Recent Progress in Triazole Based Chromogenic and Fluorogenic Chemosensor for the Detection of Hg²⁺ Metal ion: A...

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 Pb²⁺, Hg²⁺, Cd²⁺, Cu²⁺ and Al³⁺. 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 Hg²⁺ ions, attributed to changes in its absorption and emission spectra upon coordination. This unique photophysical behaviour makes triazole-based probes valuable tools for monitoring Hg²⁺ ions in environmental and biological samples. This review provides a comprehensive overview of triazole-based fluorescent chemosensors for Hg²⁺ 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.