A 1,3,4-thiadiazole functionalized Schiff base based fluorescence enhancement and colorimetric probe for detection of Cu (II) ion and its potential applications

A fluorescence enhancement probe XS-1 based on coumarin, 1,3,4-thiadiazole and Schiff base cores was synthesized for detection of Cu2+ via the CN bond hydrolysis reaction. Furthermore, Cu2+ ion induced ‘turn-on’ fluorescence emission was preserved in the presence of other competing ions which clearly suggests the high selectivity and anti-interference. In addition, remarkable changes of solution color from light pink to bright yellow and fluorescence color from colorless to bright green realized the visual detection of Cu2+ by naked eyes. The excellent characters and low detection limit (0.17 μM) enabled its application of Cu2+ detection in actual water samples and organisms/living cells. Systematic investigations were also conducted to demonstrate the behavior of XS-1 to Cu2+ ion by the help of 1H NMR titration, HRMS titration and DFT calculations.