الفهرس 
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Abstract
The present work is concerned with synthesis and characterization of new series of copper(II), with macrocyclic ligands L1 and L2 having N3S2 donating atoms in the 12-membered macrocyclic ring. As well as, copper(II) complex of the pentadentate pyridine based ligand (L1) containing two thiolate sulfur, pyridine nitrogen and two azomethines nitrogen, in addition to a series of tetradentate ligands (L2, L3 and L4) containing two thiolate sulfur, and two azomethine nitrogens have been synthesized.
The thesis consists of three chapters in addition to the references, summary and arabic summary sections. The first chapter embraces an introduction on the nature and importance of the employed ligands for synthesis the present copper(II) complexes. Also, it reports the literature survey on the previous studies of analogous ligand systems and their copper(II) complexes. As well as a literature survey on the catechol oxidase and phenoxazinone synthase functional models is reported.
The second chapter is the experimental part which describes the different methods for preparation of the newly synthesized dicarbonyl compound (2,6-pyridine dicarbaldehyde) and the different copper(II), complexes derived from them. It also presents the different chemicals, experimental tools and equipments used for preparation of this work.
The third chapter comprises the result and discussion and consists of four sections as follows:
Section number one describes the synthesis and characterization of a new series of macrocyclic copper(II) complexes 1-10. The synthesis reaction was proceed by treating ethanolic solution of copper(II) salt CuX2 (X = Cl¯, Br¯, NO3¯, CH3COO¯ or ClO4¯) with the Schiff-bases which were formed in situ by the condensation of 2,6-pyridine dicarbaldehyde or 2,6-pyridine biacetyl and the reported diamine, bis-(2-aminophenylthio)ethane, in the molar ratio 1:1:1 at room temperature. This template condensation reaction affords a new series of mononuclear macrocycle [1 + 1] copper(II) complexes with pentadentate Schiff-base ligands containing N3S2 donors. Structural characterization of the pure isolated complex species was achieved by several physicochemical methods, namely elemental analysis, electronic spectra, IR, ESR, molar conductivity, thermal analysis (TAG & DTG), and magnetic moment measurements. The stereochemistry, the nature of the copper(II) chelates, and the catalytic reactivity are markedly dependent upon the type of counter anions and the ligand substituents within the carbonyl moiety of penta dentate in suit synthesis macrocyclic ligands L1 and L2 having N3S2 donating atoms in the 12-membered macrocyclic ring.
Section number two reports the bio-mimicking of copper-oxidase enzymes namely catechol oxidase and phenoxazinone synthase of the investigated copper(II) macrocyclic chelates. The obtained results demonstrated that, there is a correlation between the structural properties of these copper(II) complexes and their oxidase biomimetic catalytic activities. Catalytic studies demonstrate that the reported copper(II) complexes are suitable as catalysts for the catalytic aerobic oxidation of 3,5-di-tert-butylcatechol (3,5-DTBCH2) to 3,5-di-tert-butyl-benzoquinone (3,5-DTBQ) (catechol oxidase activity), and o-aminophenol (OAPH) to 2-aminophenoxazine-3-one (APX) (phenoxazinone synthase activity) with dioxygen at ambient condition in good yields. Kinetic measurements revealed second-order dependence on the catalyst concentration for 3,5-DTBCH2 and first order in the case of OAPH. On the other hand for the substrate concentration dependence, a saturation type behavior was detected for both 3,5-DTBCH2 and OAPH. Addition of Lewis base, triethylamine, in both systems exhibits dramatic effect on the rate of these catalytic aerobic oxidation reactions. The probable mechanistic implications of both catalytic systems are discussed.
Section number three describes the synthesis and characterization of copper(II) complexes of the pentadentate pyridine based ligand (L1) containing two thiolate sulfur, pyridine nitrogen and two azomethines nitrogen, in addition to a series of tetradentate ligands (L2, L3 and L4) containing two thiolate sulfur, and two azomethine nitrogens. The pure isolated complexes have been characterized by elemental analyses; molar conductance, magnetic susceptibility measurements, FT-IR, UV–Vis and ESR spectroscopy and their structures have been confirmed by thermal analysis (TGA and DTG) investigations. The pyridine based Schiff base (L1) acts as dibasic N3S2 chelating ligand coordinating to copper(II) center and the coordination geometry around copper(II) center of [CuL1H2O] (1) is a distorted octahedron. The five coordinated copper(II) complexes [CuLnH2O] of the dibasic tetradentate ligands L2, L3 and L3 having the coordination chromophore N2S2O exhibit structural features similarity. The coordination geometries around copper(II) centers in (2), (3) and (4) are described as square pyramidal stereochemistry based upon the EPR and crystal filed spectral results. The electrochemical properties behaviors of the chelates have been studied by cyclic voltammetry technique.
Section number three reports also the oxidase biomimetic catalytic activity of the newly synthesized title copper(II) complexes 1-4 under study towards the aerobic oxidation of 3,5-di-tert-butylcatechol (3,5-DTBCH2) and o-aminophenol under catalytic conditions. Oxidative coupling of 2-aminophenol (OAPH) to 2-aminophenoxazine-3-one (APX) (phenoxazinone synthase activity) and the aerobic oxidation of 3,5-di-tert-butylcatechol (3,5-DTBCH2) to the light absorbing 3,5-di-tert-butyl-benzoquinone (3,5-DTBQ) (catechol oxidase activity), catalyzed by the title copper(II) complexes were studied. The rate constants of the above oxidation reactions showed linear dependence on catalyst concentration and saturation kinetics with respect to the corresponding substrate. Electrochemical data revealed a non-linear relationship between the complexes ability to oxidize the studied substrates (OAPH and 3,5-DTBCH2) and their redox potentials. Also, the present catalytic investigations demonstrated that the geometrical effects are only one facet of the complexes activity. Addition of Lewis base, triethylamine, in both systems exhibits dramatic effect on the rate of these catalytic aerobic oxidation reactions. The probable mechanistic implications of both catalytic systems are discussed.