A “turn-on” fluorescent chemosensor for the detection of Zn(II) in aqueous solution at neutral pH and its application in live cells imaging

• A“turn-on” fluorescent chemosensor for the detection of Zn(II) was designed and synthesized.
• The chemosensor was facilely synthesized through a one-step reaction from commercially available materials.
• Detection of Zn(II) can be performed in aqueous solution at neutral pH with high sensitivity.
• The chemosensor exhibits remarkably selective fluorescence enhancement to Zn(II).
• The chemosensor could be efficiently delivered to live cells for bioimaging of Zn(II).

Pyridoxal-2-hydrazinopyridine Schiff-base (1) was prepared by one-step synthesis from commercially available materials of pyridoxal and 2-hydrazinopyridine. Compound 1 could be applied as a fluorescent chemosensor for Zn(II) in aqueous solution at pH 7.4. After binding to Zn(II) with a molar ratio of 1:1, 1 exhibited 17-fold fluorescence enhancement. In addition, 1 showed a good selectivity toward Zn(II) over other metal ions, which can especially distinguish Zn(II) from Cd(II). A linear range of 5.0–20.0 μmol L−1 and a detection limit of 70 nmol L−1 were also achieved. Moreover, the utility of chemosensor 1 in bioimaging of Zn(II) in living cells was demonstrated, which suggested that 1 could be used as a Zn(II)-selective chemosensor in biological samples.

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