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 Pb2+ , Hg2+ and Cd2+ by showing different fluorescence characteristics. In ethanol/HEPES buffer medium, the addition of Cd2+ caused a yellowish-green fluorescence, while the presence of Pb2+ or Hg2+ gave rise to an orange fluorescence. Additionally, the sensor shows an irreversible fluorescence response to Pb2+ and reversible fluorescence responses to Hg2+ and Cd2+ .