Preparation of 4,4′-bis-(carboxyl phenylazo)-dibenzo-18-crown-6 dye and its application on ratiometric colorimetric recognition to Hg2+

A multifunctional dye, 4,4′-bis-(carboxyl phenylazo)-dibenzo-18-crown-6 dye (BCADC) was designed and prepared via diazotization and coupling reaction of dibenzo-18-crown-6 with p-amino benzoic acid. The dye, combining crown ether ring, azo and carboxyl group, exhibits well-defined Hg2+-selective ratiometric colorimetric behavior, with the maximum absorbance peak changing from 354 nm to 408 nm exclusively. Under the optimum conditions, the recognition to Hg2+ has a linear range of 2.5–58 × 10−7 mol L−1 with a 0.9978 correlation coefficient. The method was applied to analyse 3 environmental water samples with a detection limit of 2.9 × 10−8 mol L−1 and a relative standard deviation (R.S.D.) lower than 3.7% (n = 5). The action mechanism between BCADC and metal ions was discussed by means of Job's plots and theoretical calculations.

. In this contribution, a multifunctional dye, 4,4′-bis-(carboxyl azobenzene)-dibenzo-18-crown-6 dye (BCADC) was designed and prepared via diazotization and coupling reaction of dibenzo-18-crown-6 with p-amino benzoic acid. The dye, combining crown ether ring, azo and carboxyl group, exhibits well-defined Hg2+-selective ratiometric colorimetric behavior, with the maximum absorbance peak changing from 354 nm to 408 nm exclusively. Under the optimum conditions, the recognition to Hg2+ has a linear range of 2.5–58 × 10−7 mol L−1 with a 0.9978 correlation coefficient. The method was applied to analyse 3 environmental water samples with a detection limit of 2.9 × 10−8 mol L−1 and a relative standard deviation (R.S.D.) lower than 3.7% (n = 5). The action mechanism between BCADC and metal ions was discussed by means of Job's plots and theoretical calculations.Figure optionsDownload as PowerPoint slideHighlights
► A multifunctional colorimetric sensor with crown ether ring, azo and carboxyl group.
► Different metal ions act with the functional groups with different action mechanisms.
► The interaction between Hg2+ and BCADC is exclusive.
► The reaction mechanism is confirmed by means of experimental and theoretical proofs.
► An effective ratiometric colorimetric recognition to Hg2+ is developed.