D-A-D based reversible fluorescent probe for selective detection and cell imaging of copper ion

Two D-A-D fluorescent probes (X1 and X2) were constructed based on coumarin and 1,3,4-thiadiazole moieties and were used for visual inspection and fluorescent response of Cu2+. Both of them demonstrated high selectivity and sensitivity towards Cu2+ in DMSO-Tris-HCl solution (v/v 3:1, pH = 7.4) through distinct fluorescence and colorimetric variation. The detection limits of X1 and X2 were achieved at 13.6 nM and 12.3 nM. Furthermore, they were proven to be reversible sensors by addition of EDTA into X1/X2 + Cu2+ solution and were actually applied to test paper inspection and cell imaging. Density functional theory calculations were employed to guide experiments in the development of probes and exploration of detecting mechanism.