Synthesis and spectroscopic properties of two different structural Schiff base Zn(II) complexes constructed with/without auxiliary ligands

•The Schiff base binuclear Zn(II) complex, [Zn2(L)2∙(H2O)2]∙2DMF (1) and its coordination polymer, [Zn2(L)2∙(4,4′-bpy)2]n (2) by introducing auxiliary ligand 4,4′-bpy.•The fluorescence spectrum showed the complex 2 containing 4,4′-bpy was substantially quenching of the fluorescence as compared with the complex 1.•The LUMO and HOMO orbits of the complex 2 were occupied by the 4,4′-bpy, which is different from complex 1, resulting in 1 and 2 had different spectral properties.