AIE-based dual-mode chemosensor for hypochlorite detection in water: Environmental and biological applications in diverse water samples, zebrafish, artemia, and plants

An aggregation-induced emission (AIE)-based dual-mode probe for the fluorogenic and colorimetric detection of hypochlorite (ClO⁻), THP -2·Cl (1,1′-((((1 E 1′E)-[2,2′-bithiopHene]-5,5′-diylbis(methanylylidene))bis(hydrazin-1-yl-2-ylidene))bis(2-oxoethane-2,1-diyl))bis(pyridin-1-ium) chloride), was designed. THP -2·Cl exhibited sensitive and selective response to ClO⁻, with the activation of strong blue fluorescence and color variation from yellow to colorless in 100% water. The limits of detection in color and fluorescence variations were obtained as 4.5 × 10⁻⁶ M and 1.6 × 10⁻⁶ M. The recognition mechanism was elucidated to be an AIE activation through the cleavage of the imine bond by using electrospray ionization mass spectrometry (ESI-MS), ¹H nuclear magnetic resonance spectroscopy (NMR) titration, and theoretical calculations. Test strips coated with THP -2·Cl could be applied to probe ClO⁻ simply. The quantitative analyses for the identification of ClO⁻ in real environmental samples including drinking water, tap water, seawater, river water, and sewage were successfully achieved using THP -2·Cl. Interestingly, THP -2·Cl could visualize ClO⁻ through fluorescence in various biological system, such as live zebrafish, artemia, fresh onion tissue and celery.