A smartphone-assisted highly sensitive chromone-derived fluorescent receptor for rare-earth cerium metal ion detection: environmental monitoring and cancer cell imaging

In this work, a new chromone-based fluorescent organic material, 3-(((2,4-di-tert-butyl-5-hydroxyphenyl)imino)methyl)-4H-chromen-4-one (OSA), has been designed and developed for the selective detection of cerium (Ce³⁺) ions. The structure of the synthesized receptor OSA has been confirmed through spectroscopic techniques, including FT-IR, NMR, and mass spectral analysis. The OSA receptor exhibits selective “turn off” colorimetric and fluorometric responses for the addition of Ce³⁺ ions. Upon incremental addition of Ce³⁺ ions, the receptor OSA exhibited a linearly decreasing response, with a lowest limit of detection of 63.8 nM. By using DFT, Job's plot, and mass spectrum analysis, the binding stoichiometry between the receptor and Ce³⁺ ions was verified as a 1 : 1 ratio. Ce³⁺ ion interaction with OSA produces a noticeable color shift, which was combined with an RGB color variation study of smartphones. Furthermore, this chemosensor OSA was applied in the detection of Ce³⁺ ions in environmental water samples. Fluorescence bioimaging in ME-180 cells revealed that the receptor OSA exhibited high cell permeability and showed a fluorescence “turn-off” response upon addition of Ce³⁺ ions.