Imidazole Derivatives as ON/OFF Fluorescent Chemosensor to Detect Mercury Ion: A Mini Review

Mercury contamination poses a significant environmental and health hazard due to its high toxicity and bioaccumulative nature. The development of highly selective and sensitive sensors for Hg²⁺ ion detection has gained immense research interest. Among various chemosensors, imidazole-based fluorescent sensors have emerged as promising moiety due to their unique electronic properties, strong metal-binding affinity, and tunable fluorescence response. This review comprehensively explores the recent advancements in imidazole-functionalized fluorescent probes for Hg²⁺ sensing, highlighting different design strategies, sensing mechanisms, and structure-property relationships. This review comprehensively summarizes recent progress in the design and development of imidazole-based fluorescent probes for Hg²⁺ detection. Various sensing mechanisms including fluorescence quenching (OFF), fluorescence enhancement (ON), and ratiometric approaches are discussed in relation to their molecular design and structure-property correlations. The analytical performance of these probes is evaluated in terms of sensitivity, selectivity, response time, and applicability in complex sample matrices.