Nitrilotriacetate Ligand Research Articles

Uranium sorption by native and nitrilotriacetate-modified Bangia atropurpurea biomass: kinetics and thermodynamics

In this study, the red alga Bangia atropurpurea was modified with nitrilotriacetate (NTA) ligand and used for removal of U(VI) ions from aqueous solution using native form as a control system. The modification of B. atropurpurea biomass was realized by sequential treatment of algal biomass with glutaraldehyde and NTA ligand. Influence of U(VI) sorption parameters, such as contact time, adsorbent amount, medium pH and ionic strength, initial U(VI) ions concentration, and temperature on the removal performance of both algal biomasses were studied from aqueous solution. The hydroxyl, amino, carbonyl, and carboxyl groups were the main adsorptive groups of the biomasses as observed in FTIR data, and these groups can bind to U(VI) ions via electrostatic interactions. More than 78% of total sorption took place within 40 min, and equilibrium was established about 60 min. Maximum sorption capacities of the native and NTA-modified algal biomasses were found to be 190.2 and 328.8 mg g−1, respectively, at pH 5.5 and at 30 °C. The presence of other ionic species slightly decreased the U(VI) sorption capacity except that in Fe(III) ions. The sorption processes of U(VI) on the algal biomasses were described by the Langmuir and Temkin isotherms and pseudo-second-order kinetic models. The thermodynamic parameters, such as ΔH°, ΔS°, and ΔG°, show that the process is exothermic and spontaneous. It should be stated that the NTA-modified algal biomass has a high potential for the removal of U(VI) ions from aqueous solution.

High-Resolution Imaging and Multiparametric Characterization of Native Membranes by Combining Confocal Microscopy and an Atomic Force Microscopy-Based Toolbox.

To understand how membrane proteins function requires characterizing their structure, assembly, and inter- and intramolecular interactions in physiologically relevant conditions. Conventionally, such multiparametric insight is revealed by applying different biophysical methods. Here we introduce the combination of confocal microscopy, force-distance curve-based (FD-based) atomic force microscopy (AFM), and single-molecule force spectroscopy (SMFS) for the identification of native membranes and the subsequent multiparametric analysis of their membrane proteins. As a well-studied model system, we use native purple membrane from Halobacterium salinarum, whose membrane protein bacteriorhodopsin was His-tagged to bind nitrilotriacetate (NTA) ligands. First, by confocal microscopy we localize the extracellular and cytoplasmic surfaces of purple membrane. Then, we apply AFM to image single bacteriorhodopsins approaching sub-nanometer resolution. Afterwards, the binding of NTA ligands to bacteriorhodopsins is localized and quantified by FD-based AFM. Finally, we apply AFM-based SMFS to characterize the (un)folding of the membrane protein and to structurally map inter- and intramolecular interactions. The multimethodological approach is generally applicable to characterize biological membranes and membrane proteins at physiologically relevant conditions.

Oriented Protein Immobilization using Covalent and Noncovalent Chemistry on a Thiol-Reactive Self-Reporting Surface

We report the fabrication of a patterned protein array using three orthogonal methods of immobilization that are detected exploiting a fluorogenic surface. Upon reaction of thiols, the fluorogenic tether reports the bond formation by an instantaneous rise in (blue) fluorescence intensity providing a means to visualize the immobilization even of nonfluorescent biomolecules. First, the covalent, oriented immobilization of a visible fluorescent protein (TFP) modified to display a single cysteine residue was detected. Colocalization of the fluorescence of the immobilized TFP and the fluorogenic group provided a direct tool to distinguish covalent bond formation from physisorption of proteins. Subsequent orthogonal immobilization of thiol-functionalized biomolecules could be conveniently detected by fluorescence microscopy using the fluorogenic surface. A thiol-modified nitrilotriacetate ligand was immobilized for binding of hexahistidine-tagged red-fluorescing TagRFP, while an appropriately modified biotin was immobilized for binding of Cy5-labeled streptavidin.

