Ether-oxygen based covalent organic frameworks: a new cognitive guide

Abstract

Ether‑oxygen based covalent organic frameworks (EO-COFs) represent an emerging class of porous crystalline materials that uniquely integrate the dynamic flexibility of ether‑oxygen (EO) bonds with the structural order of covalent organic frameworks (COFs). Compared to other COFs, EO-COFs exhibit remarkable structural adaptability, excellent chemical and thermal stability, and versatile post-modification compatibility, owing to tunable conformation and robust electronic nature of the C-O-C linkages. Since their first report in 2015, EO-COFs have demonstrated considerable application potential in multiple fields, including adsorption/separation, catalysis, chemical sensing, and energy storage, etc. These materials not only inherit the flexibility of EO polymers but also significantly enhance the porosity and crystallinity of COFs, thereby expanding their functionality and application scope. However, critical knowledge gaps persist in EO-COFs research, particularly in establishing quantitative structure-performance correlations, innovating low-cost synthetic pathways, and tailoring materials for advanced application fields. Therefore, this review will systematically summarize the preparation methods, properties, and application prospects of EO-COFs and discuss the development opportunities and challenges. We anticipate this review will stimulate more perspectives and new ideas for developing advanced functionalities and expanding regimes of EO-COFs.