Engineering active sites in two dimensional covalent organic frameworks boosts the capture of iodine

The search and development of novel covalent organic frameworks (COFs) as advanced adsorbents for efficient capture of radiological iodine is of great interest. Herein, a rational modulation of active sites within COFs was reported to achieve enhanced iodine capture performance. A facile installation of electron-rich ethynyl moieties within backbones of the COF adsorbent led to a successful 38% rise of iodine adsorption capacity, from 3.34 g g-1 to 4.61 g g-1, due to the intrinsic strong interaction between ethynyl sites and iodine molecules. Moreover, this uptake can be further enhanced to be 5.07 g g-1 through the incorporation of rich basic triazine sites into the ethynyl-linked framework on account of the Lewis acidity of iodine. These results not only give a rise to extend our understanding of structure-property relationship for efficient removal of radiological iodine, but also offer new possibilities for the rational design and synthesis of novel COF-based adsorbents for separation applications.