Mass-spectrometer study of heterocyclic compounds

A study is made of mass-spectra of aldehydes and carboxylic acid esters of indoles. It is shown that the mass-spectra can be used to differentiate -carbonyl derivatives of indole from the -analogs.For Parts I–III see [1–3].     

Models of spin structures in Sr<Subscript>2</Subscript>RuO<Subscript>4</Subscript>

The mean-field method is used to calculate the bands, Fermi surfaces, and spin susceptibilities of a three-band model of the RuO₄ plane of Sr₂RuO₄ rutinate for states with different spin structures. In particular, the spiral state is studied with the “incommensurate” vector Q=2π(1/3, 1/3) corresponding to the nesting of bands with the population n=4. This state proves to be the lowest with respect to energy among other (paramagnetic, ferromagnetic, antiferromagnetic, and periodic) solutions. In the spiral state, in addition to the main α, β, and γ sheets of the Fermi surface, shadow Fermi boundaries along the Γ(0, 0)-M(π, 0) line (previously observed in the ARPES experiments) are revealed and explained. This may change the interpretation of the data on dispersionless peaks in photoemission, previously ascribed to surface states. The spin susceptibilities of the spiral state exhibit peaks in the dependence Im?(q, ω) at q=Q in accordance with the observed magnetic peak in neutron scattering. The hypothesis of the presence of spin structures with q=Q in the normal state of Sr₂RuO₄ and the methods of checking this hypothesis are discussed.     

Formation conditions and temperature dependence of forbidden reflections during resonant X-ray diffraction in zinc oxide single crystals

Different mechanisms of formation of purely resonant reflections hhl (h = 2n + 1) during resonant diffraction of X-ray synchrotron radiation in zinc oxide, whose intensity very strongly changes with an increase in temperature, are considered. Such reflections, forbidden in the dipole-dipole scattering, can be excited owing to the dipole-quadrupole scattering and the anisotropy of X-ray susceptibility induced by thermal motion of atoms and point defects. Different contributions are theoretically considered and it is shown that they can be separated owing to their different temperature dependences.     

Suppression of the anomaly of low-frequency permittivity in ferroelectric triglycine sulfate by microwaves

Microwave dielectric spectra of ferroelectric triglycine sulfate are measured in the littlestudied frequency range from 90 to 150GHz, and the suppression of low-frequency dielectric anomaly by microwaves at these frequencies is investigated. It is shown that suppression occurs only in the range of non-Debye dielectric dispersion. An additional dispersion mechanism based on the activation-diffusion model of orientational polarization and transit-time effects for quasi-free carriers is proposed to explain the microwave impact.     

Temperature transformation of microwave dielectric spectra of Rochelle salt in the dynamic conductance model

The temperature transformation of submillimeter dielectric spectra of Rochelle salt is analyzed within the framework of dynamic conductance model. The branched network of hydrogen bonds and crystallization water molecules in Rochelle salt is supposed to form a quasi-localized vibrational mode in the crystal spectrum. This mode determines the resonant dielectric response at helium temperatures, which with an increase in temperature is transformed into the relaxation response of diffusion motion.     

Synthesis of mono- and di-O-sulfates of spacer-armed lactose

Russian Chemical Bulletin - A series of spacer-armed lactose derivatives with one or two O-sulfo groups in various positions, namely, 6-O-Su-Lac, 3´,6-O-Su2-Lac, 6´-O-Su-Lac,...     

Synthesis of podands functionalized with 2-oxo(sulfanylidene)-1,2,3,4-tetrahydropyrimidine and 4,7-dihydrotetrazolo[1,5-a]pyrimidine fragments

Russian Journal of Organic Chemistry - Podands functionalized with 2-oxo(sulfanylidene)-1,2,3,4-tetrahydropyrimidine and 4,7-dihydrotetrazolo[1,5-a]pyrimidine fragments were synthesized by...