A benzothiazole-modified quinoline Schiff base fluorescent probe for selective detection of Zn2+ ions, DFT studies and its application in live cell imaging

Abstract

A benzothiazole-modified quinoline Schiff base fluorescent probe TQ was prepared by a condensation reaction, and characterized by using IR, NMR, ESI-MS. The fluorescence emission of probe TQ was weak, while displaying a strong emission at 517.5 nm in the presence of Zn²⁺. The fluorescence enhancement was highly selective toward Zn²⁺ over other common cations, with a detection limit as low as 69.5 nM. The results of Job's plot curve implied that the coordination ratio of probe TQ to Zn²⁺ was 1 : 1, and the possible coordination mode was proposed by means of ¹H NMR titration, mass spectrometry and DFT calculations. In addition, the probe can be used for the detection of Zn²⁺ in living cells and real water samples.