A Simple and Rapid Quinoline Schiff Base as a Fluorescent Probe for Zn²⁺ and Its Application in Test Strips

A simple fluorescent probe, ( E )‐ N ‐(3‐methoxy‐4‐methylphenyl)‐1‐(quinolin‐2‐yl)methanimine ( L ), was synthesized via Schiff base condensation reaction between quinoline‐2‐carboxaldehyde and 3‐methoxy‐4‐methylaniline. L can be used as a ′turn‐on′ fluorescent probe for the selective and sensitive detection of Zn 2+ ions in a CH 3 OH/HEPES medium. The detection limit was 1.04×10 −7 M. Job plot analysis shows that the binding stoichiometry of L and Zn 2+ is 1 : 1, further verified by the single crystal structure. The fluorescence‐enhanced response of L towards Zn 2+ ions may be related to the chelation‐enhanced fluorescence (CHEF) supported by theoretical calculations. By adding EDTA, the reversibility of the probe binding to Zn 2+ ions is demonstrated, enabling the construction of a functional molecular logic circuit. In addition, probe L was successfully incorporated into test strips for the quantitative detection of Zn 2+ .