A Rhodamine-Based Fluorescent Chemosensor for the Detection of Pb 2+ , Hg 2+ and Cd 2+

A new rhodamine-based fluorescent chemosensor ( 1 ) has been designed and synthesized by linking rhodamine 6G hydrazide with N -methylisatin via an imine linkage. The receptor can selectively recognize and sense Pb 2+ , Hg 2+ and Cd 2+ by showing different fluorescence characteristics. In ethanol/HEPES buffer medium, the addition of Cd 2+ caused a yellowish-green fluorescence, while the presence of Pb 2+ or Hg 2+ gave rise to an orange fluorescence. Additionally, the sensor shows an irreversible fluorescence response to Pb 2+ and reversible fluorescence responses to Hg 2+ and Cd 2+ .