Ratiometric fluorescent determination of Zn(II): a new class of tripodal receptor using mixed imine and amide linkages

We synthesized a novel receptor with a unique combination of sp2 nitrogen (–CHdouble bond; length as m-dashN–) and carbonyl groups from amide linkages. These two moieties are judiciously incorporated into the receptor design such that these sites simultaneous binding a metal ion may generate a stable five-member ring. The receptor has been used to selectively detect Zn2+ through changes in the fluorescence spectra. Upon Zn2+ binding with the receptor, the fluorescence band shifted to enhance fluorescence intensity, allowing ratiometric determination of Zn2+ concentration.