A Highly Selective Fluorescent Chemosensor for Cu2+

A new Zn2+ probe L2-Zn(L2=naphthofuran carbonylhydrazone derivant) was synthesized as a fluorescence chemosensor for Cu2+, by which Cu2+ ion could be detected with high selectivity and sensitivity in a wide pH range via a displacement "turn-off" signaling strategy. Whereas the coordination between Zn2+ and L2 resulted in a considerable enhancement of typical luminescence of a naphthalofuran group in complex L2-Zn, the addition of Cu2+ ion led to a dramatic decrease in the emission intensity of probe L2-Zn at about 503 nm(excitation at 423 nm). The competitive fluorescent experiments showed that other metal ions, such as Hg2+, Fe3+, Ag+, Ca2+, CO2+, Ni2+, Cd2+, Pb2+, Zn2+, Cr3+ and Mg2+ could not impact the detection of Cu2+. The detection limit of the novel probe L2-Zn for Cu2+ ion was as low as 2.3 x10(-7) mol/L, which is far lower than the guideline value of 1.6x10(-5) mol/L of the United States Environmental Protection Agency.