Iron Formate Research Articles

Synthesis and physicochemical properties of composites for electromagnetic shielding applications: a polymeric matrix impregnated with iron- or cobalt-containing nanoparticles

Magnetic, magnetic resonance, and structural properties of iron and cobalt nanoparticles embedded in a polyethylene matrix were studied. The materials were prepared by thermal decomposition of cobalt or iron formate in a polyethylene melt in mineral oil and contained from 2 to 40% wt. of metal. Transmission electron microscopy data indicate that the average diameter of particles is up to 8.0 nm. According to extended x-ray absorption fine structure and Mössbauer spectroscopy studies, the particles comprise a metallic core and nonmetallic shell which is chemically bound to the surrounding matrix. Electrophysical and magnetic properties of the materials prepared were studied along with their reflection and attenuation factors in the super high frequency band. The materials were found to be suitable for use in electromagnetic shielding.

The Role of Order–Disorder Transitions in the Quest for Molecular Multiferroics: Structural and Magnetic Neutron Studies of a Mixed Valence Iron(II)–Iron(III) Formate Framework

Neutron diffraction studies have been carried out to shed light on the unprecedented order-disorder phase transition (ca. 155 K) observed in the mixed-valence iron(II)-iron(III) formate framework compound [NH(2)(CH(3))(2)](n)[Fe(III)Fe(II)(HCOO)(6)](n). The crystal structure at 220 K was first determined from Laue diffraction data, then a second refinement at 175 K and the crystal structure determination in the low temperature phase at 45 K were done with data from the monochromatic high resolution single crystal diffractometer D19. The 45 K nuclear structure reveals that the phase transition is associated with the order-disorder of the dimethylammonium counterion that is weakly anchored in the cavities of the [Fe(III)Fe(II)(HCOO)(6)](n) framework. In the low-temperature phase, a change in space group from P31c to R3c occurs, involving a tripling of the c-axis due to the ordering of the dimethylammonium counterion. The occurrence of this nuclear phase transition is associated with an electric transition, from paraelectric to antiferroelectric. A combination of powder and single crystal neutron diffraction measurements below the magnetic order transition (ca. 37 K) has been used to determine unequivocally the magnetic structure of this Néel N-Type ferrimagnet, proving that the ferrimagnetic behavior is due to a noncompensation of the different Fe(II) and Fe(III) magnetic moments.

Sample handling and contamination encountered when coupling offline normal phase high performance liquid chromatography fraction collection of petroleum samples to Fourier transform ion cyclotron resonance mass spectrometry

Normal phase high performance liquid chromatography (HPLC) is used to separate a gas oil petroleum sample, and the fractions are collected offline and analyzed on a high resolution Fourier Transform Ion Cyclotron Resonance Mass Spectrometer (FT-ICR MS). The separation prior to MS analysis dilutes the sample significantly; therefore the fractions need to be prepared properly to achieve the best signal possible. The methods used to prepare the HPLC fractions for MS analysis are described, with emphasis placed on increasing the concentration of analyte species. The dilution effect also means that contamination in the MS spectra needs to be minimized. The contamination from molecular sieves, plastics, soap, etc. and interferences encountered during the offline fraction collection process are described and eliminated. A previously unreported MS contamination of iron formate clusters with a 0.8 mass defect in positive mode electrospray is also described. This interference resulted from the stainless steel tubing in the HPLC system. Contamination resulting from what has tentatively been assigned as palmitoylglycerol and stearoylglycerol was also observed; these compounds have not previously been reported as contaminant peaks.

Composite material based on iron-containing nanoparticles for applications in the problems of electromagnetic compatibility

The decomposition of iron formate is used to synthesize composite materials that represent ironcontaining nanoparticles localized in the high-pressure-polyethylene matrix with the concentration of the iron-containing component ranging from 10 to 40 wt %. The composition and structure of the materials are comprehensively analyzed using the transmission electron microscopy, X-ray phase analysis, Mossbauer spectroscopy, and electronic magnetic resonance. Electrophysical and magnetic properties of the synthesized materials and the coefficients of reflection and attenuation in the centimeter-wavelength range are studied. It is demonstrated that the composite materials can be used to provide electromagnetic compatibility, noise immunity, radio shielding, and protection of biological objects against electromagnetic radiation.

