Highly sensitive and selective “turn-on” fluorescent chemodosimeter for Cu2+ in water via Cu2+-promoted hydrolysis of lactone moiety in coumarin

A nonfluorescent coumarin derivative (1) was synthesized as an efficient "turn-on" fluorescent chemodosimeter for Cu(2+) in water. Mechanism studies suggested that 1 formed a complex with Cu(2+) in a 1:2 metal-to-ligand ratio, and a 50-fold fluorescence enhancement was observed when the complex simultaneously underwent Cu(2+)-promoted hydrolysis at ambient temperature.