Copper(II) Complexes of 1,10-Phenanthroline-Derived Ligands: Synthesis, Structural Characterization, Calculation of Molecular Orbitals and a Review on Antioxidant Activities

Tay, Karen Swee Ping (2022) Copper(II) Complexes of 1,10-Phenanthroline-Derived Ligands: Synthesis, Structural Characterization, Calculation of Molecular Orbitals and a Review on Antioxidant Activities. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

Copper complexes have been widely studied for their antimicrobial and anticancer properties. Besides, several studies have also shown that Cu(II) complexes show good antioxidant activities. Besides, functional groups such as benzoyl thiourea and 1,10-phenanthroline also have shown antioxidant activities in several studies. Therefore, ligands Cu(II) complexes with these groups with electron-donating and withdrawing substituents were synthesised; phen-nBT (L1), phen-p-OCH3BT (L2), phen-p-NO2BT (L3) [Cu(II)(phen-nBT)2](ClO4)2 (Complex 1), [Cu(II)(phen-p-OCH3BT)2](ClO4)2 (Complex 2), [Cu(II)(phen-p-NO2BT)2](ClO4)2 (Complex 3). The ligands and complexes have been characterized via various spectroscopic methods such as UV-Visible spectroscopy, Nuclear Magnetic Resonance (NMR) (for ligands) Mass Spectrometry (MS) and Fourier Transform Infrared Spectroscopy (FTIR). The results of FTIR for all ligands and complexes have shown similar major peaks (e.g. C=S, N-Haliphatic, C-Caromatic , C-Naromatic and C-Naliphatic stretchings). Besides, all three ligands showed similar peaks at 200-300nm which were the π-π* and n-π* peaks whereas the complexes has one extra peak which was the LMCT peak at 500-800nm. IR spectra and TD spectra calculated using DFT were also analysed and were consistent with the experimental results for the complexes. The structures of the complexes and the ligands were consistent with the proposed structure based on NMR and MS analysis. The magnetic susceptibility of the complexes were also calculated and was shown to be paramagnetic. Literature review was also done on the antioxidant activities of Cu (II) complexes and also the effect of electron donating group and withdrawing group on antioxidants. The mechanism of DPPH scavenging activity of the complexes were predicted to be HAT mechanism. In addition, the complexes were predicted to have higher antioxidant activities than the ligands based on literature review. Lastly, electron withdrawing group was predicted to lower antioxidant activity of the complexes whereas electron donating group will show the opposite effect