Potentiometric Studies of Nickel (II), Copper (II) and Cobalt (II) Binary Complexes with Glycine Amino Acid in Aqueous Solution

摘要

The complexation equilibria of glycine with some transition metal ions such as Cu~(2+), Co~(2+) and Ni~(2+) were studied by potentiometric method in aqueous solution. All of the titration steps were carried out at 25.0±0.1°C and ionic strength (μ) of 0.1 M supported by NaNO_3. The overall stability constants logβ's of respective species were evaluated by computer refinement of the corresponding potentiometric pH titration data using BEST computer program. The corresponding distribution diagrams were depicted as a function of pH by using SP and SPE programs. The most likely species were obtained from distribution diagrams. Complex stabilities follow the trend copper(II)>nickel(II)>cobalt(II) which is in agreement with the Irving-Williams series.