Design and synthesis of triazolyl coumarins as Hg2+ selective fluorescent chemosensors.

A series of triazolyl coumarin derivatives L1-L4, with and without spacer groups between the coumarin and the triazole groups, were synthesized as fluorescent sensors to study their binding ability and selectivity toward metal ions. Ligand L3, which contains an acetyl linker between the triazole and the coumarin, exhibited a high selectivity toward Hg(2+) in polar protic solvents MeOH-CHCl(3) (9 : 1, v/v) with fluorescent enhancement, furthermore, it was found to bind two Hg(2+) at a high concentration (>12.5 mM) of Hg(ClO(4))(2).