19F and 27Al NMR Study on the Formation of Al-EDTA-Fluoride Complex in Aqueous Solution

Yokoyama, T.; Kurisaki, Tsutomu; Kinoshita, Setsuko; Matsuo, Shorin; Wakita, Hisanobu

doi:10.2116/analsci.16.647

Cited by 5 publications

(7 citation statements)

References 11 publications

(8 reference statements)

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“…The coordination geometry of the Al(EDTA) − complex has been a subject of debate in the literature. Proposed structures have included 7-fold coordination involving the six EDTA ligands and a water molecule, 6-fold coordination involving either the six EDTA ligands or a combination of EDTA ligands and water molecules, ,,,, and a 5-coordinate structure involving four EDTA ligands and a water molecule . Of these possibilities, the strongest evidence is in support of the 6-coordinate, hexadentate structure (full coordination by the EDTA with no water ligands in the coordination sphere), which has been proposed based on 27 Al-NMR spectroscopy, 13 C- and 1 H NMR spectroscopy, and ab initio calculations .…”

Section: Resultsmentioning

confidence: 99%

“…27 Al-NMR spectroscopy has been widely used to study Al solution complexes, often in combination with ligand-targeted NMR spectroscopy, vibrational spectroscopy, and molecular modeling. The 27 Al-NMR method has been applied with varying success to virtually all classes of aqueous Al complexes, including monomeric hydrolysis species, − polymers, , inorganic complexes (e.g., sulfate and fluoride), , and organic complexes (e.g., lactate, , oxalate, citrate, , salicylate, amino acids, and EDTA ,, ). However, the method is limited due to the high sensitivity of the quadrupolar 27 Al nucleus to electric field gradients that may arise from geometric distortions and mixed ligation in the Al coordination sphere.…”

Section: Introductionmentioning

confidence: 99%

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X-ray Absorption Spectroscopy of Aqueous Aluminum-Organic Complexes

Hay

Myneni

2010

J. Phys. Chem. A

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Aqueous-phase X-ray absorption near-edge structure (XANES) spectra were collected on dissolved Al complexes with organic ligands, including desferrioxamine B, EDTA, acetohydroxamate, malate, oxalate, and salicylate. Spectral interpretations were made using the density functional theory-based modeling package StoBe. The goals of this work were to study the geometric and electronic structural characteristics of these complexes relative to Al(H(2)O)(6)(3+) and to examine the utility of the aqueous Al XANES technique as a tool for probing Al speciation and structure. In the case of EDTA, aqueous Fourier-transform infrared spectroscopy was also used to corroborate the structures of the Al(EDTA)(-) and AlOH(EDTA)(2-) complexes. Synthetic XANES spectra calculated with StoBe reproduced the observed spectral differences between Al(H(2)O)(6)(3+), Al(dfoB)(+), and Al(EDTA)(-). The narrower XANES feature observed for Al(dfoB)(+) relative to Al(H(2)O)(6)(3+) can be attributed to a weaker splitting of the Al 3p-O 2p interactions in the former, while Al(EDTA)(-) exhibits split Al 3p-ligand interactions that likely result from the mixed O/N coordination. In complexes with mixed aqua/organic-oxygen ligation (Al-acetohydroxamate, Al-malate, Al-oxalate, and Al-salicylate), spectra exhibit linear, systematic changes in peak width as a function of H(2)O to organic ligand ratio in the Al coordination sphere. These results highlight the sensitivity of the aqueous Al K-edge XANES spectrum to coordination environment and demonstrate its utility as an experimental probe for future studies of Al speciation in complex solutions.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

X-ray Absorption Spectroscopy of Aqueous Aluminum-Organic Complexes

Hay

Myneni

2010

J. Phys. Chem. A

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“…In these systems, the advantages of both precapillary (high sensitivity) and on-capillary (high selectivity) complexing method were utilized. Some ternary complexing systems have also been reported for the transition metal-EDTA complexes; metal-EDTA-ammonia, -OH diamine [37][38][39], citrate [40,41], and -F 2 [42]. These reactions, which cause perturbation in the ratio of charge to size of the complex, are expected to be useful for electrophoretic separation.…”

