The water-soluble 3-mercaptopropionic acid (MPA)-stabilized CdTe (MPA-CdTe) quantum dots (QDs) were synthesized by aqueous suspension.The study showed that the fluorescence quenching process of Cu2+ to MPA-CdTe QDs,whose largest emission peak was 599 nm,could be described well by the theory of fluorescence quenching in competitive absorption systems and its modification of Stern-Volmer equations.By fittings,the results showed a good polynomial relationship between the fluorescence intensity F0/F and the concentration of Cu2+,when the concentration was in the range of 2.28 × 10-6-18.24 × 10-6 mol/L and 4.8 × 10-7-12 × 10-7 mol/L,and two polynomial equations were respectively elucidated based on dynamic and static quenching in competitive-absorption systems:F0/F =7.999-2.470c +0.339 c2,F0/F =3.154-0.160 c +0.049 c2 and degree of fitting are 0.991 and 0.993,respectively.The detection limit was 1.326 × 10-7.

As a compound rich in citrus plants, limonin has a wide range of biological activities, but its practical application is limited because of its poor water solubility.In this paper, eight new compounds 7a-7h were designed and synthesized by introducing benzoyl hydrazone at the carbonyl position of limonin.The results showed that the water solubilities of all compounds were higher than that of limonin, especially 7a, 7d, 7e and 7f.In addition, the experiment showed that compounds 7d and 7e with substituted hydroxyl groups at the interposition and para-position of the benzene ring had strong antibacterial effects against Escherichia coli and Staphylococcus aureus, and that compound 7e had the best activity, with minimum inhibitory concentrations of 0.31 mg/mL and 1.25 mg/mL, respectively.And compound 7e had better antibacterial activiy in E.coli than sodium benzoate.