Atomically Precise Hexanuclear Ce(IV) Clusters as Functional Fluorescent Nanosensors for Rapid One‐Step Detection of PFAS

Abstract The presence of poly‐ and perfluoroalkyl substances (PFAS) in the environment is associated with adverse health effects but measuring PFAS is challenging due to the associated high cost and technical complexities of the analysis. Here, the reactivity of atomically precise metal‐oxo clusters is reported and the foundation for their use is provided as fluorescent nanosensors for PFAS detection. The material comprises crystalline, water soluble, hexanuclear cerium‐oxo clusters [Ce₆(µ₃‐O)₄(µ₃‐OH)₄]¹²⁺ decorated with glycine molecules (Ce‐Gly) characterized by fluorescence emission at 353 nm. The Ce‐Gly fluorescence is found sensitive to long chain carboxylated PFAS of CF₃–(CF₂)_n –, where n ≥ 6, such as perfluorooctanoic, perfluorononanoic and perfluorodecanoic acids. This unique reactivity leads to a change in the emission spectra in a concentration dependent manner, enabling PFAS detection through ligand exchange and aggregation‐induced emission (AIE) enhancement. No significant cross‐reactivity from potentially co‐existing species, including sulfonated PFAS, octanoic and dodecanoic acids, humic acid, and inorganic ions is observed. With an optimal concentration of 3.3 µg mL⁻¹ Ce‐Gly, the method demonstrated detection limits of 0.24 ppb for PFOA and 0.4 ppb for PFNA. These findings highlight the potential of fluorescence‐based detection strategies utilizing nanoscale probes such as Ce‐Gly as fluorescent probes and nanosensors for PFAS.