Determination of stability constants and thermodynamic parameters of some metal complexes with 2-hydroxynaphthalene-1-carbaldehydene-1-naphthylamine

The thermodynamic parameters of complexes of Cu(II), Ni(II), and Zn(II) cations with hydroxynaphthalene-1-carbaldehydene-1-naphthylamine were determined in 60% (v/v) DMF-water, at various ionic strengths (0.07, 0.13, 0.2 M NaNO3), and at different temperatures (25, 30, 35, 40 +/- 0.1 degrees C) using a spectrophotometric method. A sodium nitrate solution was used to maintain the ionic strengths. The stability constants show an inverse relationship with the ionic strengths. The thermodynamic parameters (60% (v/v) DMF-water (Delta G(0), Delta H-0, Delta S-0)) based on these formation constants were determined. The acid dissociation constant of the ligand was investigated in 60% (v/v) DMF-water and was also calculated at different temperatures.