Ethylenediaminetetraacetate Complexes Research Articles

Influence of the Procedure for Preparing Ruthenium Nanoparticles on the Internal Surface of Aluminosilicate Nanotubes on Their Catalytic Properties in Benzene Hydrogenation in the Presence of Water

The composition, structure, catalytic activity, and stability of ruthenium catalytic systems prepared using natural aluminosilicate nanotubes as a support were studied. The influence of the preparation procedure on the morphology of ruthenium nanoparticles selectively formed inside mesoporous aluminosilicate nanotubes was examined. The activity and stability of catalysts in the model reaction of benzene hydrogenation in the presence of water [V(C6H6) = V(H2O), 80°C, hydrogen pressure 3.0 MPa, reaction time 3 h] were studied. The catalyst containing 1.02 wt % ruthenium, prepared by reduction of the ruthenium ethylenediaminetetraacetate complex in a hydrogen stream at 400°С, exhibits higher activity (the benzene conversion in the 3-h reaction was 100%) and higher stability in the reaction (the benzene conversion after three reaction cycles was 95%) compared to the system with the similar ruthenium content (0.98 wt %) prepared by reduction with a sodium borohydride solution. The reduction with hydrogen leads to the formation of highly stable ruthenium nanoparticles with the mean diameter of 2 nm, tightly bound to the internal surface of aluminosilicate nanotubes.

The Structural Basis of the Binding of Various Aminopolycarboxylates by the Periplasmic EDTA-Binding Protein EppA from Chelativorans sp. BNC1.

The widespread use of synthetic aminopolycarboxylates, such as ethylenediaminetetraacetate (EDTA), as chelating agents has led to their contamination in the environment as stable metal–chelate complexes. Microorganisms can transport free EDTA, but not metal–EDTA complexes, into cells for metabolism. An ABC-type transporter for free EDTA uptake in Chelativorans sp. BNC1 was investigated to understand the mechanism of the ligand selectivity. We solved the X-ray crystal structure of the periplasmic EDTA-binding protein (EppA) and analyzed its structure–function relations through isothermal titration calorimetry, site-directed mutagenesis, molecular docking, and quantum chemical analysis. EppA had high affinities for EDTA and other aminopolycarboxylates, which agrees with structural analysis, showing that its binding pocket could accommodate free aminopolycarboxylates. Further, key amino acid residues involved in the binding were identified. Our results suggest that EppA is a general binding protein for the uptake of free aminopolycarboxylates. This finding suggests that bacterial cells import free aminopolycarboxylates, explaining why stable metal–chelate complexes are resistant to degradation, as they are not transported into the cells for degradation.

Extraction of Organic Compounds from Aqueous Solutions by the Nanofiltration Method

Extraction from aqueous solutions of oxalate and ethylenediaminetetraacetate (EDTA) ions, anionic (ASF) and nonionogenic (NSF) surfactants, and a complex of Co(III) with EDTA by the nanofiltration (NF) method was studied. It was shown that 98–99% of NSFs and EDTA, 85–90% of ASFs and oxalate ions, and 76–79% of the Co(III)–EDTA complex can be extracted with the use of a polymeric NF membrane. The possibility is demonstrated of effectively extracting EDTA and oxalate ions with an NF membrane at solution pH varied within the range 1–13 and sodium nitrate concentrations of 0 to 159 g/dm3. A conclusion is made that using the nanofiltration method is promising for effective removal of various organic complexing and surface-active substances and the Co(III)–EDTA complex from solutions with complex salt composition.

Response of Lupinus albus to Pb–EDTA indicates relatively high tolerance

ABSTRACTWhite lupin plants were grown in hydroponics with 0, 90 and 180 µmol L−1 Pb(II) ethylenediaminetetraacetate complex for 30 days. Pb distribution (shoot/root ratio) was 0.34 and 0.46 for both Pb treatments. In the shoots, no decrease in biomass nor in photosynthetic pigment levels and no changes in the concentrations of malondialdehyde and glutathione were detected. In the roots, malondialdehyde increased by 20%, glutathione 2–3.6 times and phytochelatin concentrations 4–5 times. The high tolerance of white lupin makes it a valuable plant for phytoremediation of Pb-contaminated soil.

