A rhodamine-benzothiophene based fluorescent chemosensor for Hg2+ detection: Synthesis, theoretical calculations, and investigations in solutions and biosystems

A Schiff base fluorescent chemosensor based on rhodamine and benzothiophene (denominated as RhoBenz ) was designed and synthesized for the detection of Hg 2+ ions. Comprehensive analysis of the sensor's performance was conducted including UV-vis and fluorescence titration, mass spectrometry (MS), and other quantitative evaluations such as linearity plots and Job's plot analysis. The sensor was demonstrated with excellent selectivity for Hg 2+ over other metal ions with minimal interference, high sensitivity, and a low limit of detection (0.045 μM). It is noteworthy that RhoBenz has a relatively high quantum yield (0.43). The pH response of the sensor was promising, and comparative analysis with existing probes highlighted its superior performance. In addition, RhoBenz exhibited extremely low cytotoxicity and excellent penetration, which demonstrated its promising utility in live cells and zebrafish.