Morphology and spectral properties of thin films of benzoxazole derivatives of biphenyl

We have studied the spectral properties and morphology of thin films (TVD films) formed by thermal vacuum deposition of 4,4′-bis[(E)-1-(1,3-benzoxazol-2-yl)-2-ethenyl]-1,1′-biphenyl and its substituted derivatives. We have shown that introducing bulky 2,2′-oxyhexyl substituents into the biphenyl units leads to a shift of the fluorescence maximum for the TVD films toward shorter wavelengths, a decrease in their photostability, and aggregation of the films during storage. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 3, pp. 300–303, May–June, 2007.     

Synthesis and bromination of 8-methylquinoline-5-carboxylic acid

8-Methylquinoline-5-carboxylic acid was obtained by the Skraup reaction from 3-amino-p-toluic acid or by hydrolysis of 5-cyano-8-methylquinoline. The latter was synthesized by the Rosenmund-von Braun reaction from 5-bromo-8-methylquinoline, which was obtained by bromination of 8-methylquinoline in the presence of silver sulfate. Bromination in the side chain of 8-methylquinoline-5-carboxylic acid and its nitrile was studied. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 366–368, March, 1980.     

Pyrimidines

The possibility of the direct passage from 2-hydroxypyrimidines to pyrimidines by lithium aluminum hydride reduction has been established. Thus, starting from the corresponding 2-hydroxy derivatives we have obtained 4-phenylpyrimidine, 4, 6-diphenylpyrimidine, and 4-phenylbenzo[h]quinazoline. With 2-hydroxy-4, 6-diphenylpyrimidine as an example, it has been shown that when an excess of the reducing agent is used there is more far-reaching reduction to the corresponding dihydropyrimidine.For part XII, see [1].     

Reactions of rhodium carbonyl clusters with heterobidentate ligands. Synthesis and structural characterization of the Rh6(CO)15[(C6H5)2PC6H4N(CH3)2] and {Rh6(CO)15[(C6H5)2PC6H4NH(CH3)2]}[GaX4] cluster compounds

The reaction of heterobidentate 4-(dimethylamino)phenyldiphenylphosphine with labile cluster Rh₆(CO)₁₅(NCMe) yielding a new monosubstituted cluster Rh₆(CO)₁₅(Ph₂PC₆H₄NMe₂) was described. The reactions of the resulting cluster with GaX₃ compounds were studied. The structure of all obtained compounds was completely characterized both in a solid phase and in a solution by X-ray diffraction analysis, mass spectrometry, and IR and polynuclear NMR spectroscopy.     

EPR Studies of Tl0.5Pb0.5Sr1.6Ba0.4CaCu2?xRuxO7?δ Superconductor

Bulk superconducting samples of type Tl_0.5Pb_0.5Sr_1.6Ba_0.4CaCu_2−x Ru _x O_7−δ, (Tl, Pb)/Sr-1212, with 0.0 ≤ x ≤ 0.525 were prepared by the conventional one-step solid-state reaction technique. The prepared samples were investigated using X-ray powder diffraction, electrical resistivity and electron paramagnetic resonance (EPR) measurements. Enhancement of the phase formation, superconducting transition temperature T _c and hole carriers concentration P was observed up to x = 0.075. For x > 0.075, a reverse trend was observed. EPR spectra were measured at different temperatures (120–290 K) for all prepared samples. The number of spins N participating in the resonance and the paramagnetic susceptibility χ were calculated as a function of both Ru-content and temperature. N and χ increased as the Ru-content increased. A linear relationship between logN and 1/T was established, from which the activation energy E _a was calculated as a function of the Ru-content. The temperature dependence of χ was fitted according to Curie–Weiss type of magnetic behavior. Curie constant C, Curie temperature θ, the effective magnetic moment μ and the electronic specific heat γ were estimated as a function of the Ru-content.     

Influence of the conditions of formation of nitrocellulose honeycomb-structure films on their morphology

Physicochemical features of formation and morphology of submicron honeycomb-structure nitrocellulose films with hexagonal cell symmetry were examined.     

EPR Study of the Vanadium Ions in Mg2SiO4 Crystal

Vanadium-doped forsterite crystal has been studied with X-band electron paramagnetic resonance (EPR) spectroscopy. The sample was grown by the Czochralski technique in an argon atmosphere with 2 vol% of hydrogen. The EPR spectrum of the sample at T = 15 K is predominantly represented by the V⁴⁺ ion signals that possess a characteristic eight-line hyperfine structure and are observed close to g = 2. The observation of the two magnetically nonequivalent centers in the angular dependence in the (ab) crystal plane and one center in the (ac) and (bc) planes, combined with the published optical spectroscopy data, unambiguously show that the V⁴⁺ ions are located at the silicon lattice site. Principal values of the hyperfine A and g-tensor and magnetic axes orientations of the V⁴⁺ centers have been determined. The orientation disorder of the V⁴⁺ centers has been found around the crystalline c axis but not in the (ab) crystal plane. The angular variation of the hyperfine component linewidth is described best with a disorder range of ±3.0°.     

Bromination of quinoline derivatives with N-bromosuccinimide. Isomeric composition of the bromination products by PMR and GLC

The bromination of quinoline and substituted quinolines with N-bromosuccinimide in concentrated H₂SO₄ takes place exclusively in the homocyclic part. Bromo-substituted quinolines can be obtained by this method. The bromination products were identified by PMR spectroscopy. The differences among the mono-, di-, and trisubstituted (in the benzene ring) compounds were established on the basis of the type of spectrum of the protons of the homocyclic part of the molecule. The compositions of the reaction mixtures were studied by GLC.Translated from Khimiya Geterotskiklicheskikh Soedinenii, No.8, pp.1084–1090, August, 1988.     

Modeling of coenzyme activity of biotin

Conclusions The nonenzymatic N-carboxylation of the imidazolidinone ring was accomplished by reacting the appropriate K salt with carbon dioxide gas in tert-butyl alcohol medium.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, p. 856, April, 1971.