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Portugaliae Electrochimica Acta
versão impressa ISSN 0872-1904
Port. Electrochim. Acta v.27 n.2 Coimbra 2009
Potentiometric and Spectroscopic Studies of Sulfonamide Azo-Dye Complexes with some Transition Metal Ions and Uranium
E.H. El-Mossalamy*
Chemistry Department, Faculty of Science, King Abdul Aziz University, Jeddah-Saudi Arabia
Received 1 October 2008; accepted 9 March 2009
Abstract
Molecular structure of the azo-dye derived from sulfonamide was synthesized. The elucidation of ligand and complex structures were studied by electronic, infrared and 1H NMR spectroscopies.Proton-ligand constants of sulphonamid azo-derivatives and the stability constant of Mo (III), VO (II), UO2 (II) and Co (II) metal ions with sulfonamide azodye derivatives have been determined potentiometrically in 0.1 M KCl and 30% (v/v) ethanol-water mixture. The data are discussed in terms of the electronic character of the substituents and of the change in temperature. The pK1-H values have been found to increase with increasing electron donating nature of the subsituents. The evaluated dissociation processes are non spontaneous, endothermic and entropically unfavourable. The order of the stability constants of the formed complexes was found to be Mo3+ > VO2+ > UO22+ > Co2+. The influence of substituents on the stability of the complexes was examined on the basis of an electron repelling property of the substituent. The effect of temperature on the stability of the formed complexes was studied and the corresponding thermodynamic parameters (DG, DH and DS) were evaluated and discussed. The stoichiometries of these complexes were determined conductometrically and indicated the formation of 1:1 and 1:2 (metal:ligand) complexes.
Keywords: sulfonamide azo-dyes, potentiometric, conductometic, complexation and thermodynamics.
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* Corresponding author. E-mail address: mina_elmosalamy96@hotmail.com
Permanent address: Chemistry Department, Faculty of Science, Benha University, Benha, Egypt