Stability study of some complexes of sulphamethoxazole

The interaction of certain transition metal ions Cu [II], Zn [II], Ni [II], Co [II] and Mn [II] with sulphamethoxazole have been studied in 50% ethanol-water medium at 30 and different ionic strengths following Irving-Rossitti pH titration technique. The proton-ligand and metal-ligand formation constants [log K[H1] and log beta2] calculated, show the order of stability as [Cu [II] > [Zn [II] > Ni [II] > Co [II] > [Mn [II]. Thermodynamic parameters [delta G, delta H and delta S], calculated at 30 and 0.1 M [KC1] ionic strength