Mobile hydrogen-bonding donor in covalent organic framework for efficient iodine capture

Covalent organic frameworks (COFs) show promise for applications in molecule capture such as radioactive iodine (I 2 ) capture, which is important in the development for nuclear energy and radiation medicine. However, fast and efficient I 2 capture and release have remained insufficient for practical applications. Here, we demonstrated that mobile cationic hydrogen-bonding donor in nanochannel of anionic covalent organic framework (COFs) can promote the absorption and desorption of I 2 . The adsorption rate of COF Bmim-TpPaSO 3 affording unfixed hydrogen-bonding donor 1-butyl-3-methylimidazolium ([Bmim] + ) in the nanochannel reaches 2.86 g h −1 , which is higher those of COF TpPa-SO 3 H (0.57 g h −1 ) with fixed hydrogen-bonding donor and COF TpPa-SO 3 K without hydrogen-bonding donor. The adsorption capacity was also increased from 1.50 g g −1 to 5.25 g g −1 . Experiments and quantum chemistry calculations show that introducing the hydrogen bond donor enhances the interaction of Bmim-TpPaSO 3 with iodine and induces sulfonate ion of Bmim-TpPaSO 3 to convert iodine molecules into polyiodide via charge-transfer mechanism. In addition, Bmim-TpPaSO 3 has good recyclability and storage performance. This strategy has unlimited potential to significantly improve the performance of covalent organic framework materials in the field of gas adsorption.