescent paper sensor was further developed, which shows high efficiency for the visual detection of I– similar to the abovementioned sensor, suggesting its potential in convenient and on-site sensing of I–. In addition, the paper sensor is recyclable with a remarkable fluorescence resuming ratio of 83% after 10 times cycle detection. Moreover, the developed sensor is used for the analysis of real samples. This work represents the first example of the detection of I– by an ionic porous polymer. Compared with conventional iodide sensors, the present sensor does not require unique structures to form the pseudocavity during sensing I– and can easily achieve high efficiency by incorporating ionic hydrogen bond donors into the porous network, indicating the importance of porosity and the feasibility of replacing the pseudocavity with a real cavity (or pore). More iodide sensors with high efficiency can be designed and fabricated by this novel and simple strategy.