A Novel Diarylethene-rhodamine Unit Based Chemosensor for Fluorimetric and Colorimetric Detection of Hg²

A novel fluorimetric and colorimetric chemosensor (1O) was synthesized with diarylethene-rhodamine unit and characterized by ESI-MS, ¹H NMR, and ¹³C NMR. The chemosensor can selectively recognize extremely low concentrations of Hg²⁺ over a variety of metal ions with remarkable colorimetric and fluorescent responses. The colorimetric and fluorescent changes were ascribed the reaction between 1O and Hg²⁺ destructed the rhodamine hydrazide into open-ring form which was proved by mass spectrometry and nuclear magnetic titration analyses. The detection limits of the UV absorption and fluorescence methods for Hg²⁺ were found to be 0.708 μM and 24.6 nM, respectively. Moreover, the chemosensor exhibited excellent photochromism and outstanding fatigue resistance property under alternating UV and visible light irradiation. The application potential of the chemosensor was demonstrated with the qualitative detection of Hg²⁺ in real water samples.