Mononuclear complexes ML 2 (M II = Fe, Co, Cu, Zn) and porous coordination polymer [{Fe 2 NiO(Piv) 6 }{CoL 2 } 1.5 ] n (LH is the Schiff base of pyridine-4-carboxylic acid hydrazide and pyridine-2-carbaldehyde, and Piv – is pivalate) were synthesized and characterized. The structures of the compounds were determined by X-ray diffraction analyses. Each ML 2 molecule contains two 4-pyridine fragments capable of coordinating metal ions. Polymer [{Fe 2 NiO(Piv) 6 }{CoL 2 } 1.5 ] n was formed by cross-linking of trinuclear units with the CoL 2 bridge. The temperature dependences of the magnetic susceptibility of CoL 2 , FeL 2 , and [{Fe 2 NiO(Piv) 6 }{CoL 2 } 1.5 ] n were studied. The magnetic properties of [{Fe 2 NiO(Piv) 6 }{CoL 2 } 1.5 ] n were described as a superposition of the susceptibilites of the trinuclear and mononuclear units, and their interaction was taken into account in the framework of the molecular field model. The magnetic properties of CoL 2 in the individual state and in the framework of [{Fe 2 NiO(Piv) 6 }{CoL 2 } 1.5 ] n were interpreted using a model taking into account the spin—orbit coupling in the Co 2+ ion and the splitting of its levels by crystal field. For FeL 2 , a model taking into account the zero-field splitting of the ground state of the Fe 2+ ion was used. Several redox processes were found for ML 2 in a solution and for [{Fe 2 NiO(Piv) 6 }{CoL 2 } 1.5 ] n in a suspension by cyclic voltammetry. The CoL 2 and FeL 2 complexes can catalyze the electrochemical dehalogenation of freon CF 2 ClCFCl 2 but exhibit no activity in the dehalogenation of CHCl 3 ; ZnL 2 did not show catalytic activity in the dehalogenation of both substrates.

It was shown by cyclic voltammetry that the coordination polymers [Fe2NiO(Piv)6(L)x]n, where L is a ligand containing a 1,2,4,5-tetrazine or thiazolothiazole fragment, Piv– is pivalate, and x = 1 or 1.5, possess redox activity in the solid form when deposited on an inert electrode, and the redox potentials of the transitions correlate with the corresponding redox potentials of the ligands in solutions. The coordination polymer containing bis(4-pyridyl)thiazolothiazole catalyzes the electrochemical dehalogenation of CF3CHClBr with the formation of CF2=CHCl and CF3CH2Cl.

Linking of trinuclear pivalate Fe2NiO(Piv)6 (Piv=O2CC(CH3)3) by 2,6-bis(4-pyridyl)-4-(1-naphthyl)pyridine (L) resulted in formation of 1D-porous coordination polymer Fe2NiO(Piv)6(L)·Solv, which was characterized in two forms: DMSO solvate Fe2NiO(Piv)6(L)(DMSO)·2.5DMSO (1) or water solvate Fe2NiO(Piv)6(L)(H2O) (2). X-ray structure of 1 was determined. Crystal lattice of 1 at 160K contained open channels, filled by captured solvent, while temperature growth to 296K led to the crystal lattice rearrangement and formation of closed voids. Redox-behavior of 2 was studied by cyclic voltammetry for a solid compound, deposited on glassy-carbon electrode. Redox-activity of L preserved upon incorporation in the coordination polymer. The presence of pores in desolvated sample Fe2NiO(Piv)6(L) was confirmed by the measurements of N2 and H2 adsorption at 77K. Potential barriers of the different molecules diffusion through pores were estimated by the means of molecular mechanics.

