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Title: Complexation of Pu(IV) with the Natural Siderophore Desferrioxamine B and the Redox Properties of Pu(IV)(siderophore) Complexes

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Publication Date:
Research Org.:
Subsurface Biogeochemical Research (SBR)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER)
OSTI Identifier:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Inorganic Chemistry; Journal Volume: 46; Journal Issue: 3
Country of Publication:
United States

Citation Formats

Hakim,Boukhalfa, Sean D.,Reilly, and Mary P.,Neu. Complexation of Pu(IV) with the Natural Siderophore Desferrioxamine B and the Redox Properties of Pu(IV)(siderophore) Complexes. United States: N. p., 2007. Web. doi:10.1021/ic061544q.
Hakim,Boukhalfa, Sean D.,Reilly, & Mary P.,Neu. Complexation of Pu(IV) with the Natural Siderophore Desferrioxamine B and the Redox Properties of Pu(IV)(siderophore) Complexes. United States. doi:10.1021/ic061544q.
Hakim,Boukhalfa, Sean D.,Reilly, and Mary P.,Neu. Thu . "Complexation of Pu(IV) with the Natural Siderophore Desferrioxamine B and the Redox Properties of Pu(IV)(siderophore) Complexes". United States. doi:10.1021/ic061544q.
title = {Complexation of Pu(IV) with the Natural Siderophore Desferrioxamine B and the Redox Properties of Pu(IV)(siderophore) Complexes},
author = {Hakim,Boukhalfa and Sean D.,Reilly and Mary P.,Neu},
abstractNote = {},
doi = {10.1021/ic061544q},
journal = {Inorganic Chemistry},
number = 3,
volume = 46,
place = {United States},
year = {Thu Feb 01 00:00:00 EST 2007},
month = {Thu Feb 01 00:00:00 EST 2007}
  • That microbial siderophores may be mediators of Mn(III) biogeochemistry is suggested by recent studies showing that these well known Fe(III)-chelating ligands form very stable Mn(III) aqueous complexes. In this study, we examine the influence of desferrioxamine B (DFOB), a trihydroxamate siderophore, on the dissolution of hausmannite, a mixed valence Mn(II,III) oxide found in soils and freshwater sediments. Batch dissolution experiments were conducted both in the absence (pH 4-9) and in the presence of 100 {mu}M DFOB (pH 5-9). In the absence of the ligand, there is a sharp decrease in the extent of proton-promoted dissolution above pH 5 and nomore » appreciable dissolution above pH 8. The resulting aqueous Mn{sup 2+} activities were in good agreement with previous studies, indirectly supporting the accepted two-step mechanism involving the formation of manganite and reprecipitation of hausmannite. Desferrioxamine B enhanced hausmannite dissolution over the entire pH range investigated, both via the formation of a Mn(III) complex and through surface-catalyzed reductive dissolution. Above pH 8, non-reductive ligand-promoted dissolution dominated, whereas below pH 8, dissolution was non-stoichiometric with respect to DFOB. Concurrent proton-promoted, ligand-promoted, reductive, and induced dissolution was observed, with Mn release by either reductive or induced dissolution increasing linearly with decreasing pH. The fast kinetics of the DFOB-promoted dissolution of hausmannite, as compared to iron oxides, suggest that the siderophore-promoted dissolution of Mn(III)-bearing minerals may compete with the siderophore-promoted dissolution of Fe(III)-bearing minerals.« less
  • The solution speciation in seawater of divalent trace metals (Cd, Cu, Ni, Pb, Zn) is dominated by strong, ostensibly metal-specific organic ligands that may play important roles in microbial metal acquisition and/or detoxification processes. We compare the effective stabilities of these metal-organic complexes to the stabilities of their complexes with a model siderophore, desferrioxamine B (DFOB). While metal-DFOB complexation has been studied in various dilute but often moderately coordinating media, for the purpose of this investigation we measured the stability constants in a non-coordinating background electrolyte at seawater ionic strength (0.7 M NaClO4). Potentiometric titrations of single metals (M) weremore » performed in the presence of ligand (L) at different M:L molar ratios, whereupon the stability constants of multiple complexes were simultaneously determined by non-linear regression of the titration curves with FITEQL, using the optimal binding mode for each metal. Cadmium, Ni, and Zn, like trivalent Fe, sequentially form a bi-, tetra-, and hexadentate complex with DFOB as pH increases, consistent with their coordination number of 6 and regular octahedral geometry. Copper has a Jahn-Teller-distorted square-bipyramidal geometry whereas the geometry of Pb is cryptic, involving a range of bond lengths. Supported by a thermodynamic argument, our data suggest that this impedes binding of the third hydroxamate group and that the hexadentate Cu-DFOB and Pb-DFOB complex identified in earlier reports may instead be a deprotonated tetradentate complex. Absence of the hexadentate complex promotes the formation of a dinuclear (bidentate-tetradentate) complex, M2HL2+, albeit not for Pb in 0.7 M NaCl, evidently due to extensive complexation with chloride. Stabilities of the hexadentate Ni-DFOB, Zn-DFOB, and the tetradentate Pb-DFOB complex are nearly equal, yet about 2 orders of magnitude higher and 4 orders of magnitude lower than those of the hexadentate Cd-DFOB and tetradentate Cu-DFOB complex, respectively. Linear free-energy relations defined by the rare earth elements are able to predict stabilities of the Cd, Zn, and one of the Pb complexes, but underestimate those of the Ni and Cu complexes. The comparison with metal-specific organic ligands detected in seawater yields fair agreement for three of the five metals, implying that they could be siderophore-like. The Cd- and Ni-specific ligands are much stronger and may contain quite different functional groups. Calculations with MINEQL incorporating our new stability constants indicate that very high DFOB concentrations would be required to match the extent of metal-organic complexation observed in seawater, however DFOB may well represent a much broader class of structurally related ligands.« less
  • The state of Pu(IV) in the region of hydrolysis was investigated as a function of the age and method of preparation of its nitric acid solutions. On the basis of spectrophotometric measurements it was shown that the fraction of hydrolyzed plutonium in solutions prepared by neutralization of the initial acid solution with ammonia is appreciably higher than in solutions produced by dilution of the initial solution with a solution with set pH value. Dependences reflecting the increase in the hydrolysis of Pu(IV) with time in the interval pH = 1.0-2.2 were obtained, and it was established that the transition ofmore » hydroxo forms to the ionic state under conditions of 0.2 N HNO/sub 3/ is a slow process. It was shown that the increase in the adsorption of plutonium on BaSO/sub 4/ and the decrease in it on mordenite with increasing pH of the solution are due to an increase in the amount of hydroxo forms of plutonium in solution.« less