A new fluorescent probe for the detection of Hg2＋ was designed and synthesized via attaching N-methylisatin to rhodamine B hydrazide through an imine linkage. In an ethanol-Tris buffer medium, the addition of Hg2＋ caused a strong orange fluorescence and a visual color change from colorless to pink. Other coexisting metal ions did not interfere with the detection of Hg2＋. The research on the detection of Hg2＋ in natural water suggested the possibility of practical applications in environment monitoring. Based on ESI-MS analysis, the Hg2＋-sensing mechanism was proposed.
A quinoline-based colorimetric chemosensor （QDB） for Cu2＋ was synthesized by coupling quinoline-2- carbaldehyde with 4-（dimethylamino）benzohydrazide. Although most transition metal cations can cause redshiffs in the UV-vis spectrum of QDB, the response of the chemosensor for Cu2＋ can be easily distinguished because it exhibits the largest redshift together with a color change from colorless to red in response to Cu2＋. Other metal ions have no effect on the specific response of QDB to Cu2＋. The significant redshift and color change were attributed to Cu2＋-induced deprotonation of NH in the sensor.
Xiao-Bo LiZhi-Gang NiuLing-Ling ChangMen-Xia ChenEn-Ju Wang
