A highly sensitive and selective colorimetric/fluorescent probe for the detection of Ag+ based on a croconium dye

A novel colorimetric and fluorescent probe, 2,5-bis[3-ethyl-2-methylbenzothiazole]-croconine ( BBC ) has been synthesized and characterized. The BBC dye can effectively recognize Ag + in the presence of potentially competitive metal ions (Co 2+ , Na + , Cd 2+ , K + , Mg 2+ , Zn 2+ , Ca 2+ , Ba 2+ , Ni 2+ , Cr 3+ , Al 3+ ), which exhibited visible color change and fluorescence spectra behaviors. The Benesi-Hildebrand plot accurately showed the binding constant of BBC- Ag + . Correspondingly, the 1:1 stoichiometric structure of BBC and Ag + was evaluated by using Job’s plot. Moreover, the complex mechanism of BBC toward Ag + were also investigated by Fourier transform infrared (FT-IR) and 1 H nuclear magnetic resonance ( 1 H NMR). The results indicated that BBC could be used as a high effective colorimetric and fluorescent sensor to identify Ag + .