Malays. J. Anal. Sci. Volume 30 Number 4 (2026): 1765

 

Research Article

 

Synthesis and conductivity evaluation of a novel Cu(II) complex derived from 4-(diphenylamino)benzaldehyde-4-(ethyl)thiosemicarbazone: An integrated EIS and DFT investigation

 

Wan M. Zulhilmi Wan M. Kharul Anwar1*,  Khadijah Hilmun Kamarudin1,2 and Uwaisulqarni M. Osman1,2

 

1Faculty of Science and Marine Environment, Universiti Malaysia Terengganu, 21030 Kuala Nerus, Terengganu, Malaysia.

2Advanced Nano Materials Research Group (ANOMA), Ionic State Analysis (ISA) Laboratory, Universiti Malaysia Terengganu, 21030 Kuala Nerus, Terengganu, Malaysia.

 

*Corresponding author: p5779@pps.umt.edu.my

 

Received: 28 October 2025; Revised: 23 April 2026; Accepted: 10 May 2026; Published: 30 August 2026

 

Abstract

A new Cu(II) complex containing the 4-(diphenylamino)benzaldehyde-4-(ethyl)thiosemicarbazone ligand (CuL2) was synthesised via the reaction of 4-(diphenylamino) benzaldehyde-4-(ethyl)thiosemicarbazone ligand with copper(II) acetate. The resulting CuL2 complex was characterised using various spectroscopic and analytical techniques, namely, CHNS elemental analysis, Fourier transform infrared spectroscopy (FTIR), magnetic susceptibility, molar conductivity, and ultraviolet-visible (UV-Vis) spectroscopy. The FTIR analysis confirmed the mononegative bidentate coordination of the ligand to the Cu(II) ion through the azomethine (C=N) and thiosulfur (C=S) functional groups, with characteristic bands at 497 and 443 cm-1, respectively. The experimental HOMO-LUMO band gap of 2.76 eV indicates that the Cu(II) complex exhibited semiconducting behaviour. The UV-Vis spectrum showed an absorption at 738 nm (d→d transition) while magnetic susceptibility measurements (1.72 BM) supported a square planar geometry for CuL2. Solid biopolymer electrolyte (SBE) films doped with CuL2 were prepared using a solution casting method, in which a mixture of carboxymethylcellulose (CMC) served as the polymer matrix, polyethylene glycol (PEG) acted as the plasticiser, and isophthalic acid (IA) served as the deprotonator. Electrochemical impedance spectroscopy (EIS) analysis revealed that the highest electrical conductivity of 1.08 x 10-4 Scm-1 at 353 K was achieved with the SBE composition of CMC (1 g) + PEG (0.1 ml) + CuL2 (15 wt%) + IA (15 wt%). Moreover, the prepared SBE composition followed Arrhenius behaviour with a low activation energy (Ea) of 0.34 eV, indicating that only a small amount of thermal energy is required to activate the charge carriers.

 

Keywords: Synthesis,thiosemicarbazone complex, conductivity, solid biopolymer electrolyte

 

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