Synthesis and structure of methyltriphenylphosphonium dicyanodibromoaurate [Ph3PCH3] [Au(CN)2Br2]

Methyltriphenylphosphonium dicyanodibromoaurate (1) [Ph3PMe]+[Au(CN)2Br2]- was synthesized by the reaction of potassium dicyanodibromoaurate with methyltriphenylphosphonium bromide in an aqueous solution and was structurally characterized. The complex is a yellow-col-ored, air-resistant crystalline substance with a clear melting point. The structure of the compound was established by IR spectroscopy, NMR spectroscopy and X-ray diffraction analysis. An intense absorption band was observed in the IR spectrum of compound at 2220 cm-1, corresponding to the stretching vibrations of cyano groups. The absorption band of the deformation vibrations of the P-SPh bonds in the IR spectrum is at 1438 cm-1. In the recorded 1N, 13S, and 31R NMR spectra, signals are observed for the number, value of chemical shifts and integral intensity that do not contradict the proposed complex structure. The X-ray diffraction analysis of crystal 1 was carried out on a Bruker D8 QUEST diffractometer (MoKα radiation, λ = 0.71073 A, graphite monochrom-ator). [C21H18AuBr2N2P, M = 686.13, crystal system triclinic, space group P-1, a = 8.802(5), b = 8.989(5), c = 15.233(11) A, V = 1143.8(13) A3, Z = 2, μ = 10.002 mm-1, F(000) = 644, crystal size 0.41x0.30x0.22 mm]. According to the X-ray diffraction analysis (XRDA) data there are two types of centrosymmetric crystallographically independent monomeric dicyanodibromoaurate anions and methyltriphenylphosphonium cations in the crystal of compound MFDDA. The cations have a distorted tetrahedral configuration: the CPC angles equal 108.8(2)°-110.0(2)°, the P-S distances are 1.791(5)-1.800(5) A. All SAuC and BrAuBr trans-angles are 180.0° in the [Au(CN)2Br2]-an-ions. The Au-C distances in anions differ from each other and equal 2.040(7), 2.024(1), 1.991(2) A. These values are close to the sum of the covalent radii of atoms (2.03 A). The Au-Br bond lengths are equal to 2.4162(14), 2.4591, 2.474(5) A in dicyanodibromoaurate anions. Formation of the crystal structure occurs due to formation of weak N···N-S hydrogen bonds between cations and anions (2.68, 2.59, 2.38 A) and Br···N-S (3.03, 3.02 A). Complete tables of coordinates of atoms, bond lengths and valence angles are deposited at the Cambridge Crystallographic Data Centre. © 2020, Ivanovo State University of Chemistry and Technology.Ministry of Education and Science of the Russian Federation, Minobrnauka: 4.6151.2017/8.9South Ural State University is grateful for the financial support of the Ministry of Education and Science of the Russian Federation (grant No. 4.6151.2017/8.9)

Interaction of ballistic quasiparticles and vortex configurations in superfluid He3-B

The vortex line density of turbulent superfluid He3-B at very low temperature is deduced by detecting the shadow of ballistic quasiparticles which are Andreev reflected by quantized vortices. Until now the measured total shadow has been interpreted as the sum of shadows arising from interactions of a single quasiparticle with a single vortex. By integrating numerically the quasi-classical Hamiltonian equations of motion of ballistic quasiparticles in the presence of nontrivial but relatively simple vortex systems (such as vortex-vortex and vortex-antivortex pairs and small clusters of vortices) we show that partial screening can take place, and the total shadow is not necessarily the sum of the shadows. We have also found that it is possible that, upon impinging on complex vortex configurations, quasiparticles experience multiple reflections, which can be classical, Andreev, or both.Comment: To appear in Phys Rev

Dibenzo[ f,h]furazano[3,4- b]quinoxalines: Synthesis by Intramolecular Cyclization through Direct Transition Metal-Free C-H Functionalization and Electrochemical, Photophysical, and Charge Mobility Characterization

