Abstract
Binary and ternary complex formation equilibria of M(II) with SAH-hydrazone ligand (2-((2-phthalazin-1-yl)hydrazono)methyl)phenol) in presence of phenylalanine (Phe) as a representative example of amino acids have been studied using the pH-metric titrations. The pH-titrations of the reaction mixtures have been shown 1:1:1 (M: SAH: Phe) ternary complex formation. The stability constants and stoichiometries of the formed binary and ternary complexes have been calculated at I = 0.1mol dm(-3) NaCl in 60% (v/v) DMSO-water solution. The stability order of complexes with reference to the metal ions has been followed this order Cu(II) > Ni(II) > Co(II) > Mn(II) in concord with the Irving-Williams stability order. The stability of mixed-ligand complexes was quantitatively matched with the stability of the binary complexes with reference to Delta log(10)K, Delta log(10)beta and log(10)X parameters. The speciation of different species in solution has been evaluated as a function of pH. Additionally, the effect of temperature on protonation of ligands and formation of mixed-ligand complexes (M-SAH-Phe) was investigated. The thermodynamics were calculated and discussed