A turn-on fluorescent probe based on quinoline and coumarin for rapid, selective and sensitive detection of hypochlorite in water samples

A fluorescent probe L-Cu²⁺ based on quinoline, coumarin and Cu²⁺ has been synthesized and characterized for hypochlorite determination. After copper ion was added to the solution of ligand L, the fluorescence quenching at 490 nm might result from a ligand–metal charge transfer (LMCT) process and its strong coordination ability for Cu²⁺. In the presence of hypochlorite, the structure of ligand L was destroyed to form 7-(diethylamino)-coumarin-3-carboxylic acid, and the fluorescence was restored at 460 nm. In this case, L-Cu²⁺ complex could be used as a fluorescent probe to detect hypochlorite, with the advantages of rapid, selective, wide linear range and low detection limit.