Preparation and properties of barium-ferrite-containing glass ceramic fibers via an electrospinning/sol–gel process

Barium-ferrite-containing glass ceramic fibers were successfully prepared by the combination of a sol–gel process and electrospinning technique using basic iron formate, barium acetate and boric acid as the starting materials. After leaching of barium borate matrix, pure phase BaFe12O19 fibers were obtained. The relationship of aged time and viscosity of the precursor solution was studied and the results showed that the viscosity corresponding to the spinnable state was 1–4 Pa s. The morphology, structure and magnetic properties of the obtained fibers were characterized with scanning electron microscopy, transmission electron microscopy, fourier transform infrared spectroscopy, thermo gravimetric analysis–differential scanning calorimetry, vibrating sample magnetometer. The X-ray diffraction results indicate that only the M-type Ba-ferrite and Ba-borate exist. The fibers had rough surface and hollow structure with the diameter no more than 1 μm. The fibers were composed of 40 nm BaFe12O19 nanoparticles embedded in the borate matrix. The coercivity and saturation magnetization of the synthesized fibers were 4,106.9 Oe and 17.8 emu/g, respectively.

Dual Organism Transcriptomics of Airway Epithelial Cells Interacting with Conidia of Aspergillus fumigatus

BackgroundGiven the complex nature of the responses that can occur in host-pathogen interactions, dual transcriptomics offers a powerful method of elucidating these interactions during infection. The gene expression patterns of Aspergillus fumigatus conidia or host cells have been reported in a number of previous studies, but each focused on only one of the interacting organisms. In the present study, we profiled simultaneously the transcriptional response of both A. fumigatus and human airway epithelial cells (AECs).Methodology16HBE14o- transformed bronchial epithelial cells were incubated with A. fumigatus conidia at 37°C for 6 hours, followed by genome-wide transcriptome analysis using human and fungal microarrays. Differentially expressed gene lists were generated from the microarrays, from which biologically relevant themes were identified. Human and fungal candidate genes were selected for validation, using RT-qPCR, in both 16HBE14o- cells and primary AECs co-cultured with conidia.Principal FindingsWe report that ontologies related to the innate immune response are activated by co-incubation with A. fumigatus condia, and interleukin-6 (IL-6) was confirmed to be up-regulated in primary AECs via RT-qPCR. Concomitantly, A. fumigatus was found to up-regulate fungal pathways involved in iron acquisition, vacuolar acidification, and formate dehydrogenase activity.ConclusionTo our knowledge, this is the first study to apply a dual organism transcriptomics approach to interactions of A. fumigatus conidia and human airway epithelial cells. The up-regulation of IL-6 by epithelia and simultaneous activation of several pathways by fungal conidia warrants further investigation as we seek to better understand this interaction in both health and disease. The cellular response of the airway epithelium to A. fumigatus is important to understand if we are to improve host-pathogen outcomes.

ChemInform Abstract: Generation of Cationic and Neutral Iron Formate, HCOOFe, in the Gas Phase.

ChemInform Abstract: Generation of Cationic and Neutral Iron Formate, HCOOFe, in the Gas Phase.

Intensely Colored Mixed-Valence Iron(II) Iron(III) Formate Analogue of Prussian Blue Exhibits Néel N-Type Ferrimagnetism

The reaction of colorless iron(II) formate or the mixed-valence cluster Fe(3)O(MeCOO)(6)(H(2)O)(3) with formic acid in dimethylformamide exposed to air at 110 degrees C affords black crystals of the mixed-valence (Me(2)NH(2))[Fe(II)Fe(III)(HCOO)(6)] three-dimensional (3D) structure in which the cations occupy half of the channels. The structure consists of alternating layers of Fe(II)O(6) [Fe(1)-O(1), 2.119(1) A] and Fe(III)O(6) [Fe(2)-O(2), 2.0049(9) A] octahedra bridged by anti-anti-bonded formates to afford an open-framework 3D structure. The structure is very similar to those of (Me(2)NH(2))[Fe(II)(HCOO)(3)] and [Fe(III)(HCOO)(3)].HCOOH, both of which are colorless. The black crystals appear dark-purple (lambda(max) approximately 520 nm) when powdered. The room-temperature Mössbauer spectrum confirms the 1:1 ratio of Fe(II) (delta = 1.03 mm/s, DeltaE(Q) = 1.16 mm/s) and Fe(III) (delta = 0.62 mm/s, DeltaE (Q) = 0.49 mm/s). Magnetic ordering that includes negative magnetization at low fields occurs at low temperature. The only molecular-based magnetic materials in which this phenomenon has been observed are the 2D polyiron(II,III) oxalates A[Fe(II)Fe(III)(C(2)O(4))(3)] (A = R(4)N(+) cation).

