A chemosensor showed colorimetric sensing for copper(ii) and fluoride by changing color from yellow to colorless and to orange.

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A new highly selective and multifunctional chemosensor 1 for the detection of Co 2+ , Cu 2+ and CN À , based on 4-diethylaminosalicyl aldehyde and thiophene-2-carbohydrazide moieties, was designed and synthesized. 1 could simultaneously detect both Co 2+ and Cu 2+ by changing its color from colorless to yellow in aqueous solution. The binding modes of 1 to Co 2+ and Cu 2+ were determined to be a 2 : 1 complexation stoichiometry through job plot and ESI-mass spectrometry analysis. The detection limits (0.19 mM and 0.13 mM) of 1 for Co 2+ and Cu 2+ were lower than the DEP guideline (1.7 mM) of Co 2+ and the WHO guideline (31.5 mM) of Cu 2+ for drinking water. Importantly, 1 could detect and quantify Co 2+ and Cu 2+ in real water samples. Moreover, the resulting Co 2+ -2$1 complex sensed cyanide through naked-eye, showing recovery from Co 2+ -2$1 to 1. The sensing mechanisms of Cu 2+ by 1 were explained by theoretical calculations. Scheme 4 Proposed sensing mechanism of CN À by Co 2+ -2$1 complex. Fig. 10 (a) Absorption spectral changes of competitive selectivity of Co 2+ -2$1 complex (20 mM) toward CN À (30 equiv.) in the presence of other anions (30 equiv.) in bis-tris buffer/DMSO (95/5, v/v). (b) The color changes of competitive selectivity of Co 2+ -2$1 complex (20 mM) toward CN À (30 equiv.) in the presence of other anions (30 equiv.).This journal is

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A new dual chemosensor 1 for the colorimetric detection of Fe 2+/3+ and the fluorometric detection of Zn 2+ has been developed and characterized. The sensor 1 has proven to be highly selective to Fe 2+/3+ with a color change from colorless to dark green in a near-perfect aqueous solution. 1 had low detection limits (1.21 mM for Fe 3+ and 1.18 mM for Fe 2+ ), which are lower than the World Health Organization guideline (5.36 mM) for drinking water. Moreover, 1 showed a selective detecting ability for Zn 2+ by 'OFF-ON' fluorescent response in aqueous solution. The detection limit (1.05 mM) of 1 for Zn 2+ was much lower than World Health Organization guideline (76 mM) for drinking water. Interestingly, it could be recycled simply through treatment with an appropriate reagent such as EDTA (ethylenediaminetetraacetic acid). The sensing mechanism of 1 for Zn 2+ was explained by the theoretical calculations. In particular, the sensor 1 could be used to quantify iron and zinc in water samples.