DOI: https://doi.org/10.55373/mjchem.v25i4.144

Keywords: Thiosemicarbazone; metal complexes; spectroscopy; polymer electrolytes

Abstract

This is a continuation of our previously published spectroscopy and conductivity studies of thiosemicarbazone derivatives. In this study, the 4-(diphenylamino)benzaldehyde-4-(3-fluorophenyl) thiosemicarbazone (LH) ligand was synthesized from the reaction between 4-diphenylamino-benzaldehyde and 3-fluorophenyl thiosemicarbazide. The NiL2, CuL2, and CoL2 complexes containing the LH ligand were also synthesized and characterized by elemental analysis, infrared spectroscopy, magnetic susceptibility, molar conductivity and UV-Vis spectroscopy. The LH ligand was characterized via 1H NMR and 13C NMR spectroscopy. FTIR data was used to determine the coordination mode of the ligand with the Ni(II) metal ion. The FTIR spectra showed that LH behaved as a mononegative bidentate ligand with all metal ions, through its azomethine (N=C) and (C-S) groups. The electronic spectra and magnetic measurements suggest a square planar geometry for both the NiL2 and CuL2 complexes, with μeff values of 0.00 and 2.36 B.M, respectively. However, CoL2 was likely to possess a tetrahedral geometry, with μeff = 4.02 B.M. All complexes displayed non-electrolytic behaviour with low molar conductance values in the range of 5.97 – 13.20 Ω-1 cm2 mol-1. Polymer electrolyte (PE) films were mixed with carboxymethyl cellulose (CMC) polymer, propylene carbonate as a plasticizer and the LH/NiL2/CuL2/CoL2 compound as a dopant, and prepared using a solution casting technique. The conductivity of the prepared PE films was studied using Electrochemical Impedance Spectroscopy (EIS). The conductivity values observed for the LH ligand, NiL2, CuL2, and CoL2 complexes were 5.58×10-8, 7.72×10-8, 9.58×10-7 and 3.10×10-8 S cm-1, respectively. Thus, the presence of metal ions may affect the conductivity of polymer electrolytes.