Synthesis, structure and redox properties of new cobalt(II) and nickel(II) complexes with 6-ferrocenyl-2,2′-bipyridyl

New ionic complexes [ML₂(MeCN)₂]?2Otf (M = Co or Ni; L = 6-ferrocenyl-2,2′-bipyridyl) were synthesized and characterized by single-crystal X-ray diffraction. Cyclic voltammograms of the compounds [ML₂(MeCN)₂]?2Otf in CH₂Cl₂ show good cycle stability over 100 cycles in the quasi-reversible oxidation potential range (from −0.25 to 0.5 V).     

Correlation effects in Auger spectra of Ni and Cu nanoclusters

Results of experimental research of exciton-like two-hole states in nanoclusters of narrow-band metals (Ni, Cu) on surface of high-oriented pyrolitic graphite by X-ray photoelectron and Auger electron spectroscopy are presented. It was found that the evolution of the electronic structure in Ni nanoclusters with the decreasing of their sizes can lead to appearance of long-living two-hole states in the valence band. One-particle and two-particle density of states are analyzed, and the Auger-electron spectra confirming the presence of the bound and localized states are obtained.     

Identification of radiation‐induced radical structure in azocalix[4]arene: an EPR study

A macrocyclic azocalix[4]arene (1) based ester derivative was synthesized. The single crystals of azocalix[4]arene were produced by slow evaporation of concentrated ethyl acetate solutions. These single crystals were exposed to ⁶⁰Co gamma rays with a dose rate of 0.980 kGy h^‐1 for 48 and 72 h to produce a stable free radical. Electron paramagnetic resonance (EPR) measurements were performed in three mutually perpendicular planes of the single crystal in the magnetic field, in addition, temperature dependence of the EPR signal was studied between 120 K and 450 K. The spectra were found to be temperature and angular dependent. Analysis based on the spectra recorded showed that a free radical was formed by fission of a C–H bond. This radical is described as ^?C_aHC_bH₃ The averages of the principal values of the hyperfine parameters and g‐factor are: g = 2.0034, A_Ha = 1.28 mT, A_H1=H2 = 1.00 mT, and A_H3 = 0.49 mT. Copyright © 2013 John Wiley & Sons, Ltd.     

Approach to thermal properties and electronic polarizability from average single bond strength in ZnOBi2O3B2O3 glasses

The glass transition temperature (T_g), density, refractive index, Raman scattering spectra, and X-ray photoelectron spectra (XPS) for xZnO-yBi₂O₃-zB₂O₃ glasses (x=10-65, y=10-50, z=25-60 mol%) are measured to clarify the bonding and structure features of the glasses with large amounts of ZnO. The average electronic polarizability of oxide ions (α_O2−) and optical basicity (Λ) of the glasses estimated using Lorentz-Lorenz equation increase with increasing ZnO or Bi₂O₃ content, giving the values of α_O2−=1.963 Å³ and Λ=0.819 for 60ZnO-10Bi₂O₃-30B₂O₃ glass. The formation of BOBi and BOZn bridging bonds in the glass structure is suggested from Raman and XPS spectra. The average single bond strength (B_MO) proposed by Dimitrov and Komatsu is applied to the glasses and is calculated using single bond strengths of 150.6 kJ/mol for ZnO bonds in ZnO₄ groups, 102.5 kJ/mol for BiO bonds in BiO₆ groups, 498 kJ/mol for BO bonds in BO₃ groups, and 373 kJ/mol for BO bonds in BO₄ groups. Good correlations are observed between T_g and B_MO, Λ and B_MO, and T_g and Λ, proposing that the average single bond strength is a good parameter for understanding thermal and optical properties of ZnOBi₂O₃B₂O₃ glasses.     

Comparison of steady and transient optical responses between a four-level Tripod system and a three-level Lambda system

We study and compare the steady and transient optical responses of a four-level system and a three-level system, which are dressed by two and three laser fields, respectively. In the three-level system, a transmissivity window (a reflectivity platform) may be induced on the probe resonance by a traveling-wave (standing-wave) coupling field. In the four-level system, both transmissivity window and reflectivity platform are remarkably modified when a traveling-wave driving field is applied on two-photon resonance with the probe, but change little when the traveling-wave driving field is largely two-photon detuned. This implies that the four-level system can be safely treated as a three-level one in certain frequency regions of interest. Transient behaviors of atomic coherence on the probe resonance are also examined in both three-level and four-level systems to further confirm this conclusion. Our new findings are beneficial to achieve a novel all-optical routing scheme by simultaneously creating a transmissivity window and a reflectivity platform on a single resonance, and may also be used to simplify theoretical treatments in the situations where numerical calculations are complicated and intractable in the presence of at least one standing-wave field.     

Syntheses and characterization of a new class of mono‐ and heterodinuclear derivatives of boron derived from Schiff bases

Reactions of 2‐isopropoxy‐1, 3, 2‐ benzodioxaborole with equivalent amounts of Schiff base ligands having two hydroxyl groups ( 1a–3a ) yield mononuclear derivatives with one residual hydroxy group. The reactions of these mononuclear derivatives with hexamethyldisilazane in a 2:1 ratio yield heterodinuclear derivatives. All these newly synthesized derivatives have been characterized by elemental analyses and molecular weight measurements. Tentative structures have been proposed on the basis of IR and NMR (¹H, ¹³C, ¹¹B,²⁹Si)spectral data and Fab‐mass studies. Schiff bases and their corresponding mono‐ and heterodinuclear derivatives of boron have also been screened for antifungal activities. Copyright © 2010 John Wiley & Sons, Ltd.     

Study of Spectroscopic Properties of Yb-doped Calcium Fluorapatite

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Synthesis and physicochemical properties of 9,10-phenanthrenequinone monoxime and its nitro derivatives

Phenanthrenequinone monoxime and its mono-, di-, and trinitro derivatives were synthesized. The acidity constants and their variation with the number and position of nitro groups were determined. The electronic and IR spectra of the nitro compounds were studied. The bands in the electronic spectra were assigned based on quantum-chemical calculations in the Pariser—Parr—Pople approximation. Correlations between the pK _a values and some calculated characteristics of the compounds under study were found. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1106–1110, June, 1999.