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

Abstract

A fluorescent sensor for Zn2+ and Cd2+ 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 M2+/EDTA (M = Zn2+ or Cd2+). Upon addition of Zn2+ or Cd2+, 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 Zn2+ and Cd2+ 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 × 104 L mol−1 for Zn2+ and 4.36 × 104 L mol−1 for Cd2+, respectively. And the detection limit of 1o for Zn2+ and Cd2+ 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 Zn2+ and Cd2+ in tap water sample with a high accuracy.