Synthesis and luminescent properties of new europium-containing copolymers based on norbornene functional derivatives

New copolymers containing oxadiazole, carbazole, and europium-containing fragments in the side chains were synthesized by ring-opening metathesis polymerization. The polymeric materials obtained were characterized by IR spectroscopy, GPC and DSC methods, and elemental analysis. All the copolymers possess strong metal-centered photoluminescence in solution and in thin film. In the electroluminescence spectra, the emission of the europium cations is exhibited and a broad band with the maximum at 507 nm is observed, which supposedly is attributable to the emission of the electroplexes between the polymeric matrix and the europium-containing fragments.     

Counterion effects on the isotopic properties of the Cl<Superscript>−</Superscript> and Li<Superscript>+</Superscript> ions in aqueous solutions

The reduced partition function ratios between isotopic forms (β-factors) were calculated by the ab initio RHF/6-311++G**(3df, 3p) and MP2/6-311++G**(3df, 3p) quantum-chemical methods for hydrated chloride ion and ion pair hydrates NaCl·nH₂O and LiOH · nH₂O. The influence of the Na⁺ cation on the β-factor value and the chlorine isotope separation factor in the precipitation of NaCl from concentrated aqueous solutions was found to be substantial. At the same time, the presence of OH^? counterions had no noticeable effect on the β-factor of the hydrated Li⁺ cation.     

Mass-spectrometric study of intramolecular coordination Si → O Interaction in gaseous (aroyloxymethyl)trifluorosilanes and methyl(aroyloxymethyl)fluorosilanes

Conclusions Mass-spectrometric criteria were developed for the assessment of the intramolecular coordination Si O interaction in the molecules of (aroyloxymethyl)trifluorosilanes and their analogs, methyl(aroyloxymethyl)difluorosilanes, and dimethyl(aroyloxymethyl)fluorosilanes. The successive replacement of fluorine atoms by methyl groups leads to a decrease in the intramolecular interaction of the silicon and carbonyl oxygen atoms.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1508–1511, July, 1987.     

Synthesis of lanthanide pyrazolonate complexes by the reactions of 1-Phenyl-3-methyl-4-(2,2-dimethylpropan-1-oyl)pyrazol-5-one with metallic lanthanides. Crystal structures of [Ln(Bu t -PMP)3]2 (Ln = Gd, Tb, and Tm)

Lanthanide pyrazolonate complexes Ln(Bu ^t -PMP)₃ (Ln = Pr, Nd, Gd, Tb, Tm, and Lu) are synthesized by the reactions of 1-phenyl-3-methyl-4-(2,2-dimethylpropan-1-oyl)pyrazol-5-one (Bu ^t -PMPH) with metallic lanthanides in the presence of catalytic amounts of the corresponding metal triiodides. The yields of the products are close to quantitative ones. The synthesized compounds can sublime in vacuo (10^?3 Torr) in the temperature range from 235 to 270°C. X-ray diffraction analyses of the sublimed complexes show that they are dimers [Ln(Bu ^t -PMP)₃]₂ (Ln = Gd, Tb, and Tm) in which metal atoms are linked by two bridging pyrazolonate fragments. The coordination environment of the lanthanide is a distorted one-capped trigonal prism.     

Study of thermochemical properties of lanthanides pentafluorophenolates with coordination ligands

Saturated vapor pressure of lithium pentafluorophenolate and the lanthanide complexes as a function of temperature has been determined by the Knudsen effusion method. Processing of the pressure data allowed the calculation of thermodynamic parameters of the compounds sublimation. Mass spectra and differential scanning calorimetry data are presented.     

Mass spectra of new groups of functionalized heterocycles. 4. 1-Alkyl-2-(alkylthio)pyrroles

The electron impact-induced fragmentation of 1-alkyl-2-(alkylthio)pyrroles is accompanied by rearrangements of the molecular and fragment ions with ring expansion.     

Laser emission efficiency of semiconductor target of gas diode in the picosecond range

Laser radiation excited in a cadmiumsulfide semiconductor target (ST) (λ = 522 nm) by a high-intensity subnanosecond electron beam (EB) with an energy of 70–150 keV has a maximum intensity of 3 · 10⁷W/cm² at an efficiency of~10%. Lasing arose at the EB exciting pulse front. The laser radiation pulse shape reproduced the EB pulse shape.     

Stability analysis of cylindrical shells containing a fluid with axial and circumferential velocity components

The stability of an elastic circular cylindrical shell of revolution interacting with a compressible liquid (gas) flow having both axial and tangential components is analyzed. The behavior of the fluid is studied within the framework of potential theory. The elastic shell is described in terms of the classical theory of shells. Numerical solution of the problem is performed using a semianalytical finite element method. Results of numerical experiments for shells with different boundary conditions and geometric dimensions are presented. The effects of fluid rotation on the critical flow velocity and the effect of axial fluid flow on the critical angular velocity of fluid rotation were estimated.