Regulating Host-Guest Interactions in a Mixed-Ligand Metal-Organic Framework for Short-Chain PFAS Detection

Per- and polyfluoroalkyl substances (PFAS) are widely present in solid matrices and aqueous environments, and their bioaccumulation and inherent toxicity pose severe threats to human health. Emerging short-chain PFAS present formidable challenges for the design of their sensing material, owing to their amphiphilic structures that induce weak host-guest interactions and the absence of intrinsic UV-vis absorption and luminescence properties. Herein, a functionalized metal-organic framework, UiO-66-0.8NH₂, was synthesized as a high-performance luminescence sensor for the selective detection of perfluorohexanoic acid (PFHxA), a typical short-chain PFAS. Benefiting from its precisely tailored pore structure and favorable host-guest interactions, UiO-66-0.8NH₂ exhibits a sensitive and visual "turn-on" fluorescence response toward PFHxA in aqueous media. Mechanism studies revealed that the synergistic effect of hydrophobic and electrostatic interactions, regulated by the ratio of mixed ligands, contributes to the strong affinity between the sensing material and PFHxA. This work provides a finely regulated system for the facile and rapid detection of PFAS in water and reveals the key structural factors governing the effective sensing performance of MOF-based materials.