Fluorescence-based ratiometric sensors as emerging tools for CN^- detection: Chemical structures, sensing mechanisms...

Hazardous cyanide anions (CN^-) are increasingly threatening the environment and human health due to their widespread use in industry and many other fields. Over the past three decades, a large number of probes have been reported to sensitively and selectively detect this toxic anion, while a rather limited number of ratiometric fluorescent probes have been developed. The ratiometric probes have significant potential in bio-imaging and biomedical applications because of the ability to detect CN^- in a quick, convenient and affordable way. In this review, we introduce 42 ratiometric fluorescent probes reported in the past 6 years (2018-2023) for CN^- detection. Our description includes the chemical structures, photo-physical properties, CN^- sensing mechanisms, solution color changes, limits of detection (LODs) and/or various applications of these chemical probes. This review provides guidelines for design and development of a new ratiometric probe for effective CN^- detection.