Determination of stability constants at 25C for the interaction in aqueous solution of serine with Co (II), Ni (II), Cd (II), Zn (II), and Cu (II) ions
Values of thermodynamic stability constants at 25°C for the complexes of serine with the metal ions. Co^2+, Ni^2+, Cd^2+, Zn^2+, and Cu^2+ were obtained from pH titration data. All measurements were made in aqueous solution, and data were obtained at three different ionic strengths for each metal ion studied. It was assumed that the activity of the zwitterion is unity. The effect of metal ion hydrolysis upon the log K values was taken into account for the calculations. For all the metal ions studied, stability constants for MA^+, MA_2, and MA_3^- were reported with the exception of copper (II) which formed only MA^+ and MA_2 complexes. The stabilities of the complexes studied follow the sequence: Cd^2+ < Co^2+ < Zn^2+ < Ni^2+ < Cu^2+. The value of log K for each step of metal serine interaction, in all cases, increases in the order. K_3 < K_2 < K_1. Under the conditions studied, it was assumed that the metal ion coordinates through the amino nitrogen and the carboxyl oxygen of the serine only. There was no evidence that the hydroxyl group of serine took part in coordination with the metal ions. All calculations of stability constants were carried out using an IBM 7040 computer.
College and Department
Chemistry and Biochemistry
BYU ScholarsArchive Citation
Ma, Liak Hwe, "Determination of stability constants at 25C for the interaction in aqueous solution of serine with Co (II), Ni (II), Cd (II), Zn (II), and Cu (II) ions" (1968). Theses and Dissertations. 8302.
Serine, Thermochemistry, Chemical equilibrium