Stability constants of complexes of molybdate and tungstate ions with o-hydroxy aromatic ligands

Natansohn, S.; Krugler, Joel I.; Lester, Joseph E.; Chagnon, Mark; Finocchiaro, Robert S.

doi:10.1021/j100459a027

Cited by 19 publications

(4 citation statements)

References 3 publications

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“…The wild type strain of A. vinelandii produces at least five different types of siderophores: azotobactin, a pyoverdine-like siderophore with one catechol, one hydroxamate, and one α-hydroxycarboxylic acid group; the tris(catechol) protochelin; the bis(catechol) azotochelin; and the mono(catechols) aminochelin and 2,3-dihydroxybenzoic acid (2,3-DHBA) . In this bacterium, the presence of W and Mo affects the nature and the concentration of catechol siderophores which form strong complexes with tungstate in addition to Fe and Mo – . Here, we investigate how the catechol siderophores released by A. vinelandii modulate W uptake and toxicity.…”

Section: Introductionmentioning

confidence: 99%

Catechol Siderophores Control Tungsten Uptake and Toxicity in the Nitrogen-Fixing Bacterium Azotobacter vinelandii

Wichard

Bellenger

Loison

et al. 2008

Environ. Sci. Technol.

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Molybdenum (Mo) and tungsten (W), which have similar chemistry, are present at roughly the same concentration in the earth's continental crust, and both are present in oxic systems as oxoanions, molybdate and tungstate. Molybdenum is a cofactor in the molybdenum-nitrogenase enzyme and is thus an important micronutrient for N2-fixing bacteria such as Azotobacter vinelandii (A. vinelandii). Tungsten is known to be toxic to N2-fixing bacteria, partly by substituting for Mo in nitrogenase. We showthatthe catechol siderophores produced by A. vinelandii, in addition to being essential for iron acquisition, modulate the relative uptake of Mo and W. These catechol siderophores (particularly protochelin), whose concentrations in the growth medium increase sharply at high W, complex all the tungstate along with molybdate and some of the iron. The molybdenum-catechol complex is taken up much more rapidly than the W complex, allowing A. vinelandii to satisfy its Mo requirement and avoid W toxicity. Mutants deficient in the production of catechol siderophores are more sensitive to tungstate and have higher cellular W quotas than the wild type. The binding of metals by excreted catechol siderophores allows A. vinelandii to discriminate in its uptake of essential metals, such as Fe and Mo, over that of toxic metals, such as W, and to sustain high growth rates under adverse environmental conditions.

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Section: Introductionmentioning

confidence: 99%

Catechol Siderophores Control Tungsten Uptake and Toxicity in the Nitrogen-Fixing Bacterium Azotobacter vinelandii

Wichard

Bellenger

Loison

et al. 2008

Environ. Sci. Technol.

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“…Although (Honig and Kustin, 1973) Lactate (lac) [MoO 2 (lac) 2 ] 2- (Cruywagen et al, 1993b) Azotochelin (azo) [MoO 2 (azo)] 3- (Bellenger et al, 2007;Bellenger et al, 2008) Cysteine (cys) [MoO 3 (cys)] 2- (Cavaleiro et al, 1990) Aspartate (asp) [MoO 3 (asp)] 2- (Cruywagen et al, 1993a) Mandelate (man) [MoO 2 (man) 2 ] 2- Oxalate (ox) [MoO 2 (ox) 2 ] 2- (Cruywagen et al, 1986) Malate (mal) [MoO 2 (mal) 2 ] 2- (Cruywagen et al, 1997) Citrate (cit) [MoO 2 (cit)] - Catecholate (cat) [MoO 2 (cat) 2 ] 2- (Kustin and Liu, 1973) Tannic acid (tan) [MoO 2 (tan) x ] 2- (Kiboku and Yoshimura, 1958;Wichard et al, 2009) Thiomalate (malS) [MoO 2 (malS) 2 ] 2- (Caldeira and Gil, 1986) Thiolactate (lacS) [MoO 2 (lacS) 2 ] 2- (Caldeira and Gil, 1986) Various o-hydroxy aromatic ligands (hydroxyAr) [MoO 2 (hydroxyAr)] 2- (Natansohn et al, 1980) a Multiple species are possible depending on reaction pH and relative concentrations of reactants. See references for more information.…”

Section: Discussionmentioning

confidence: 99%

Molybdenum speciation and burial pathway in weakly sulfidic environments: Insights from XAFS

