TURKISH JOURNAL OF PHARMACEUTICAL SCIENCES, cilt.11, ss.33-44, 2014 (Scopus)
In this study, a potentiometric titration technique has been used to determine stability constants for
the various complexes of Zn(II), Co(II), Cd(II) and Mn(II) with creatinine and two amino acids. Stability
constants of ternary systems have been evaluated by the method suggested by Irving-Rossotti at 25°C and
0.11M ionic strength (kept constant with NaC104) in aqueous solution. 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 were calculated
as follows: logK=3.20 for Zn(II)-L-cysteine-creatinine,logK1=4.24 and logK2=3.58 for Co(II)-L-cysteinecreatinine2,
logK=3.22 for Cd(II) - L-cysteine - creatinine, logK=3.65 for Mn(II) - L-cysteine - creatinine
and logK=5.34 for Co(II)-BDHL-cysteine-creatinine, logK=5.30 for Cd(II)-BDHL-cysteine-creatinine,
logK,=5.35 and logK =3.93 for Zn(II) - BDHL-cysteine - creatinine^, logK,=5.40 and logK =3.49 for
Mn(II) - BDHL-cysteine - creatinine,,