Colorimetric and fluorometric chemosensors for mercury ( <scp>II</scp> ) detection: Recent advances and applications

Abstract Mercury contamination remains a serious environmental and public health concern because of its extreme toxicity, persistence and bioaccumulation in living systems. The demand for rapid, sensitive and selective detection has driven significant research into chemosensors as practical alternatives to conventional analytical methods. This review provides a concise overview of the recent developments (2015–2025) in colorimetric and fluorometric chemosensors for Hg 2+ detection. It focuses on organic molecular probes, such as rhodamine, coumarin, and Schiff base derivatives, as well as emerging nanomaterial‐based systems. The underlying sensing mechanisms, including chelation‐enhanced fluorescence (CHEF), photoinduced electron transfer (PET) and intramolecular charge transfer (ICT), are discussed in detail in this review. The comparative performance of these sensors is evaluated with respect to selectivity, sensitivity, detection limits and practical applicability. Many sensors have demonstrated nanomolar detection limits and reliable performance in real samples. This review highlights the progress in portable test strips and intracellular imaging, and presents the challenges and opportunities for developing improved sensors for environmental and biological mercury monitoring.