Synthesis, Characterization and Antioxidant Studies of Schiff Base Derived from 4-Methyl-3-Thiosemicarbazide, Trans-Chalcone and Its Metal Derivative

Khor, Jia Wei (2022) Synthesis, Characterization and Antioxidant Studies of Schiff Base Derived from 4-Methyl-3-Thiosemicarbazide, Trans-Chalcone and Its Metal Derivative. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

This project aims to study the antioxidant effect of the ligand and metal complex to determine whether they will product synergistic antioxidant power or not. In this project, a new Schiff base ligand named (Z)-2-((E)-1,3-diphenylallylidene-N-methylhydrazine-1-carbothioamide (MTTC) was synthesised via condensation reaction of 4-methyl-3-thiosemicarbazide and trans-chalcone in 1:1 molar ratio. The ligand was then reacted with zinc acetate dihydrate in 2:1 ligand to metal ions molar ratio to form the zinc (II) complex, Zn(MTTC)2. Both ligand and metal complex synthesised were characterized by spectral, conductivity measurement and thermal analysis techniques including Fourier transform infrared (FTIR) spectroscopy, Ultraviolet-Visible (UV-Vis) spectroscopy, flame atomic absorption spectroscopy (FAAS), 1H and 13C nuclear magnetic resonance (NMR) spectroscopy, direct insertion mass spectrometry (DIMS), single crystal X-ray diffraction (SXRD) and differential scanning calorimetry (DSC). Through the characterisation, it was found that the MTTC Schiff base exists predominantly in thione (C=S) tautomer in both solid and liquid state. On the other hand, the Zn(MTTC)2 exists in thiol tautomer (C–SH) in solid state. In addition, the synthesised ligand and metal complex were further evaluated for their antioxidant potency via ferric reducing antioxidant power (FRAP) assay. It was found that both MTTC and Zn(MTTC)2 exhibited only approximately 3% of the reducing power of ascorbic acid, thus suggesting they are weak antioxidants