Electrochemically Assisted Synthesis of Covalent Organic Frameworks via In Situ Oxidation of Alcohol Monomers

Electrochemical synthesis provides a promising strategy in the synthetic industry because of its benign conditions, strong economic viability, and environmental friendliness, but its application in the synthesis of COFs is still challenging. Here, we report an electrochemical-assisted synthesis strategy to prepare imine-linked COFs directly from inexpensive aromatic multialcohols via in situ formation of aldehyde monomers followed by a Schiff base reaction with amine monomers in one pot. Unlike conventional strategies, this synthetic methodology avoids the time-consuming presynthesis and purification steps of organic monomers, enabling the economical and efficient fabrication of imine-linked COFs. Three aromatic multialdehydes and 11 different COFs are successfully synthesized, and compared with COFs made via other reported procedures, the obtained COFs have higher crystallinity and porosity. Furthermore, highly efficient electrochemical oxidation of multialcohols into multialdehydes using KBr/ABNO as a double mediator was first demonstrated, resulting in the distillation-free synthesis of high-purity aldehydes (>98% purity) by simple filtration, which deserves broader investigation for other porous organic materials.