Cytotoxic and genotoxic potential of Cr(VI), Cr(III)-nitrate and Cr(III)-EDTA complex in human hepatoma (HepG2) cells

Chromium (Cr) and ethylenediaminetetraacetate (EDTA) are common environmental pollutants and can be present in high concentrations in surface waters at the same time. Therefore, chelation of Cr with EDTA can occur and thereby stable Cr(III)-EDTA complex is formed. Since there are no literature data on Cr(III)-EDTA toxicity, the aim of our work was to evaluate and compare Cr(III)-EDTA cytotoxic and genotoxic activity with those of Cr(VI) and Cr(III)-nitrate in human hepatoma (HepG2) cell line. First the effect of Cr(VI), Cr(III)-nitrate and Cr(III)-EDTA on cell viability was studied in the concentration range from 0.04 μg mL−1 to 25 μg mL−1 after 24 h exposure. Further the influence of non-cytotoxic concentrations of Cr(VI), Cr(III)-nitrate and Cr(III)-EDTA on DNA damage and genomic stability was determined with the comet assay and cytokinesis block micronucleus cytome assay, respectively. Cell viability was decreased only by Cr(VI) at concentrations above 1.0 μg mL−1. Cr(VI) at ≥0.2 μg mL−1 and Cr(III) at ≥1.0 μg mL−1 induced DNA damage, while after Cr(III)-EDTA exposure no formation DNA strand breaks was determined. Statistically significant formation of micronuclei was induced only by Cr(VI) at ≥0.2 μg mL−1, while no influence on the frequency of nuclear buds nor nucleoplasmic bridges was observed at any exposure. This study provides the first evidence that Cr(III)-EDTA did not induce DNA damage and had no influence on the genomic stability of HepG2 cells.

Synthesis and photoluminescence of red emitting phosphors of europium complex intercalated layered double hydroxide

An inorganic-organic red emitting phosphor, europium ethylenediaminetetraacetate complex ([Eu(EDTA)]-) anions intercalated Mg/Al and Zn/Al layered double hydroxides (LDHs) were synthesized through an ion exchange method. X-ray powder diffraction (XRD) results exhibit that a nearly vertical arrangement of [Eu(EDTA)]– anions with the maximal dimension in the gallery is adopted. Measurement of the excitation and emission spectra show that the two materials display high red luminescence from Eu3+ ions. Furthermore, Mg/Al LDH containing europium complex has higher luminescence intensity than Zn/Al LDH, which probably was related with more inversion asymmetry sites of Eu3+ occurring in the Mg/Al LDH.

Synthesis and Characterization of Artificial Antigens for Copper and Application for Development of an Indirect Competitive Enzyme-Linked Immunosorbent Assay

Copper was conjugated to two carrier proteins using penicillin G sodium salt to synthesize artificial antigens for copper. The antigens were identified by ultraviolet spectrometry, circular dichroism, and inductively coupled plasma–optical emission spectrometry. The results of ultraviolet spectrometry showed characteristic absorption peak shifts between haptens and carrier proteins. Circular dichroism showed that the secondary structure of the conjugates was an α-helix. These results suggested that the artificial antigens for copper were synthesized successfully. The polyclonal antibodies of copper were produced by immunizing New Zealand white rabbits with copper antigens. An indirect competitive enzyme-linked immunosorbent assay based on the polyclonal antibodies was developed. The concentration of copper ion was quantified based on the ability of its ethylenediaminetetraacetic acid complexes to inhibit the binding of the goat anti-rabbit immunoglobulin G conjugated with horseradish peroxidase and, subsequently, color formation in the assay. The assay showed an IC50 value of 0.475 microgram per milliliter with a detection limit of 0.007 microgram per milliliter. The antibody showed high affinity with copper and low cross-reactivity with other metals. The recovery of copper from fortified water was between 78.0 and 122 percent. The results indicate that the assay is a convenient supplemental analytical tool for monitoring copper ions in aquatic environments.

