A quinoline–polyamine conjugate as a fluorescent chemosensor for quantitative detection of Zn(II) in water

A simple ligand (L1), a diethylenetriamine bearing two end quinoline fragments, was synthesized. Without metal cations, L1 shows no fluorescence at pH 2–13; however, Zn2+ addition creates strong fluorescence at pH 5–12. The emission intensity exhibits linear and stoichiometrical response to the Zn2+ amount. No remarkable emission enhancement was, however, observed for other cations.