Synthesis, characterization, biological and electrical conductivity studies of some Schiff base metal complexes
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.