Synthesis and crystal structure of 1,3,5-tris [4-(phenylethynyl)phenyl]benzene

The crystal structure of 1,3,5-tris[4-(phenylethynyl)phenyl]benzene (1) has been investigated. Compound1 represents a model of the repeating unit of the most typical polyphenylene, which contains 1,3,5-trisubstituted benzene rings (chain centers) and acetylenic groups (complex-forming and cross-linking centers) in the main chain. The acetylene groups of neighboring molecules have a tendency to close mutual arrangement, which is favorable for their topochemical interaction. However, the relative conformational rigidity of molecules1 restricts not only the possibility of the optimal adjustment of the reactive sites of neighboring molecules to one another, but also hampers the close packing of molecules in the crystal, which contains channels filled by the solvent molecules (chloroform).Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1986–1992, November, 1994.The work was carried out with the financial support of the International Science Foundation and the American Crystallographic Association.     

Luminescence properties of α-Al2O3 dosimetric crystals exposed to a high-current electron beam

The spectra of pulsed cathodoluminescence (PCL) and thermoluminescence (TL) in TLD-500 detectors, which were exposed to a strong beam from a pulsed electron accelerator, have been studied. Additional bands in the PCL spectrum and new peaks in the TL curves, which are due to impurity ions, have been revealed. Luminescence bands of F- and F⁺-centers cannot be used in the dosimetry of strong electron beams using TLD-500 detectors because of the saturation of dose dependence and the decrease in the TL yield. It is shown that high doses from these beams can be measured by recording TL in the luminescence band of impurity titanium ions.     

Effect of bismuth nanolayers on the oriented growth of fullerene C<Subscript>60</Subscript> on an amorphous substrate

The effect of a bismuth sublayer with an effective thickness of 0.5 to 4 nm on the structure of C₆₀ fullerene films grown on amorphous substrates (silicon covered with a natural oxide layer; glass) using the quasi-closed-volume method is studied. An x-ray diffraction study of fullerene films showed that the intensity ratio between the (220) and (111) peaks depends nonmonotonically on the sublayer thickness. In the bismuth sublayer thickness range 0.5–2.0 nm, fullerene films are found to exhibit a growth texture with the 〈110〉 axis; the average crystallite size was ～20 µm. The quality of the texture can be improved by varying the fullerene growth temperature.     

The contribution of the central region of the electron energy spectrum to the total double photoionization cross section of helium in the asymptotic nonrelativistic energy region

The double photoionization of helium at high photon energies is considered using a nonrelativistic approach. The central region of the energy spectrum and its contribution to the total process cross section and to the ratio between the double and single ionization cross sections are studied. Interelectronic interaction in the initial state is included exactly, whereas the interaction between the fast outgoing electrons is calculated by perturbation theory. A detailed derivation of the expression for the cross section ratio between double and single ionizations is given. The corresponding results obtained by other authors are analyzed and corrected.     

New sources of “active” halogen bis(dialkylamide)hydrogen dibromobromates, efficient reagents for destruction of ecotoxicants

Bis(dialkylamide)hydrogen dibromobromates were synthesized and their reactivity was investigated in decomposition of diethylphosphonic, diethylphosphoric, and 4-toluenesulfonic acids 4-nitrophenyl esters. The nucleophilic reactivity of a typical α-nucleophile, hypobromite ion, is independent of the source of the active bromine. The cetyltrimethylammonium dibromobromate is a unique reagent for destruction of ecotoxicants. In weakly alkaline media the half-life of 4-nitrophenyl diethylphosphonate did not exceed 6 s at [BrO^?] 0.02 mol l^?1, and the apparent reaction rate compared to water increased ～40-fold. The main factor governing the micellar effects of surfactants is concentrating the substrate in the micellar pseudophase.     

Investigation of preheating of laser thermonuclear targets

The preheating level of the thermonuclear fuel and of the gas-compressing shell is the main criterion of the target-compression efficiency in experiments on laserdriven thermonuclear fusion. This paper contains the result of investigations of electronic, radiative, and impact preheating in experiments on compression and heating of hlgh-aspect shell targets in the Del'fin-l laser-derived thermonuclear facility. A procedure, based on analysis of the epithermal emission of the plasma, is considered for measuring the target preheating by fast electrons. The radiative and impact preheating of compressing shells in DD gas are estimated. The results of the investigation demonstrate the high degree of adiabaticity of the compression of the thermonuclear fuel in experiments with the Del'fin-l facility.Nuclear Plasma Laboratory of the Lebedev Physics Institute. Translated from Preprint No. 3, Lebedev Physics Institute, Academy of Sciences of the USSR, Moscow, 1990.     

Azines and Azoles: CXXII. New Regioselective Synthesis of 1-Substituted 6-Alkyluracils

Readily available 5-acyl-4-hydroxy-3,6-dihydro-2H-1,3-thiazine-2,6-diones with primary alkyl- and arylamines in mild conditions (boiling in propan-2-ol) to give Schiff bases. In more rigid conditions (boiling in DMF), the reaction is accompanied by COS liberation and provides 1-substituted 6-alkyluracils. This previously unknown reaction possesses a considerable synthetic potential and can be considered as a new, general, and regioselective synthetic approach to 1-substituted 6-alkyluracils.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 1, 2005, pp. 146–158.Original Russian Text Copyright © 2005 by Yuskovets, Moskvin, Mikhailov, Ivin.For communication CXXI, see [1].     

The influence of ions on the structure of water

Journal of Structural Chemistry - The main features of the changes produced by ions in water may be summarized as follows. The influence of ions on the structure of the “free” water...     

Mild template synthesis of a copper(II)-containing macrocyclic compound with 4,4,6-trimethyl-2,3,7,8-tetraazanonen-6-dithiohydrazide-1,9 in a gelatin-immobilized matrix

The complexing processes in the triple copper(II)–thiocarbohydrazide–propanone system taking place in a copper(II) hexacyanoferrate(II) gelatin-immobilized matrix in contact with aqueous-alkaline solutions (pH12), containing thiocarbohydrazide and propanone, have been studied. Template synthesis leading to a macrocyclic coordination compound with the tetradentate N,N,S,S-donor ligand, (4,4,6-trimethyl-2,3,7,8-tetraazanonen-6-dithiohydrazide-1,9), occurs under these specific conditions when thiocarbohydrazide and propanone are the ligand synthons.