Potentiometric studies of mixed complexes of Cobalt(II) and Copper(II) with L-asparagine and adenine

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Demir H. D., Pekin M., Cücü A., Dölen E., Aboul-Enein H. Y.

Toxicological and Environmental Chemistry, vol.71, no.3-4, pp.357-367, 1999 (Scopus) identifier

  • Publication Type: Article / Article
  • Volume: 71 Issue: 3-4
  • Publication Date: 1999
  • Doi Number: 10.1080/02772249909358806
  • Journal Name: Toxicological and Environmental Chemistry
  • Journal Indexes: Scopus
  • Page Numbers: pp.357-367
  • Keywords: Adenin, Cobalt(II) and Copper(II) complexes, L-asparagine, Mixed complexes, Stability constants
  • Marmara University Affiliated: Yes

Abstract

A potentiometric titration technique has been used to determine the stability constants for the various complexes of Co(II) and Cu(II) with L-asparagine and from DNA base, e.g. adenine. Stability constants of ternary systems have been evaluated by the method suggested by Irwing-Rossotti. In addition, the conditional constants were calculated as a function of pH. The maximum values of the conditional formation constants were found to be in accordance with the mixed-ligand complex formation constants in a determined pH region. Furthermore, the molar fractions of different species from mixed complexes were calculated by means of formation constants. The values of stability constants of mixed-ligand complexes at 25°C are as follows: log K = 5.25 for Co(II)-L-asparagine-adenine; log K = 9.30 for Cu(II)-L-asparagine-adenine. The ionic strength was kept constant at I = 0.20 with NaClO4.