Linking of the trinuclear pivalate fragment Fe2CoO(Piv)6 by the redox-active bridge Ni(L)2 (compound 1; LH is Schiff base from hydrazide of 4-pyridinecarboxylic acid and 2-pyridinecarbaldehyde, Piv(-) = pivalate) led to formation of a new porous coordination polymer (PCP) {Fe2CoO(Piv)6}{Ni(L)2}1.5 (2). X-ray structures of 1 and 2 were determined. A crystal lattice of compound 2 is built from stacked 2D layers; the Ni(L)2 units can be considered as bridges, which bind two Fe2CoO(Piv)6 units. In desolvated form, 2 possesses a porous crystal lattice (SBET = 50 m(2) g(-1), VDR = 0.017 cm(3) g(-1) estimated from N2 sorption at 78 K). At 298 K, 2 absorbed a significant quantity of methanol (up to 0.3 cm(3) g(-1)) and chloroform. Temperature dependence of molar magnetic susceptibility of 2 could be fitted as superposition of χMT of Fe2CoO(Piv)6 and Ni(L)2 units, possible interactions between them were taken into account using molecular field model. In turn, magnetic properties of the Fe2CoO(Piv)6 unit were fitted using two models, one of which directly took into account a spin-orbit coupling of Co(II), and in the second model the spin-orbit coupling of Co(II) was approximated as zero-field splitting. Electrochemical and electrocatalytic properties of 2 were studied by cyclic voltammetry in suspension and compared with electrochemical and electrocatalytic properties of a soluble analogue 1. A catalytic effect was determined by analysis of the catalytic current dependency on concentrations of the substrate. Compound 1 possessed electrocatalytic activity in organic halide dehalogenation, and such activity was preserved for the Ni(L)2 units, incorporated into the framework of 2. In addition, a new property occurred in the case of 2: the catalytic activity of PCP depended on its sorption capacity with respect to the substrate. In contrast to homogeneous catalysts, usage of solid PCPs may allow selectivity due to porous structure and simplify separation of product.

The results are presented of a study of the electrochemical activation and dehalogenation of geminal (CF3CCl3, CF3CClBr2) and vicinal (CF2ClCFCl2, CF2BrCF2Br, CF2BrCFClBr) Freons and their joint conversion with sulfur and carbon dioxides with the formation of fluorine-containing sulfinic and carbonic acids. The influence of the conditions for carrying out these reactions (structure of the Freons, the electrolysis regime, the nature of the medium, electrode materials, electron transfer mediators, etc.) on their path and the yields of the targeted products are elucidated.

The effect of the nature of the solvent (DMF, DMSO, CH3CN, N-methylpyrrolidinone, THF) and supporting electrolyte (Bu4NBr, Et4NBr, Et4NClO4,Me4NBr, LiBF4, NaBF4, and KBF4) on the electrochemical activation and carboxylation of fluorine-containing aromatic imines by the action of CO2 was studied for the case of p-and m-fluorobenzylideneaniline. It was shown that factors promoting the formation of intimate ion pairs between the radical-anions of the imines – the initial products of the processes in the electrochemical activation of the imines – and the cations of the supporting electrolyte (decrease of the polarity of the medium and decrease of the radius of the cation in the supporting electrolyte) significantly reduce the effectiveness of electrochemical carboxylation right down to its complete cessation.

A comparative analysis was carried out on the laser desorption/ionization (LDI) mass spectra of fluorine derivatives of N-phenylphenylglycine using different targets. The extent of generation of molecular ions of the fluorine-containing amino acids was shown to depend significantly on the nature of the target surface. Alkali metal chlorides (LiCl, NaCl, KCl, and CsCl) have the highest efficiency among the targets studied (standard metal target, polished monocrystalline silicon, glass, silica) in the generation of molecular ions of fluorine-containing amino acids, which increases in the series LiCl < NaCl < KCl < CsCl.

