A single schiff base molecule for recognizing multiple metal ions: A fluorescence sensor for Zn(II) and Al(III) and colorimetric sensor for Fe(II) and Fe(III)

• A simple and easy-to-make fluorescent and colorimetric sensor for Zn2+, Al3+, Fe2+ and Fe3+ was designed and synthesized.
• This sensor can be used to simultaneously detect Zn2+, Al3+, Fe2+ and Fe3+ ions over other cations with high selectivity.
• Fe2+ and Fe3+ resulted in an instant color change of 1 from colorless to orange and purple, respectively.

A simple and easily synthesized fluorescent and colorimetric chemosensor 1, based on juloidine-imidazole moieties as a binding and signaling unit, has been synthesized in a one-step procedure. Receptor 1 showed immediate responses toward Zn2+ and Al3+ ions through selective fluorescence enhancement in buffer-acetonitrile and dimethylformamide (DMF) solution, respectively. Moreover, receptor 1 sensed the two states (Fe(II) and Fe(III)) of iron by “naked eye” with a different color. Upon the addition of Fe2+ and Fe3+ into each solution of 1, the color of the solutions instantly changed from colorless to orange for Fe2+ and to purple for Fe3+. Thus, this sensor provides a novel approach for selectively recognizing the biologically important three elements in the human body simultaneously, for Zn2+ and Al3+ by emission spectra and Fe2+ and Fe3+ by the naked eye.

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