A coumarin based ICT probe for fluoride in aqueous medium with its real application

Area of Science:

• Chemical Sensing
• Anion Detection
• Organic Synthesis

Background:

• Development of selective chemosensors for anions is crucial in environmental and biological monitoring.
• Coumarin-based hydrazone derivatives offer promising platforms for designing fluorescent and colorimetric sensors.

Purpose of the Study:

• To synthesize and characterize a new coumarin-based hydrazone (receptor 1) for selective fluoride ion detection.
• To investigate the sensing mechanism and performance of receptor 1 in aqueous DMSO solutions and real-world samples.

Main Methods:

• Synthesis and characterization of coumarin-based hydrazone (receptor 1).
• Colorimetric and UV-vis spectroscopic studies for anion sensing.
• Nuclear Magnetic Resonance (NMR) titration studies to elucidate binding modes.
• Quantum mechanical calculations (TD-DFT) to support experimental observations.

Main Results:

• Receptor 1 selectively detected fluoride ions with a distinct red color change in aqueous DMSO (5:95, v/v).
• The sensor also demonstrated naked-eye fluoride detection in a toothpaste sample.
• UV-vis spectroscopy showed bathochromic shifts to 514 nm (fluoride) and 484 nm (acetate), with association constants in the 10^5 M^-1 range.
• (1)H NMR titrations and TD-DFT calculations supported the proposed binding mechanism.

Conclusions:

• The synthesized coumarin-based hydrazone (receptor 1) is a highly selective and sensitive sensor for fluoride ions.
• Receptor 1 exhibits potential for practical applications in detecting fluoride in complex matrices like toothpaste.
• The combination of experimental and computational methods provides a comprehensive understanding of the anion sensing mechanism.