A possibility of obtaining fluorine-containing N-phenylphenylglycine derivatives at yields of up to 85% via the electrochemical carboxylation of corresponding benzalanilines was shown. The influence of imine's electron structure, the nature of supporting electrolyte and cathodic material on such processes is examined. It was found, that increasing electron accepting ability of the substituents in benzylidene and aniline fragments of the imine molecule lead to decrease of amino acid yields. The dependence of the N-phenyl-p-fluorophenylglycine yield on the cathode material (Zn, GC, Cu, Ag, Pt) and on the nature of the supporting electrolytes (Bu4NBr, Et4NBr, Et4NClO4, PhCH2Me3NClO4, LiBF4, LiClO4, NaBF4 and KBF4) Was investigated. The highest amino acid yields were obtained at cathodes (GC and Zn) that do not exhibit specific adsorption of fluorine-containing imines, as well as in the presence of background salts (Alk(4)NBr) whose cations do not show tendency to strong ion pairing with anion radicals formed by the electrochemical activation of the imines. (c) 2008 Elsevier B.V. All rights reserved.

On the basis of a study of the processes involved in the electrochemical activation of a series of fluorine-containing aromatic imines with and without the presence of carbon dioxide it was shown that the initial stage of such processes is the formation of imine radical-anions, which can both undergo spontaneous transformations and react with CO2 with the formation of fluorine-containing amino acids. A correlation was established between the effects of the electronic structure of the imines on the electrochemical characteristics of their reduction and on the stability of the radical-anions. A relationship was established between the parameters of electrochemical activation of the imines in the presence of CO2 and the yields of the amino acids.

The features of production and use of fuel coal suspensions of three basic types: water-, alcohol-, and oil-coal, are analyzed.

Measurements are performed of the intensity of radiation in the visible and near IR spectra from 0.5 to 3.0 μm upon solidification in ambient air of a pool of melt of pure alumina in a powder bed of the same material. The results are given as the time and wavelength dependences of effective temperatures. It is demonstrated that the intensity of radiation upon crystallization is defined by the optical properties of melt and crystal, as well as by the melt thickness and temperature field in the melt which existed prior to the beginning of cooling. The presence of an almost horizontal region on the solidification plateau is due to the existence of an isothermal two-phase zone; however, with a melt thickness of several millimeters, such a region is observed only in the wavelength range from 0.5 to 0.9 μm.

The results are given of calculations of temperature fields in a plane layer of Al2O3 crystal under conditions of combined radiative-conductive energy transfer under fast heating by concentrated radiation of a CO2 laser with the formation of a thin layer of melt on the surface. Experiments are performed in the heating of ceramic samples of Al2O3 and samples remelted from Al2O3 powder; in these samples, the intensities of outgoing radiation and the reflectivity are measured for different wavelengths. The experimental results are compared with the calculation results. It is demonstrated that the adopted mathematical model, which fails to reflect the important part played by kinetics in the abrupt variation of the absorption coefficient in Al2O3 melt, needs to be refined.

The reductive electrochemical activation of three C2 freons, and one C1 freon, in four different room temperature ionic liquids (RTILs), is reported. Electrochemistry was performed using glassy carbon (GC), platinum and silver cathodes. The apparent reduction potentials for the freons ranged from −1.0V vs. Pt to −2.8V vs. Pt, depending on the freon structure, cathode material and RTIL medium. Discharge potentials were found to be distinctly more cathodic in RTIL media, relative to organic solvents (dimethylformamide), due to the significant ohmic loss within the cell as a consequence of the viscous nature of the RTIL media. Similarly, cathodic currents were greatly suppressed in RTILs due to low mass transport rates. The electrocatalytic nature of Ag cathodes is maintained in RTIL media with some systems exhibiting over 1V reduction in discharge potentials.

The effect of various factors (the nature of the medium and the electrode material, the electronic structure of the Freons, etc.) on the electrochemical activation and dehalogenation of a series of Freons [F113 (CF 2 ClCFCl 2 ), F13B1 (CF 3 Br), F114B2 (CF 2 BrCF 2 Br), and F113B2 (CFClBrCF 2 Br)] in various low-temperature ionic liquids (LTIL) [1-butyl-3-methylimidazolium, 1-butyl-1-methylpyrrolidinium, and trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl)imides and 1-butyl-3-methylimidazolium hexafluorophosphate, tetrafluoroborate, and trifluoroacetate] at various electrodes (glassy carbon, Pt, Ag) was studied. It was established in particular that the investigated processes are affected substantially by the electrical conductivity and viscosity of the medium. With decrease of the latter the peak potential in the cyclic voltammetry of the electrochemical reduction of the Freons is shifted toward less negative values while the current increases. It was found that a silver cathode has a specific effect on the electrochemical activation of the Freons in the LTILs, and this may be due to the formation of complexes Ag⋯Hal⋯R f between the Freons and silver atoms on the electrode surface, in which cleavage of the C—Hal bond is facilitated. Such processes are compared with the processes realized in the traditional solvent dimethylformamide.

