Metal-Organic Frameworks Built with Selenophene-Based Trimers for Perfluoroalkyl Substances Removal from Drinking Water.

Per- and polyfluoroalkyl substances (PFAS) are persistent organic pollutants that have attracted growing concern owing to their widespread presence in drinking water and limited removal by conventional remediation technologies. This challenge has driven increasing interest in porous materials capable of selectively removing PFAS under environmentally relevant conditions. Among these, zirconium-based metal-organic frameworks (MOFs) have shown great potential for water-related applications due to their chemical and hydrolytic stability. In this work, we report the design, synthesis, and characterization of two UiO-68-type mixed-linker MOFs, UiO-68-SSeS and UiO-68-TzSeTz, incorporating selenophene-based heteroaromatic dicarboxylate linkers through a solvent-assisted linker exchange strategy. The heterocyclic linkers 5,5'-(selenophene-2,5-diyl)-bis-(thiophene-2-carboxylate) (H2SSeS) and 2,2'-(selenophene-2,5-diyl)-bis-(thiazole-5-carboxylate) (H2TzSeTz) were successfully embedded within UiO-68 while preserving its fcu topology. The performance of the two MOFs as sorbents toward PFAS in tap water was evaluated under environmentally relevant conditions using a mixture of PFAS differing in chain length and functional group. Both materials display a clear selectivity toward long-chain PFAS, with UiO-68-SSeS showing particularly high removal efficiency for perfluoroundecanoic acid (PFUnDA). These results demonstrate that rational linker design represents an effective approach to modulate the adsorption behavior of UiO-type MOFs, opening future perspectives for functional materials in water remediation.