A new fluorescent chemosensor based on 2,2′-bipyridyl acylhydrazone Schiff base: Synthesis, sensing properties, and coordination behaviors

An aggregation-induced emission (AIE) active acylhydrazone ligand (H4L) containing a 2,2′-bipyridyl unit was designed and synthesized. The sensing properties of H4L with a series of metal ions were investigated via UV–vis spectra and fluorescence emission spectra. The UV–vis spectra showed that H4L displayed a selective recognition to Cu2+ ions in a mixed solution of DMF/water. The fluorescence emission spectra showed that H4L had a quenching effect upon addition of Cu2+ ions, while the fluorescence was enhanced when Zn2+ ions were added. The crystal structures of Cu(II) and Zn(II) complexes, formulated as {[Cu3(L4−)Cl2(H2O)2]·2DMF}n (1) and [Zn4(H2L2−)4]·8H2O (2), accounted for the coordination modes of H4L with Cu2+ and Zn2+ ions. In addition, electrochemical properties of the two complexes were also investigated.