Stability constants of the ternary complexes formed between vanadium(III)-salicylic acid and amino acids

In this work, the ternary complex formation between vanadium(III), salicylic acid (H(2)Sal) as primary ligand and the amino acids glycine, alpha-alanine, beta-alanine, proline, serine, threonine, methionine and phenylalanine (HL) as secondary ligands, in aqueous solution at 25 degrees C using 3.0 mol.dm(-3) KCl as the ionic medium was studied. The analysis of the potentiometric data using the least squares computational program LETAGROP indicates the formation of the species [V(Sal)(HL)](+), V(Sal)(L), [V(Sal)(L)(OH)(-), [V(Sal)(L)(OH)(2)](2-), [V(Sal)(2)(L)](2-) and [V(Sal)(2)(L)(OH)](3-) in the ternary V(III)-H(2)Sal-amino acid (HL) systems studied. The values of Delta log K '' for ternary systems involving amino acids have been evaluated and discussed. The species distribution diagrams as a function of pH were briefly discussed. (C) 2015 Elsevier B.V. All rights reserved.