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Mössbauer Spectroscopic Study Of An Iron(III) Complex With Crown Porphyrin

Plots of the relative areas (A refers to the left scale) and intensities (B refers to the right scale) of (1) the doublet and (2) the extended absorption vs. the temperature

Mössbauer Spectroscopic Study Of An Iron(III) Complex With Crown Porphyrin. Pankratov D.A., Stukan R.A., Al'Ansari Ya.-F., Savinkina E.V., Kiselev Yu.M. //Russian Journal of Inorganic Chemistry. 2011. V. 56. № 10. P. 1603-1608

A complex of 57Fe with 5-{4-[((4′-hydroxybenzo-15-crown-5)-5′-yl)diazo]phenyl}-10,15,20-triphenylporphyrin was studied by Mössbauer spectroscopy. The presence of signals of two types in the spectra (a doublet and an extended absorption band over a wide velocity range) suggests that the Fe atoms occupy two structurally different positions in this complex. The dependences of the doublet asymmetry on temperature and the angle between the normal to the sample plane and the γ-ray beam were studied. The isomer shift δ of the doublet in the temperature range from 360 to 5 K changes from 0.25 to 0.41 mm/s, while the quadrupole splitting remains virtually unchanged (Δ ≈ 0.65 mm/s). The relaxation-type absorption over a wide velocity range, the relative area of which strongly varies with temperature, can be described by a broad singlet with the following parameters: δ = 0.30–0.44 mm/s and Γ = 2.8–3.38 mm/s. According to the δ values, both signals are due to Fe(III) derivatives.

The structures and properties of metalloporphyrins (MPs), such as hemoglobin, chlorophyll, and vitamin В12, involved in vital processes depend on the complexing metal and the peripheral substituents. A great number of MPs are chemically inert and thermally stable, have high molar absorption coefficients in the UV-Vis and near-IR ranges, and show reversible redox transitions. This accounts for the interest in comprehensive study of the corresponding properties using a variety of physicochemical techniques.

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Vibrational Spectra of Platinum Superoxo Complexes

Raman spectra of solutions of hexahydroxoplatinate(IV) and а syperoxo platinum(IV) соmрlех in 3 М КОН

Vibrational spectra of platinum superoxo complexes. Pankratov D.A., Kiselev Yu.M., Sokolov V.B. //Russian Journal of Inorganic Chemistry. 2000. V. 45. № 9. P. 1388-1393Search the full text below. Ищи полный текст ниже.

Aqueous alkaline (KOH, KOD) solutions of hexahydroxoplatinate and "blue" superoxohydroxo-platinate complexes were studied by Raman spectroscopy. The spectra of superoxo complexes shows the bands at 1020 and 1060 cm-1 that arise from the O2- moiety. Solid samples of platinum hydroxide and the precipitates isolated from "blue" solutions were studied by IR and Raman spectroscopy. The spectra of hexahydroxoplatinate(IV) were assigned assuming the C3i symmetry of the Pt(OH)62- group. The Raman spectra of the decomposition products of the solid superoxo complex (νO-O = 1080 cm-1 for O2-) show the bands that arise from a platinum peroxo complex (νO-O = 829 cm-1 for O22-).

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Ab Initio Calculations Of Hydroxoplatinum Compounds: II. Binuclear Platinum(IV) Superoxo Complexes

Equilibrium structure of the binuclear monobridged platinum superoxo complexes [(OH)5Pt(μ-O2)Pt(OH)5]3–Ab Initio Calculations Of Hydroxoplatinum Compounds: II. Binuclear Platinum(IV) Superoxo Complexes. Pankratov D.A., Dement'ev A.I., Kiselev Yu.M. //Russian Journal of Inorganic Chemistry. 2008. V.53. №2. P.247-253.Search the full text below. Ищи полный текст ниже.

