A fluorescent sensor for Zn2+ and Cd2+ based on a diarylethene derivative with an indole-2-methylhydrazone moiety

A fluorescent sensor for Zn 2+ and Cd 2+ based on a diarylethene derivative with an indole-2-methylhydrazone moiety was constructed. • A diarylethene derivative with an indole-2-methylhydrazone moiety was developed. • The black-to-green fluorescence color change can be reversed with stimuli by Zn 2+ /Cd 2+ and EDTA. • The sensor was successfully applied to measure the level of Zn 2+ and Cd 2+ in tap water. A fluorescent sensor for Zn 2+ and Cd 2+ based on a diarylethene derivative with an indole-2-methylhydrazone moiety was constructed. The photochromism and photoswitchable fluorescence can be reversibly modulated by UV/Vis light and M 2+ /EDTA (M = Zn 2+ or Cd 2+ ). Upon addition of Zn 2+ or Cd 2+ , an obviously large red-shift emission peak by 105 nm, and fluorescence quantum yields enhanced by 72-fold and 48-fold, respectively, with a concomitant black-to-green fluorescence color change was observed. The 1:1 stoichiometry complexes with Zn 2+ and Cd 2+ were confirmed by both Job's plot and Benesi-Hildebrand expression. As a result, the binding constants between sensor and metal ions were calculated to be 8.88 × 10 4 L mol −1 for Zn 2+ and 4.36 × 10 4 L mol −1 for Cd 2+ , respectively. And the detection limit of 1o for Zn 2+ and Cd 2+ was 3.82 × 10 −7 mol L −1 , and 5.74 × 10 −7 mol L −1 , respectively. Moreover, the fluorescent can be used to detect Zn 2+ and Cd 2+ in tap water sample with a high accuracy.