Wagner

Chappaz

Lyons

2017

Geochimica et Cosmochimica Acta

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Sedimentary molybdenum (Mo) accumulation is a robust proxy for sulfidic conditions in both modern and ancient aquatic systems and has been used to infer changing marine redox chemistry throughout Earth's history. Accurate interpretation of any proxy requires a comprehensive understanding of its biogeochemical cycling, but knowledge gaps remain concerning the geochemical mechanism(s) leading to Mo burial in anoxic sediments. Better characterization of Mo speciation should provide mechanistic insight into sedimentary Mo accumulation, and therefore in this study we investigate Mo speciation from both modern (Castle Lake, USA) and ancient (Doushantuo Formation, China) environments using X-Ray Absorption Near Edge Structure (XANES) spectroscopy. By utilizing a series of laboratory-synthesized oxythiomolybdate complexes-many containing organic ligands-we expand the number of available standards to encompass a greater range of known Mo chemistry and test the linkage between Mo and total organic carbon (TOC). In weakly euxinic systems ([H 2 S (aq) ] < 11 µM), or where sulfide is restricted to pore waters, natural samples are best represented by a linear combination of MoO 3 , MoO x S 4-x 2-(intermediate thiomolybdates), and [MoO x (cat) 4-x ] 2-(cat = catechol, x = 2 or 3). These results suggest a revised model for how Mo accumulates in weakly sulfidic sediments, including a previously unrecognized role for organic matter in early sequestration of Mo and a de-emphasized importance for MoS 4 2-(tetrathiomolybdate).

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“…The complexation in acidic medium between the tetrahedral molybdate МоО4 2− and reagents bearing a catechol moiety (L) leads to the production of octahedral anionic products in which the molar L-to-Mo ratio is 1-to-1: [Mo VI О3(OH)L] 3− , [Mo VI О2(OH)2L] 2− , and [Mo VI О(OH)3L] − . As the acidity decreases, complexes with a molar ratio of 2:1 (L:Mo) are also formed [31][32][33].…”

Section: Molar Ratios and Formula Of The Ternary Complexmentioning

confidence: 99%

“…, and [Mo VI O(OH) 3 L] − . As the acidity decreases, complexes with a molar ratio of 2:1 (L:Mo) are also formed [31][32][33].…”

Section: Molar Ratios and Formula Of The Ternary Complexmentioning

confidence: 99%

Spectrophotometric Determination of Molybdenum(VI) as a Ternary Complex with 4-Nitrocatechol and Benzalkonium Chloride

et al. 2022

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A new liquid—liquid extraction system for molybdenum(VI) was studied. It contains 4-nitrocatechol (4NC) as a complexing chromogenic reagent and benzalkonium chloride (BZC) as a source of heavy cations (BZ+), which are prone to form chloroform-extractable ion-association complexes. The optimum conditions for the determination of trace molybdenum(VI) were found: concentrations of 4NC and BZC (7.5 × 10−4 mol dm−3 and 1.9 × 10−4 mol dm−3, respectively), acidity (3.75 × 10−2 mol dm−3 H2SO4), extraction time (3 min), and wavelength (439 nm). The molar absorptivity, limit of detection, and linear working range were 5.5 × 104 dm3 mol−1 cm−1, 5.6 ng cm−3, and 18.6–3100 μg cm−3, respectively. The effect of foreign ions was examined, and the developed procedure was applied to the analysis of synthetic mixtures and real samples (potable waters and steels). The composition of the extracted complex was 1:1:2 (Mo:4NC:BZ). Three possible structures of its anionic part [MoVI(4NC)O2(OH)2]2− were discussed based on optimizations at the B3LYP/3-21G level of theory, and simulated UV/Vis absorption spectra were obtained with the TD Hamiltonian.

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Stability constants of complexes of molybdate and tungstate ions with o-hydroxy aromatic ligands

Cited by 19 publications

References 3 publications

Catechol Siderophores Control Tungsten Uptake and Toxicity in the Nitrogen-Fixing Bacterium Azotobacter vinelandii

Catechol Siderophores Control Tungsten Uptake and Toxicity in the Nitrogen-Fixing Bacterium Azotobacter vinelandii

Molybdenum speciation and burial pathway in weakly sulfidic environments: Insights from XAFS

Spectrophotometric Determination of Molybdenum(VI) as a Ternary Complex with 4-Nitrocatechol and Benzalkonium Chloride

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