A Review on Pyridine Based Colorimetric and Fluorometric Chemosensor for Detection of Hg2+ ion.

Abstract

Pyridine, N-containing heterocyclic organic compound, displays strong coordination capabilities with various metal ions. It can be synthesized through various methods, such as Friedlander synthesis, heterocumulene synthesis, cross-coupling reactions, the Radziszewski reaction, Bonnemann cyclization, as well as cobalt-catalyzed synthesis. Experimental and spectroscopic analyses have demonstrated a strong binding affinity between pyridine and several heavy metal ions, including Pb²⁺, Hg²⁺, and Cd²⁺ ions. The escalating environmental pollution caused by the disposal of heavy metal ions in rivers, open air, and water reservoirs poses a significant threat to both ecosystem and human health. To address these environmental challenges, a cost-effective and easily synthesized chemosensor has been prepared for identifying toxic heavy metal ions in various samples. Pyridine's photophysical properties make it an effective sensor for detecting Hg²⁺ ions, displaying fluorescence quenching or enhancement in their presence. The coordination between pyridine and Hg²⁺ ions lead to shifts in the absorption spectra. The pyridine-based sensor has been evaluated for its sensitivity, selectivity, and detection limits under different experimental conditions. Pyridine's solubility and environmental stability make it applicable for real-time detection, making pyridine probes valuable tool for monitoring toxic Hg²⁺ ions in the environment. The results demonstrate that the pyridine-based chemosensor exhibits good selectivity and sensitivity for targeting Hg²⁺ ions, with detection limits within acceptable ranges. This review (from years 2011 to 2023) emphasizes the preparation of various substituted pyridine compounds as selective, sensitive, and specific sensors for real-time detection of Hg²⁺ ions.