Stepwise Post‐Modification of Pyridine‐Imine COFs for Enhanced Hydrolytic Stability and Proton Conductivity

Abstract

Abstract Emerging as a type of promising material for proton conduction, covalent organic frameworks (COFs) assembled from dynamic imine bonds face a challenge of surmounting hydrolytic instability to achieve long‐term performance in humid environments. In this work, we report a post‐synthetic strategy to simultaneously enhance the hydrolytic stability and hydrophilicity of a pyridine‐imine‐based COF, COF‐LIFM7, without compromising its crystallinity and porosity. A bifunctional monomer containing amino and acetal groups was employed to construct the primary framework, which was subsequently modified via amide formation and pyridine N‐oxidation to yield COF‐LIFM7‐Amide and COF‐LIFM7‐Amide‐N + O − . These stepwise modifications increased the polarity and hydrogen‐binding sites within COF pores to improve water affinity, leading to a three‐order‐of‐magnitude enhancement in the proton conductivity for COF‐LIFM7‐Amide‐N + O − , reaching 1.9 × 10 −3 S cm −1 at 95% relative humidity and 70 °C. This study highlights a generalizable post‐synthetic approach for tuning the pore chemistry of COFs to achieve high performance in proton‐conducting applications under humid conditions.