The purpose of this work was development and application of the purification system suitable for the treatment of the acid mine drainage (AMD) accumulated in the "Robule" Lake, which represents the part of the Bor copper mining and smelting complex, Serbia. The study was undertaken in order to minimize adverse ...

A one-dimensional iron(ii) coordination polymer, [Fe(3)(hpdc)(2)(H(2)O)(6)]·2H(2)O (H(3)hpdc = 2-hydroxypyrimidine-4,6-dicarboxylic acid) has been synthesized and characterized. The compound exhibits field-induced two-step magnetic phase transitions and a coexistence of spin-canting and metamagnetism, and undergoes a structural transformation from single-crystalline to amorphous state upon dehydration, accompanied by significantly enhanced spontaneous magnetization and critical ...

Uptake and molecular speciation of dissolved Hg during formation of Al- or Fe-ettringite-type and high-pH phases were investigated in co-precipitation and sorption experiments of sulfate-cement treatments used for soil and sediment remediation. Ettringite and minor gypsum were identified by XRD as primary phases in Al systems, whereas gypsum and ferrihydrite ...

Reactions of iron, silicon, and R = Gd, Dy, or Y in 1:1 Mg/Al mixed flux produce well-formed crystals of R(5)Mg(5)Fe(4)Al(x)Si(18-x) (x ≈ 12). These phases have a new structure type in tetragonal space group P4/mmm (a = 11.655(2) Å, c = 4.0668(8) Å, Z = 1 and R(1) = ...

A strain of Klebsiella oxytoca, isolated from acid pyrite-mine drainage, characteristically produces a ferric hydrogel, consisting of branched heptasaccharide repeating units exopolysaccharide (EPS), with metal content of 36 wt%. The high content of iron in the EPS matrix cannot be explained by a simple ferric ion bond to the sugar ...

In the iron(II)-thiolate models of cysteine dioxygenase, the thiolate ligand is a key factor in the oxygen activation. In this contribution, four model compounds have been theoretically investigated. This comparative study reveals that the thiolate ligand itself and its relative position are both important for the activation of O2. Before ...

Chromate mobility, reactivity, and bioavailability in soil environments are affected by adsorption reactions on iron oxide minerals, but the adsorption mechanisms remain controversial. In this study, we employed in situ attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and theoretical frequency calculations to characterize chromate adsorption on 2-line ferrihydrite. The ...

A simple method is presented to synthesize asymmetric mixed ligand iron(ii) diimine complexes using bipyridinyl functionalized carbon nanotubes. The synthesis of these complexes was realized using subsequent dip coating processes. The in situ formed mixed ligand complexes were used in aqueous media to act as building blocks in biosensor devices.

Dialuminiummacrocycles based on bisglyoximato moieties were prepared and their coordination chemistry with Fe(II) and Pd(II) was investigated. The bridging aluminium centers were supported by several types of tetradentate diphenoxide diamine ligands. The nature of the ancillary ligands bound to aluminium was found to affect the overall geometry and symmetry of ...

High-aspect-ratio Fe(1-x)Mn(x)Si nanowires with room-temperature ferromagnetism were synthesized by a chemical vapor deposition (CVD) method in one step. This is the first report of ternary silicide nanowires using magnetic Mn ions to partially replace metal sites in the host matrix. Here we report the excellent magnetic characteristics of Fe(1-x)Mn(x)Si nanowires, ...

Fe(II) complexes containing the fluorinated ligand 1,2-bis(perfluorophenyl)ethane-1,2-dionedioxime (dAr(F)gH(2); H = dissociable proton) exhibit relatively positive Fe(II/I) reduction potentials. The air-stable difluoroborated species [(dAr(F)gBF(2))(2)Fe(py)(2)] (2) electrocatalyzes H(2) generation at -0.9 V vs SCE with i(cat)/i(p) ≈ 4, corresponding to a turnover frequency (TOF) of ∼20 s(-1) [Faradaic yield (FY) = 82 ...

Several nonheme iron enzymes and biomimetic model complexes catalyze a substrate halogenation reaction. Recent computational studies (Borowski et al. J Am Chem Soc 132:12887-12898, 2010) on α-ketoglutarate dependent halogenase proposed an initial isomerization reaction that is important to give halogenated products. We present here a series of density functional theory ...

Iron(II) efficiency: The iron complexes of N(4) ligands, derived from proline and benzimidazole, exhibited an unprecedented activity and enantioselectivity for the epoxidation of a variety of di- and trisubstituted enones. This system, based on synthetic non-heme iron catalysts, provides ready access to a wide range of epoxyketones of high enantiomeric ...

Accurate sex assignment of ancient human remains usually relies on the availability of coxal bones or well-preserved DNA. Iron (Fe) and copper (Cu) stable isotope compositions ((56) Fe/(54) Fe and (65) Cu/(63) Cu, respectively) were recently measured in modern human blood, and an unexpected result was the discovery of a ...

