Syntheses, Structures, and Magnetic Properties of Two Dinuclear Iron(III) Citrate Complexes

Shweky, Itzhak; Bino, Avi; Goldberg, David; Lippard, Stephen J.

doi:10.1021/ic00101a001

Cited by 95 publications

(97 citation statements)

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“…This shows that the buffer present was strong enough to prevent any change in pH which would cause discoloration. Discoloration was observed in both dyed agars with citric acid and DFO; both ligands can complex UO 2 2ϩ and Fe 3ϩ (2,36,45). These results prove that discoloration in the dyed agars is caused only by ligands that sequester the metal ion from the dye.…”

Section: Discussionmentioning

confidence: 55%

Development and Application of an Assay for Uranyl Complexation by Fungal Metabolites, Including Siderophores

Renshaw¹,

Halliday

Robson

et al. 2003

Appl Environ Microbiol

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An assay to detect UO 2 2؉ complexation was developed based on the chrome azurol S (CAS) assay for siderophores (B. Schwyn and J. B. Neilands, Anal. Biochem. 160:47-56, 1987) and was used to investigate the ability of fungal metabolites to complex actinides. In this assay the discoloration of two dyed agars (one containing a CAS-Fe 3؉ dye and the other containing a CAS-UO 2 2؉ dye) caused by ligands was quantified. The assay was tested by using the siderophore desferrioxamine B (DFO), and the results showed that there was a regular, reproducible relationship between discoloration and the amount of siderophore added. The ratio of the discoloration on the CAS-UO 2 2؉ agar to the discoloration on the CAS-Fe 3؉ agar was independent of the amount of siderophore added. A total of 113 fungi and yeasts were isolated from three soil samples taken from the Peak District National Park. The fungi were screened for the production of UO 2 2؉ chelators by using the CAS-based assay and were also tested specifically for hydroxamate siderophore production by using the hydroxamate siderophore auxotroph Aureobacterium flavescens JG-9. This organism is highly sensitive to the presence of hydroxamate siderophores. However, the CAS-based assay was found to be less sensitive than the A. flavescens JG-9 assay. No significant difference between the results for each site for the two tests was found. Three isolates were selected for further study and were identified as two Pencillium species and a Mucor species. Our results show that the new assay can be effectively used to screen fungi for the production of UO 2 2؉ chelating ligands. We suggest that hydroxamate siderophores can be produced by mucoraceous fungi.

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Section: Discussionmentioning

confidence: 55%

Development and Application of an Assay for Uranyl Complexation by Fungal Metabolites, Including Siderophores

Renshaw¹,

Halliday

Robson

et al. 2003

Appl Environ Microbiol

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“…The remaining deprotonated terminal carboxylate is non-coordinating, with two close C À O bond lengths (C5 À O4 1.243(2), 3À ion in compound 6 (from ref. [14] and this work). [22] In this latter case, electron density peaks were attributed to water oxygen atoms instead of ammonium nitrogen atoms.…”

Section: Resultsmentioning

confidence: 68%

“…[c] From reference [14]. Crystal data for 7 were collected at 170 K, making the resolution of the disorder easier than in previously reported structures [12,19,20] for which the crystal data were collected at room temperature.…”

Section: R(f)mentioning

confidence: 99%

“…[13] The X-ray structure of such an [Fe 2 -(cit) 2 3 ] 3À . [14] These dinuclear complexes were obtained in the presence of pyridine and neocuproine, respectively, the protonated forms of these bases acting as the counter-cations in the complexes. The authors suggest that the two complexes are in equilibrium in aqueous solution, and that one or other of them crystallizes according to the base used.…”

Section: Introductionmentioning

confidence: 99%

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New Trends in the Chemistry of Iron(III) Citrate Complexes: Correlations between X‐ray Structures and Solution Species Probed by Electrospray Mass Spectrometry and Kinetics of Iron Uptake from Citrate by Iron Chelators

Gautier‐Luneau

Merle

Phanon

et al. 2005

Chemistry A European J

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Despite the crucial role of "iron(III) citrate systems" in the iron metabolism of living organisms (bacteria as well as plants or mammals), the coordination chemistry of ferric citrate remains poorly defined. Variations in the experimental conditions used for the preparation of so-called ferric citrates (iron salt, Fe:cit molar ratio, base, pH, temperature, solvent) lead to several different species, which are in equilibrium in solution. To date, six different anionic complexes have been structurally characterized in the solid state, by ourselves or others. In the work described herein, we have established the experimental conditions leading to each of them. Five were obtained from aqueous solution. With the exception of a nonanuclear species (of which fragments have been detected), all were identified in aqueous solution on the basis of electrospray ionization mass spectrometry. In addition, the spectra revealed a new trinuclear species, which could not be crystallized. Kinetic studies of iron uptake from citrate species by iron chelators confirmed the results indicated by the ESI-MS studies. These studies also allowed the relative molar fraction of mononuclear versus polynuclear complexes to be determined, which depends on the Fe:cit molar ratio.

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“…Only a few examples of similarly coordinated diiron complexes are known, which either lack a neutral bridging ligand, such as dimeric bis(acetylacetonato)iron(II) [14], and/or contain iron (III). Two examples of the latter type of complex are the tris(μ-hydroxo)-bridged mixed-valent species, [Fe 2 (OH) 3 (tmtacn) 2 ] 2+ (tmtacn = N,N′,N″-trimethyltriazacyclononane) [15], and ferric citrate [16].…”

Section: Resultsmentioning

confidence: 99%

Unexpected assembly of a novel triply bridged diiron(II) core by a bidentate Schiff base ligand

Smith

Day

Que

et al. 2007

Inorganica Chimica Acta

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The unusual dinucleating properties of a simple bidentate Schiff base (LH, 1) in the presence of weakly coordinating methanol solvent lead to the self-assembly of [Fe II 2 (2) (b and t refer to bridging and terminally bound ligands, respectively). Complex 2 is the first diiron (II) species in which the two metal centers are triply bridged by single atoms in an asymmetric fashion, involving both μ-O Ph and μ-OH Me bridges. This binding mode produces an Fe···Fe distance of 3.139 (1) Å. Dinucleation appears to be driven by a combination of ligand deficiency and solvent-mediated chemistry reminiscent of host-guest interactions. The presence of a μ-MeOH ligand is unprecedented in iron chemistry. Parallel-mode EPR spectra of complex 2 recorded at 4 K show an intense negative signal at g || ≈ 16, suggesting the dimeric form exists in solution.

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Syntheses, Structures, and Magnetic Properties of Two Dinuclear Iron(III) Citrate Complexes

Cited by 95 publications

References 0 publications

Development and Application of an Assay for Uranyl Complexation by Fungal Metabolites, Including Siderophores

Development and Application of an Assay for Uranyl Complexation by Fungal Metabolites, Including Siderophores

New Trends in the Chemistry of Iron(III) Citrate Complexes: Correlations between X‐ray Structures and Solution Species Probed by Electrospray Mass Spectrometry and Kinetics of Iron Uptake from Citrate by Iron Chelators

Unexpected assembly of a novel triply bridged diiron(II) core by a bidentate Schiff base ligand

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