Synthesis of a Quinoline-Coumarin Fluorescent Probe and its Applications.

In this study, probe T is synthesized via a condensation reaction from 7-diethylamino-3-formylcoumarin and 2-(quinolin-8-yloxy) acetohydrazide. It demonstrates a strong recognition ability for Cu and S in the CHCN/HEPES (9:1, V/V, pH = 7.34) buffer system. Upon the addition of Cu, the probe solution undergoes a visible color change from yellow-green to brown-yellow, with a noticeable red shift of 30 nm in the maximum absorption wavelength. Under UV light, the solution fluorescence is significantly quenched, with a quenching rate of 98.6% and a detection limit of 0.289 µmol/L. The complex T-Cu formed by probe T and Cu enables continuous recognition of S, demonstrating a fluorescence recovery phenomenon with a recovery rate of 88.9% and a detection limit of 0.01 µmol/L. Probe T demonstrates excellent recognition ability for Cu and S at pH 4 ~ 9 and can be recycled for 4 times. Additionally, probe T was effectively employed in fabricating test strips for the rapid and convenient detection of Cu and S, and for determining Cu and S in living cells, owing to its excellent permeability and low cytotoxicity.