UC Davis

Small molecules can display certain electronic and structural features that enable their use for metal-sensing applications in different fields. Of the reported metal sensors, there has been increasing interest in copper sensing in the past decade, given the biological importance of copper as well as its presence as a potential contaminant in water and fuels. Molecules used for copper(II) sensing generally consist of a fluorophore/chromophore and a ligand for selective metal ion recognition. This review article focuses on literature contributions since the year 2010 concerning small molecule copper(II) sensors that provide a naked-eye color response in solution. We present molecular structural features and sensing mechanisms for the colorimetric and fluorometric detection of copper(II) ions in different environmental, agricultural, and biological samples. In addition, the sensing performance of these chemosensors is compared and discussed, which could aid in the future design of chemosensors for copper(II). Finally, we outline the challenges and future prospects of fluorophore/chromophore–ligand chemistry in applications of small molecules for fluorometric and colorimetric assays of copper(II).