Highly selective and sensitive coumarin-triazole-based fluorometric 'turn-off' sensor for detection of Pb²⁺ ions

Area of Science:

• Environmental Chemistry
• Analytical Chemistry
• Materials Science

Background:

• Lead ions (Pb²⁺) pose significant health risks, causing severe cardiovascular, neurological, developmental, and reproductive disorders, especially in children.
• The development of selective and sensitive sensors for Pb²⁺ detection is crucial for environmental monitoring and public health.

Purpose of the Study:

• To develop a novel triazole-based fluorescent sensor (L5) for the selective and sensitive detection of Pb²⁺ ions.
• To evaluate the sensor's performance, including sensitivity, selectivity, binding stoichiometry, and detection limit.
• To create practical, low-cost test strips for on-site Pb²⁺ detection.

Main Methods:

• Synthesis and characterization of the triazole-based fluorescent sensor L5.
• Spectroscopic analysis (fluorescence quenching) to determine sensor response to Pb²⁺.
• Preparation and testing of L5-impregnated test strips for visual Pb²⁺ detection.

Main Results:

• Chemosensor L5 exhibited selective fluorescence quenching upon binding with Pb²⁺ ions.
• A visible color change from colorless to yellow was observed, facilitating naked-eye detection.
• The sensor demonstrated high sensitivity (detection limit of 1.9 nM) and selectivity for Pb²⁺ in a phosphate-buffered solution.
• A 1:1 binding stoichiometry and a binding constant of 6.76 × 10⁶ M^-1 were determined.
• Low-cost, easy-to-prepare test strips showed practical utility for efficient Pb²⁺ detection.

Conclusions:

• The developed triazole-based fluorescent sensor L5 is a highly sensitive and selective tool for Pb²⁺ detection.
• The sensor's ability to induce a visual color change and its incorporation into test strips highlight its potential for practical, on-site environmental monitoring applications.