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 (H2L 1 ) or 2-hydroxy-5-chloroacetophenone (H2L 2 ) 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.

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New complexes of the Ti(III), Cr(III), Mn(III) and Fe(III) with hydrazones, derived from the condensation of 4-nitrobenzoylhydrazide with either 2-hydroxy-5-chloroacetophenone or 2-hydroxy-5-methylacetophenone, have been synthesized and characterized by elemental analyses, magnetic moment, electronic and infrared spectra and thermogravimetric analysis. Both ligands coordinated with metal ions in a tridentate dinegative fashion through their deprotonated phenolic-0, deprotonated enolic-O and imine nitrogen atoms. The thermal decomposition of ligands and complexes has been studied using non-isothermal thermogravimetry. Kinetic parameters such as activation energy, frequency factor, free energy change and entropy change of decomposition of complexes have been determined by employing the methods of Coats-Redfern and Horowitz-Metzger. The antibacterial and antifungal activities of the ligands and their complexes have been assessed by screening the compounds against £. coli, S. abong, S. aureus, P. arugineosa, B. subtilis, A. niger and C. albicans respectively. The measurements of the electrical conductivity of ligands and their metal complexes were carried out in the temperature range 308 -410 K in their compressed pellet form .The electrical activation energy values of the complexes were calculated from Arrhenius plots and lie in the range 0.368-0.759 eV. The complexes show a low value of conductance at room temperature; however their conductivities 225 Brought to you by | Western University Authenticated Download Date | 6/8/15 9:48 AM Vol. 29, No. 4, 2009 Synthesis and Characterization of Ti(III), Cr(lII), Mn(lll) increase as the temperature increases above 335K, indicating their semiconducting behaviour.

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