SYNTHESIS, CHARACTERIZATION AND EVALUATION OF BIOLOGICAL ACTIVITY OF SOME METAL (II) COMPLEXES OF L-METHIONINE AND L-LEUCINE
SYNTHESIS, CHARACTERIZATION AND EVALUATION OF BIOLOGICAL ACTIVITY OF SOME METAL (II) COMPLEXES OF L-METHIONINE AND L-LEUCINE
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Date
2018-07
Authors
IORHEMBA, Michael Aondona
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Abstract
Abstract Eight metal(II) amino acids complexes in aqueous basic solution, [CuL2], [CuL12], [CoL2], [CoL1], [ZnL2], [ZnL12], [NiL2], and [NiL12] with L=L-methionine and L1=L-leucine were synthesized and analyzed by gravimetric analyses, molar conductivity measurements, magnetic susceptibility measurements, powder X-ray diffraction analysis, UV-Vis and IR spectroscopies.Molar conductivity measurements showed that the complexes are non-electrolytic, suggesting a metal-ligand ratio of 1:2 for the complexes, with respect to the amino acids. Solubility studies indicated DMSO as the most suitable solvent for dissolving the compounds;hence, all solvent bound analyses were carried out in DMSO. The IR spectra showed that the amino acids acted as bidentate ligands with coordination involving the carboxyl oxygen and the nitrogen of the amino group. Electronic spectra and magnetic susceptibility measurements suggested a square planar geometry for Cu(II), tetrahedral for both Zn(II) and Ni(II) complexes, and octahedral for those of Co(II). Magnetic susceptibility studies also revealed that the complexes of Cu, Co and Ni are paramagnetic while those of Zn are diamagnetic. The result also suggested L-methionine and L-leucine to be weak field ligands as they formed high spin complexes with Co(II) ion ([CoL] = 6.0 BM, [CoL1] = 5.10 BM) and tetrahedral complexes with Ni(II) ion.Gravimetric analyses showed that the complexes of Cu, Co and Zn contain one mole of water of crystallization while those of Ni contain two moles.Powder XRD studies suggested that the amino acid complexes are crystalline in nature and that they possibly crystallized in monoclinic fashion. The agar diffusion antimicrobial studies revealed that the amino acids are biologically active with their metal complexes showing significantly enhanced activity against the studied microbial strains in comparison to the free ligands.
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A DISSERTATONSUBMITTED TO THE SCHOOL OF POSTGRADUATE STUDIES, AHMADU BELLO UNIVERSITY, ZARIA
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD
OF MASTER OF SCIENCE DEGREE IN INORGANIC CHEMISTRY
Keywords
SYNTHESIS,, CHARACTERIZATION,, EVALUATION,, BIOLOGICAL ACTIVITY,, METAL,, COMPLEXES,, L-METHIONINE,, L-LEUCINE