Ultrasound-induced recrystallization of covalent organic frameworks with greatly enhanced crystallinity

Existing approaches for improving COFs' crystallinity rely almost exclusively on manipulating reaction parameters during synthesis, leaving post-synthetic strategies largely unexplored. Here, we report a simple yet broadly applicable post-synthetic sonication strategy that markedly enhances the crystallinity of COFs. This strategy was validated across six representative COFs-including both imine and β-keto enamine linkages-all of which exhibited a dramatic enhancement in crystallinity.