Constructing quinazolinone-anchored electron-rich covalent organic frameworks by photocatalytic reductive cyclization for idealizing iodine capture

Constructing ideal adsorbent for the capture of radioactive iodine often requires both high adsorption capacity and fast adsorption kinetics. However, this remains a challenging issue. Herein, we present an effective method to idealize iodine capture with both ultrahigh adsorption capacity and fast adsorption rate through the construction of quinazolinone-anchored covalent organic frameworks (COFs). Post-synthesis modification was employed to functionalize two vinyl free-standing COFs with quinazolinone units through in-situ photocatalytic reductive cyclization between vinyl and 2-aminobenzamide units. The developed material, ECUT-COF-13, exhibits not only I-2 uptake capacity as high as 10.81 g g(-1), exceeding all established adsorbents for such use, but also very fast adsorption rate of 1.4 gh(-1), surpassing all previously reported two-dimensional COFs. The outstanding I-2 capture performance mainly results from an electron-rich mechanism, since anchoring quinazolinone units in COFs will lead to enhanced pi-conjugated net and ultrahigh nitrogen content. The results demonstrate not only a new avenue for functionalizing COFs, but also a general electron-rich strategy for COFs.