A quinoline based fluorescent probe that can distinguish zinc(II) from cadmium(II) in water

A new quinoline based fluorescent probe (DQ) for Zn2+ and Cd2+ has been designed and synthesized. The new probe shows quite different fluorescence response to Zn2+ and Cd2+ in aqueous solution. IR and NMR spectra demonstrated that the different response is caused by amide tautomerization of the probe molecule when coordinating with Zn2+ and Cd2+. The dissociation constants of Zn2+ and Cd2+ complex were detected to be 3.36 and 30.62 nM, respectively. Other metal ions have no effect on the fluorescence spectrum of the probe. Thus the new probe can detect Zn2+ and Cd2+ in water with high selectivity and sensitivity.