Herein, we describe the synthesis of unsymmetrically substituted dibenzo[f,h]furazano[3,4-b]quinoxalines by intramolecular cyclization through direct transition metal-free C-H functionalization. The electrochemical and photophysical properties for several polycycles have been measured. In thin films of the dibenzo[f,h]furazano[3,4-b]quinoxalines, hole mobility is in the order of 10-4 cm2 V-1 s-1. The results show that the HOMO and LUMO energy levels are appropriate for using the compounds as hole-transport materials in thin-film devices, in particular, organic and perovskite solar cells. Copyright © 2020 American Chemical Society.Russian Foundation for Basic Research, RFBR: 18-33-00103-mol_aRussian Science Foundation, RSF: 18-13-00409The research was financially supported by the Russian Science Foundation (project no. 18-13-00409). Y.A.K would like to acknowledge the financial support for the part of the synthetic section from the Russian Foundation for Basic Research (research project no. 18-33-00103-mol_a). The authors are grateful to Grigory A. Kim for carrying out the DFT calculations, which were performed by using “Uran” supercomputer of the Institute of Mathematics and Mechanics of the Ural Branch of the Russian Academy of Sciences. NMR experiments were carried out by using equipment of the Center for Joint Use “Spectroscopy and Analysis of Organic Compounds” at the Postovsky Institute of Organic Synthesis of the Ural Branch of the Russian Academy of Sciences

Two Ways of Cyclization of 5-imidazolylthioureas with Dimethyl Acetylenedicarboxylate

Two ways of cyclization of imidazolyl derivatives of thiourea with dimethylacetylene dicarboxylate (DMAD) were studied. Reaction of N,N'-disubstituted thioureas with DMAD led to formation of a thiazoline ring whereas transformation of trisubstituted thioureas under the same conditions give the novel imidazo[1,5-c][1,3,5]thiadiazine heterocyclic system. © ARKAT USA, Inc.The authors thank Russian Foundation for Basi c Research (RFBR grant 08-03-00376-a) and CRDF BRHE-2008 (grant Y5-C-05-04) for financial and material support

Transition to superfluid turbulence governed by an intrinsic parameter

Hydrodynamic flow in both classical and quantum fluids can be either laminar or turbulent. To describe the latter, vortices in turbulent flow are modelled with stable vortex filaments. While this is an idealization in classical fluids, vortices are real topologically stable quantized objects in superfluids. Thus superfluid turbulence is thought to hold the key to new understanding on turbulence in general. The fermion superfluid 3He offers further possibilities owing to a large variation in its hydrodynamic characteristics over the experimentally accessible temperatures. While studying the hydrodynamics of the B phase of superfluid 3He, we discovered a sharp transition at 0.60Tc between two regimes, with regular behaviour at high-temperatures and turbulence at low-temperatures. Unlike in classical fluids, this transition is insensitive to velocity and occurs at a temperature where the dissipative vortex damping drops below a critical limit. This discovery resolves the conflict between existing high- and low-temperature measurements in 3He-B: At high temperatures in rotating flow a vortex loop injected into superflow has been observed to expand monotonically to a single rectilinear vortex line, while at very low temperatures a tangled network of quantized vortex lines can be generated in a quiescent bath with a vibrating wire. The solution of this conflict reveals a new intrinsic criterion for the existence of superfluid turbulence.Comment: Revtex file; 5 pages, 2 figure

Influence of a lignification and mineralization of leaf tissues on resistance to a brown rust in common wheat plants

