Customized anion-exchange covalent organic frameworks for efficient extraction of natural products

Extracting highly value-added products from natural systems with low concentrations and complex constituents is of great significance but remains a massive challenge. Herein, a series of dual-functional covalent organic frameworks with both anion exchange and pore adsorption abilities are designed and fabricated using the quaternary amine monomer doping strategy. Attributed to abundant ion exchange sites and selective pore adsorption, the COFs demonstrate high selectivity and loading capacity and fast adsorption for natural products (glycyrrhetinic acid, a high-value natural product), surpassing commercially available materials. Additionally, high-purity (>99%) glycyrrhetinic acid with a >90% extraction efficiency from natural fermentation systems is successfully achieved using a solid-phase extraction column with COFs as the separation medium. The separation column demonstrates outstanding reusability and reproducibility, providing great potential for COFs to serve as robust separation mediums for challenging natural product purification.