Dual detection of Hg2+ and Pb2+ by a coumarin-functionalized Schiff base in environmental and biosystems

Fluorescent chemosensors are often preferred for tracking toxic ions because of their non-destructive measurement and ease of use in environmental real samples and biosystems. Exploring high selectivity, great sensitivity, and biocompatible fluorophores with facile, accessible and dual-responsive features is currently highly demanding. A coumarin-based naphthol hydrazone Schiff base chemosensor, NaChro, is designed and synthesized in a two-step process to detect toxic metal ions with strong emission. Fluorescence spectra analysis demonstrates that the probe binds to Hg2+ and Pb2+ ions with a 1:1 and a 2:1 stoichiometry, respectively, with high sensitivity, short response time and minimal interference from other metal ions. The observed reversible turn-on reaction was attributed to the inhibition of C = N isomerization and excited-state intramolecular proton transfer (ESIPT) processes once the ions were introduced. The practical applications of NaChro are successfully addressed in paper strips, various water samples, HeLa cells and Zebrafish, demonstrating that the probe can detect and track Hg2+ and Pb2+ ions in environmental samples and biosystems.

A coumarin-based portable fluorescent probe for rapid turn-on detection of amine vapors

Amines are widely used in many fields including agriculture, dyes, medicine and food processing. However, volatile amine vapors could initiate acute and serious damage to human bodies. Thus, highly efficient detection of volatile amine vapors has great importance for academic research as well as practical application. In this work, a turn-on type fluorescent sensor BZCO has been developed, which could be used to detect volatile amine vapors. The portable BZCO sensor can be easily prepared through immersing filter paper into its CH₂Cl₂ solution and then evaporating it to dryness. This paper-based amine vapor sensor exhibits high sensitivity with a relatively low detection limit at 3.82 ppm. It also has good selectivity for discriminating amine vapors from volatile organic solvents. The detection mechanism has been confirmed by UV-vis spectral analysis. The practical applications of this paper-based BZCO sensor, such as detection of food spoilage and fluorescent security ink, have been investigated. This work has developed a new fluorescent sensor BZCO, which has broad applications in various fields, including amine gas detection, security and anti-counterfeiting materials.