Highly Sensitive and Selective Turn-on Fluorescent Probe for Hg²⁺ Based on Rhodamine 6G-Thiourea Conjugate

Area of Science:

• Analytical Chemistry
• Materials Science
• Environmental Science

Background:

• Mercury (Hg2+) is a highly toxic heavy metal pollutant.
• Development of sensitive and selective fluorescent probes is crucial for Hg2+ detection.
• Rhodamine-based probes offer advantages in fluorescence sensing.

Purpose of the Study:

• To synthesize and characterize a novel fluorescent probe for Hg2+ detection.
• To investigate the sensing mechanism and selectivity of the probe.
• To evaluate the probe's performance in a mixed solvent system.

Main Methods:

• Synthesis of rhodamine 6G-thiourea conjugate (RGTU).
• Spectroscopic analysis (fluorescence, UV-Vis) of RGTU with Hg2+.
• Interference studies with common metal ions.
• Job's plot and 1H NMR for complexation analysis.

Main Results:

• RGTU probe exhibited a dramatic fluorescence enhancement upon addition of Hg2+.
• A visible color change was observed, indicating Hg2+ binding.
• The probe showed high selectivity for Hg2+ over other tested metal ions.
• Complexation studies confirmed a 1:1 binding ratio between RGTU and Hg2+.

Conclusions:

• The synthesized RGTU probe is a sensitive and selective chemosensor for Hg2+.
• The probe operates via spirolactam ring opening induced by Hg2+.
• RGTU holds potential for practical applications in environmental monitoring of mercury.