Abstract

F.  I.  El-Dossoki1, M. S. Refat1 and I. Grabchev2

Potentiometric studies on azomethine substituted benzanthrone dyes (derivatives of 3-amino benzanthrone containing electron donating groups in ortho or/and para position of the benzene nucleus) [BA1 = o-hydroxy benzaldehyde; BA2 = p-hydroxy benzaldehyde] and its complexes with Ni(II), Cu(II), Zn(II), Cd(II), UO2(II), La(III) and Zr(IV) have been carried out in different ionic strengths (0.05, 0.10 and 0.15 molar KCl), at different temperatures (298, 303, 308 and 313 K) and in ethanol-water media of varying compositions (50% and 80% V/V). The ionization constants of the two ligands and the stability constants of its complexes with the mentioned cations were investigated and discussed. The thermodynamic parameters (DG, DH and DS) were calculated and studied. The ionization constants were found to be increased as the ionic strength and the temperature increased while the stability constants of the complexes increased as the ionic strength and the temperature increased. Also the conductometric titrations have been made to characterize the composition of the stoichiometric complexes formed between the investigated ligands and metal cations. The conductometric results show that the ratio of the metal-ligand are 1:1 and 1:2 which quite agree with the results of potentiometric studies.

3-azomethine; Benzathrone dyes

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