Recent Progress in Triazole Based Chromogenic and Fluorogenic Chemosensor for the Detection of Hg Metal ion: A Review.

Triazole, a heterocyclic organic molecule containing nitrogen, exhibits strong coordination abilities with various metal ions. Several synthetic techniques, including Claisen-Schmidt condensation, Huisgen-1,3-dipolar cycloaddition reaction (CuAAC), Pellizzari synthesis, Einhorn-Brunner synthesis, Dimroth rearrangement and Boulton-Katritzky Rearrangement have been employed to synthesize triazole derivatives. Experimental and spectroscopic investigations have demonstrated that triazole possesses a high binding affinity for heavy metal ions such as Pb, Hg, Cd, Cu and Al. The increasing environmental pollution caused by the uncontrolled discharge of heavy metal ions into water bodies and open spaces poses a serious threat to ecosystem and public health. To address this issue, a cost-effective and efficient chemosensor based on triazole has been developed for selective detection of toxic heavy metal ions. Notably, triazole exhibits fluorescence quenching or enhancement upon interaction with the Hg ions, attributed to changes in its absorption and emission spectra upon coordination. This unique photophysical behaviour makes triazole-based probes valuable tools for monitoring Hg ions in environmental and biological samples. This review provides a comprehensive overview of triazole-based fluorescent chemosensors for Hg ions detection, covering advancements made between 2010-2025. The study highlights the high specificity, excellent sensitivity, and low detection limits of these sensors, emphasizing their potential for practical applications in environmental monitoring and analytical chemistry.