Synthesis, characterization and electrochemical studies of transition metal complexes containing 3,6-bis(3,5-dimethylpyrazolyl) pyridazine ligand Sintesis, pencirian dan kajian elektrokimia bagi kompleks logam peralihan mengandungi ligan 3,6-bis(3,5-dimetilpirazolil) piridazina

Document Type

Article

Publication Date

1-1-2021

Abstract

Four novel coordination complexes were synthesized based on 3,6-bis (3,5-dimethylpyrazolyl) pyridazine ligand with Cu(II), Fe(II), Ni(II) and Co(II) metals. The synthesized complexes were characterized using several analyses. The infrared (IR) spectra for all the complexes showed a significant shift at the ligand methyl group (C-H), pyrazole ring (C=N), pyridazine ring (C-N) and (N-N) at 2926 cm-1, 1137 cm-1, 1162 cm-1 and 970 cm-1, respectively. The elemental analyses of the complexes confined to the stoichiometry of 1:2 ratio between the ligand and the metal cation. The presence of the metal in the complexes was confirmed using the FESEM-EDX analysis. The complexation of the metals to the ligand was evidenced when all the complexes exhibit a significant shift in the position of the characteristic ligand band at around 260 nm due to the HOMO → LUMO π → π* transitions of the pyridazine and pyrazoles groups in the UV-Vis spectrum. Cyclic voltammetry (CV) method was used to explore the redox characteristics of the complexes. The Cu(II), Fe(II) and Ni(II) complexes exhibited quasi-reversible single electron transfer process while no peak was observed in Co(II) complex upon scanning from-1.5 to 1.5 V vs. Ag/AgCl. This observation is speculated to be the effect of poor complexation in between the metal and the ligand. The potential recorded for Cu(II) complex at 0.03 V vs. Ag/AgCl was corresponded to the reduction of Cu(II) to Cu(I) while the potential at 0.75 V was due to the oxidation of Cu(I) to Cu(II). For the Fe(II) complex, the redox couple Fe(II)/Fe(III) was recorded at-0.47 V and-0.67 V during its oxidation and reduction process respectively. Finally, the peak at 0.71 V in the CV of Ni(II) complex is attributed to its oxidation process of Ni(I) to Ni(II) while the peak at 0.12 V is due to its reduction from Ni(II) to Ni(I). © 2021, Malaysian Society of Analytical Sciences. All rights reserved.

Keywords

Coordination complex, Electrochemical behavior, Pyridazine, Transition metal

Publication Title

Malaysian Journal of Analytical Sciences

Divisions

CHEMISTRY

Funders

Universiti Malaya [Grant no. IMRC/AISTDF/CRD/2018/000048]

Volume

25

Issue

1

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