Synthesis and Characterization of Fluorite-Like Ce-Zr-Y-La-O Systems

Ce-Zr-O and Ce-Zr-Y-La-O materials obtained under various conditions and at varying component ratios are characterized. At Ce/Zr ≈ 1, a tetragonal phase that can hardly be distinguished from a cubic phase by X-ray diffraction forms in the ternary system. Raising the precipitation temperature favors the formation of two-phase systems. Promoting the Ce/Zr = 0.26–0.62 materials with both yttrium and lanthanum favors the formation of a single-phase specimen, namely, a (Ce, Zr, Y, La)O₂ fluorite-like solid solution at 600°C. This structure persists up to 1150°C. The specific surface area of the (Ce, Zr, Y, La)O₂ materials is primarily determined by their calcination temperature: S_sp = 50–80 m²/g at 600°C and 0.6–0.8 m²/g at 1150° C. The specimens calcined at 600°C are mesoporous, with uniformly sized pores of mean diameter 32 ± 2 Å, and have no micropores. According to TPR data, the specimens calcined at 600°C are reduced with hydrogen in two steps that can apparently be interpreted as surface and bulk reduction. The Ce/Zr = 0.26 and 0.40 specimens calcined at 1150°C are reduced in a single step, giving rise to TPR peaks at 707 and 686°C, respectively, and their degree of reduction increases with decreasing Ce/Zr.     

Study of the extraction of strontium(II) and lead(II) by crown and dithiacrown ethers

A study was carried out on the extraction of strontium(II) and lead(II) picrates by chloroform solutions of crown and dithiacrown ethers. The benzene ring substituents in benzodithia-18-crown-6 only slightly affect the extraction of strontium and lead cations and their separation. The introduction of an adamantyl group onto the benzene ring markedly increases the extraction of lead and the separation selectivity of these cations. The use of dithia derivatives of benzo-18-crown-6 is less efficient for the extraction of both strontium and lead, though the selectivity of their separation is almost the same as in the extraction with benzo-18-crown-6.M. V. Lomonosov Moscow State University, 119899 Moscow. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1125–1129, August, 1997.     

Semiempirical calculations of the electronic spectra of organometallic compounds: Estimation of solvent and counterion effects

The electronic spectra of the [Ru(NH₃)₅pz]²⁺, [Ru(NH₃)₅pz]³⁺, and [Ru(CN)₅pz]³⁻ complexes are calculated by the CI INDO method. The effect of solvation on the spectra is considered in a point charge approximation and in terms of the parametric model of a charged sphere enveloping the metal fragment. Interrelation of these approaches is discussed. Data on the molecular electrostatic potentials created by the complexes are presented to substantiate the models. St. Petersburg State University. Translated fromZhurnal Strukturnoi Khimii, Vol. 37, No. 4, pp. 603–618, July–August, 1996. Translated by I. Izvekova     

Chemistry of Polypyridine Ruthenium Complexes: VII. Electronic Structure and Photochemistry of cis-[Ru(2,2'-bpy)2(L)(Cl)]+ Complexes

The electronic absorption spectra and photochemical behavior of the complexes of cis-[Ru(bpy)₂ · (L)(Cl)]⁺ (bpy is 2,2'-bipyridyl) with pyridine (L = py) and 4-substituted pyridines [L = methyl-, amino-, and cyanopyridine, and 4,4'-bipyridyl (bipy)]. Photoirradiation of acetonitrile solutions of the complexes results in substitution of ligand L by a solvent molecule. A correlation was revealed between the photolysis quantum yield and the coordination-induced ligand L-to-metal charge transfer.     

Cubane derivatives

New substituted cubane-1,4-dicarboxamides and 4-bromocubanecarboxamides containing the nitroxyl group and amino acid fragments along with the cubane skeleton were synthesized. The cardiac pharmacological activity (both the effect on aorta relaxation and the calcium channel blocking activity) of most of nitroxyalkyl derivatives is equal to or higher than that of N-(2-nitroxyethyl)nicotinamide (nicorandil).     

Perturbation calculation of oscillator strengths for the isoelectronic series of light atoms

Transition probabilities and oscillator strengths are calculated for the configurations 1s² 2sⁿ¹ and 1s² 2s^n1-1 2pⁿ²⁺¹, which are, respectively, of the form P=a/Z (1+/Z+) andf=/Z (1+/Z+). Numerical values are given fora, ,, and.     

O-acylated flavonoid glycoside of the needles ofPicea obovata

Summary From the needles of the Siberian spruce we have isolated a new diacylated flavonoid glycoside (I) for which we have established the structure of 3-(3-O-p-coumaroyl-6-O-feruloyl-glucopyranosyloxy)-4,5,7-trihydroxyflavone.The new acylated glucoside 6-O-feruloylastragalin (III) has been obtained and characterized for the first time.All-Union Scientific-Research Institute of Medicinal Plants, Moscow. Irkutsk Institute of Organic Chemistry, Siberian Branch of the Academy of Sciences of the USSR. M. M. Sechenov First Moscow Medical Institute. Translated from Khimiya Prirodnykh Soedirenii, No. 5, pp. 570–576, September–October, 1978.     

O-acylated flavonoid glycosides of the needles ofPinus sylvestris III. Di-p-coumaroyltrifolin

Summary A new diacylated flavonol glycoside has been isolated for the first time from Scotch pine needles, and for it the structure of 3,4,5,7-tetrahydroxyflavone 3-0-(3,6-di-O-p-coumaroyl--D-galactopyranoside) has been established.In the course of the chemical study of the compound isolated, the previously undescribed 6-O-p-coumaroyltrifolin was isolated and characterized.All-Union Scientific-Research Institute of Medicinal Plants, Moscow. Irkutsk Institute of Organic Chemistry, Siberian Branch of the Academy of Sciences of the USSR. I. M. Sechenov First Moscow Medical Institute. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 332–336, May–June, 1978.     

Noncatalytic hydrophosphorylation and hydrothiophosphorylation of hydroxyaldehydes

Nucleophilic addition of secondary phosphone oxides and phosphine sulfides to 2-hydroxyacet-, 2-hydroxybenz-, and 3,4-dihydroxybenzaldehydes proceeds under mild conditions (48–50°C, THF) and allows tertiary phosphine oxides and phosphine sulfides with several hydroxyl groups to be prepared.     

Interactions between nonpolar surfaces in mixed solutions of cationic and nonionic surfactants

The interaction energy between hydrophobic SiO₂ particles in aqueous solutions of a cationic surfactant (dodecylpyridinium bromide, DDPB), a nonionic surfactant (Triton X-100, TX-100), and their mixed solutions was measured as a function of concentration. Synergism has been observed in mixed surfactant solutions: the surfactant concentration required for achieving the set interaction energy in the mixed solutions was lower than in the solutions of the individual surfactants. The molecular interaction parameters in surfactant mixtures were calculated using the Rosen model. Chain-chain interactions between nonionic and cationic surfactants were suggested as the main reason for the synergism.