Morphological control of covalent organic frameworks in a PEG–H2O system

Abstract

Covalent organic frameworks (COFs), as an emerging crystalline porous material, have drawn considerable attention in many fields. Therefore, facile preparations of COFs using green and mild methods are necessary and worthwhile goals. In this study, four COFs with different morphologies were successfully synthesized by adopting 1,3,5-tris(4-aminophenyl)benzene (TAPB) and 2,5-dimethoxybenzene-1,4-dicarboxaldehyde (DMTP) as ligands via a green reaction medium composed of polyethylene glycol 400(PEG-400) and water (H₂O). In addition, the versatility of this green reaction medium in the synthesis of other COFs was also investigated. More importantly, we have preliminarily explored the mechanism by which PEG-based aqueous solutions modulate the morphology of COFs. This unique strategy not only avoids the use of higher temperatures and harmful organic solvents but also opens up a new idea for the morphological regulation of COFs to a certain extent.