A highly selective fluorescent chemosensor for Cd(II) based on 8-hydroxyquinoline platform

Tris[2-(8-chinolinyloxy)ethyl]amine (L) has been developed as a highly selective fluorescent chemosensor for Cd2+ based on the chelation-enhanced fluorescence (CHEF) mechanism. Its sensing behavior toward metal ions was investigated by absorption and fluorescence spectroscopy. In buffer solution (10 mM Tris–HCl, pH = 7.4) of L, the presence of Cd2+ induces the formation of a metal–ligand (Cd2+–L) complex, which exhibits a strong, increasing fluorescent emission centered at 417 nm. The binding mode of the Cd2+–L complex has been found to be 1:1 based on the fluorescence/absorption titration and further confirmed by X-ray crystallography.