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Abstract
The present work comprises a study of the kinetics and mechanism of oxidation of ternary cobalt (II) complexes involving nitrilotriacetato cobalt (II ) and three different amino acids ( valin, glutamic, aspartic acid ) by periodate and their antitumour efficacies against hepatoma cell line.
1- Chapter ( I ) : Introduction.
The introduction contains electron transfer, outer–sphere and inner-sphere mechanism which have been discussed. The nature, properties and biological activity of cobalt (II) and its complexes have been briefly discussed. The nature, properties, chemical behavior and different species in aqueous solutions of periodate have been reported. The literature concerning the oxidation of organic and inorganic compound in aqueous solutions and in aqueous organic solvents by periodate are mentioned. The nature, properties and biological important of amino acids and NTA and their metal complexes have been briefly discussed.
2-Chapter ( II ) : Experimental.
Chemicals, preparation of metal complexes, the experimental procedures and the technique for the kinetic studies and methods for the data were determined
3- Chapter ( III ) : Results and discussion.
This part includes the layout of the results obtained and their discussions. The effect of various parameters on the rate of reaction has been discussed. This chapter contains three parts:
Part( I ) :
The kinetics of oxidation of [CoII(NTA)(Asp)(H2O) -3] by periodate in aqueous solutions have been studied . The rate of the reaction increases with the increasing of (periodate concentration,1/ H+, temperature, ionic strength, catalysts).. This reaction is firest order respected to complex concentration. The oxidation of this complex obeys the following rate law in absence of catalyst
Rate = [CoII NTA Asp(H2O)3-] [ H4IO6-]{ k4 K6 +(k5K7K5 / [H+]) }
rate law in presence of MnII catalyst
Rat={k3 [ Mn +3] + k4 K2 [IVI]}[CoII NTA Asp(H2O)] 3-])
The enthalpy of activation (∆H*) and entropy of activation (∆S*) were calculated, and it was proved that the electron transfer proceeds through an inner-sphere path way by replacement of coordination H2O in the complex species, by IO4-
The study of the antitumour activity of this complex comparing by NTA and Co-NTA was also determined.
Part( II ) :
In aqueous solutions, the kinetics of oxidation of [CoII(NTA)(Glue)(H2O)3-] by periodate have been studied . The rate of the reaction was found to be increased with the increase of the ionic strength, 1/H+, temperature ,periodate concentration and catalysts. The rate of reaction is firest order with respect to complex concentration. The mechanism proceeds via an inner-sphere pathway The oxidation of this complex obeys the following rate law in absence of catalyst
Rate = [CoII NTA Glue (H2O)3-] [H4IO6- ]{ k4 K6 +(k5K7K5 / [H+])
rate law in presence of MnII catalyst
Rat={ [CoII NTA Glue (H2O)] 3- {k3 [ Mn +3] + k5 K2 [IVI]}
The activation parameters ∆H* and ∆S* for these reaction have been also calculated using the transition state theory equation (Eyring Equation).
Part( III ) :
The kinetics of oxidation of [CoII(NTA)(Val)(H2O)2-2] by periodate have been studied in aqueous solutions. The reaction rate was increased with the increase of pH, complex concentration, ionic strength, periodate concentration, temperature, catalysts. This reaction is first order respected to complex concentration. The mechanism of oxidation of this complex was passed through the inner-sphere mechanism.
rate law in absence of catalyst
d[CoIII]/dt=[CoII(NTA)Val(H2O)2]2-] [H4IO6 –] { K1k3 + K2k4K4/[H+] }
rate law in presence of MnII catalyst
rate=[CoII(NTA)Val (H2O)2]2- ][ k2[Mn +3] + k3 K2 [ IVI]] The enthalpy of activation (∆H*) and entropy of activation (∆S*) were calculated.
This complex showed potent antitumour activity against HepG2 cell line compared to NTA and Co-NTA