X-ray photoelectron spectra and structure of iron polynuclear complexes

Iron trimethylacetate complexes with different ligands have been investigated by X-ray photoelectron spectroscopy (XPS). The Fe 2p, Fe 3p, C 1s, O 1s, and N 1s spectra obtained at successive replacement of the Fe-O coordination bonds with Fe-N bonds have been analyzed. A satellite component is found in the spectra of iron trimethylacetate complexes, which is indicative of the high-spin state of Fe^II and Fe^III iron atoms. The XPS data made it possible to determine the degree of covalence of the metal-ligand bonding and reveal two nonequivalent states for iron atoms.     

New star-like polydimethylsiloxanes: synthesis,properties, and application

Russian Chemical Bulletin - New star-like polydimethylsiloxanes with a cis-tetraphenylcyclotetrasilsesquioxane fragment as the core (branching center) were synthesized and characterized. The...     

Coatings and surfactants based on oligovinylsiloxanes

Silicate glass and cotton fabric are hydrophobized via treatment of their surface by vinyltriethoxysilane and oligovinylsiloxane. The data of electron microscopy for chemical analysis and the values of contact angles suggest that the hydrophobicity of the surface layer develops via the polymerization of vinyl groups. The arrangement of vinyl groups in neighboring units in oligovinylsiloxane is favorable for formation of a more uniform solid coating with enhanced hydrophobicity. The use of oligovinylsiloxane and its derivatives with amino and carboxyl groups as surfactants in the heterophase polymerization of styrene makes it possible to obtain stable suspensions with a narrow particle size distribution.     

Complexes of cobalt(II) halides with 2-(1<Emphasis Type="Italic">H</Emphasis>-pyrazol-1-yl)-4(3<Emphasis Type="Italic">H</Emphasis>)-pyrimidinone

The electronic structures of complexes of cobalt(II) halides with 2-(1H-pyrazol-1-yl)-4(3H)-pyrimidinone have been studied by X-ray photoelectron spectroscopy. The Co2p _3/2 lines of cobalt atoms, N1s lines of nitrogen atoms, and O1s lines of oxygen atoms in the X-ray photoelectron spectra have been analyzed. Based on these data for the free and coordinated ligands, the atoms of the ligand coordinated to the central metal atom are determined. The coordinated organic compound serves as an electron-donating ligand. The results obtained are consistent with IR and UV-Vis spectroscopic data.     

Diagnostics of gold-containing surgical-dressing materials with X-ray and synchrotron radiation

An analysis of biocompatible and antibacterial Au-gauze nanocomposites for medical purposes using X-ray and synchrotron radiation is conducted. The samples are produced by the modification of medical cotton gauze by Au organosol in isopropanol, which is synthesized via the metal-vapor method. The nanocomposites are examined with X-ray photoelectron spectroscopy, as well as with X-ray adsorption diffraction spectroscopy (EXAFS/XANES) and small-angle X-ray scattering using synchrotron radiation.     

H2 molecules encapsulated in extended Ben cluster cages: toward light-metal nanofoams for hydrogen storage

Efficient storage of hydrogen is a bottleneck problem for hydrogen-based energy solutions. We demonstrate the feasibility of trapping a pair of hydrogen molecules in beryllium cluster cages. The systems are constructed by merging two smaller units with single molecules trapped, which are known to be stable in isolation. The resulting (H(2))(2)@Be(n) species can have hydrogen cores and beryllium shells of different shapes, and we report the calculated energy barriers for hydrogen exit from the cage. The relative stabilities are related to the molecular structure and charge distributions, and some initially counterintuitive features are explained. Aspects of the release of hydrogen from such structures, and of possible scaling up to larger extended systems of fused cages, are discussed in terms of hydrogen storage. The predicted capacity could potentially be sufficient for practical usage.     

Production of a Novel Material Based on a Collagen–Chitosan Composite and Ibuprofen in a Supercritical Medium

A novel material for biomedical applications was obtained from a collagen–chitosan composite and ibuprofen by a fluid process using supercritical carbon dioxide. The material was characterized by IR and X-ray photoelectron spectroscopy. The applicability of XPS analysis of biomaterials for quantification of loaded therapeutic agents is demonstrated.     

Interplay between charge and vibrational delocalization in cationic helium clusters

The stable structures and low temperature thermodynamics of cationic helium clusters are investigated theoretically using a diatomics-in-molecules model for the potential energy surfaces and a computational framework in which both electronic and nuclear degrees of freedom are treated on a quantum mechanical footing. While the charge is generally carried by two atoms, vibrational delocalization significantly spreads out the charge over multiple isomers for clusters containing five or more helium atoms. Our calculations indicate that large clusters are essentially fluid with a well-defined solvation shell around the charged core.     

Dehydrogenation of isopropyl alcohol on modified cobalt catalyst

The effects of plasmochemical processing and of Ce, K, and Hf additives on the rate of dehydrogenation for isopropyl alcohol on a 5 wt % Co/SiO₂ catalyst is studied under static and flow conditions. Glow discharge plasma in O₂ and Ar and high-frequency electrodeless plasma in H₂ (HF-H₂) are used. Except for one sample containing Hf, an increase in catalytic activity is observed due to the formation of new active centers. The change in the composition of the initial catalyst’s surface after treatment with Ce and with oxygen, argon, and HF-H₂ plasmas is determined by means of X-ray photoelectron spectroscopy. The change in the size and shape of Co particles after treating the catalyst with HF-H₂ plasma and Ce is determined via X-ray phase analysis. It is suggested that the new catalytic centers formed after treatment in O₂ and Ar plasma contain carbon atoms with C1s bond energies of 282.1 eV; after treatment with HF-H₂ plasma, active centers contain hydrogen and carbon atoms with C1s bond energies of 282.5 eV; with cerium, the C1s bond energy is 297.7 eV.