الفهرس 
Chapter 1: IntroductionOnly 14 pages are availabe for public view
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Abstract
The present work is concerned with synthesis and characterization of two new ternary copper(II), complexes with the mixed ligand system of LL′ in which L is 1,1′,4,4′- tetra methyl ethylenediamine (Me4en) and L′ is the ethylene diamine tetra acetic acid for complex 1 and N-methyl iminodiacetic in the case of complex 2.
The thesis consists of three chapters in addition to the references, summary and Arabic summary sections. The first chapter embraces an introduction on the natural phenolic compounds and their biological significance. Also it reports the literature survey on the previous works of the current area of study. As well 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 copper(II), complexes. It also presents the different chemicals, experimental tools and equipments used for preparation of this work. In addition kinetic experiments details, spectroscopic and several physicochemical techniques are described.
The third chapter comprises the results and discussion and consists of four sections as follows:
Section number one describes the synthesis and characterization of the new ternary copper(II) complexes 1 and 2. Structural characterization of the pure isolated complex species was achieved by several physicochemical methods, namely elemental analysis, electronic spectra, IR, ESR, molar conductivity, cyclic voltammetry and magnetic moment measurements. X-ray powder diffraction (PXRD) technique was employed to determine the full structure
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of complex 1. Further the structural formulation of complex 2 was confirmed by X-ray structural analysis for a single crystal.
Section number two reports the bio-mimicking of the native copper-oxidase enzymes namely catechol oxidase and phenoxazinone synthase of the present copper(II) chelates. The studied phenols include catechol, 4-methyl catechol, 4-nitro catechol, 3,5-di-tert-butyl- catechol and o-amino phenol. Spectrophotometric technique was used for study the current oxides mimicking catalytic activity of the inspected copper(II) complexes. When the studied catalytic reactions continued for 24 hour the spectral monitoring shows the formation of a sole product i. e. 3,5-DTBQ and APX. This finding excluded further oxidative cleavage of 3,5-DTBQ and confirms a single pathway oxidation reaction. The obtained results showed that the amount of the oxidation products in the absence of the catalyst can be neglected when compared to that produced in the presence of the catalyst. Electrochemical studies were carried out to check the correlation between the structural features of the studied complexes and their catechol oxidase and phenoxazinone synthase mimetic activity.
The detailed kinetic study educated us a lot about how the current catalytic systems work. For this purpose we adopted Michaelis – Menten model for the enzyme kinetic which is the more convenient model. In this case one assumes that the following steps are involved in the studied catalytic reaction: the reversible formation of catalyst – substrate intermediate, followed by its conversion to the product. These assumptions find support from the kinetic trace obtained by the stopped-flow spectrophotometry monitored at 400 nm for the reaction of the current complexes with the studied catechols and representative plots are given. As well similar spectral profiles at 433 nm during the catalytic oxidative
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dimerization reaction of the related substrate o-APH3 are described. The present stopped follow kinetic studies demonstrate that, the binding of catecholate anion e.g. 3,5-DTBC2- or o-APH2¯ to copper(II) center is the initial step of the catalytic oxidation reactions. In this situation the pathway of electrons transfer is undoubtedly donor – acceptor interactions which proceed via the inner-sphere mechanism.
The obtained results demonstrated that, there is a correlation between the structural properties of the prepared copper(II) complexes and the oxidase biomimetic catalytic activities. Also the catalytic studies demonstrated that the reported copper(II) complexes are suitable and efficient catalysts for the aerobic oxidation of the studied phenols. Electrochemical data for the present copper(II) complexes revealed a non-linear relationship between the complexes ability to oxidize the studied substrates and their redox potentials. from the obtained results, it is also found that the catalytic activity of the investigated copper(II) complexes towards the oxidation of o-aminophenol is lower than that of catechols oxidation. On the basis of the kinetic data plausible mechanistic path ways were proposed by assuming ternary complex formation between the catalyst, the substrate and the molecular oxygen, in which the latter one is the rate-determining step.