A new highly selective and sensitive fluorescent probe for Zn2+ and its application in cell-imaging

• A new fluorescent probe for Zn2+ based on tuned ICT effect.
• Significant fluorescence emission shifts and changes in color towards Zn2+.
• Potential applications in the cell-imaging.
• High sensitivity at ppb level with a detection limit lower than that regulated by EPA.

A new fluorescent probe, 3-((4-([2,2′:6′,2″-terpyridin]-4′-yl)phenyl)ethynyl)-7-methoxy-2H-chromen-2-one (ZC-F7) composed of coumarin as the fluorophore and terpyridine as the receptor is designed and synthesized. Based on the intramolecular charge transfer (ICT) effect, the probe exhibits significant variation on emission wavelengths with shifts more than 100 nm after combined with Zn2+, in accordance with the conversion of emission colors from blue to green. Good selectivity and sensitivity of this probe towards Zn2+ can be found even on the ppb level in aqueous solution. The Job's plot test suggests a 1:1 stoichiometry between ZC-F7 and Zn2+. The application of the fluorescence probe in bio-imaging is also demonstrated, proving its potential usage in fields such as environment protection, water treatment and safety inspection.