Synthesis, structural diversity, DFT and luminescence properties of Ni(II), Zn(II) and Cd(II) complexes derived from a 2, 2′-bipyridyl hydrazone Schiff base

Abstract

A new 2, 2′-bipyridyl hydrazone Schiff base ligand (H2L) was synthesized, and four novel complexes, namely, [Ni2(L2−)2]‧3CH3OH (1), [Zn2(L2−)2]‧DMF‧3H2O (2), [Cd3(H2L)2Cl6(H2O)2]‧2H2O (3), and {[Zn2(L2−)Cl2]‧CH3OH}n (4), were obtained via the solvent evaporation method. The four complexes were structurally investigated by single-crystal X-ray diffraction and additionally characterized by powder X-ray diffraction, infrared spectroscopy and element analysis. X-ray analytical results show that complexes 1 and 2 exhibit dinuclear double helicates with similar structures. Complex 3 exists as a trinuclear structure with two different configurations in the cadmium ions. Complex 4 exists as a one-dimensional coordination polymer with two different configurations in the zinc ions. The diverse architectures of the complexes show that the spacer 2, 2′-bipyridyl ligands and metal ions have significant impacts on the structures and the coordination modes. Furthermore, thermogravimetric analysis, DFT and luminescence properties of the complexes have been investigated, and electrochemical studies for complex 1 were carried out as well.