Synthesis, structural characterization, magnetic and EPR studies of heterometallic Cu2Cr2 and Cu2Ga2 complexes

Two heterometallic complexes [{Cu(phen)2}2{Cr2(μ-OH)2(nta)2}][Cr2(μ-OH)2(nta)2]·8H2O (I) and [{Cu(phen)2}2{Ga2(μ-OH)2(nta)2}][Ga2(μ-OH)2(nta)2]·dmf·16H2O (III), where nta is the nitrilotriacetate ligand and dmf is dimethylfomamide, phen is ο,ο′-phenanthroline, have been prepared and structurally characterized by single-crystal X-ray crystallography. Both compounds display an ionic type structure, with close geometric parameters, containing {Cr2(μ-OH)2(nta)2} and {Ga2(μ-OH)2(nta)2} entyties for I and III, respectively. These dimeric di-μ-hydroxy units exhibit different coordination functions. In the tetranuclear Cu2Cr2 and Cu2Ga2 complex cations they are involved in a bidentate bridging form being linked to the cooper atoms through two symmetrically related oxygen atoms of the carboxylate groups. The anionic forms [Cr2(μ-OH)2(nta)2]2− and [Ga2(μ-OH)2(nta)2]2− are non-coordinating and only involved in a multiple hydrogen bonds architecture.Comparative analysis of the temperature dependence of EPR spectrum and magnetic susceptibility of compound I and III, showed that the magnetic properties of tetranuclear cluster [{Cu(phen)}2Cr2(OH)2(nta)2] are dominated by strong antiferromagnetic interaction between chromium ions (JisoCrCr=−13.4cm−1). The interaction between chromium(III) and copper(II) ions via syn–anti carboxylic groups has a small antiferromagnetic values (JisoCrCu=−0.23cm−1). The small anisotropy of the exchange interaction between chromium ions manifests itself only in the EPR spectra.

Bis(tetraphenylarsonium) di-μ-hydroxido-bis[(nitrilotriacetato)cobalt(III)] octahydrate

In the title compound, (C24H20As)2[Co2(C6H6NO6)2(OH)2]·8H2O, the CoIII atom in the binuclear centrosymmetric anion is octa­hedrally surrounded by one N atom and three O atoms of the tetra­dentate nitrilo­triacetate ligand and two μ-hydroxide ligands. The crystal packing is controlled by C—H⋯O and O—H⋯O hydrogen-bonding inter­actions. The crystal employed in this study proved to be a two-component twin around (01).

Two novel molybdenum complexes containing [Mo2O2S2]2+ fragment: synthesis, crystal structures and catalytic studies

AbstractMo2O2S2(HGly)(Gly)2 1 and K6[Mo2O2S2(nta)2][Mo2O2S2(ntaH)2]·4H2O 2 were synthesized by the reactions of (NH4)2MoS4 and amino acids L (L = glycine, nitrilotriacetic acid) in ethanol–water medium at ambient temperature. The two complexes were characterized by elemental analysis, infrared spectra, UV–visible spectra, TG–DTA and XPS. X‐ray crystallographic structural analyses revealed that compound 1 is a binuclear MoSglycinate complex, a glycinate ligand is coordinated to each molybdenum atom through its amine nitrogen and carboxylato oxygen, respectively, and the third glycinate acts as a bridge through its two carboxylato oxygens linking the two molybdenum atoms. Compound 2 is also a binuclear MoS complex with two nitrilotriacetate ligands, each of which is coordinated to a molybdenum atom via its two β‐carboxylato oxygens and a nitrogen atom. Simultaneously, each molybdenum atom in 1 and 2 is chelated to a terminal oxygen and two bridging sulfurs to complete the octahedral configuration. Their catalytic activities in the reduction from C2H2 to C2H4 as well as other binuclear MoSpolycarboxylate complexes, a [Fe4S4] single cubane and a chainlike MoFeS compound were investigated and it was found that 1 exhibited relatively good catalytic activity. Copyright © 2007 John Wiley & Sons, Ltd.

PH Dependent formations of dinuclear molybdenum(V) and incomplete cubane molybdenum(IV) complexes with nitrilotriacetate

Nitrilotriacetato oxomolybdenum(V) dinuclear complex (NH 4) 4[ cis-Mo 2O 4(nta) 2] · 7H 2O ( 1) (H 3nta = nitrilotriacetic acid) and its incomplete cubane-type trinuclear molybdenum(IV) complex [Mo 3O(OH) 3(Hnta) 3] · Cl · 3H 2O ( 2) are isolated in a weak acidic and an acidic solutions, respectively (pH 4.5 and 1.0). The nitrilotriacetate ligand in the anion 1 or the cation 2 displays tridentate mode through the nitrogen atom and the oxygen atoms of β-carboxy groups. Unusual protonations of bridged oxygen atoms in 2 have not effect on the skeleton of molybdenum(IV) cap Mo 3O unit. There are obvious dissociations of molybdenum(V) complexes based on 13C NMR observations in solution.