Preparation of Zn–Al layered double hydroxide intercalated with triethylenetetramine-hexaacetic acid by coprecipitation: uptake of rare-earth metal ions from aqueous solutions

A Zn–Al layered double hydroxide intercalated with triethylenetetramine-hexaacetic acid (TTHA·Zn–Al LDH) was prepared by the dropwise addition of a Zn–Al nitrate solution to a TTHA solution at a constant pH value of 10.0. The TTHA·Zn–Al LDH could uptake rare-earth metal ions such as Nd3+ ions from aqueous solutions. This can be attributed to the chelating ability of the TTHA ions in the interlayer, i.e., Nd–TTHA complexes could be formed in the interlayer. However, the TTHA·Zn–Al LDH could hardly uptake Sr2+ ions from aqueous solutions, indicating that the TTHA ions in the interlayer did not function as effective chelating agents for Sr2+ ions. Therefore, TTHA·Zn–Al LDH could uptake Nd3+ ions selectively from an aqueous mixture of Nd3+ and Sr2+ ions. This was confirmed by the fact that the uptake amount after 120 min was 0.078 and 0.007 mmol g−1 for Nd3+ and Sr2+, respectively, when TTHA·Zn–Al LDH was added to a 1 : 1 mixed nitrate solution of Nd3+ and Sr2+ ions. In this case, the degree of selectivity, i.e., the Nd/Sr molar ratio, was 10.7. Furthermore, TTHA·Zn–Al LDH was superior to ethylenediaminetetraacetate (EDTA)·Zn–Al LDH for the uptake of Nd3+ ions, which can be attributed to the order of the stability of the metal–chelate complexes: Nd–TTHA complex > Nd–EDTA complex.

Lanthanides as NMR Probes of Fast Molecular Dynamics at High Magnetic Fields and Temperature Sensors: Conformational Interconversion of Erbium Ethylenediaminetetraacetate Complexes

(1)H NMR measurements are reported for D2O solutions of paramagnetic complex [Er(H2O)(EDTA(4-))](-) (I) for temperature interval 273-319 K. Diamagnetic complex [Lu(H2O)(EDTA(4-))](-) (II) was used as an NMR reference compound. The spectra obtained have been analyzed using a band-shape analysis technique in the framework of dynamic NMR (DNMR) taking into account the temperature dependence of lanthanide-induced shifts. Intramolecular dynamics in I was assigned to the interconversion of Δ-λE-δδδδ and Δ-δE-δδδδ conformers with estimated activation free energy ΔG(‡)(298 K) = 50 ± 4 kJ/mol. The methodology of paramagnetic 4f-element probe applications on the example of Er(3+) for the study of free-energy changes in chemical exchange processes, as well as the advantages of this method in comparison with DNMR studies of diamagnetic substances, is discussed. In accordance with the literature reviewed, the fulfilled experimental study is the first example of intramolecular dynamics determination for erbium complexes. An additional advantage of the investigation is in the approach proposed which extends the range of measurement of the NMR rate constants for paramagnetic 4f-element complexes compared to diamagnetic ones. Coordination compounds investigated represent a new type of thermometric NMR sensors and lanthanide paramagnetic probes for in situ temperature control in solutions.

Remediation of an electroplating contaminated soil by EDTA flushing: chromium release and soil dissolution

Remediation of soils contaminated with Cr (as Cr(III) complexes/precipitates and/or Cr(VI) oxyanion) and cationic metals (Cu, Ni, Zn, and Pb) by ethylenediaminetetraacetate (EDTA) flushing has been challenging and rarely investigated. This study aimed to evaluate the efficiency of EDTA flushing for metal extraction of soil from an electroplating site, with a specific focus on chromium release and soil dissolution. Column flushing tests were performed on a sandy soil contaminated by electroplating activities in the field. Three EDTA concentrations (5, 10, and 20 mM) and flow interruptions were employed to investigate the operation of EDTA flushing. Results demonstrated that Cr, Cu, and Ni were continuously released along with dissolution of Fe, Al, Mg, and Mn throughout the entire flushing process (up to 600 pore volumes), whereas Zn and Pb removal primarily occurred in the first 50–200 pore volumes. By comparing the Cr and Fe release patterns, the observed Cr release by EDTA flushing possibly resulted from a combination of dissolution of Fe oxides, dissolution of metal–chromate precipitates, and ligand competition for the surface sites (substitution reaction). The latter two mechanisms appeared to be more influential at the early stage. It was also revealed that soil dissolution was predominant, and metal extraction became inefficient at the later stage of flushing, especially with the concentrated EDTA solution. On the other hand, when the flushing process was temporarily paused (i.e., flow interruptions), Cr, Cu, Ni, and Zn concentrations elevated, whereas Pb levels in the effluent decreased, indicating the significance of rate-limited metal exchange of newly formed metal–EDTA complexes. In consideration of EDTA utilization efficiency and potential ecological risks, diluted EDTA solution is recommended for field applications.

