Direct Synthesis of Amide-Linked COFs via Ester-Amine Exchange Reaction
R.L Li, Song‐Chen Yu, Wei Jiang, Jiale Zhou, Zi-Cong Wang, Xiao‐Rui Ren, Wei Feng, Yahong Zhou, Dong Wang, Li‐Jun Wan
Abstract
Achieving both crystallinity and stability is challenging for covalent organic frameworks (COFs) as the reversible reaction required for enhancing crystallinity compromises stability. Amide linkages, a type of chemically stable bond for COF construction, are predominantly synthesized via postmodifications. This work presents a direct and convenient method for synthesizing highly crystalline amide-linked COFs via the ester-amine exchange reaction. The reaction is irreversible, as demonstrated by the investigation of model reactions and COF TAPT-TTPF polymerization process. The water absorption capacity of COF TAPT-TTPF was 0.56 g/g at 25 °C and 94% relative humidity. Meanwhile, via direct synthesis, we grew COF TAPT-TTPF on anodized aluminum oxide membranes to form COF@AAO composite membranes. The composite membrane achieved an output power density of 7.70 W/m 2 under a 50-fold salinity gradient in osmotic energy conversion. This direct polymerization protocol improves the convenience and accessibility of amide-linked COFs.