A new fluorescence sensor based on diarylethene with a N′-(quinolin-8-ylmethylene)benzohydrazide group for Zn2+ detection

A novel photochromic diarylethene 1O composed of a N'-(quinolin-8-ylmethylene)benzohydrazide group as the binding unit for metal ions and perfluorodiarylethene as a photoswitching trigger has been designed and synthesized. 1O exhibited sensitivity to light irradiation and Zn2+. Stimulated by UV/Vis light and Zn2+, distinct changes were observed in the UV-vis and fluorescence spectra. The binding of Zn2+ caused the open-ring absorption band of 1O to display an intense absorption band at 412 nm with a notable color change from colorless to yellow. Furthermore, Zn2+ induced a fluorescence "turn-on" of 1400-fold and a fluorescence color change form dark to bright green due to the chelation-enhanced fluorescence effect. A Job's plot established the 1:1 stoichiometry of the complex formation between 1O and Zn2+, and the limit of detection for Zn2+ is as low as 3.2 x 10(-8) mol L-1. Therefore, the compound could be used as a selective and sensitive fluorescence ratiometric sensor for the detection of Zn2+. Finally, we demonstrated that the sensor can penetrate into HeLa cells and could be used for the determination of intracellular Zn2+.