A novel fluorescent covalent organic framework for the selective detection of fluoride ion

A novel fluorescent covalent organic framework containing trimethyl silicon group (COF-TMS) was designed and prepared via the Povarov reaction to be used to detect fluorine ions, on account of the interaction between the silicon and the fluorine ions. Trimethyl silicon, as an electron-donating functional group, was replaced with hydrogen atom and the electronic state of the whole material changed. In this process, the change of COF-TMS structure resulted in the fluorescence color changing from red to blue obviously. Furthermore, the structure and optical property of COF-TMS did not change when there are anions such as H 2 PO 4 − , ClO 4 − , SO 4 2− , CO 3 2− , Cl − , Br − , I − , and NO 3 − in the solution. Notably, the crystallinity also became particularly high in this process, with perfectly regular hexagonal pore structures being clearly observed in the micron range. This work provides a new idea for the future study of COFs in the field of fluorescence through the combination of COFs structure and fluorescence color transformation.