A Selective Colorimetric and Turn-on Fluorescent Chemosensor for Hg²⁺ in Aqueous Solution

Area of Science:

• Analytical Chemistry
• Materials Science
• Environmental Science

Background:

• Mercury (Hg2+) is a toxic heavy metal pollutant.
• Developing selective and sensitive sensors for Hg2+ is crucial for environmental monitoring.
• Fluorescent probes offer advantages in sensitivity and real-time detection.

Purpose of the Study:

• To synthesize and characterize a novel receptor FT for Hg2+ detection.
• To investigate the cation-sensing properties of FT.
• To evaluate the selectivity and sensitivity of FT for Hg2+.

Main Methods:

• Synthesis of the thiophene appended fluorescein-hydrazone derivative (FT).
• Colorimetric and fluorescence spectroscopy for cation binding studies.
• Determination of association constant and detection limit for Hg2+.

Main Results:

• Receptor FT exhibited a selective colorimetric change from colorless to orange upon binding to Hg2+.
• The FT-Hg2+ complex showed a high association constant (3.03 × 10^9 M^-1).
• A low detection limit for Hg2+ (0.24 ppm) was achieved.

Conclusions:

• Receptor FT is a promising selective and sensitive sensor for Hg2+ detection.
• The developed sensor can be applied in environmental analysis for mercury monitoring.
• The simple colorimetric and fluorescence turn-on response facilitates practical applications.