5879-69-6Relevant academic research and scientific papers
Schiff bases of hydroxyacetophenones and their copper(II) and nickel(II) complexes: Synthesis, antioxidant activity and theoretical study
Ali Alomari, Abdulaziz,Ibrahim, Mohamed Mustafa,Mohamed, Musa E.
, p. 2505 - 2511 (2016)
The synthesis of a series of Schiff base ligands derived from tryptamine and 5-methoxy-2-hydoxyacetophenone, 5-methyl-2-hydroxyacetophenone and 2-hydoxyacetophenone together with their copper(II) and nickel(II) complexes is presented. The ligands and complexes were characterized by elemental analysis, IR, 1H and 13C NMR, UV-visible spectroscopy as well as magnetic measurements. Semi empirical quantum mechanical calculations and DFT calculations were performed to model the structures of the compounds. The complexes were found to have the general formula [M(L)2]. Spectral studies reveal that these Schiff bases act as bidentate ligands and coordinate to the metal center through deprotonated phenolate oxygen and azomethine nitrogen atoms. Nickel(II) complexes establish square planar geometry around the central metal, whereas distorted tetrahedral geometry is proposed for copper(II) complexes. Electronic energy, molecular orbitals energy, HOMO-LUMO gap, ionization potentials, heat of formation and dipole moments were also optimized. The compounds are screened for their antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl free radical (DPPH?) and ferric-reducing antioxidant power (FRAP) assays in which butylated hydroxytoluene (BHT) is used as a reference. The investigations reveal that the ligands appear to be more effective antioxidants, but also copper(II) complexes show good activity. Methoxy-substituted ligand shows an enhanced activity over BHT in the FRAP assay.
