Tailoring flexible aliphatic covalent organic frameworks with hydroxyl sites: A novel platform for efficient...

The development of advanced adsorbents enabling rapid and sensitive detection of endocrine-disrupting bisphenols (BPs) is essential for safeguarding ecosystems and human health. Covalent organic frameworks (COFs) hold great promise for the adsorption of BPs, but conventional rigid aromatic architectures suffer from limited molecular recognition capability. Herein, we design a hydroxyl-functionalized flexible aliphatic COF (TFT-TAH COF) via the polymerization of 2,3-dihydroxydicarbohydrazid (TAH) and 1,3,5-tris(4-formyl-phenyl) triazine (TFT) for efficient extraction and sensitive detection of BPs (BPA, BPF, BPAF, and BPF). The flexible aliphatic linker exposes more active sites, thereby displaying excellent BPs adsorption capacity (654-1111 mg g^-1) and rapid adsorption kinetics (equilibrium within 30 s). TFT-TAH COF gave good affinity for BPs through the synergistic effects of size matching, hydrogen bonding, and π-π interactions. In addition, a novel analytical method was developed for BPs determination by coupling TFT-TAH COF-based dispersive solid-phase extraction with high-performance liquid chromatography, achieving low detection limits of 0.03-0.1 ng mL^-1 and satisfactory precision with relative standard deviations≤5.7 %. Moreover, recoveries for the spiked lake, river, drinking water, bottled water, and milk samples ranged from 89.8 to 101.6 %. This work pioneers an innovative approach to fabricating flexible aliphatic-linked COFs for environmental monitoring and food safety.