The thermodynamic functions of formation and transfer of copper(II) and nickel(II) ethylenediaminetetraacetate complexes with ammonia in aqueous-ethanolic solutions

The formation of mixed-ligand NiEdtaNH32− and CuEdtaNH32− complexes in an aqueous-ethanolic solvent with the mole fractions of ethanol 0.1 and 0.2 at 298.15 K and ionic strength I = 0.4 (KNO3) was studied calorimetrically. The thermodynamic characteristics of formation and transfer parameters of these complexes were calculated. The influence of the mixed solvent on the thermodynamic characteristics of these reactions was studied.

Yttria coating synthesized by reactive flame spray process using Y-EDTA complex

To obtain thick metal oxide films with low energy consumption at a low cost, metal ethylenediaminetetraacetic (EDTA) complexes were applied to the flame spray method as raw materials. This new method actualized the synthesis of yttria using a conventional flame spray machine with C2H2 and O2. A micrometer-thick yttria film was deposited from a Y-EDTA complex powder within 1min on a stainless steel plate. The organic components in the EDTA raw material were completely decomposed by the addition of oxygen into the flame, and the deposited films contained crystalline phases of Y2O3. We demonstrated that the reactive flame spray process using metal-EDTA complexes is convenient for obtaining metal oxide films at a low cost.

Removal of Cyanide in Ni(II)–Cyanide, Ni(II)–Cyanide–EDTA, and Electroplating Rinse Wastewater by Ferrate(VI)

Cyanide is found as free cyanide and metal–cyanide complexes in metal finishing rinse wastewaters. Experiments were performed to seek removal of cyanide in Ni(II)–cyanide and Ni(II)–cyanide–ethylenediaminetetraacetate (EDTA) solutions by the environmentally friendly oxidant, ferrate(VI) (FeO 4 2− , Fe(VI)) as a function of pH (8.0–11.0). Incomplete removal of cyanide in Ni(II)–cyanide solutions (≤60%) was observed at the studied pH range. However, cyanide removal efficiency approached to 100% in Ni(II)–cyanide–EDTA solutions. Formation of Ni(II)–cyanide and Ni(II)–EDTA complexes and relative rates of the reactions of Fe(VI) with various species (water, cyanide, Ni(II)–cyanide, and EDTA) present in solutions were responsible for the variation in removal efficiencies in mixtures at various pH. The oxidation of cyanide by Fe(VI) produced cyanate. Tests using electroplating rinse wastewaters demonstrated that Fe(VI) was highly effective in removing cyanide.

New Violet Phosphor Sr7Al12O25:Eu2+ Synthesized from Sr–Al–O:Eu Powder Mounted on Polycrystalline Alumina

A new violet phosphor was synthesized by sintering under the reduction condition from the Sr–Al–O:Eu powder oxidized from an ethylenediaminetetraacetic (EDTA) complex on a polycrystalline alumina plate. The crystalline phase of violet phosphor was determined to be Sr7Al12O25 by the change in the crystallinity of the product with a change in the composition of the raw material. The emission wavelength of the phosphor was 410 nm for Sr7Al12O25:Eu2+. For the composition of Sr:Al:Eu = 6.86:8:0.14 in the EDTA complex with sintering at 1400 °C, Sr7Al12O25:Eu2+ was obtained only in the crystalline phase of Sr7Al12O25 and exhibited the highest emission intensity of 410 nm in our experiment. The sintering temperature at sintering and composition of metals in the EDTA complex affected the emission wavelength change from 410 to 460 nm because of change in crystallinity. These changes indicate that the emission color in the range from violet to green is controlled by composition change or sintering temperature.

