Key Laboratory for Advanced Materials and Institute of Fine Chemicals, Joint International Research Laboratory of Precision Chemistry and Molecular Engineering, Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai, China.
Leverhulme Centre for Functional Materials Design, Materials Innovation Factory and Department of Chemistry, University of Liverpool, Liverpool, UK.
Nature. 2022 Apr;604(7904):72-79. doi: 10.1038/s41586-022-04443-4. Epub 2022 Apr 6.
Covalent organic frameworks (COFs) are distinguished from other organic polymers by their crystallinity, but it remains challenging to obtain robust, highly crystalline COFs because the framework-forming reactions are poorly reversible. More reversible chemistry can improve crystallinity, but this typically yields COFs with poor physicochemical stability and limited application scope. Here we report a general and scalable protocol to prepare robust, highly crystalline imine COFs, based on an unexpected framework reconstruction. In contrast to standard approaches in which monomers are initially randomly aligned, our method involves the pre-organization of monomers using a reversible and removable covalent tether, followed by confined polymerization. This reconstruction route produces reconstructed COFs with greatly enhanced crystallinity and much higher porosity by means of a simple vacuum-free synthetic procedure. The increased crystallinity in the reconstructed COFs improves charge carrier transport, leading to sacrificial photocatalytic hydrogen evolution rates of up to 27.98 mmol h g. This nanoconfinement-assisted reconstruction strategy is a step towards programming function in organic materials through atomistic structural control.
共价有机框架（COFs）因其结晶度而有别于其他有机聚合物，但由于框架形成反应的可逆性较差，因此获得坚固、高结晶度的 COFs 仍然具有挑战性。更具可逆性的化学方法可以提高结晶度，但这通常会导致 COFs 具有较差的物理化学稳定性和有限的应用范围。在这里，我们报告了一种通用且可扩展的方法，基于意想不到的框架重构，来制备坚固、高结晶度的亚胺 COFs。与单体最初随机排列的标准方法相反，我们的方法涉及使用可逆且可移除的共价键合链来对单体进行预组织，然后进行受限聚合。通过这种重构途径，通过简单的无真空合成程序，以极大地提高了结晶度和更高的孔隙率来生产重构 COFs。重构 COFs 中结晶度的提高改善了载流子输运，从而导致牺牲型光催化析氢速率高达 27.98mmol h g。这种纳米受限辅助的重构策略是通过原子结构控制对有机材料进行功能编程的一个步骤。