Aromatic substances in plant tissues can have protective effect against fungal diseases. One of the key enzymes in aromatic metabolism of plants, CAD (cinnamyl-alcohol dehydrogenase, dehydrogenase of cinnamyl alcohol; EC 1.1.1.195), at a number of species of plants exerts impact on the content of aromatic substances and on protective properties of tissues from fungal infections. When studying a collection of cultivars of bread wheat Triticum aestivum L., polymorphic on CAD, distinctions on extent of defeat are found by brown rust (with Puccinia recondita f. sp. Tritici as a causative agent). The purpose of the work was studying of features of structure and chemical composition of the tissues of a leaf promoting increased resistance. On a phytopathologic plot, against artificial infection with spores of a brown rust, two samples of spring bread wheat 3-13-15-4 and 3-4-14-3 were affected 1–5 % and 30 %, respectively. An analysis of various substances content in the leaf tissue at the contrast samples was conducted. Large plaques and spot consisting of mineral compounds were observed on the leaf surface of the more resistant plant. In ashes of leaves and ashes of a lignin differences in the maintenance of a number of mineral elements were also found. Lignin content on the dry mass of a leaf differed slightly (14.2 % vs 12.3 %), however there are differences in chemical composition. It is possible that the observed differences lead to afflict the plants with leaf rust to such different degrees. In that case these characteristics can be used for diagnostics of potential resistance of cultivars to fungal infection

Comparative Analysis of Self-Aggregation of Liquid Crystalline Pt(II) Complexes in Solution and in Neat Films

Two novel cycloplatinated complexes that differ by the presence/absence of a lateral fused cyclopenteno ring, respectively, were prepared. Although contributing to only a few percentage of the whole molecular volume, the presence of this aliphatic protuberance appears to be essential for the emergence of liquid crystalline behaviour. This pair of two similar compounds, non-mesomorphic complex and mesomorphic complex, was prepared as a model to assess the possible link of the self-aggregation in solution with the appearance of the liquid crystallinity in molten state. NMR dilution studies in CDCl3 solution and X-ray diffusion study in neat films show qualitative similarity of the aggregated structures formed by liquid crystalline complex. Solution studies may therefore be a useful additional tool to the characterization of the liquid crystalline properties and other self-association processes of Pt(II) complexes. © 2021We thank Northumbria University, CNRS, University of Strasbourg and Russian Foundation for Basic Research (project No. 18-03-00232A ) for the support of this work

Composite defect extends cosmology - 3He analogy

Spin-mass vortices have been observed to form in rotating superfluid 3He-B following the absorption of a thermal neutron and a rapid transition from the normal to superfluid state. The spin-mass vortex is a composite defect which consists of a planar soliton (wall) which terminates on a linear core (string). This observation fits well within the framework of a cosmological scenario for defect formation, known as the Kibble-Zurek mechanism. It suggests that in the early Universe analogous cosmological defects might have formed.Comment: RevTeX file, 5 pages, 2 figures, submitted to Phys. Rev. Lett., modified according to referee repor

OPTIMIZATION OF THE TEMPERATURE-TIME PROGRAM FOR ELECTROTHERMAL MOLECULAR ABSORPTION DETERMINATION OF IODINE

Various experimental factors influencing the shape of the pyrolysis curve for the BaI molecule were studied in this paper. Dividing the pyrolysis stage into two stages and increas-ing the cleaning time made it possible to optimize the pyrolysis curve

Quantum Turbulence

The present article reviews the recent developments in the physics of quantum turbulence. Quantum turbulence (QT) was discovered in superfluid $^4$He in the 1950s, and the research has tended toward a new direction since the mid 90s. The similarities and differences between quantum and classical turbulence have become an important area of research. QT is comprised of quantized vortices that are definite topological defects, being expected to yield a model of turbulence that is much simpler than the classical model. The general introduction of the issue and a brief review on classical turbulence are followed by a description of the dynamics of quantized vortices. Then, we discuss the energy spectrum of QT at very low temperatures. At low wavenumbers, the energy is transferred through the Richardson cascade of quantized vortices, and the spectrum obeys the Kolmogorov law, which is the most important statistical law in turbulence; this classical region shows the similarity to conventional turbulence. At higher wavenumbers, the energy is transferred by the Kelvin-wave cascade on each vortex. This quantum regime depends strongly on the nature of each quantized vortex. The possible dissipation mechanism is discussed. Finally, important new experimental studies, which include investigations into temperature-dependent transition to QT, dissipation at very low temperatures, QT created by vibrating structures, and visualization of QT, are reviewed. The present article concludes with a brief look at QT in atomic Bose-Einstein condensates.Comment: 13 pages, 5 figures, Review article to appear in J. Phys. Soc. Jp