Uranyl ion complexation by the tripodal ligand nitrilotriacetate

Reaction of uranyl nitrate with N-(2-acetamido)iminodiacetic acid (ADA) under hydrothermal conditions resulted in the hydrolysis of the amide group and the isolation of the complex [(UO2)(HNTA)(H2O)2], in which each nitrilotriacetate ligand, protonated at the N site, bridges three metal atoms to give rise to infinite ladder-like ribbons built from 2:2 metallacycles.

PH dependent transformation of nitrilotriacetato molybdates (VI) – Synthesis, spectral and structural characterization

Investigation on the aqueous coordination chemistry of nitrilotriacetato molybdate (VI) resulted in the isolation of molybdenum(VI) nitrilotriacetato complexes Na 6 n {[Mo 2O 5(ntaH) 2][(nta) 2Mo 2O 5]} n · 12 nH 2O ( 1) and (NH 4) 3 n [Mo 2O 5H(nta) 2] n · 4 nH 2O ( 2) (H 3nta = nitrilotriacetic acid). The complexes have been characterized by elemental analyses, IR, NMR spectroscopies and X-ray structural analyses. The anions of complexes 1 and 2 contain a linear (O 2Mo)O(MoO 2) core with the bridging oxo group lying at a center of symmetry. Each molybdenum atom is octahedrally coordinated by two terminal oxo groups, a bridging oxygen and a tridentate nitrilotriacetate ligand, which binds through the nitrogen atom and two μ-O carboxylates, while the other carboxylate remains free. Strong hydrogen bonds are found to exist in the two complexes. This is supported by IR and NMR spectra, and revealed by single crystal X-ray analysis. The complexes 1 and 2 show obvious decomposition in solution based on 13C NMR observations.

Synthesis and Structure of a Neodymium Complex with the Nitrilotriacetate Ligand: [NdIII(nta)]n

AbstractA neodymium complex, [Nd(nta)]n (1) (H3nta = nitrilotriacetic acid) was synthesized and characterized by X‐ray diffraction analysis. Compound 1 exhibits a three‐dimensional network, in which the NdIII ion is coordinated by one nitrogen atom and seven carboxyl oxygen atoms with dodecahedral coordination. One striking feature is that in the Nd coordination center there is no water ligand found.

Crystal Structures and Luminescence Properties of [Ln(NTA)2·H2O]3-Complexes (Ln = Sm3+, Eu+3, Gd3+, Tb3+, Ho3+, and NTA = Nitrilotriacetate)

Crystal structures of lanthanide complexes with NTA (NTA = nitrilotriacetate) are reported. The complexes of <TEX>$[Ln(NTA)_2{\cdot}H_2O]^{3-}$</TEX> (Ln = Sm, Eu, Gd, Tb and Ho) crystallize in the orthorhombic space group Pccn. In the structures, the trivalent lanthanide ions are completely encapsulated via coordination to the two nitrogen atoms and the six carboxylate oxygen atoms of the two NTA ligands, and one water oxygen atoms. The complexes form a slightly distorted capped-square-antiprism polyhedron. Of the complexes, <TEX>$[Eu(NTA)_2{\codt}H_2O]^{3-}$</TEX>,\;[Tb(NTA)_2{\cdot}H_2O]^{3-}\;and\;[Dy(NTA)_2{\cdot}H_2O]^{3-}$</TEX> excited at the 325 He-Cd line produce very characteristic luminescence features, arising mostly from the f <TEX>${\to}$</TEX> f transitions. The absolute quantum yields of these complexes are determined at room temperature. Surprisingly, the <TEX>$[Dy(NTA)_2{\cdot}H_2O]^{3-}$</TEX> complex is more luminescent than the <TEX>$[Eu(NTA)_2{\cdot}H_2O]^{3-}\;and\;[Tb(NTA)_2{\cdot}H_2O]^{3-}$</TEX> complexes.

Polymeric aqua(nitrilotriacetato)erbium(III)

In the structure of the title compound, [Er(C(6)H(6)NO(6))(H(2)O)](n), the Er atoms are eight-coordinated by one N atom and six O atoms from three symmetry-related nitrilotriacetate (NTA) ligands, and by one O atom of a water molecule, adopting a distorted square-antiprismatic geometry. The Er atoms are linked by the NTA ligands into layers, which are interconnected via O-H.O hydrogen bonds between the water molecules and the carboxylate O atoms. The asymmetric unit contains one Er atom, one NTA ligand and one water molecule, all of which are located in general positions.