Influence of the starting powders on the synthesis of nickel ferrite

AbstractThe thermal decomposition of freeze‐dried nickel(II)‐iron(III) formate was investigated by means of DTA, TG, mass spectrometry and X‐ray powder diffractometry. For the preparation of homogeneous freeze‐dried nickel(II)‐iron(III) formate precursors, a rigorous control of nickel ion concentration in the precursor solution was required. The decomposition of the reactive nickel(II)‐iron(III) formate does not only reflect aspects of single formates, but also an interaction between components which lowers the decomposition temperature. Crystalline nickel ferrite powders were obtained at 600‐800°C. This temperature is quite lower than 1100°C employed for the ceramic method. In the presence of air, the regeneration of nickel ferrite from the taenite phase (γNi,Fe) is accomplished at 800°C. This temperature is also 300°C below the temperature employed when the mixtures NiO:α‐Fe2O3 or Ni:2Fe are the starting powders. The main reason for the high reactivity of the freeze‐dried formates and the taenite alloy is the large homogeneity of these precursors. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Catalytic conversions of chloroolefins over iron oxide nanoparticles 2. Isomerization of dichlorobutenes over iron oxide nanoparticles stabilized on the surface of ultradispersed poly(tetrafluoroethylene)

Nanosized iron oxides stabilized on the surface of ultradispersed poly(tetrafluoroethylene) (UPTFE) granules were synthesized by the thermal destruction of iron formate in boiling bed of UPTFE on the surface of heated mineral oil. The particle size of nanoparticles (∼6 nm) containing 5, 10, and 16 wt.% Fe depends weakly on the temperature of synthesis and iron to polymer ratio. The metal state is determined by the synthesis conditions. The nanoparticles synthesized at 280 °C consist mainly of the Fe3O4 and Fe2O3 phases. The samples obtained at 320 °C also contain iron(II) oxide. The catalytic properties of the obtained samples were tested in dichlorobutene isomerization. Unlike isomerization on the iron oxide nanoparticles supported on silica gel, reaction over the UPTFE supports proceeds without an induction period. The sample with 10 wt.% Fe containing magnetically ordered γ-Fe2O3 nanoparticles possesses the highest catalytic activity. Fast electron exchange between the iron ions in different oxidation states and high defectiveness of the nanoparticles contribute, most likely, to the catalytic activity.

Iron(II) Formate [Fe(O2CH)2]·1/3HCO2H: A Mesoporous Magnet − Solvothermal Syntheses and Crystal Structures of the Isomorphous Framework Metal(II) Formates [M(O2CH)2]·n(Solvent) (M = Fe, Co, Ni, Zn, Mg)

AbstractRecrystallisation of iron(II) formate dihydrate from formic acid under solvothermal conditions results in single‐crystals of the iron(II) formate, α‐Fe(O2CH)2·1/3HCO2H. The crystal structure of this phase has been determined by X‐ray diffraction and reveals an open framework structure with formic acid molecules occupying channels in the lattice which is stable even after removal of the solvent molecules. Magnetic susceptibility and Mössbauer measurements show that the compound undergoes 3D magnetic ordering below TC = 16 K. α‐Fe(O2CH)2·1/3HCO2H and the corresponding magnesium, cobalt, nickel and zinc formates form an isomorphous series. In contrast to the iron compound, the magnetic behaviour of the cobalt analogue is dominated by antiferromagnetic interactions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Synthesis and thermal decomposition of freeze-dried copper–iron formates

The thermal decomposition of freeze-dried formate precursors for copper–iron oxides was investigated by means of DTA, TG, mass spectroscopy and X-ray powder diffractometry. The freeze-dried copper formate is crystalline. Its decomposition at about 200 °C releases formic acid (HCOOH) and carbon dioxide (CO 2) as main primary gaseous decomposition products beside metallic copper as a solid product. However, the decomposition of the amorphous freeze-dried iron formate starts with a dehydration process which ends up at about 200 °C. Further decomposition in several superimposed steps, between 220 °C and 330 °C, results in the delivery of: (a) HCOOH and CO 2 (with reduction of Fe(III) to Fe(II)), (b) HCOOH and CO or H 2CO and CO 2 (without reduction). Meanwhile, several secondary decomposition products are characterized by mass spectroscopy. Regarding the complex copper–iron formate, its decomposition does not reflect only some aspects of the single formates, but also an interaction between the components which lows down the decomposition temperature. Because of the intermediate formation of metallic copper, properties of the reactive homogeneous precursor are lost and the formation of the single-phase copper iron oxides requires an annealing temperature close to that of a mixed oxide technique.

