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 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.