Sodium (nitrilotriacetato)magnesate pentahydrate

In the title compound, triaqua-μ-nitrilotriacetato-magnesiumsodium dihydrate, [MgNa(C 6 H 6 NO 6 )(H 2 O) 3 ].2H 2 O, a nitrilotriacetate ligand chelates one Mg atom via three Mg-O bonds and one Mg-N bond. Each ligand also binds to two Na atoms and another Mg atom such that an infinite layer of stoichiometry MgNa(C 6 H 6 NO 6 )(H 2 O) 3 is formed. Adjacent layers are bound via hydrogen bonds with two interlayer water molecules.

Adsorption of Nitrilotriacetate (NTA), Co and CoNTA By Gibbsite

AbstractAdsorption of Co2+ nitrilotriacetic acid (NTA) and equal-molar Co2+ and NTA by a low surface area (LSA) commercial gibbsite (3.5 m2 g−1) was investigated in batch as a function of pH (4.5 to 10.5), adsorbate (0.5 to 10 µM) and adsorbent (0.5 to 75 g L−1) concentrations and ionic strength (0.01 to 1 M NaClO4). The adsorption of Co2+ (Co-only) and the acid form of NTA (NTA-only) by gibbsite in 0.01 M NaClO4 exhibit cation-like and anion-like adsorption edges, respectively. For the equal-molar CoNTA chelate, Co and NTA adsorption edges were similar but not identical to the Co-only and NTA-only edges. Differences suggest the existence of a ternary CoNTA surface complex with the Co in the intact chelate coordinated to surface hydroxyls. NTA-only adsorption was insensitive to ionic strength variation, indicating weak electrostatic contributions to surface coordination reactions. This is consistent with the formation of inner-sphere surface NTA complexes and ligand exchange reactions in which monodentate, bidentate and binuclear NTA surface complexes form. Cobalt adsorption increases (edge shifts to lower pH by 1 pH unit) on LSA gibbsite as ionic strength increases from 0.01 to 1 M NaClO4. For the same ionic strength change, a similar shift in the Co-only edge was observed for another commercial gibbsite (16.8 m2 g−1); however, no change was observed for δ-Al2O3. Ionic strength shifts in Co2+ adsorption by gibbsite were described as an outer-sphere CoOH+ surface complex using the triple-layer model. Results suggest that, at waste disposal sites where 60Co and NTA have been co-disposed, NTA will not promote ligand-like adsorption of Co for acid conditions, but will reduce cation-like adsorption for basic conditions. Thus, where gibbsite is the dominant mineral sorbent, NTA will not alter 60Co mobility in acidic pore waters and groundwaters; however, NTA could enhance 60Co mobility where alkaline conditions prevail, unless microbial degradation of the NTA occurs.

Transferrin, a mechanism for the holoprotein formation from nitrilotriacetato-Fe(III)-transferrin mixed complex

Holotransferrin formation from the mixed transferrin-nitrilotriacetatoFe(III) iron complex (THFeL) in the presence of carbonate has been investigated between pH 6.5 and 8.5. Both C- and N-sites seem equivalent towards the interaction with bicarbonate. Bicarbonate interacts with THFeL to yield a new mixed complex, T’H2FeL; apparent rate constant, 2.25 s-1. T’H2FeL, then, loses two protons and the nitrilotriacetate ligand to yield the holoprotein, T’Fe; the two protons dissociation constant, Ka = 4.35 X 10-15 M2. This is accompanied by a gain of about ten orders of magnitude in the stability of the iron-protein complex and can be of interest for a better understanding of iron-uptake by the protein in natural media.

Synthesis, spectrum and single crystal structure of a peroxovanadium complex of nitrilotriacetate ligand without water of crystallization, K 2[VO(O 2)NTA

Crystals of the formula K 2[VO(O 2)NTA] with NTA = nitrilotriacetate have been prepared and characterized by IR and single-crystal X-ray diffraction methods. The structure of the anion of the complex shows that the vanadium atom has a distorted pentagonal bipyramidal environment surrounded by one oxo group, one peroxo group, three oxygen atoms and one nitrogen atom from the NTA ligand.

