A highly sensitive “ON–OFF–ON” fluorescent probe with three binding sites to sense copper ion and its application for cell imaging

•A ‘pinwheel’ shaped three binding sites fluorescent probe was developed.•The probe showed high sensitive and selective recognition for Cu2+.•The probe can be used in biological imaging.

Traditional single binding site probes for metal ions usually lack the ability to form stable products in the recognition process. Herein, a novel three binding sites “ON–OFF–ON” fluorescent probe, triformylphloroglucinol 3-amino-9-ethylcarbazole hydrazone was introduced to overcome this defect. After testing the optical properties of triformylphloroglucinol 3-amino-9-ethylcarbazole hydrazone, the data show that this compound is an excellent fluorescent probe for copper ion and the probe can be released by introduction of citric acid, oxalic acid, pyrophosphoric acid and sodium thiosulfate. Finally, cell permeability and live cell imaging of copper ions are also demonstrated, which is useful.

Graphical abstractA ‘pinwheel’-shaped fluorescent probe has been developed for high sensitive and selective detection of copper ions. And subsequent addition of anions made the probe become an ‘ON–OFF–ON’ fluorescent probe. Furthermore, the probe was applied as a Cu2+ sensor in living cells.Figure optionsDownload full-size imageDownload as PowerPoint slide