Metal complex-based probes for the detection of chloride ions

Chloride ions play vital roles in a variety of biological and environmental processes, making their accurate and efficient detection critical for both research and practical applications. In this perspective, we explore the recent advancements in the development of metal complex-based probes for chloride ion detection, with a focus on complexes involving transition and lanthanide metals. These probes offer remarkable selectivity and sensitivity, achieved through diverse mechanisms such as metal coordination, hydrogen bonding, electrostatic interactions, and halogen or chalcogen bonding. Such interactions enable detection limits to reach the nanomolar range, fulfilling the stringent requirements for both biological and environmental monitoring. We discuss the range of detection methods, including UV-visible absorption, luminescence, electrochemical techniques, and ¹H NMR spectroscopy, that facilitate real-time chloride ion sensing. The applications of these samples span from biomedical diagnostics, such as tracking chloride flux in live cells, to environmental assessments, addressing the growing concern of chloride pollution. This perspective emphasizes the versatility and diagnostic power of metal complex-based probes, highlighting their adaptability under complex biological and environmental conditions and their potential for broad impacts in chloride ion monitoring.