The reaction between magnetite and aqueous Fe(2+) has been extensively studied due to its role in contaminant reduction, trace-metal sequestration, and microbial respiration. Previous work has demonstrated that the reaction of Fe(2+) with magnetite (Fe(3)O(4)) results in the structural incorporation of Fe(2+) and an increase in the bulk Fe(2+) content ...

ABSTRACT: The non-heme iron enzyme cysteine dioxygenase (CDO) catalyzes the S-oxygenation of cysteine by O2 to cysteine sulfinic acid. The synthesis of a new structural and functional mod-el of the cysteine-bound CDO active site, [FeII(N3PyS)(CH3CN)]BF4 (1) is reported. This complex is pre-pared with a new facially chelating 4N/1S(thiolate) pentadentate ligand. ...

Magnesium silylamide complexes Mg[N(SiHMe(2))(2)](2)(THF)(2) and Mg[N(SiPhMe(2))(2)](2) were synthesized according to transsilylamination and alkane elimination protocols, respectively, utilizing Mg[N(SiMe(3))(2)](2)(THF)(2) and [Mg(n-Bu)](2) as precursors. Cage-like periodic mesoporous silica SBA-1 was treated with donor solvent-free dimeric [Mg{N(SiHMe(2))(2)}(2)](2), [Mg{N(SiMe(3))(2)}(2)](2) and monomeric Mg[N(SiPhMe(2))(2)](2), producing hybrid materials [Mg(NR(2))(2)]@SBA-1 with magnesium located mainly at the external surface. ...

Combined spectroscopic (UV/visible, MS and EPR), electrochemical (CV) and theoretical approaches were used to evaluate the relevant interactions of morin and quercetin, as well as their respective iron(iii) complexes with DPPH, tempone, hydroxyl and superoxide radicals. The results on iron complexation specify the stoichiometry and the relevant structural forms entering ...

High-spin FeIV-oxo species are known to be kinetically competent oxidants in non-heme iron enzymes. The properties of this oxidant are not as well understood as the corresponding intermediate-spin oxidant of heme complexes. The present work gives a detailed characterization of the structurally similar [Fe(IV)H3buea(O)]-, [Fe(III)H3buea(O)]2- and [Fe(III)H3buea(OH)]- (H3buea = tris[(N'-tert-butylureaylato)-N-ethylene]aminato) ...

Bond cleavage: An iron(II)-α-hydroxy ketone complex of a facial tridentate nitrogen donor ligand undergoes a CC bond cleavage reaction in the presence of dioxygen to form two equivalents of carboxylic acids. This reaction is a functional model of 2,4'-dihydroxyacetophenone dioxygenase.

C(2) +N(1) : The transition-metal-catalyzed reaction of alkenes with azides is an important tool for the formation of aziridines. Besides many recently published ruthenium, copper, and manganese catalysts, a novel macrocyclic tetracarbene iron(II) catalyst promotes the synthesis of aziridines in good yields and with low catalyst loadings.

Friedreich's ataxia (FRDA) causes selective atrophy of the large neurons of the dentate nucleus (DN). High iron (Fe) concentration and failure to clear the metal from the affected brain tissue are potential risk factors in the progression of the lesion. The DN also contains relatively high amounts of copper (Cu) ...

Reaction of tris(5-amino-2-ethoxy-3-isopropylphenyl)methane and pyridine-2,6-dicarbonyl-dichloride affords a multi-dentate cryptand in 48% yield. Metallation with iron(iii) chloride results in a substantial conformational change of this ligand to give a trianionic triiron(iii) complex. Ferric cations line the periphery of the internal cavity with each adopting a square pyramidal N(3)Cl(2) coordination environment.

Aliphatic aldoxime dehydratase (Oxd) catalyzes the dehydration of aliphatic aldoximes (R-CH═N-OH) to the corresponding nitriles (R-C≡N). Quantum mechanics/molecular mechanics (QM/MM) calculations are performed to elucidate the catalytic mechanism of the enzyme on the basis of the X-ray crystal structure of the Michaelis complex. On the basis of the calculations, we ...

We report on the synthesis of eleven pentameric cyclic helicates formed by imine condensation of alkyl monoamines with a common bis(formylpyridine)-bipyridyl-derived building block and iron(II) and chloride ions. The cyclic double helicates were characterized by NMR spectroscopy, mass spectrometry and, in the case of a 2,4-dimethoxybenzylamine-derived pen-tameric cyclic helicate, X-ray ...

Nanoscale metal fluorides are promising candidates for high capacity lithium ion batteries, in which a conversion reaction upon exposure to Li ions enables access to the multiple valence states of the metal cation. However, little is known about the molecular mechanisms and the reaction pathways in conversion that relate to ...

