Dioxouranium(VI) mixed ligand complexes containing 8-hydroxyquinoline and some amino acids

The formation equilibria of binary and ternary complexes of UO2(VI) with 8-hydroxyquinoline (HL) and some amino acids (HL) in 40% EtOH-H2O solution have been investigated by a potentiometric technique. The stepwise formation constants of the complexes formed in solution were calculated using the non-linear, least-squares computer program MINIQUAD. The concentration distribution of the complex species was resolved. Mixed ligand complexes of the general formula [UO2LL'-(H2O)(n)](NO3)(m), where HL = 8-hydroxyquinoline; HL' = glycine, alanine, L-valine, proline, leucine, beta-phenylalanine and H2L' = histidine or histamine, n = 0 or 2 and m = 0 or 1, have been synthesised and characterized by elemental analyses, electrolytic conductance, electronic spectra, IR, H-1 NMR spectra and thermogravemetric studies. The uranium atom in these complexes is 6- or 8-coordinate. Both HL and HL' are bidentate, bonding through N or O atoms (phenolate or ionized COO- groups).