Section: System Designmentioning

confidence: 99%

“…, and citrate [37,41,42]. Since the mixed-ligand system suitable for the CZE separation was the one which altered the charge of the complexes, the ML-OH system was employed in this work.…”

mentioning

confidence: 99%

Direct fluorometric detection of paramagnetic and heavy metal ions at sub‐amol level using an aromatic polyaminocarboxylate by CZE: Combination of pre‐ and on‐capillary complexation technique

et al. 2007

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The low sensitivity of simple CZE for detecting metal ions is a long-standing problem even when an LIF detection system is employed. We have successfully achieved an ultrasensitive CE-LIF using a simple CZE mode (typical detection limit: 10(-11)-10(-10) mol/dm(3)). Both the design of a newly synthesized ligand and the combination of a precapillary derivatizing technique with an on-capillary ternary complexing technique have enabled us to achieve this extremely low LOD and high resolution of large metal complexes. The direct fluorescent detection of the paramagnetic metal ions was achieved for the first time despite their intrinsic fluorescent quenching nature. The fluorescent ligand (L) consists of a polyaminocarboxylate chelating moiety, a strongly emissive fluorescein moiety and a spacer connecting the two portions. The migration behavior of various metal-L complexes was investigated. The resolution among the complexes was improved by the introduction of a ternary complex equilibrium of the kinetically stable mother complexes with OH(-) ion. The analytical potential of our simple system was examined, and it was proved that the system was one of the most sensitive methods without the need for any preconcentration process.

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“…23, 24 Its coordination in water is less clear, with conflicting interpretations arising based on spectroscopic measurements. Iyer et al proposed a hexadentate binding for EDTA based on a comparison of the 27 Al-NMR chemical shifts of AlEDTA -and other Al-aminocarboxylate complexes. 25 Recently, Jung et al studied the structure of aqueous Al-EDTA by 13 C and 1 H NMR spectroscopy and also proposed an octahedral, hexadentate structure for aqueous AlEDTA -, similar to that observed in the crystalline structure.…”

Section: Introductionmentioning

confidence: 99%

Coordination Studies of Al-EDTA in Aqueous Solution

Coskuner

Jarvis

2008

J. Phys. Chem. A

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The degree of aluminum toxicity is based on its complexation with organic ligands. One of these complexes is AlEDTA- (Al = aluminum, EDTA = ethylenediaminetetraacetate), the structure of which in aqueous solution has been debated on the basis of X-ray absorption and NMR measurements with different interpretations proposing different coordination. In addition, there is a lack of consensus regarding the relationship of crystalline AlEDTA- and its geometry in solution. This debate must be resolved, not merely for scientific interest, but because the use of an incorrect coordination might lead to the wrong interpretation of bioactivity and kinetics data. In this work, we predict the coordination of Al in aqueous AlEDTA- by employing ab initio calculations and Car-Parrinello molecular dynamics simulations. Our results indicate that AlEDTA- favors Al in octahedral coordination in aqueous solution. Furthermore, the predicted crystalline and solution-phase structures of AlEDTA- are similar and agree well with recent X-ray measurements, supporting the strong chelating nature of this metal-organic complex in aqueous solution.

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19F and 27Al NMR Study on the Formation of Al-EDTA-Fluoride Complex in Aqueous Solution

Cited by 5 publications

References 11 publications

X-ray Absorption Spectroscopy of Aqueous Aluminum-Organic Complexes

X-ray Absorption Spectroscopy of Aqueous Aluminum-Organic Complexes

Direct fluorometric detection of paramagnetic and heavy metal ions at sub‐amol level using an aromatic polyaminocarboxylate by CZE: Combination of pre‐ and on‐capillary complexation technique

Coordination Studies of Al-EDTA in Aqueous Solution

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