Novel 8-hydroxyquinoline substituted open chain dioxotetraamine and its metal complexes: Synthesis and property studies in aqueous solution

A novel 8-hydroxyquinoline substituted dioxotetraamine (L) has been designe d, synthesized and fully characterized. At 25 degreesC and l=0.1 mol . dm(- 3) NaNO3, the stepwise protonation equilibria of the ligand have been studi ed by potentiometric titrations and the stability constants have been deter mined. The binding ability of L to metal ions such as Cu(II), Co(II), Mn(II ) and Zn(II) has been investigated and the difference in stabilities betwee n metal ion complexes has been also discussed. The results show that 8-hydr oxyquinoline is a stronger donor group than the open chain dioxotetraamine and at molar ratio ligand: metal=1:1, the former is 100% chelated to metal ions while dioxotetraamine could only be partially coordinated.