Strategic incorporation of α-diimine structures into nitrogen-enriched covalent organic frameworks for enhanced organic iodine capture

Here we pioneer the design of a nitrogen-rich covalent organic framework (Tph-Pa) with a special α-diimine structure for the effective capture of organic iodine. Tph-Pa, consisting of pyridine-2,5-dicarboxaldehyde and 5,10,15,20-Tetrakis(4-aminophenyl)porphyrin, exhibits abundant nucleophilic N sites for interactions including α-diimine, imine and porphyrin to interact with iodine, and achieves an impressive static adsorption capacity of 1.66 g g −1 for CH 3 I. Furthermore, the adsorption of CH 3 I on Tph-Pa is predominantly controlled by electron density of N sites (α-diimine > imine > porphyrin), which efficiently facilitates the chemical N-methylation adsorption of CH 3 I. This work highlights the exceptional iodine capture capability of α-diimine-functionalized COFs.