Colorimetric assay of Sn(II) species via nitro-to-amine conversion of nitronaphthalimides

Abstract A novel colorimetric probe for the determination of Sn 2+ species was developed via the nitro-to-amine conversion of nitronaphthalimides. The 4-nitronaphthalimide-based probe ( 1 ) exhibited pronounced colorimetric signaling behavior toward Sn 2+ ions in acidic aqueous DMSO solution. The changes in the absorption spectra induced by the aforementioned conversion were substantial and could be analyzed by ratiometry, i.e., using the absorbance ratio at the two characteristic wavelengths of probe 1 and its Sn 2+ signaling product. Sn 2+ -selective signaling of 1 was achieved in the presence of common metal ions and anions as well as the oxidized Sn 4+ species. The detection limit obtained by means of an office scanner was 4.8 × 10 –6 M. Thus, an easily accessible compound ( 1 ) could be utilized as a selective and sensitive reaction-based probe for the colorimetric assay of Sn 2+ ions for laboratory and industrial applications.