Crystal structure of Li(H2O)3[GaEdta

The ethylenediaminetetraacetate complex Li(H2O)3[Ga(Edta)] was synthesized and its crystal structure composed of octahedral (Ga(Edta)− anions connected to the Li(H2O)3+ ion through the oxygen atom was studied. Five of the six hydrogen atoms of water molecules are involved in weak hydrogen bonds with the oxygen atoms of four Ga(Edta)− complexes, the complex anion is hydrogen-bonded to five water molecules. In addition, shortened contacts C(221)–H(22A)…O(112) between the Ga(Edta)− anions were found. As a result, the molecular packing in the crystal is determined by the three-dimensional lace of hydrogen bonds. The results are compared with published data for the lithium salts of Bi(III), Sb(III), Fe(III), Ni(II), and Hg(II) ethylenediaminetetraacetates.

Magnetic resonance microscopy of iron transport in methanogenic granules

Interactions between anaerobic biofilms and heavy metals such as iron, cobalt or nickel are largely unknown. Magnetic resonance imaging (MRI) is a non-invasive method that allows in situ studies of metal transport within biofilm matrixes. The present study investigates quantitatively the penetration of iron (1.75 mM) bound to ethylenediaminetetraacetate (EDTA) into the methanogenic granules (spherical biofilm). A spatial resolution of 109 × 109 × 218 μm 3 and a temporal resolution of 11 min are achieved with 3D Turbo Spin Echo (TSE) measurements. The longitudinal relaxivity, i.e. the slope the dependence of the relaxation rate (1/ T 1) on the concentration of paramagnetic metal ions, was used to measure temporal changes in iron concentration in the methanogenic granules. It took up to 300 min for the iron–EDTA complex ([FeEDTA] 2−) to penetrate into the methanogenic granules (3–4 mm in diameter). The diffusion was equally fast in all directions with irregularities such as diffusion-facilitating channels and diffusion-resistant zones. Despite these irregularities, the overall process could be modeled using Fick’s equations for diffusion in a sphere, because immobilization of [FeEDTA] 2− in the granular matrix (or the presence of a reactive barrier) was not observed. The effective diffusion coefficient ( D ejf ) of [FeEDTA] 2− was found to be 2.8 × 10 −11 m 2 s −1, i.e. approximately 4% of D ejf of [FeEDTA] 2− in water. The Fickian model did not correspond to the processes taking place in the core of the granule (3–5% of the total volume of the granule), where up to 25% over-saturation by iron (compare to the concentration in the bulk solution) occurred.

Electrochemical detection of the explosive, hexamethylene triperoxide diamine (HMTD)

A rapid electrochemical detection scheme for the improvised explosive, hexamethylene triperoxide diamine (HMTD) is demonstrated. This is based on the hydrolysis of HMTD releasing H 2O 2 and the electrochemical redox cycling of Fe II/IIIEDTA via the following scheme: Fe IIIEDTA + e −→Fe IIEDTA Fe IIEDTA + HOOH→Fe IIIEDTA + HO + HO − where FeEDTA is the ethylenediaminetetraacetate complex. Cyclic voltammetric results indicate an electrocatalytic (EC′) mechanism. Mass transport aided chronoamperometry at a carbon disk electrode ( E step = − 400 mV vs. Ag/AgCl) gave a limit of detection of 30 μM (3 S b/ m). Most interestingly, the hydrolysis of HMTD was found to be rapid under mild reaction conditions which was found to be complete, and nearly instantaneously when exposed to a 50/50 (v/v%) water/acetonitrile solution at pH 2.1. This is in contrast with previous investigations that require harsher conditions. Neutralization or further derivatization steps were not necessary as the Fe II/IIIEDTA complex acted as an electron shuttle under these conditions. These results indicate a basis for a fast, one-step, and inexpensive detector for HMTD. Based on the results of a previous study, the simultaneous detection of HMTD with another improvised explosive, triacetone triperoxide is a strong possibility.

