Speciation study of nickel(II)-1,10-phenanthroline-amino acid ternary complexes in 1.0 M NaCl at 25 °C

Abstract

Ternary Ni(II) complexes formed with 1,10-phenanthroline (Phen) and the amino acids glycine (Gly, HL), α-alanine (Ala, HL), β-alanine (βAla, HL), proline (Pro, HL), phenylalanine (Phe, HL), methionine (Met, HL), serine (Ser, HL) and threonine (Thr, HL) were studied in aqueous solution using 1.0 M NaCl at 25 °C as an ionic medium. The systems were studied by potentiometric measurements. Analysis of the potentiometric data was done with the least-squares-based program LETAGROP, supporting the formation of species Ni(Phen)(HL)2+, Ni(Phen)(L)+, Ni(Phen)(L)(OH), Ni(Phen)2(L)+ and Ni(Phen)(L)2. Species distribution diagrams were generated and the relative stabilities were analyzed using Δ log10 K, log10 X and % RS values.