Overview on recently reported fluorometric sensors for the detection of copper ion based on internal charge transfer (ICT), paramagnetic effect and aggregation induced emission (AIE) mechanisms

• Review of fluorescence sensors working through ICT, paramagnetic effect and AIE. • Applications of three recognition mechanisms for fluorimetric detection of Cu 2+ ion. • The structure, selectivity and sensitivity of such chemosensors have been summarized. • This would be useful for further design of fluorescent sensors for Cu 2+ ion. Copper is the third most abundant and a crucial metal for the biological processes. But, excessive accumulation of copper in body is linked with several disorders. In this article, recent advances (in between 2018 and 2020) on small molecule-based fluorescent sensors for the detection of Cu 2+ ion have been reviewed. The probes working on the principle of internal charge transfer (ICT), paramagnetic effect and aggregation induced emission (AIE) are covered. Molecular design, sensitivity and the specificity of the sensors have been focused along with their applications.