HemAT from Bacillus subtilis (HemAT-Bs) is a heme-containing O(2) sensor protein that acts as a chemotactic signal transducer. Binding of O(2) to the heme in the sensor domain of HemAT-Bs induces a conformational change in the protein matrix, and this is transmitted to a signaling domain. To characterize the specific ...

Rechargeable lithium batteries have risen to prominence as key devices for green and sustainable energy development. Electric vehicles, which are not equipped with an internal combustion engine, have been launched in the market. Manganese- and iron-based positive-electrode materials, such as LiMn(2)O(4) and LiFePO(4), are used in large-scale batteries for electric ...

Only a small fraction of all available metals has been used as electrode materials for carbon-based devices due to metal-graphene interface debonding problems. We report an enhancement of the bonding energy of weakly interacting metals by using a metal-graphene-metal sandwich geometry, without sacrificing the intrinsic π-electron dispersions of graphene that ...

The defined Fe hydride complex FeH(CO)(NO)(Ph(3)P)(2) is highly active as a catalyst for selective hydrosilylation of internal alkynes to vinylsilanes. Depending on the silane employed either E- or Z-selective hydrosilylation products were formed in excellent yields and good to excellent stereoselectivities.

A new {Fe(NO)(2)}(10) dinitrosyl iron complex possessing a 2,9-dimethyl-1,10-phenanthroline ligand has been prepared. This complex exhibits dioxygenase activity, converting NO to nitrate (NO(3)(-)) anions. During the oxygenation reaction, formation of reactive nitrating species is implicated, as shown in the effective o-nitration with a phenolic substrate.

Photo opportunity: A highly efficient and stable hybrid artificial photosynthetic H(2) evolution system is assembled by using a semiconductor (ZnS) as light-harvester and an [Fe(2) S(2) ] hydrogenase mimic ([(μ-SPh-4-NH(2) )(2) Fe(2) (CO)(6) ]) as catalyst for H(2) evolution. Photocatalytic H(2) production is achieved with more than 2607 turnovers (based ...

ETHNOPHARMACOLOGICAL RELEVANCE: Lauha bhasma (iron ash) is one of the iron-based herbo-metallic preparations used in Ayurvedic medicine for treating various ailments due to iron deficiency. MATERIALS AND METHODS: The preparation of Lauha bhasma (iron ash) requires normal purification (heat treatment in vegetable and animal products), special purification (treatment with herbal ...

An iron(II) complex with a pyridine-containing 14-membered macrocyclic (PyMAC) ligand L1 (L1 = 2,7,12-trimethyl-3,7,11,17-tetra-azabicyclo[11.3.1]heptadeca-1(17),13,15-triene), 1, was prepared and characterized. Complex 1 contains low-spin iron(II) in a pseudo-octahedral geometry as determined by X-ray crystallography. Magnetic susceptibility measurements (298 K, Evans method) and Mössbauer spectroscopy (90 K, δ = 0.50(2) mm/s, ΔE(Q) ...

In the centrosymmetric dimeric title complex, [Fe(2)(C(14)H(10)N(2)O(4))(2)Cl(2)(C(2)H(6)OS)(2)]·2C(2)H(6)OS, two {Fe(L)Cl(DMSO)} units (L is the tridentate ligand 4-nitro-2-{[2-(oxidometh-yl)phen-yl]imino-meth-yl}phenolate; DMSO is dimethyl sulfoxide) are bridged by two O atoms, with an Fe⋯Fe separation of 3.1838 (8) Å. The coordination polyhedron of the Fe(III) atoms can be described as distorted octa-hedral, with four Fe-O, one Fe-N ...

The title compound, Mn(4)(H(2)O)(4)[Ge(OH)(2)(HPO(4))(2)(PO(4))(2)], was synthesized by the solvothermal method. Its crystal structure is isotypic with the iron and cobalt analogues [Huang et al. (2012 ▶). Inorg. Chem.51, 3316-3323]. In the crystal structure, the framework is built from undulating manganese phosphate sheets parallel to (010) inter-connected by GeO(6) octa-hedra (at ...

The present study focuses on the formation and reactivity of hydroperoxo-iron(III) porphyrin complexes formed in the [Fe(III) (tpfpp)X]/H(2) O(2) /HOO(-) system (TPFPP=5,10,15,20-tetrakis(pentafluorophenyl)-21H,23H-porphyrin; X=Cl(-) or CF(3) SO(3) (-) ) in acetonitrile under basic conditions at -15 °C. Depending on the selected reaction conditions and the active form of the catalyst, the formation ...

