Abstract
The protonation constants of monoxime HL1 and dioxime H2L2, derived from 1-(o-hydroxybenzoyl) propane-1,2-dione were determined by pH-metric method. The stability constants of their complexes with a series of lanthanide metal ions increase in the order of Gd(III) < Nd(III) < Dy(III) < Sm(III) < Tb = Er(III) < La(III) < Eu(III) at M:L ratio of 1:3 at different temperatures (20, 30, and 40 degrees C) and constant ionic strength in dioxin-water mixtures (25-75% v/v). The thermodynamic parameters were determined and indicated that the ligand dissociation and complex formation reactions were exothermic.