A pyridoxal-based dual chemosensor for visual detection of copper ion and ratiometric fluorescent detection of zinc ion

A pyridoxal-based fluorescein derivative was synthesized by reacting fluorescein hydrazide and pyridoxal hydrochloride in ethanol and characterized by NMR, ESI-MS and X-ray. The optical properties of probe were investigated in methanol: HEPES solution. The probe displayed selectivity for Cu2+, which was characterized using UV–visible spectroscopy. Moreover, the process also allowed visual detection of Cu2+ by a colorless to yellow change. In contrast, selectivity toward Zn2+ was determined in the emission spectra showing OFF–ON type fluorescence changes from colorless to green. This represents the first reported pyridoxal-based sensor capable of detecting both Cu2+ and Zn2+ using two different modes. Furthermore, it can be used to bioimaging.