Zhang Yingdan, He Pan, Zhang Meicheng, Zhang Jie, He Ningning, Zou Yingdi, Fan Zhiying, Deng Chan, Li Yang, Ma Lijian
Key Laboratory of Radiation Physics & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu, 610064, China.
Small. 2024 Dec;20(52):e2407874. doi: 10.1002/smll.202407874. Epub 2024 Oct 20.
The stability of covalent organic frameworks (COFs) is crucial for their applications in demanding environments. However, increasing the stability of COFs often comes with challenges such as higher synthesis difficulty, lower crystal quality, and reduced controllability during synthesis, making it difficult to regulate dimensions and morphology, thereby impacting the processing and shaping of stable COFs. Herein, the study presents a novel confined polymerization approach guided by hydrogen bonding preassembly to synthesize a soluble and stable COF featuring β-ketoenamine linkage. The presence of relatively weaker hydrogen bonds accelerates the orderly arrangement of monomers, ensuring appropriate spacing, and orientations among functional groups. This facilitates efficient covalent polymerization, leading to the creation of the framework while minimizing the "self-correction" mechanism during crystal growth, thereby enhancing the efficiency of COF synthesis. Furthermore, this method offers precise control over the size of the synthesized COF. The resulting crystalline COF can be toggled between dissolution and precipitation states, facilitating the fabrication of mixed matrix membranes (MMMs) through leveraging the solubility properties of COF. Overall, this pioneering strategy yields valuable insights for advancing weak bond assembly-mediated confined polymerization approaches, the controlled synthesis of stable COFs, and the preparation and processing of soluble COFs in diverse applications.
共价有机框架（COF）的稳定性对于其在苛刻环境中的应用至关重要。然而，提高COF的稳定性往往伴随着诸如合成难度增加、晶体质量降低以及合成过程中可控性降低等挑战，这使得调节尺寸和形态变得困难，从而影响了稳定COF的加工和成型。在此，该研究提出了一种由氢键预组装引导的新型受限聚合方法，以合成具有β-酮烯胺连接的可溶性稳定COF。相对较弱的氢键的存在加速了单体的有序排列，确保了官能团之间适当的间距和取向。这有利于高效的共价聚合，在晶体生长过程中形成框架的同时最大限度地减少“自校正”机制，从而提高COF合成的效率。此外，该方法能够精确控制合成的COF的尺寸。所得的结晶COF可以在溶解和沉淀状态之间切换，通过利用COF的溶解性来促进混合基质膜（MMM）的制备。总体而言，这一开创性策略为推进弱键组装介导的受限聚合方法、稳定COF的可控合成以及可溶性COF在各种应用中的制备和加工提供了有价值的见解。
