FORMATION CONSTANTS IN THE TERNARY SYSTEMS Co(II)- L-CYSTEINE-ADENINE and Zn(II)-L-CYSTEINE-ADENINE2

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Cücü A., Pekin M., Demircan Demir H.

MAIN GROUP METAL CHEMISTRY, vol.23, no.12, pp.781-787, 2000 (SCI-Expanded)

  • Publication Type: Article / Article
  • Volume: 23 Issue: 12
  • Publication Date: 2000
  • Doi Number: 10.1515/mgmc.2000.23.12.781
  • Journal Name: MAIN GROUP METAL CHEMISTRY
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.781-787
  • Marmara University Affiliated: Yes

Abstract

In the present note, a Potentiometrie titration technique has been used to determine stability constants for the

various complexes of Co(II) and Zn(II) with L-cysteine and from DNA bases i.e. 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 given pH

region. In addition, the mole 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:

logK=9.50 for Co(II)-L-cysteine-adenine; logK,=6.85 and logK,=6.00 for Zn(II)-L-cysteine-adenine2. The

ionic strength was kept constant at 1=0.20 with NaCl04.