The structural and spectral data have been obtained by ab initio methods for the [(OH)4Pt(μ-O2)(μ-OH)Pt(OH)4]2-, [(OH)4Pt(μ-O2)(μ-OH)Pt(OH)4(OH)]3-, [(OH)5Pt(μ-O2)Pt(OH)5]3-, and [(H2O)(OH)4Pt(μ-O2)Pt(OH)4•(H2O)]- clusters, corresponding to binuclear platinum (IV) superoxo complexes with one and two bridges. The data obtained are in good agreement with experimental data and make it possible to judge the structure of available complexes.

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Chlorination As A Means For Changing The Composition Of Iron-Containing Nanoparticles In A Polyethylene Matrix

Mössbauer spectra of chlorine-treated nanocomposites synthesized from (a) iron(III) formate, (b) iron(III) acetate, and (c) iron(III) chloride

Chlorination As A Means For Changing The Composition Of Iron-Containing Nanoparticles In A Polyethylene Matrix, Pankratov D.A., Yurkov G.Yu., Astaf'ev D.A., Gubin S.P. //Russian Journal of Inorganic Chemistry. 2008. Т. 53. № 6. С. 933-942

Mössbauer spectroscopy, X-ray powder diffraction, and transmission electron microscopy were used to study the reactions of Fe3O4 or FeCl2·4H2O nanoparticles stabilized in a polyethylene (HPPE) matrix with gaseous chlorine and hydrogen chloride. These reactions produce FeCl2·2H2O nanoparticles, which retain the particle size and distribution over the HPPE matrix intrinsic to precursor nanoparticles. We propose chemical modification of iron-containing nanomaterials as a means for manufacturing iron(II) chloride nanoparticles.

The synthesis and study of various nanomaterials and their properties have recently become a focus of research due to their unique electronic, optical, magnetic, and other physical and chemical properties. The physical and chemical properties of nanomaterials are primarily determined by their chemical composition. Therefore, preparing materials containing nanoparticles of the desired chemical composition is a problem faced by researchers. A considerable number of processes are known to yield metal-containing nanoparticles: chemical, electrochemical, pyrolytic, spark, micellar, and mechanochemical [10]. 

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Constrained growth of anisotropic magnetic δ-FeOOH nanoparticles in the presence of humic substances

Function distribution magnetic splitting the mossbauer spectrum for different temperatures of the composite d-FeOOH-HSConstrained growth of anisotropic magnetic δ-FeOOH nanoparticles in the presence of humic substances. Polyakov A.Yu., Goldt A.E., Sorkina T.A., Perminova I.V., Pankratov D.A., Goodilin E.A., Tretyakov Y.D. //CrystEngComm. 2012. V.14. №23. P.8097-8102.Search the full text below. Ищи полный текст ниже.

Natural polyelectrolytes, humic substances, are suggested to control in situ growth of feroxyhyte nanoparticles of a highly reduced mean size and with enhanced colloidal stability in salt solutions. The feroxyhyte is formed as 2-5 nm thick and 20 × 20 nm wide nanoflakes due to the blocking of developing facets of feroxyhyte and constraints caused by diffusion limitations of ionic constituents across partially charged branches of humic substances.

Superparamagnetic iron oxide nanoparticles (SPIONs) are known as effective biocompatible agents for various biomedical applications like drug delivery, in vivo magnetic resonance imaging, cell and protein separation, hyperthermia and transfection. At present, synthesis and application of rods, disks, fibers, tubes, sheets, ellipsoids, dumbbell-shaped, acorn-shaped and other anisotropic nanoparticles attract growing attention because of their unique properties. Aggregation is a serious problem in the preparation and storage of such magnetic nanoparticles limiting considerably their practical applications. This problem can be solved by a surface modification of nanoparticles with organic macromolecules, their preparation in the presence of surfactants, application of hydrophilic, surface-active ligands improving biocompatibility and resulting in multifunctional nanoparticles for medical diagnostics.

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