compounds,namely,2-thenaldehyde-4-dimethylaminobenzoylhydrazone(1),2-furaldehyde-4-dimethylaminobenzoylhydrazone(2) and benzaldehyde-4-dimethylamino benzoylhydrazone(3) were synthesized，and fully characterized by 1H NMR,13C NMR and MS spectra.The interactions between metal ions and compound 1,2 and 3 were investigated by UV-Vis absorption spectroscopy.The results indicated that compound 1 selectively bound with Hg2+ by formation of a 1∶1 stable complex of 1-Hg2+ with binding constant of 9.7×104 L?mol-1.A good linear relationship was obtained for Hg2+ in the range of 1.0-18 μmol/L,and the limit of detection was 0.28 μmol/L.Some other coexistent competitive cations such as Cu2+,Fe3+ and Ni2+ did not interfer the detection of Hg2+.Thus compound 1 could be used as a potential colorimetric and naked-eye chemosensor for Hg2+.For compound 2,it showed spectral responses to Hg2+,Cd2+ and Zn2+by formation of 1∶1 metal complexes.The binding constants were determined to be 6.5 × 104 L?mol-1 for the complex of 2 with Hg2+ and 5.0× 105 L?mol-1 for the complex of 2 with Zn2+ in acetonitrile,respectively.However,compound 3 did not show any spectral response for the metal ions tested.Obviously,the high selectivity of compound 1 toward Hg2+ was ascribed to the binding sites from assembly of various atoms,in which both S and O atoms participated in the coordination interaction with Hg2+.