South African Journal of Chemistry
On-line version ISSN 1996-840X
Print version ISSN 0379-4350
SOBOLA, Abdullahi Owolabi; WATKINS, Gareth Mostyn and VAN BRECHT, Bernadus. Synthesis, characterization and antimicrobial activity of copper(II) complexes of some ortho-substituted aniline Schiff bases; crystal structure of bis(2-methoxy-6-imino)methylphenol copper(II) complex. S.Afr.j.chem. (Online) [online]. 2014, vol.67. ISSN 1996-840X.
This study presents the synthesis, characterization and antimicrobial activity of copper(II) complexes of some ortho-substituted aniline Schiff bases (L1-L8). The Schiff bases and their respective copper(II) complexes were characterized by a combination of elemental analysis, infrared and UV/Visible studies. The structures of the ligands were also confirmed from 1H- and 13C-NMR spectral data. The infrared and electronic transition studies showed that the ligands are bidentate coordinating via the imine nitrogen and the phenolic oxygen atoms in a planar configuration. Introduction of aqueous ammonia to the ethanolic solution of L3/L4 and Cu(OAc)2.H2O aliquot yielded an ammonia-based complex due to the hydrolysis of the imine bond. The crystal structure of the resulting complex indicated a square planar geometry. The copper(II) ion crystallizes in the monoclinic system with a space group of P21/c having a = 10.9309, b = 4.85600, c = 17.7030, α = γ = 90 ° and β = 119.658 °. The geometry is slightly distorted from planarity with O1-Cu1-N1 bond angles of 92.19 ° and 87.8 °. The Schiff base ligands and their respective copper(II) complexes were screened for their in vitro antibacterial and antifungal activity against Escherichia coli ATCC® 8739™*, Staphylococcus aureus subsp. aureus ATCC® 6538™*, Bacillus subtilis subsp. spizizenii ATCC® 6633™* and Candida albicans ATCC® 2091™*. The o-vanillin-based ligands exhibited higher activity than the salicylaldehyde derivatives which were virtually non-active against the tested organisms.
Keywords : o-Vanillin; substituted-aniline; Schiff bases; Cu(II) complexes; antimicrobial activity.