Chromene Carbohydrazide- Schiff Base as a Highly Selective Turn-Off Fluorescence Chemosensor for In³⁺ Ion and its...

Area of Science:

• Analytical Chemistry
• Materials Science
• Organic Chemistry

Background:

• Development of selective fluorescent probes for metal ion detection is crucial for environmental and biological monitoring.
• Indium(III) ions play significant roles in various industrial applications, necessitating sensitive detection methods.

Purpose of the Study:

• To design and synthesize a new Schiff-base derivative (probe L) for selective fluorescence sensing of Indium(III) ions.
• To investigate the photophysical properties and sensing mechanism of probe L towards In(III) ions.

Main Methods:

• Synthesis of a 7-(diethylamino)-2-oxo-2H-chromene-3-carbohydrazide based Schiff-base probe (L).
• Spectroscopic analysis (UV-Vis absorption and fluorescence emission) in various solvent systems.
• Investigation of probe L's response to In(III) ions using fluorescence spectroscopy, Job's plot, ESI mass spectrometry, and 1H NMR titration.
• Computational studies using DFT/TD-DFT to elucidate the binding mechanism.
• Development and testing of solid-state sensor strips.

Main Results:

• Probe L exhibited selective "turn-off" fluorescence response to In(III) ions in DMSO:H2O (7:3, pH 7.4) with a limit of detection of 5.93 nM.
• The probe formed a 1:2 complex with In(III) ions, exhibiting chelation-enhanced fluorescence quenching (CHEFQ).
• The sensor demonstrated instantaneous response, reversibility, and successful application on solid test strips for on-site detection.

Conclusions:

• The synthesized Schiff-base probe (L) is a highly selective and sensitive chemosensor for In(III) ions.
• The developed sensor strips offer a practical platform for rapid, user-friendly, and on-site detection of Indium(III) ions.