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

Zhengquan Yan, Hu Lei, Nie Li, Lv Hong, Zhengquan Yan, Hu Lei, Nie Li, Lv Hong

Index: Spectrochim. Acta. A. Mol. Biomol. Spectrosc. 79(3) , 661-5, (2011)

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Abstract

Graphical abstract . 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 Hg 2+-selective ratiometric colorimetric behavior, with the maximum absorbance peak changing from 354 nm to 408 nm exclusively. Under the optimum conditions, the recognition to Hg 2+ 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.