The new, structurally characterized hydrido carbonyl tetrahydridoborate iron pincer complex [(iPr-PNP)Fe(H)(CO)(η(1) -BH(4) )] (1) catalyzes the base-free hydrogenation of ketones to their corresponding alcohols employing only 4.1 atm hydrogen pressure. Turnover numbers up to 1980 at complete conversion of ketone were reached with this system. Treatment of 1 with aniline (as ...

SrCo(0.8)Fe(0.2)O(3-δ) is a controversial material whether it is used as an oxygen permeable membrane or as a cathode of solid oxide fuel cells. In this paper, carefully synthesized powders of perovskite-type Sr(x)Co(0.8)Fe(0.2)O(3-δ) (x = 0.80-1.20) oxides are utilized to investigate the effect of A-site nonstoichiometry on their electrochemical performance. The ...

Parameters that influence the zero valent iron mediated degradation of the pharmaceutical diazepam (DZP) were evaluated including the iron concentration and its pre-treatment, the effect of complexation with EDTA and oxic versus anoxic condition. It was observed that acid pre-treatment of iron particles is important for degradation efficiency and that ...

Understanding the interaction of a protein with a relevant ligand is crucial for the design of an artificial metalloenzyme. Our own interest is focused on the synthesis of artificial monooxygenases. In an initial effort, we have used the periplasmic nickel-binding protein NikA from Escherichia coli and iron complexes in which ...

The studies described herein focus on the 1,3-dipolar cycloaddition reaction between first-row transition metal-azide complexes and alkyne reagents, i.e. an inorganic variant of the extensively used "click reaction". The reaction between the azide complexes of biologically-relevant metals (e.g., Fe, Co and Ni) found in metalloenzyme active sites and alkyne reagents ...

The first high-valent iron oxo complex on the phthalocyanine platform has been prepared from iron tetra-tert-butyl-phthalocyanine and m-chloroperbenzoic acid and characterized by low temperature UV-vis, cryospray MS, EPR, X-ray absorption and high resolution X-ray emission methods.

A general comparison of fundamental distinctions between the FeO(2+) and FeS(2+) complexes in an identical cyanide or isocyanide ligand environment for methane hydroxylation has been probed computationally in this work in a series of hypothetical [Fe(IV) (X)(CN)(5) ](3-) , [Fe(IV) (X)(NC)(5) ](3-) , (X = O, S) complexes. We have ...

An Fe(IV) O group meets with H(2) O(2) ! Reaction of high-valent iron with the reactive oxygen species (ROS) hydrogen peroxide (H(2) O(2) ) is in general reserved for heme centers. Employing a biomimetic metal complex, the direct reaction of a mononuclear nonheme oxoiron(IV) species with H(2) O(2) was observed ...

Simple cationic sandwich complexes that contained alkyl- or halogen substituents provided ionic liquids (ILs) with the bis(perfluoroalkanesulfonyl)imide anion. Ferrocenium- and cobaltocenium ILs [M(C(5) H(4) R(1) )(C(5) H(4) R(2) )][Tf(2) N] (M=Fe, Co) and arene-ferrocenium ILs [Fe(C(5) H(4) R(1) )(C(6) H(5) R(2) )][Tf(2) N] were prepared and their physical properties were ...

The impact of oxidative stress on mobilization of endogenous retroviruses and their effects on cell fate is unknown. We investigated the action of H(2)O(2) on retrotransposition of an EGFP-tagged mouse LTR-retrotransposon, VL30, in an NIH3T3 cell-retrotransposition assay. H(2)O(2) treatment of assay cells caused specific retrotranspositions documented by UV microscopy and ...

The center of attention: IscS cysteine desulfurases and IscU scaffolds are involved in biological iron-sulfur cluster assembly. The X-ray structure of an anaerobically produced, mutated (Fe(2) S(2) -(IscS-IscU(D35A) ))(2) complex reveals a cluster coordinated by three IscU cysteines and the IscS active cysteine. In air-exposed crystals the cluster is oxidized ...

In the title compound, [Fe(C(23)H(21)O(2))(2)(C(5)H(8)N(2))(2)]·CH(2)Cl(2), the Fe(2+) cation is coordinated by the N atoms of two 3,5-dimethyl-pyrazole ligands and the carboxyl-ate O atoms from two tetra-methyl-terphenyl-carboxyl-ate ligands, forming an FeN(2)O(2) polyhedron with a slightly distorted tetra-hedral coordination geometry. Intra-molecular N-H⋯O and C-H⋯O hydrogen-bonding inter-actions stabilize the mol-ecular conformation. The dihedral ...

Several chemical elements are required by living organisms in addition to the four elements carbon, hydrogen, nitrogen and oxygen usually present in common organic molecules. Many metals (e.g. sodium, potassium, magnesium, calcium, iron, zinc, copper, manganese, chromium, molybdenum and selenium) are known to be required for normal biological functions in ...