24 research outputs found

    Towards a new attenuating compound: a potentiometric, spectrophotometric and NMR equilibrium study on Fe(III), Al(III) and a new tetradentate mixed bisphosphonate-hydroxypiridinonate ligand

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    Coordination properties toward Fe(III) and Al(III) of a mixed bisphosphonate-hydroxypyridinonate ligand are presented. Potentiometric, spectrophotometric and NMR results allowed to conclude that Fe(III) and AI(III) coordination takes place on the pyridinone moiety. The high steric hindrance prevents the possibility of simultaneous coordination of both groups to the same metal ion. Quantum mechanical calculations confirm this finding allowing to determine the minimal length of the linker necessary for a stable conformation of complexes in which Fe(III) is coordinated both by pyridinone and bisphosphonate groups. (c) 2008 Elsevier Inc. All rights reserved

    Bisphosphonate chelating agents: complexation of Fe(III) and Al(III) by 1-phenyl-1-hydroxymethylene bisphosphonate and its analogues

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    Bisphosphonate ligands were found to be very efficient chelating agents for both Al(III) and Fe(III) ions. Potentiometric and spectroscopic data allow evaluation of the coordination equilibria in the solutions containing 1-phenyl-1-hydroxymethylene bisphosphonate and its three analogues with Al(III) and Fe(III) ions. At pH below 4 the bis-complexes are formed, while above pH 4 the major species are equimolar, monomeric for Al(III) or dimeric for Fe(III) complexes. The large steric hindrance and high electric charge are the major factors influencing the complex stoichiometry. The formation of the dimeric Fe(III) with mu-oxo or mu-hydroxo bridges were supported by measurements of the magnetic moments using Evans' method. The stabilities of the complexes formed are higher than those found for deferiprone, L1, used in clinics as a chelating agent
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