Amphiphilic Fluorescent Aggregate for Highly Selective Detection of Trifluoroacetic Acid in Water

Abstract Trifluoroacetic acid (TFA), the shortestchain perfluoroalkyl carboxylic acid (PFCA), is one of the main per‐ and polyfluoroalkyl substances (PFAS) in the environment, posing a growing threat to public health and water safety. The selective detection of TFA, especially in aqueous media, remains a big challenge due to its high polarity, small molecular size, and structural simplicity. Herein, a supramolecular amphiphilic fluorescent probe is synthesized through surfactant‐induced assembly of fluorinated amino acid‐grafted cyclodextrin (CD‐DFP·CTAB) for TFA sensing. Based on rich F···F interaction, hydrogen interaction, and hydrophilic‐hydrophobic interaction, TFA is selectively incorporated into the hydrophilic region of the aggregate and triggers aggregation‐induced fluorescence. Comparatively, other long‐chain PFCAs (e.g., PFOA) will insert the hydrophobic core, disrupting chromophore clustering and diminishing fluorescence. With this novel probe, the sensor achieves selective TFA detection over a wide concentration range (0–500 ppm) with a detection limit of 0.25 ppm. The high recovery rates in real water sample analysis further demonstrate the promising detection performance of TFA analysis in complicated water matrix. To the best of current knowledge, the amphiphilic probe reported in this study is the first fluorescent probe leveraging hydrophilicity/hydrophobicity differentiation for TFA detection, which opens up a new approach for PFAS monitoring in the environment.