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

Exposure to even very low concentrations of Pb2+ is known to cause cardiovascular, neurological, developmental, and reproductive disorders, and affects children in particular more severely. Consequently, much effort has been dedicated to the development of colorimetric and fluorescent sensors that can selectively detect Pb2+ ions. Here, we describe the development of a triazole-based fluorescent sensor L5 for Pb2+ ion detection. The fluorescence intensity of chemosensor L5 was selectively quenched by Pb2+ ions and a clear color change from colorless to yellow could be observed by the naked eye. Chemosensor L5 exhibited high sensitivity and selectivity towards Pb2+ ions in phosphate-buffered solution [20 mM, 1:9 DMSO/H2 O (v/v), pH 8.0] with a 1:1 binding stoichiometry, a detection limit of 1.9 nM and a 6.76 × 106  M-1 binding constant. Additionally, low-cost and easy-to-prepare test strips impregnated with chemosensor L5 were also produced for efficient of Pb2+ detection and proved the practical use of this test.