Hydrazinium metal(II) and metal(III) ethylenediamine tetraacetate hydrates

Hydrazinium metal ethylenediaminetetraacetate complexes of molecular formula (N2H5)2[Mg(edta)·H2O], (N2H5)3[Mn(edta)··H2O](NO3)·H2O, N2H5[Fe(edta)·H2O], N2H5[Cu(Hedta)·H2O] and N2H5[Cd(Hedta)·H2O]·H2O have been synthesized and characterized by elemental and chemical analysis, conductivity and magnetic measurements and spectroscopic techniques. The thermal behaviour of these complexes has been studied by thermogravimetry and differential thermal analysis. The data set provided by the simultaneous TG-DTA curves of the complexes shows the occurrence of three or four consecutive steps such as dehydration, ligand pyrolysis and formation of metal oxides. X-ray powder diffraction patterns of copper and cadmium complexes show that they are not isomorphous. These studies suggest seven coordination for Mg,Mn, Fe complexes and six coordination for Cu and Cd derivatives.

Two-dimensional layer architecture assembled by Keggin polyoxotungstate, Cu(II)–EDTA complex and sodium linker: Synthesis, crystal structures, and magnetic properties

Reaction of Keggin polyoxotungstate with copper(II)–EDTA (EDTA=ethylenediamine tetraacetate) complex under mild conditions led to the formation of hybrid inorganic–organic compounds Na 4(OH)[(Cu 2EDTA)PW 12O 40]·17H 2O (1) and Na 4[(Cu 2EDTA)SiW 12O 40]·19H 2O (2). The single-crystal X-ray diffraction analyses reveal their two structural features: (1) one-dimensional chain structure consisting of Keggin polyoxotungstate and copper(II)–EDTA complex; (2) Two-dimensional layer architecture assembled by the one-dimensional chain structure and sodium linker. The results of magnetic measurements in the temperature range 300–2 K indicated the existence of ferromagnetic exchange interactions between the Cu II ions for both compounds. In addition, TGA analysis, IR spectra, and electrochemical properties were also investigated to well characterize these two compounds.

Factors Affecting the Interlayer Arrangement of Transition Metal–Ethylenediaminetetraacetate Complexes Intercalated in Mg/Al Layered Double Hydroxides

AbstractTransition metal (M)–ethylenediaminetetraacetate (edta) complexes {[M(edta)]2–} have been intercalated in layered double hydroxides (LDHs) by a hydrothermal method using MgAl–NO3 LDH as the precursor. The factors affecting the orientation of the incorporated [M(edta)]2– in the resulting well‐ordered materials were investigated. Whilst varying the metal cation in the intercalated complex has no major influence on the orientation of the [M(edta)]2– (M = Co, Ni, Cu, Zn) anion in the interlayer galleries, there is a marked dependence on layer charge density. The observed basal spacings of 1.402–1.461 nm for Mg2Al–M(edta) LDH and 1.254 nm for Mg3Al–Zn(edta) LDH can be ascribed to bilayer and monolayer arrangements, respectively, of the [M(edta)]2– anion. When the Mg/Al ratio is varied in the range 2.2–2.7 the two guest arrangements coexist. The evolution of the interlayer arrangement of [M(edta)]2– in LDHs with increasing temperature was studied by variable‐temperature in‐situ XRD measurements, variable‐temperature in‐situ FT‐IR, and combined thermogravimetric analysis and mass spectrometry (TGA‐MS). In the case of Mg2Al–M(edta) LDH, a metastable phase with a similar monolayer structure to that found in Mg3Al–M(edta) LDH was detected by XRD in the range 140–300 °C. Cooling of the calcined solid to room temperature in air leads to the recovery of the original bilayer structure. The reversible nature of the structural transformation indicates that a reorientation of the guest [M(edta)]2– complex in the interlayer galleries occurs on heating, rather than a grafting process. Heat treatment of Mg3Al–M(edta) LDH results only in a gradual contraction of the basal spacing associated with the loss of interlayer water without any reorientation of the guest [M(edta)]2– complex. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)