Chemically derived optical sensors for the detection of cesium ions

Cesium is an alkali metal of high reactivity, is used in photoelectric cells and atomic clocks, and also acts as a catalyst for promoting organic reactions. Although cesium is mildly toxic in nature, its radioactive counterparts have been considered as hazardous pollutants owing to their adverse health effects. Therefore, it is desirable to develop techniques for the rapid detection of cesium ions in environmental and biological systems. A variety of methods have contributed significantly toward the detection of cesium ions. However, the method based on chemically derived optical sensors has the advantages of being nondestructive, having high sensitivity, and having high applicability to biological systems. In this review, we mainly discuss fluorescent optical chemosensors that have been used for the detection of cesium ions with the particular aim to provide a general design strategy. Fluorescent molecular chemosensors provide easily assessable evident information (e.g., color/fluorescence change) about the targeted species, which in turn is indispensable for an efficient detection method.