Abstract
Metal complexes of VO(IV), Zr(IV), Th(IV) and UO2(VI) with Schiff base ligands derived from 4-nitrobenzoylhydrazide with 2-hydroxy-5-methylacetophenone (H2L1) or 2-hydroxy-5-chloroacetophenone (H2L2) have been prepared. All the complexes have been characterized on the basis of elemental analyses, magnetic susceptibility measurement, electronic and IR spectra and thermogravimetric analysis. The IR spectral data suggested that the ligands behave as dibasic tridentate moiety towards the central metal ion coordinating through phenolic oxygen, enolic oxygen and azomethine nitrogen atoms. The elemental analyses show a 1:1 metal:ligand stoichiometry for all the complexes except Th(IV) which has 1:2 stoichiometry. The thermal analysis evidenced that thermal transformations of complexes are processes according to TG curves including dehydration, thermolysis and oxidative degradation of Schiff base. The final product of decomposition is the most stable metallic oxide. The kinetic analysis of the thermogravimetric data was performed by using the Coats-Redfern method. Solid state electrical conductivity of the complexes has been measured in their compressed pellet form over a 310-413 K temperature range. All the complexes show semiconducting behavior as their conductivity increases with increasing temperature and a function of ionic size. All the complexes along with ligands were also screened for their antibacterial and antifungal activities. KEY WORDS: Aroylhydrazones, Metal complexes, Biological activity, TGA, Electrical conductivity Bull. Chem. Soc. Ethiop. 2014, 28(2), 255-264.DOI: http://dx.doi.org/10.4314/bcse.v28i2.9
Highlights
Hydrazones constitute an important class of compounds with a wide spectrum of pharmacological properties
The acid hydrazides have gained importance due to their remarkable applications in the medicinal field. As these compounds are known to have good biological activities related to the coordination of bio-metals, the methyl hydrazones can be used in chelation therapy as they have potential binding sites which form stable complexes
The tendency of aroylhydrazones to give intensely coloured metal chelates allows their use as extraction reagents for the spectroscopic determination of several metal ions [3, 4]
Summary
Hydrazones constitute an important class of compounds with a wide spectrum of pharmacological properties. As these compounds are known to have good biological activities related to the coordination of bio-metals, the methyl hydrazones can be used in chelation therapy as they have potential binding sites which form stable complexes. Antibacterial and antifungal activities of the ligands and their complexes were tested against the bacteria E. coli, S. abony, P. aeruginosa, S. aureus and B. subtilis and fungi A. niger and C. albicans by the agar cup plate method [11].
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