State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, China.
College of Chemistry and Chemical Engineering, Liaoning Normal University, Dalian 116029, China.
Molecules. 2023 Jan 3;28(1):449. doi: 10.3390/molecules28010449.
Radioactive iodine-capturing materials are urgently needed for the emerging challenges in nuclear waste disposal. The various pore structures of covalent organic frameworks (COFs) render them promising candidates for efficient iodine adsorption. However, the detailed structure-property relationship of COFs in iodine adsorption remains elusive. Herein, two polymorphic COFs with significantly different crystalline structures are obtained based on the same building blocks with varied molecular ratios. The two COFs both have high crystallinity, high specific surface area, and excellent chemical and thermal stability. Compared with the [C+C] topology (PyT-2) with an AA stacking form, the [C+C] topology (PyT-1) with an AB stacking form has more twisted pore channels and complex ink-bottle pores. At ambient conditions, PyT-1 and PyT-2 both exhibit good adsorption properties for iodine capture either in a gaseous or liquid medium. Remarkably, PyT-1 presents an excellent maximum adsorption capacity (0.635 g g), and the adsorption limit of PyT-2 is 0.445 g g in an -hexane solution with an iodine concentration of 400 mg L, which is highly comparable to the state-of-the-art iodine absorption performance. This study provides a guide for the future molecular design strategy toward novel iodine adsorbents.
放射性碘捕获材料是核废料处置中新兴挑战所急需的。共价有机框架（COFs）的各种孔结构使它们成为高效碘吸附的有前途的候选材料。然而，COFs 在碘吸附中的详细结构-性能关系仍难以捉摸。在此，基于具有不同分子比的相同构建块获得了两种具有显著不同晶体结构的多晶 COFs。这两种 COF 都具有高结晶度、高比表面积以及优异的化学和热稳定性。与具有 AA 堆积形式的 [C+C] 拓扑结构（PyT-2）相比，具有 AB 堆积形式的 [C+C] 拓扑结构（PyT-1）具有更多扭曲的孔道和复杂的墨水瓶孔。在环境条件下，PyT-1 和 PyT-2 都表现出良好的吸附性能，无论是在气态还是液态介质中都能捕获碘。值得注意的是，在碘浓度为 400mg/L 的正己烷溶液中，PyT-1 的最大吸附容量为 0.635gg，PyT-2 的吸附极限为 0.445gg，与最先进的碘吸收性能高度可比。这项研究为新型碘吸附剂的未来分子设计策略提供了指导。
