Luminescence of ytterbium complexes with octaphenyltetraazaporphyrins

We have synthesized outer complexes of ytterbium with octaphenyl-and octa(para-tert-butylphenyl)tetraazaporphyrins, in which for the first time we have detected luminescence of ytterbium with maximum at 980 nm. We have shown that the 4f-luminescence quantum yield in the complexes depends primarily on the nature of the outer ligand. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 5, pp. 693–696, September–October, 2006.     

Transformation of director configuration upon changing boundary conditions in droplets of nematic liquid crystal

The transformation of the director configuration upon changing boundary conditions from planar to homeotropic for bipolar nematic droplets dispersed in a polymeric matrix was studied. The characteristic textural patterns are presented for droplets with different concentrations of homeotropic surfactants, and their orientational structure is identified. The scenario predicted earlier by G.E. Volovik and O.D. Lavrentovich (ZhETF 85, 1997 (1983)) for the transformation of orientational structure of nematic droplets from bipolar to radial, without the formation of additional disclinations, is revealed. It is shown that, by using the computational method of minimization of the director elastic-strain energy in the droplet bulk and by introducing the inhomogeneous boundary conditions, one can obtain orientational structures that are analogous to the observed ones.     

Effect of non-central interactions on energy and lattice dynamics of molecular crystals

Atom-atom, multipole-multipole and three-body potentials have been used to calculate the energy and lattice dynamics of β-paradichlorobenzene, phenanthrene and m-chloronitrobenzene. Non-central interactions are shown to give a significant contribution to the intermolecular interaction energy but have little effect on the phonon spectrum of the crystals.     

Oxidation with p-(methoxycarbonyl) perbenzqic acid 1. Stereochemistry of epoxidation of Δ5-steroids

Conclusions We have examined the dependence of the stereospecificity of epoxidation of ⁵-steroids by p-(methoxy-carbonyl) perbenzoic acid on substrate structure and solvent.Deceased.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 447–449, February, 1978.     

Synthesis of monodisperse submicron spherical poly(methylmethacrylate) particles and the molecular dynamics simulation

The molecular-dynamics method has been used to determine the conformational states of poly(methyl methacrylate) chains in a medium composed of water and a monomer (methyl methacrylate). Experimentally detected spherical particles resulting from polymerization have been found to take the form of droplet-type aggregates containing several chains, with the water and monomer concentrations in the aggregates differing from those in the dispersion medium. It has been shown that the methyl methacrylate concentration in an initial reaction mixture of about 20% is optimal for the formation of spherical droplet-type aggregates. It has been experimentally established that spherical poly(methyl methacrylate) particles with a narrow size distribution are formed at a methyl methacrylate concentration of ≈23%.     

Synthesis of macrocyclic compounds with steric barriers in macroheterocycle proceeding from (Z)-1,2,3,6-tetrahydrophthalic and phthalic acids

Using 1,2-dibromoethane, (E)-1,4-dibromo-2-butene, (Z)-1,2,3,6-tetrahydrophthalic and phthalic acids we obtained along [1+1] scheme uncommon macrocyclic compounds containing ester groups, multiple bonds, and amide moieties in the macroheterocycle. The neutralization of bis-acids with ethylenediamine gave the corresponding macrocyclic diammonium salts that on heating to the melting point were converted into the corresponding macrocyclic diamides. The structure of compounds obtained was established from the elemental analyses, IR and NMR spectra.