Investigation of the effects of hydration and amphiphilic properties of nootropic drugs of piracetam and pramiracetam

An investigation of the hydration and amphiphilic properties of the piracetam and pramiracetam molecules has been conducted by theoretical conformational analysis and the Monte Carlo method; their localization and orientation at the water-lipophilic medium interface have been determined, which made it possible to explain the characteristics of the pharmacological action of the drugs.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 28, No. 4, pp. 355–358, July–August, 1992.     

Magnetic field effects detected by exciplex fluorescence and preferential solvation in binary solvents. The effect of temperature

At 20–70 °C, the temperature has almost no effect on the semisaturation field,B _1/2, or on the magnetic effects detected by exciplex fluorescence (pyrene/N,N-dimethylaniline) in binary benzene-DMSO mixtures. In individual solvents (ethanol, methanol) heating leads to a noticeable increase in the magnetic effect, whileB _1/2 decreases. The results obtained corroborate a previously proposed hypothesis that polar microclusters are formed in binary solvents with components of different polarity. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1821–1823, October, 1993.     

New guanosine derivatives: facile O6-phosphorylation,thiophosphinylation sulfonylation and silylation of guanosine derivatives by 4-dimethylaminopyridine catalized reaction

Appropriately protected guanosine derivatives were successfully converted to the corresponding O⁶-substituted guanosine derivatives by treatment with dialkyl- or diaryl-phosphoryl halides, dialkyl- or diaryl-phosphinothioyl halides, arenesulfonyl chlorides, and trialkylsilyl chlorides.     

Platinum nanoparticles generated in functionality-enhanced reaction media based on polyoctadecylsiloxane with long-chain functional modifiers

Functionality-enhanced nanostructured matrices generated by intercalating polyoctadecylsiloxane (PODS) with octadecene (ODC) or octadecylamine (ODA) are employed as reaction media in which to grow Pt nanoparticles. Small-angle X-ray scattering (SAXS) signatures confirm that the amphiphilic PODS matrix orders into lamellae with a periodicity (d) of 5.24 nm, which corresponds to the siloxy bilayer and a double layer of alkyl tails. The regular packing of the hydrophobic tails becomes distorted upon introduction of ODC or ODA. Incorporation of K[(C2H4)PtCl3].H2O (a Zeise salt) into the PODS/ODC matrix, followed by reduction of the Pt ions by NaBH4 or H2, results in the localization of Pt compounds and nanoparticles along the siloxy bilayers, which remain dimensionally unchanged. Electron density profiles deduced from PODS/ODA, however, provide evidence for considerable structural reorganization upon metalation with H2PtCl6.6H2O. In this case, the siloxy bilayers broaden due to the presence of PtCl62- ions, and the hydrophobic layers become distorted due to the formation of (PtCl62-)(ODAH+)2 complexes. Subsequent reduction by NaBH4 restores the inherent PODS organization, while H2 reduction partially preserves the distorted matrix, indicating that some Pt nanoparticles form in close proximity to the siloxy bilayer. Transmission electron microscopy reveals that relatively monodisperse Pt nanoparticles measuring approximately 1 nm in diameter are located along the siloxy bilayers, whereas anomalous SAXS further indicates that nanoparticles form aggregates of comparable size to d within the PODS double layers.     

Isomerization of perfluorinated cyclic amines under the action of antimony pentafluoride

Conclusions When perfluorinated tertiary cyclic amines containing a substituent at the nitrogen atom are heated with antimony pentafluoride, they isomerize to the corresponding azomethines.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 646–649, March, 1989.     

Equilibrium NH-acidity of 1,4-dihydropyridines and 4,5-dihydroindeno[1,2-b]pyridines

The patterns governing the dependence of NH-acidity on the presence of -, - and -substituents in the 1,4-dihydropyridine ring and on their nature have been established by comparison of the pK_a values of monocyclic 1,4-dihydropyridines and 4,5-dihydroindenopyridines. Additional data were obtained on the influence of the the electronic effects of sulfur-containing substitutents on the reaction center in the dihydropyridine molecules.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1228–1231, September, 1989.     

Catalyzed collapse and enhanced hydrogen storage of BN nanotubes

The novel morphology of BN nanotubes with a collapsed structure has been discovered by a metal-catalyzed treatment. The collapse causes the dramatic enlargement of a specific surface area of BN nanotubes and remarkably enhances the hydrogen storage capacity of BN nanotubes.     

Transformations of Cyclohexane under the Action of in situ Generated Aluminum Halides

Transformations of inert cyclohexane into dimethyldecalins under mild conditions in the presence of a simple catalytic system consisting of aluminum metal and halomethanes were studied.     

Structure and Catalytic Properties of a Cu2+-Containing Hydrogel of Zirconium Dioxide

The distribution of Cu²⁺ ions in ZrO₂ and sulfated ZrO₂ hydrogel phases was studied by EPR spectroscopy and voltammetry. The formation of the following three types of copper structures was observed: mononuclear Cu²⁺ complexes (A), magnetic associates (B), and Cu²⁺ compounds (C) that gave no EPR signals under the conditions used in the spectroscopic measurements. The specific catalytic activity of various Cu²⁺ compounds in the liquid-phase reaction of 2,3,5-trimethyl-1,4-hydroquinone oxidation was determined. The copper complexes C were found to exhibit the highest catalytic activity.     

Intensity measurement for Kβ η satellites in the radiative auger effect

Calculations have been performed on the integral shapes of the K lines, which are long-wave satellites of the K ₁ lines, for Cl, Ti, and Fe, where allowance has been made for interference between states in the 2p^–1 and 3p^–2p configurations. The calculations show that these satellites represent short-wave branches of the K lines strengthened by the 3p-1s transition with simultaneous M electron ejection. The strong interference between the amplitudes of these processes in the final state means that it is in principle quite impossible to speak of the intensities of the K satellites without stating how they are isolated from the measured spectrum.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 34–39, September, 1984.