2-Hydroxybenzaldehyde-(4,6-Dimethylquinolin-2-yl)-Hydrazone (HBDH), Synthesis, Characterization, and Ligational Behavior Towards Some Metals

Abstract

2-Hydroxybenzaldehyde-(4,6-dimethylquinolin-2-yl)-hydra-zone, and its metal complexes with Cu(II), Co(II), Ni(II), and Zn(II) have been synthesized and characterized using elemental analyses, spectral analyses (IR, UV, 1 H-NMR, MS), thermal analyses (TGA and DTG), conductance and magnetic measurements. The results showed that 2-hydroxybenzaldehyde-(4,6-dimethylquinolin-2-yl)-hydrazone acts as mononegative tridentate ligand coordinating to the metal ions through quinoline nitrogen, azomethine nitrogen and phenolic oxygen after deprotonation. The difference between ν as and ν as stretching vibrations indicates that acetate group binds to the metal ions in a bi-dentate fashion. An octahedral stereochemistry has been suggested for all metal ions. The vibrational spectra of the ligand and its metal complexes have been calculated using semi-empirical calculations, AM1, PM3 and ZINDO/1 methods, to facilitate the assignments of the experimental spectra. Also, the optical band gap (Eg) of the metal complexes has been calculated. The optical transition energy (Eg) is direct and equals 2.40, 2.62 and 2.71 ev for Co, Ni and Cu complexes, respectively.