A new fluorescent probe for Zn2+ with red emission and its application in bioimaging

A new fluorescent probe, (E)-3-(3-(4-([2,2':6',2 ''-terpyridin]-4'-yl)phenyl)acryloyl)-7-(diethylamino)2H-chromen-2-one (ZC-F4), composed of coumarin as the fluorophore and terpyridine as the receptor was designed and synthesized. This probe showed good selectivity and sensitivity towards Zn2+ even at the ppb level with significant variation of emission wavelength (more than 100 nm shifts) after combination with Zn2+. One can observe that the emission colour changed from green to red. A Job's plot test suggested a 1 : 1 stoichiometry between ZC-F4 and Zn2+, and the theoretical calculation based on density functional theory has been carried out to gain an insight into the sensing mechanism. Furthermore, imaging of Zn2+ in cells was also performed to test its feasibility in biology. This fluorescence probe should be a promising candidate for applications in cell-imaging, environment protection, water treatment and safety inspection.