Constructing redox-active 3D covalent organic frameworks with high-affinity hexameric binding sites for enhanced uranium capture

The arduousness of nuclear waste disposal and the serious consequences of nuclear accidents motivate the development of efficient solid-phase extractants to provide enhanced protection. Herein, we report the first example of a hydroquinone-functionalized 3D covalent organic framework (DHBA-TAPM) with unique redox activity and high-affinity hexameric binding sites to be well suited as an efficient platform for selective capture and in situ reduction of radionuclide uranium. The high-affinity hexameric binding sites laced on the open 3D interconnected nanochannels showed high accessibility, and hollow tubular morphology enhanced the perme-ability, allowing greatly improved the utilization efficiency of the binding site. In addition, compared with ad-sorbents based on physical and/or chemical adsorption, the synergistic effect of the redox mineralization mechanism and high-affinity hexameric binding sites of DHBA-TAPM can significantly reduce the impact of binding site protonation under highly acidic conditions in chemisorption, thereby increasing the capture ca-pacity. As a result, the DHBA-TAPM far outperform than other analogous adsorbents in terms of adsorption capacity and kinetics for uranium under highly acidic conditions. This work provides a facile strategy for the synthesis of functionalized 3D COFs and opens up the application of redox-active 3D COFs in environmental remediation.