The results are given of measurements of the normal-hemispherical reflectivity of alumina ceramics in the semitransparency region for the wavelengths of 0.488, 0.6328, 1.15, and 3.39 μm. The measurements are performed in vacuum both in the process of fast heating by concentrated radiation of a CO2 laser from room temperature to ∼2900 K with the formation of a thin layer of melt and in the process of subsequent cooling after the heating radiation is switched off. The heating time is approximately 2.25 s, with the density of heating radiation flux of approximately 1600 W/cm2. The effect of abrupt variation of the absorption coefficient during melting and solidification on the thermal-radiation characteristics is analyzed. The results demonstrate that the absorption coefficient of the melt in the semitransparency region is higher in vacuum than in the air.

The results are given of measurements of the normally hemispherical reflectivity of alumina ceramics in the semitransparency region for the wavelengths of 0.488, 0.6328, 1.15, and 3.39 μm. The measurements are performed both in the process of fast heating of ceramics in the air by concentrated radiation of a CO2 laser with fluxes of different densities from room temperature to ∼2900 K with the formation of a thin layer of melt and in the process of subsequent cooling after the heating radiation is discontinued. The heating time is approximately 2.25 s, with the density of heating radiation flux of approximately 1200 W/cm2 and 1600 W/cm2. It is demonstrated that the reflectivity in the process of heating depends significantly on the flux density. By the end of the heating period and under the effect of a flux of higher density, the layer of melt formed on the ceramic surface is optically infinite for reflection at all wavelengths, while no optical infinity is attained at a lower flux density. The effect of abrupt variation of the absorption coefficient during melting and solidification on the thermal-radiation characteristics is analyzed.

Two known models of the viscosity superanomaly effect are analyzed: the microrheological model developed by Uriev and the kinetic model proposed by Stolin and coworkers. The possibility of using these models for analyzing the flow curves of real structured disperse systems with a yield point is evaluated. As is shown, within these approaches one can distinguish the conditions under which three types of flow in structured disperse systems are observed.

The effect of the cathode material (GC, Pt, Ag) on the electrophilic dehalogenation of C-2 Freons [F113 (CF2ClCFCl2), F113B2 (CF2BrCFClBr), and F114B2 (CF2BrCF2Br)] was studied. Such reactions lead to the formation of valuable chlorotrifluoro-or tetrachloroethylenes. It was found that a silver cathode has a promoting effect on the investigated processes compared with the other materials (GC, Pt). The optimum reaction conditions within the present investigation were determined.

The results are given of numerical calculations of temperature fields under conditions of free cooling and rapid crystallization of a pool with molten alumina formed as a result of heating a sample by concentrated laser radiation, as well as of “effective” brightness temperatures corresponding to the radiation leaving the sample. Measurements are performed of the effective brightness temperatures and reflectivity for different wavelengths in the process of cooling molten alumina and zirconia formed as a result of heating ceramics by concentrated laser radiation. Comparison of the calculation and experimental results reveals the important part played by the extended two-phase zone formed in semitransparent oxides in the formation of temperature fields and related thermal-radiation properties.

-The rheological properties of the aqueous suspensions of palygorskite and bentonite are investigated within a wide range of the solid phase concentrations. It is established that, as the concentration of the dispersed phase in the suspensions of these clay minerals increases, the areas are identified on the flow curves near the critical concentration ϕ cr , which testify the onset of the rearrangement of the structure of systems. These areas precede the appearance of the regions of the viscosity superanomaly.