A highly selective "turn-on" water-soluble fluorescent sensor for gallium ion detection

Area of Science:

• Analytical Chemistry
• Materials Science
• Supramolecular Chemistry

Background:

• Development of selective and sensitive chemosensors for metal ion detection is crucial for environmental monitoring and biological studies.
• Existing methods for gallium ion (Ga3+) detection often lack the required sensitivity, selectivity, or simplicity for real-world applications.

Purpose of the Study:

• To design and synthesize a novel organic sensor for the selective detection of gallium ions (Ga3+).
• To investigate the sensing mechanism and photophysical properties of the sensor in the presence of various metal ions.
• To evaluate the sensor's performance for detecting Ga3+ in aqueous solutions and real water samples.

Main Methods:

• Synthesis and single-crystal structure determination of the novel sensor (E)-N'-(3-(tert-butyl)-2-hydroxybenzylidene)thiophene-2-carbohydrazide.
• Fluorescence spectroscopy, photophysical experiments, Electrospray Ionization-Mass Spectrometry (ESI-MS), and 1H NMR titration to study the interaction with metal ions.
• Density Functional Theory (DFT) calculations to rationalize experimental observations and optimize molecular configurations.

Main Results:

• The synthesized sensor exhibits excellent 'turn-on' fluorescence response selectively towards gallium ions (Ga3+) in aqueous media.
• The sensor demonstrated high selectivity and specificity for Ga3+ over other common metal ions.
• Low limits of detection (LOD = 58 nM) and quantification (LOQ = 192 nM) were achieved, with successful application in real water samples.

Conclusions:

• The novel thiophene-based sensor provides a highly sensitive and selective platform for Ga3+ detection.
• The developed sensor and test strips offer a promising tool for practical applications in environmental and analytical chemistry.
• The combined experimental and computational approach provides a fundamental understanding of the sensing mechanism.