Structure of dipotassium (nitrilo-κN-triacetato-κ3O,O'',O'''')oxoperoxovanadate(V)–water (1/2)

K 2 [V(C 6 H 6 NO 6 )O(O 2 )].2H 2 O, M r =401.28, orthorhombic, Pnam, a=7.597 (5), b=12.951 (3), c=13.131 (5) A, V=1291.9 (1) A 3 , Z=4, D x =2.06 g cm -3 , λ(Mo Kα)=0.71069 A, μ=14.4 cm -1 , F(000)=808, T=295 K, R=0.019 for 1820 unique reflections. Vanadium is surrounded by a sevenmembered coordinating pentagonal bipyramid formed by a tetradentate nitrilotriacetate ligand, a bidentate peroxo group and a vanadyl oxygen. The bipyramid is symmetrical relative to the mirror plane passing through the V atom, the apical O atoms, the equatorial N atom and the midpoint between the peroxo O atoms. The nitrilotriacetate ligand forms three glycinate rings with the V atom, one of which coincides with the mirror plane, the two others being symmetrical relative to the plane

Crystal and molecular structure of a new µ-oxo-bridged iron(III) dimer formed with the nitrilotriacetate ligand

The molecular structure of the oxo-bridged dimer barium µ-oxo-bis{aqua[nitrilo-κN-triacetato(3–)-κ3O,O′,O″]ferrate(1–)}–water(1/4), Ba[{Fe(nta)(H2O)}2O]·4H2O, which has an Fe–O–Fe angle of 153.2(6)° has been determined by X-ray crystallography. The iron ions are six-co-ordinate with one tetradentate nta ligand and one water molecule completing the co-ordination sphere. The relationship of this compound to other iron–nta complexes is discussed in the context of the hydrolysis reactions of iron(III) in aqueous solutions.

Structures of sodium zinc nitrilotriacetate monohydrate (173 K) and disodium hydrogen nitrilotriacetate (293 K)

NaZn(C6H6NO6).H20: Mr =29544, orthorhombic, P212121, a = 7.869 (4), b =9.783 (6), c = 12.292 (6) A,, V = 946-3 A, 3, Z = 4, Dx = 2.07 gcm -3, A (So Kc~) = 0.71073A,, /z=27.4cm -I Final R=0.052 for 859 unique reflections. The nitrilotriacetate ion is coordinated to the Zn 2+ ion in a tetradentate fashion. The remaining two octahedral sites about the Zn 2÷ ion are occupied by O atoms of different nitrilotriacetate ions. A comparison of the structure with other published structures identifies a common geometry, termed the 'butterfly' geometry, for transition-metal complexes with nitrilotriacetate ligands. The Na ÷ ions bridge the nitrilotriacetatozinc ions thereby holding the structure intact. The water molecule is coordinated to the five-coordinate Na ÷ ion. Na2(C6H7NO6): M, = 235-10, cubic, P213, a = 9-417 (2) ~, V = 835.1 A, 3, Z = 4, Dx = 1.87 g cm -3, A(Cu K6)= 1.54178 ~, p.=23.3 cm -l Final R = 0.034 for 208 unique reflections. The structure is the first observation of the zwitterionic form of the nitrilotriacetate ion as a tridentate chelating ion. The [C6H7NO6Na]- ions are linked together by a complex network of bridging Na ÷ ions. The differences in the coordination of the nitrilotriacetate ligand to the metal ions in these structures illustrate the versatile, multidentate chelating capabilities of the ligand.

Oxidation of first-row bivalent transition-metal complexes containing ethylenediaminetetra-acetate and nitrilotriacetate ligands by free radicals: a pulse-radiolysis study

The kinetics of reaction of OH radicals with the ligands (L) ethylenediaminetetra-acetate (edta) and nitrilotriacetate (nta), and their complexes [ML](M = ZnII, CuII, NiII, CoII, FeII, and MnII), have been studied. All these reactions have similar rate constants, although a hydrogen-abstraction reaction from the ligand is observed for the free ligands and their complexes with ZnII, MnII, and CoII. For [Co(edta)]2– a partial oxidation to [Co(edta)]– is observed. On the other hand, when M = NiII, CuII, or FeII the metal is oxidized by the OH radicals. The reasons for these observations are discussed in detail. The spectra, and kinetics of decomposition, of the unstable intermediates formed by the reactions of the OH radicals are reported and discussed. The reactions of nickel(III) complexes with I–, Br–, and O2 are reported. The kinetics of oxidation of the complexes (M = FeII, MnII, or CoII) by [O2]–·, ˙O2CH2CMe2OH, [Br2]–·, [(NCS)2]–·, and [I2]–·, the latter only with M = FeII, have also been studied. The kinetics indicate an inner-sphere mechanism for these reactions. The kinetics of hydrolysis of [MnIIIL(X)] and [CoIIIL(X)] thus formed are reported.