Synthesis and characterization of Li(I)-M(II) (M = Co, Ni) heterometallic complexes as molecular precursors for LiMO2

Lithium-containing heterometallic complexes with cobalt (Li₂Co₂(Piv)₆(2,4-Lut)₂ (2, Piv is the pivalate anion) and Li₂Co₂(O₂CCH₂Bu^t)₆(2,4-Lut)₂ (3)) and with nickel (Li₂Ni₂(Piv)₆(DME)₂ (4) and Li₂Ni₂(Piv)₆(2,2′-bpy)₂ (5)) were synthesized. The structures of the complexes were established by X-ray diffraction. The magnetic properties of complexes 2 and 4 were studied. The thermal behavior of compounds 2, 3, and 5 was investigated. It was shown that the compounds under study can be used as molecular precursors for the synthesis of lithium cobaltate and nickelate.     

Broadband dynamic phase matching of high-order harmonic generation by a high-peak-power soliton pump field in a gas-filled hollow photonic-crystal fiber

Hollow-core photonic-crystal fibers are shown to enable dynamically phase-matched high-order harmonic generation by a gigawatt soliton pump field. With a careful design of the waveguide structure and an appropriate choice of input-pulse and gas parameters, a remarkably broadband phase matching can be achieved for a soliton pump field and a large group of optical harmonics in the soft-x-ray-extreme-ultraviolet spectral range.     

Influence of dispersion on the physicochemical properties of metatitanic acid

Li₂TiO₃ and H₂TiO₃ samples with various degrees of dispersion were investigated by X-ray diffraction, NMR spectroscopy, and electronic microscopy. It was shown that H₂TiO₃ has a distinct structure and exhibits high sorption activity in relation to rare earth elements. The sorption activity of H₂TiO₃ grows due to the increase in specific surface of samples.     

Unsymmetrical dyes derived from 7,8‐dihydrobenzo[c,d]furo[2,3‐f]indole

On the basis of the 7,8‐dihydrobenzo[c,d]furo[2,3‐f]indole nucleus, a number of unsymmetrical carbocyanines as well as styryl dyes have been synthesized and their absorption spectra have been measured. Starting from the deviations of long‐wavelength maxima, the value of electron‐donor ability D has been estimated for the heterocycle under study and a number of dye end groups have been ranked by their electron‐donor properties. Experimental inferences are supported by the quantum chemically calculated bond length alternations and energy levels for the dyes concerned. Copyright © 2009 John Wiley & Sons, Ltd.     

Synthesis of silyl,germyl, and phosphino-substituted acylketenes from pivaloylethoxyacetylene

The reaction of pivaloylethoxyacetylene with silicon halides, which has been found to occur as a 1,4-addition, leads to allenic ethers, which readily eliminate ethyl halides and are converted to previously unknown types of ketenes—stable element-substituted acylketenes. Germanium-substituted acylketenes are also formed; however, clear evidence of 1,4-addition of germanium halides was not obtained. In the reaction between Ph₂PCl and pivaloylethoxyacetylene, phosphorus (III) substituted acylketenes initially formed underwent rapid [3 + 3] cyclodimerization.     

Synthesis and characterization of 4,5‐dihydro‐1H‐pyrazolo[3,4b][1,4]azaphosphinines

1,3,3‐Trimethyl‐2‐(1‐R‐3‐methyl‐5‐pyrazolyliminoethylidene)indolines were shown to undergo phosphorylation with phosphorus(III) halides at the two nucleophilic carbon centers to give fused 1,4‐azaphosphinine ring systems. Chemical properties of the synthesized compounds were characterized. For some representative compounds, detailed NMR spectroscopic investigations were performed, including the determination of ³¹P, ¹H and ³¹P, ¹³C coupling constants. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 391–398, 1999     

Current-voltage characteristics of thin poly(biphenyl-4-ylphthalide) films

The paper considers the features of the charge transport near to the threshold of the transition of polymer films to the high conductive state, induced by a small uniaxial pressure. The problem has not been solved so far, how the energy structure of a wide-band-gap organic dielectric varies near this threshold. The current-voltage characteristics of poly(biphenyl-4-ylphthalide) films at different uniaxial pressures were measured and analyzed. The interpretation of the obtained results is carried out within the framework of the space charge limited conduction model. The estimation of the injection model of transport parameters such as the charge carrier mobility and concentration, trapping state concentration and others are carried out. The analysis of the obtained results allows to make the following preliminary conclusion. Pressure increase promotes formation of a narrow trap band near the quasi-Fermi level resulting from the increase in the injection. This can give rise to a sharp magnification of the charge carrier mobility and even transition to the metallic state.