*1Abubakar A. Ahmed, 1Mohammed B. Fugu, 1Naomi P. Ndahi, 2Hussaini A. Barma, 1Ibrahim M. Wakil and 1Ibrahim Waziri
1Department of Pure and Applied Chemistry, Faculty of Physical Sciences, University of Maiduguri,
P.M.B. 1069, Maiduguri, Borno State, Nigeria
2Department of Chemistry, Kashim Ibrahim University, P. M. B. 1122, Maiduguri, Borno State, Nigeria
*Corresponding author’s Email: abubakarabdullahiahmed28@gmail.com, doi.org/10.55639/607.02010095
ABSTRACT
The growing global menace of antimicrobial resistance and oxidative stress related disorders have prompted the search for adequate and effective bifunctional molecules that have the proclivity of circumventing the duo. In this work, we synthesized and explored the antioxidant and antimicrobial potency of a Schiff base,2-bromo-4-chloro-6-((E)-((5-chloro-2-((E)-(2-hydroxybenzylidene) amino) nphenylimino)methyl)phenol (H2L) obtained by condensing 4-chloro-1,2 diaminobenzene, salicylaldehyde and 3-bromo-5-chlorosalicylaldehyde in 1:1:1 molar ratio. The complexes of Ni2+ and Cu2+ were further synthesized. A comprehensive physicochemical and spectroscopic characterization including elemental analysis, High Resolution Mass Spectrometry (HRMS), 1H and 13C Nuclear Magnetic Resonance (NMR), UV-Visible, and Fourier Transform Infrared (FTIR) Spectroscopy, molar conductance and magnetic susceptibility were performed. The data established the asymmetry of the Schiff base coordinated to the metal centres via the azomethine N-atom and phenolic O-atoms, forming four coordinate square planar geometry for both Ni(II) and Cu(II) complexes. Furthermore, bioassay results demonstrated that H2L showed mild activity against Gram negative bacteria (Escherichia coli and Salmonella Typhi) and fungus Candida albicans as determined by disc diffusion method. By contrast, this compound showed no effect against Gram-positive bacterial species (Streptococcus aureus and Bacillus subtilis). After complexation, the NiL chelate gained potency against B. subtilis with inhibition zone diameter, IZD = 10.00 ± 0.00 mm while the CuL against S. aureus and B. subtilis with IZD of 12.00 ± 0.00 and 12.00 ± 0.00 mm, respectively. DPPH scavenging potency of these compounds follows the order: CuL > H2L > NiL with CuL possessed the best efficacy of 98.46% recorded at concentration of 0.5 mg mL –1.
KEYWORDS
Asymmetric_Schiff
base,
4-chloro-1,2
diaminobenzene,
4-chloro-o
phenylenediamine.
.

