An Ultrastable Crystalline Acylhydrazone-Linked Covalent Organic Framework for Efficient Removal of Organic Micropollutants from Water.

As an important member of crystalline porous polymers, acylhydrazone-linked covalent organic frameworks (COFs) have gained much attention in recent years. However, the low structural stability imparts a limit towards their practical applications. To tackle this problem, we report here a new and simple strategy to increase the chemical stability of acylhydrazone-linked COFs by incorporating azobenzene groups in the conjugated framework. Through reinforcing the π-π stacking interactions between the adjacent layers with increased π-surface, it is surprising to find that the resulting materials exhibit extremely stability in harsh environments, such as strong acid, strong base, aqueous educing agent and boiling water, even exposed to air for one year. As a proof-of-concept, such framework has been used to remove various organic micropollutants such as antibiotics, plastic components, endocrine disruptors, and carcinogens from water with high capacity, fast speed and excellent reusability over a wide pH range at environmentally relevant concentrations. The results provide a new avenue to significantly enhance the stability of COFs for practical applications.