Ternary complexes of substituted catechols and dipeptides with copper(II)

Abstract

The formation constants of the ternary complexes [CuA(L)], where A refers to the monoanions of glycylglycine (A¹), glycyl-L-alanine (A²), or glycyl-L-leucine (A³) and L to the dianions of catechol (L¹), pyrogallol (L²), 4,5-dihydroxybenzene-1,3-disulphonic acid (L³), or naphthalene-2,3-diol (L⁴), were determined by potentiometric titration in a queous medium at 30°C and I= 0.2 mol dm^–3(NaClO₄) using the SCOGS computer program. The enhanced stability of the ternary complexes is attributed to possible hydrogen bonding between the two ligands through a water molecule.