Abstract
The binary and ternary complex systems of Fe(III), Pb(II), Co(II), Al(III), La(III), Sr(II), Cr(III), Ti(II), Zr(IV) and Th(IV) with sulfathiazole (as the primary ligand) and the amino acid glycine (as the secondary ligand) have been assessed potentiometrically at a temperature of 25.0 +/- 0.1 degrees C and a concentration of 0.1 M NaClO4 in a 25% (v/v) ethanol-water solution. To investigate the effect of the secondary ligand on the formation of 1:1 M: Sulfathiazole, the stoichiometries and stability constants of binary complexes consisting of the above metal ions in a 1:1, 1:2 and/or 1:3 ratio were assessed. The protonation constants of the complexes were measured for the m M: Sulfathiazole: Glycine system at a 1:1:1 ratio. In the case of Al(III) and Th(IV), glycine as a secondary ligand prefers to bind with a [M-Sulfathiazole] binary complex rather than to the metal ion complex in an aqueous solution. In all cases, the stability order of the binary (M: Sulfathiazole) and ternary (M: Sulfathiazole: Glycine) complexes was examined.