Efficient Colorimetric Fluoride Anion Sensor Based on π-Conjugated Carbazole Small Molecule

Area of Science:

• Analytical Chemistry
• Materials Science

Background:

• Detecting fluoride anions with high selectivity and sensitivity is essential but challenging.
• Visual detection methods are desirable for simplicity and accessibility.

Purpose of the Study:

• To develop a novel colorimetric sensor for fluoride anions.
• To investigate the sensitivity and selectivity of the sensor for fluoride detection.

Main Methods:

• Synthesis of a novel conjugated organic dye, N-tert-butyldimethylsilyl-3,6-diiodocarbazole (CA-TBMDS).
• Colorimetric detection of fluoride anions in tetrahydrofuran.
• Proton nuclear magnetic resonance titration to confirm the sensing mechanism.

Main Results:

• CA-TBMDS demonstrated high sensitivity for fluoride anions with a detection limit of 3 × 10⁻⁵ M.
• A distinct color change from colorless to yellow was observed, enabling naked-eye detection.
• The sensor showed high selectivity in the presence of various interfering ions.
• Intermolecular proton transfer was identified as the sensing mechanism.

Conclusions:

• CA-TBMDS is a highly sensitive and selective colorimetric sensor for fluoride anions.
• The developed sensor allows for simple, naked-eye detection of fluoride.
• N-butyldimethylchlorosilane-based organic dyes show potential as fluoride anion chemosensors.