Synthesis and characterization of dibarium iron(II) formate tetrahydrate

The Ba(HCOO) 2–Fe(HCOO) 2–H 2O system has been studied by the solubility method at 25 °C and formation of a new double salt with composition Ba 2Fe(HCOO) 6·4H 2O was established. The double salt has been characterized by X-ray powder diffraction and thermal analysis. Ba 2Fe(HCOO) 6·4H 2O is isostructural with the double salts Ba 2Me(HCOO) 6·4H 2O (Me=Co, Ni, Cu, and Zn) and crystallizes in the triclinic system (space group P 1 ) with lattice parameters a=8.902(3) Å, b=7.125(2) Å, c=6.901(3) Å, α=98.85(5)°, β=108.81(4)°, and γ=82.47(3)°. The presence of two steps in the thermal dehydration process of the double salt has been established by means of DSC at lower heating rates. The enthalpy of dehydration has been determined.

Radiation-Induced Transformations of Iron(II) Formate

The solid-phase decomposition of the iron formate crystal hydrate Fe(HCOO)2 · 2H2O under exposure to 60Co γ-rays or 3.5-MeV electrons was studied. It was found that the irradiation of this salt to absorbed doses of 0.1–2 MGy resulted in the radiolysis of water of crystallization and the HCOO– anion and in the reduction or oxidation of the Fe2+ cation. The composition of the solid-phase (γ-Fe, α-Fe, FeO, γ-Fe e-Fe2O3, Fe3O4, and FeCO3) and gaseous (H2O, CO, CO2, HCOOH, and CH4) radiolysis products of the substance was determined.

Generation of cationic and neutral iron formate, HC(O)OFe, in the gas phase

Generation of cationic and neutral iron formate, HC(O)OFe, in the gas phase

The thermal decomposition of iron(III) formate

The thermal decomposition of iron(III) formate takes place through competitive formate anion decomposition (to yield CO+H 2O) and electron transfer from formate to Fe(III) (to yield Fe(II) formate(s) and CO, CO 2, H 2 and H 2O as gaseous products). The processes are overlapped by reactions that yield HCOH.

Iron(II) formate dihydrate

Iron(II) formate dihydrate

Magnetic Behaviour of the Dihydrate Formates M(HCOO)2 2 H20 of the Transition Metals M  Mn, Fe, Co, Ni

AbstractMagnetic structures of the dihydrate formates of the transition metals (Mn, Fe, Co, Ni) are reported which are determined by means of neutron diffraction experiments. The magnetic moment directions are interpreted in terms of crystal field anisotropy. In order to determine the influence of anisotropy on the magnetic ordering some mixed compounds of manganese and iron formates are examined. For all these salts the metallic A ions (000, 01‐21‐2) linked together by formic groups show, below TN, a canted antiferromagnetic ordering. The metallic B ions (‐1‐2‐ 0, −1‐2− 0 ‐1‐2‐) not linked together show an ordered moment atlow temperature with respect to TN. In the manganeseand nickel formates the observed directions of the magnetic moments are notrelated to the axis of the oxygen octahedron and are due to a competition between the dipolar anisotropy and a weak single ion anisotropy. In the cobalt and iron counterparts the crystal field effects are strongly dominant and responsible for the observed moment arrangement. In iron formate the Fe2+ ions behave like a pure Ising model. The magnetic behaviour of the Mn formate is strongly affected by iron impurities. For iron concentrations higher than 0.1 the properties of the solid solutions are those of the pure iron salt since in the range of iron concentration 0 < x< 0.1 the solid solutions show a complex behaviour which can be interpreted by a variation of exchange and anisotropy energies.

Etude par diffraction neutronique du formiate de fer dihydrate

The magnetic structure of Fe (HCOO) 2, 2H 2O has been solved by neutron diffraction. Below T N = 3.7° K the spins of Fe atoms in OOO and O 1 2 1 2 ( A site) order antiferromagneticaly ( A x f y A z . At low temperature (0.4°K) the B spins ( 1 2 1 2 O and 1 2 1 2 ) begin to order antiferromagnetically with respect to the A spins. We do not see any spins reorientation up to magnetic field of 20 koe. The iron formate properties are compared with those of the manganese salt.

Studies on the Morphological Properties of Iron Particles Prepared by Reduction of Iron Salts

Iron powders were produced by reduction of iron oxide which prepared by calcination of iron oxalate, oxyhydrate, sulphate and formate, and also were produced by direct reduction of these salts at 400°C, 600°C and 800°C. Their morphological properties were determined by optical microscope and electron microscope.Observation by electron microscope showed that iron particles produced, in all cases, consisted of small unit particle which were linked with each other, resulting in an aggregate. The size of the unit particle increased with increasing temperature and time of reduction. The aggregates of iron powders prepared at the lower reduction temperature, resemble, in shape, the original crystals of the mother salts or the particles of oxides, and thus the shape of aggregates prepared from oxalate was rod like, from oxyhydrate needle like, and from formate rod like. When the reduction temperature was high, however, material transport occured between aggregates and the aggregates lost their original shape. The effects of preparating method on the size and shape of the iron particle were also observed.