Spectrophotometric study of binary and ternary systems involving metal ions and benzylidenepyruvates: Equilibria in aqueous solutions

Nenhuma Miniatura disponível

Data

1984-12-01

Autores

Melios, Cristo B. [UNESP]
Torres, Vera R. [UNESP]
Mota, Márcia H. A. [UNESP]
Tognolli, Joãeo O. [UNESP]
Molina, Manuel [UNESP]

Título da Revista

ISSN da Revista

Título de Volume

Editor

Resumo

The protonation of 4-dimethylaminobenzylidenepyruvate (DMBP) and 2-chloro-4-dimethylaminobenzylidenepyruvate (2-CI-DMBP) and their complex formation with Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Pb(II), Cd(II) and Al(III) have been studied by potentiometric and spectrophotometric methods at 25 °C and ionic strength 0.500 M, held with sodium perchlorate. The stability order found for 1 :1 complexes of both ligands is Al(III) > Cu(II) > Pb(II) > Ni(II) > Zn(II) > Co(II) > Cd(II) > Mn(II). The stability changes move in the same direction as the pKa of the ligands. The results are compared with literature values reported for metal ion pyruvate systems. Thermodynamic stabilities of ternary complexes formed in Cu(II)-B-L- systems, where B = 2,2′-bipyridyl (bipy), ethylenediamine or glycinate and L = DMBP or 2-CI-DMBP, were also determined. The Cu(bipy)L+ species are more stable than would be expected on purely statistical grounds. The importance of the :t system associated with bipy on the enhanced stability of its mixed ligand complexes is stressed. Analytical applications of the investigated ligands are outlined.

Descrição

Palavras-chave

Benzylidenepyruvates, Binary and ternary metal ion complexes, Equilibria, Spectrophotometry

Como citar

The Analyst, v. 109, n. 3, p. 385-389, 1984.