Selective and sensitive fluorescence chemosensor for the hypochlorite anion in water

Area of Science:

• Analytical Chemistry
• Chemical Sensing
• Fluorescence Spectroscopy

Background:

• Hypochlorite (ClO-) is a key reactive oxygen species (ROS) involved in biological processes and environmental monitoring.
• Developing selective and sensitive chemosensors for ClO- detection is crucial for various applications.
• Existing methods may lack selectivity or ease of use.

Purpose of the Study:

• To develop a highly sensitive and selective fluorescent chemosensor for the detection of hypochlorite (ClO-).
• To enable both fluorimetric and colorimetric (naked-eye) detection of ClO-.
• To validate the chemosensor's performance in complex matrices like natural water samples.

Main Methods:

• Design and synthesis of a rhodamine 6G-based spirolactam chemosensor.
• Utilizing an oxidized irreversible ring-opening mechanism for fluorescence activation.
• Spectroscopic analysis (fluorescence and UV-Vis) for detection and quantification.
• Testing selectivity against various ROS, anions, and metal ions.
• Evaluating performance in natural water samples across a pH range.

Main Results:

• The chemosensor exhibits a >60-fold fluorescence enhancement upon reaction with ClO-.
• Remarkable selectivity was observed for ClO- over other ROS and common ions.
• A visible color change from colorless to pink facilitates naked-eye detection.
• The detection limit for ClO- is as low as 2 × 10⁻⁸ M (S/N=3).
• The sensor functions effectively within a pH range of 6-11.5 and in natural water samples.

Conclusions:

• The developed chemosensor offers a sensitive, selective, and user-friendly platform for ClO- detection.
• The dual-mode detection (fluorimetric and colorimetric) enhances its practical applicability.
• The chemosensor demonstrates robust performance in real-world environmental samples, highlighting its potential utility.