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

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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Emission Mössbauer Study Of "Cobalt Peroxide"

Emission Mössbauer Study Of "Cobalt Peroxide". Pankratov D.A., Portachenko T.A., Perfil'ev Yu.D. //Moscow University Chemistry Bulletin. 2008. V.49. №5. P.292-296.

The product interaction cooled alcohol solutions of the cobalt (II) chloride with hydrogen peroxide as described as CoO₂ studied by emission Möessbauer spectroscopy. We show that dark green product is the cobalt (III) oxide.

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

Constrained 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.

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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Potassium hexahydroperoxostannate: synthesis and structure

Potassium hexahydroperoxostannate: synthesis and structure. Ippolitov E.G., Tripol'skaya T.A., Prikhodchenko P.V., Pankratov D.A. //Russian Journal of Inorganic Chemistry. 2001. V.46. №6. P.851-857

Polycrystalline potassium hexahydroperoxostannate was prepared by replacement of hydroxo groups in potassium hexahydroxostannate upon its dissolution in hydrogen peroxide. A comparative study of the product and the starting hydroxostannate by powder X-ray diffraction analysis, thermogravimetry, and IR, ²H, ³⁹K, and ¹¹⁹Sn NMR, and Mössbauer spectroscopy was carried out. The peroxo compound K₂Sn(OOH)₆ crystallizes in the hexagonal system with a = 7.264(7) Å, c = 10.168(4) Å. IR, NMR, and Mössbauer spectroscopy data show that the tin coordination polyhedron in the peroxo compound is an octahedron formed by the coordinated hydroperoxo groups.

Previously, sodium hexahydroperoxostannate was prepared and characterized by powder X-ray diffraction analysis, thermogravimetry, IR, ¹H NMR, and Mossbauer spectroscopy, and by thermodynamic and kinetic method. The tin atom in this compound were found to occur in the octahedral environment of hydroperoxo group. It appeared pertinent to confirm the possibility of formation of this type of tin compound by preparing a new hydroperoxo complex. To this end, we performed the first synthesis of potassium hexahydroperoxostannate. Comparative study of potassium hexahydrosstannate (1) and hexahydroperoxosstannate (2) and their deuterated analogue (1a and 2a, respectively) was carried out by powder X-ray diffraction analysis, thermogravimetry, and IR, NMR (²H, ³⁹K and ¹¹⁹Sn), and Mossbauer spectroscopy.

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