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Abstract Since the 50s of last century, many thiosemicarbazides have provoked wide interest for their significant biological and pharmaceutical activities, such as antibacterial, antiviral, antimalarial, antileprotic and antineoplastic as well as anticancer activity. The current interest in thiosemicarbazides is due to the presence of various donor atoms (O, N and S-donors), which exhibit diverse bonding modes leading to different structural motifs. The main aim of the present thesis is focused on the preparation and characterization, elemental analyses, thermal (TGA and DTGA), spectral (IR, UV-Visible, EI-mass, NMR and ESR), XRD and magnetic measurements of new complexes of (Z)-N-benzoyl-N’-(1H-1,2,4-triazol-3-yl)carbamimidothioic acid (H2L1) and N-(benzo[d]thiazol-2-ylcarbamothioyl)benzamide (H2L2) with Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Hg(II) and U(VI)O2 2+ metal ions. Also, molecular computational calculation and biological activity studies were carried out. A brief description of the overall work in this thesis can be summarized as follow: Chapter one displays different publications concerning the complexation of thiosemicarbazides with a great attention to the compounds similar to that investigated and their biological activities. The second chapter covers the experimental part and illustrates the experiments used in this work. It includes a list of reagents, stock solutions along with the physical measurements and instrumentation, as well as the working procedures and a description for the preparation of ligands and its metal complexes. In addition, this chapter includes the -282- Summary recommended procedures for the antioxidant, antitumor and the anti-microbial activity of the prepared metal complexes. Chapter three deals with the results and discussion which are summarized to give the following information: 1- The proposed chemical formulae of the ligands and their metal complexes are in good agreement with the stoichiometries concluded from their analytical data of carbon, hydrogen, nitrogen, chloride and metal contents. 2- Most of complexes have high melting points (>300˚C) and insoluble in most organic solvents. 3- The coordination sites of the ligand, the nature of metalligand bonds and the nature of the acetate groups and the existence of the solvated molecules have been elucidated using IR spectra. Different modes of chelation for the investigated ligands are suggested based on careful comparison between the spectra of the ligands and their corresponding complexes. The data obtained are summarized as: H2L1 acts as: i. NN neutral bidentate via (C=N)* and (C=N) of hetero ring moiety in Cr(III) and Co(II) complexes. ii. NO uni-negative bidentate via the enolized (C-O) with deprotonation and (C=N) in the complexes of Cu(II) and Fe(III) chlorides in addition to complexes of Zn(II) and UO2 2+ acetate. iii. OS mono-negative bidentate in Cd(II) and Hg(II) complexes via (C=O) and the deprotonated thiol groups. iv. NOS mono-negative tridentate via the deprotonated -SH, (C=O) and (C=N) ring groups in Zn(II) chloride complex. v. Binegative tridentate and tetradentate in Mn(II) and the binuclear Ni(II) complexes, respectively. H2L2 acts as: -283- Summary i. NSO neutral tridentate in Cu(II) complex. ii. NSO mononegative tridentate in Co(II) complex. iii.NSO binegative tridentate in Fe(III) complex. iv. OS mononegative bidentate in Mn(II) complex. v. NO mononegative bidentate in Ni(II), Cr(III) and Zn(II) complexes. vi. NS mononegative bidentate in Cd(II) and Hg(II) complexes. 4- The 1H NMR spectra of the diamagnetic Zn(II), Cd(II) and Hg(II) complexes of H2L2 are used to detect the potential coordination sites. 5- The geometries are suggested of the prepared complexes based on the data evaluated from spectral and magnetic measurements; [Zn(HL1)(OAc)(H2O)], [Cd(HL1)Cl(H2O)], [Hg(HL1)Cl(H2O)], [Zn(HL1)Cl].0.5H2O, [Cd(HL2)Cl(H2O)], [Hg(HL2)Cl(H2O)] and [Zn(HL2)2].2H2O are quite near to a tetrahedral geometry predicting sp3 hybridization. On the other hand, [Ni2(HL1)Cl2(H2O)2].4H2O complex showed mixed geometries (tetrahedral and square planar) with sp3 and dsp2 hybridization. On the other hand, all other complexes afforded an octahedral geometry with d 2 sp3 or sp3 d 2 hybridization. 6- The geometries of both Cu(II) complexes were elucidated using ESR spectra confirming an octahedral geometry for both complexes 7- Good information about the geometry and crystal lattice system, lattice parameters for Co(II) and Ni(II) complexes using the powder X-ray diffraction pattern confirming the proposed geometry for complexes. 8- Detailed thermal analysis for the prepared complexes was performed in the temperature range 20-800 ˚C. The thermograms show the decomposition steps after which a -284- Summary constant weight is observed corresponding to the remaining part of the complex. 9- In order to assess the influence of the structural properties of the ligands and the type of the metal on thermal behaviour of the complexes, the order (n) and the heat of activation (Ea) of the various decomposition stages are determined from the TGA and DTGA using HorowitzMetzger and Coats-Redfern methods. This section includes also the determination of the thermodynamic parameters of activation (ΔH* , ΔS* and ΔG* ) which can be calculated by Erying equation. 10-The final part in this chapter deals with the antimicrobial activity, antitumor and antioxidant activity for both ligands and their metal complexes. |