Yang Xiubei, Jiang Di, Fu Yubin, Li Xuewen, Liu Guojuan, Ding Xuesong, Han Bao-Hang, Xu Qing, Zeng Gaofeng
CAS Key Laboratory of Low-Carbon Conversion Science and Engineering, Shanghai Advanced Research Institute (SARI), Chinese Academy of Sciences (CAS), Shanghai, 201210, P. R. China.
University of Chinese Academy of Sciences, Beijing, 100049, P. R. China.
Small. 2024 Nov;20(44):e2404192. doi: 10.1002/smll.202404192. Epub 2024 Jul 14.
The tunable pore walls and skeletons render covalent organic frameworks (COFs) as promising absorbents for gold (Au) ion. However, most of these COFs suffered from low surface areas hindering binding sites exposed and weak binding interaction resulting in sluggish kinetic performance. In this study, COFs have been constructed with synergistic linker and linkage for high-efficiency Au capture. The designed COFs (PYTA-PZDH-COF and PYTA-BPDH-COF) with pyrazine or bipyridine as linkers showed high surface areas of 1692 and 2076 m g, providing high exposed surface areas for Au capture. In addition, the Lewis basic nitrogen atoms from the linkers and linkages are easily hydronium, which enabled to fast trap Au via coulomb force. The PYTA-PZDH-COF and PYTA-BPDH-COF showed maximum Au capture capacities of 2314 and 1810 mg g, higher than other reported COFs. More importantly, PYTA-PZDH-COF are capable of rapid adsorption kinetics with achieving 95% of maximum binding capacity in 10 min. The theoretical calculation revealed that the nitrogen atoms in linkers and linkages from both COFs are simultaneously hydronium, and then the protonated PYTA-PZDH-COF are more easily binding the AuCl , further accelerating the binding process. This study gives the a new insight to design COFs for ion capture.
可调谐的孔壁和骨架使共价有机框架（COFs）成为有前景的金（Au）离子吸附剂。然而，这些COFs大多存在比表面积低的问题，这阻碍了结合位点的暴露，且结合相互作用较弱，导致动力学性能迟缓。在本研究中，通过协同连接体和连接方式构建了用于高效捕获金的COFs。设计的以吡嗪或联吡啶为连接体的COFs（PYTA-PZDH-COF和PYTA-BPDH-COF）显示出1692和2076 m²/g的高比表面积，为金捕获提供了高暴露表面积。此外，连接体和连接方式中的路易斯碱性氮原子易于质子化，这使得能够通过库仑力快速捕获金。PYTA-PZDH-COF和PYTA-BPDH-COF的最大金捕获容量分别为2314和1810 mg/g，高于其他报道的COFs。更重要的是，PYTA-PZDH-COF具有快速的吸附动力学，在10分钟内可达到最大结合容量的95%。理论计算表明，两种COFs连接体和连接方式中的氮原子同时质子化，然后质子化的PYTA-PZDH-COF更容易结合AuCl₄⁻，进一步加速了结合过程。本研究为设计用于离子捕获的COFs提供了新的见解。
