Ab Initio Study of Conformational Properties of ( Z, Z)-, ( E, Z)-, and ( E, E)-Cyclonona-1,5-dienes

Ab initio calculations at the HF/6-31G^* level of theory for geometry optimization and MP2/6-31G^*//HF/6-31G^* for a single point total energy calculation are reported for the important energy-minimum conformations and transition-state geometries of (Z,Z)-, (E,Z)-, and (E,E)-cyclonona-1,5-dienes. The C₂ symmetric chair conformation of (Z,Z)-cyclonona-1,5-diene is calculated to be the most stable form; the calculated energy barrier for ring inversion of the chair conformation via the C_s symmetric boat-chair geometry is 58.3kJmol^–1. Interconversion between chair and twist-boat-chair (C₁) conformations takes place via the twist (C₁) as intermediate. The unsymmetrical twist conformation of (E,Z)-cyclonona-1,5-diene is the most stable form. Ring inversion of this conformation takes place via the unsymmetrical chair and boat-chair geometries. The calculated strain energy for this process is 63.5kJmol^–1. The interconversion between twist and the boat-chair conformations can take place by swiveling of the trans double bond with respect to the cis double bond and requires 115.6kJmol^–1. The most stable conformation of (E,E)-cyclonona-1,5-diene is the C₂ symmetric twist-boat conformation of the crossed family, which is 5.3kJmol^–1 more stable than the C_s symmetric chair–chair geometry of the parallel family. Interconversion of the crossed and parallel families can take place by swiveling of one of the double bonds and requires 142.0kJmol^–1.     

Ab Initio Study of Conformational Properties of ( Z, Z)-, ( E, Z)-, and ( E, E)-Cyclonona-1,5-dienes

Summary. Ab initio calculations at the HF/6-31G^* level of theory for geometry optimization and MP2/6-31G^*//HF/6-31G^* for a single point total energy calculation are reported for the important energy-minimum conformations and transition-state geometries of (Z,Z)-, (E,Z)-, and (E,E)-cyclonona-1,5-dienes. The C₂ symmetric chair conformation of (Z,Z)-cyclonona-1,5-diene is calculated to be the most stable form; the calculated energy barrier for ring inversion of the chair conformation via the C_s symmetric boat-chair geometry is 58.3kJmol^–1. Interconversion between chair and twist-boat-chair (C₁) conformations takes place via the twist (C₁) as intermediate. The unsymmetrical twist conformation of (E,Z)-cyclonona-1,5-diene is the most stable form. Ring inversion of this conformation takes place via the unsymmetrical chair and boat-chair geometries. The calculated strain energy for this process is 63.5kJmol^–1. The interconversion between twist and the boat-chair conformations can take place by swiveling of the trans double bond with respect to the cis double bond and requires 115.6kJmol^–1. The most stable conformation of (E,E)-cyclonona-1,5-diene is the C₂ symmetric twist-boat conformation of the crossed family, which is 5.3kJmol^–1 more stable than the C_s symmetric chair–chair geometry of the parallel family. Interconversion of the crossed and parallel families can take place by swiveling of one of the double bonds and requires 142.0kJmol^–1.     

Transport through a slab membrane governed by a concentration-dependent diffusion coefficient: Part IV. D(C)/D0=1+(αC)−β(αC)

Using the specific functional form D(C)/D₀=1+(αC)−β(αC)² an investigation has been made of (isothermal) transport through a slab membrane under ‘simple’ boundary conditions and governed by a diffusion coefficient, D(C), which, with increasing concentration, at first increases, passes through a maximum value and finally decreases. The flux, integral diffusion coefficient and concentration profile characteristic of steady-state permeation have been evaluated; special attention has been paid to the positions of such profiles in relation to the corresponding linear distribution associated with a constant diffusion coefficient.The corresponding transient-state transport has been studied within a framework of the time-lag ‘early-time’ and ‘ ’ procedures. Expressions for the ‘adsorption’ and ‘desorption’ time-lags are given. The concentration-dependence of these time-lags, of the (four) integral diffusion coefficients derived from them and of the arithmetic-mean time-lag ratios have been considered in some detail. The ‘early-time’ and ‘ ’ finite-difference procedures have likewise been employed to derive four further integral diffusion coefficients, so enabling a comparison to be made of the nine integral coefficients pertaining to established experimental techniques.Particular interest attaches to the situation for which n≡β(αC₀)=1 (where C₀ is the ingoing or upstream concentration of diffusant) resulting in D(C₀) being symmetrical about C₀/2. Some consideration has been given, in general, to features of transient-state transport when governed by a symmetrical D(C).     

Mild hydrothermal synthesis, crystal structure, spectroscopic and magnetic properties of the [M=Fe, x=2.08, y=1.58; M=Co, Ni, x=2.5, y=2] compounds

The [M=Fe (1), x=2.08, y=1.58; M=Co (2), x=2.5, y=2; Ni (3), x=2.5, y=2] compounds have been synthesized using mild hydrothermal conditions at 170 °C during five days. Single-crystals of (1) and (2), and polycrystalline sample of (3) were obtained. These isostructural compounds crystallize in the orthorhombic system, space group Aba2, with a=9.9598(2), b=18.8149(4) and c=8.5751(2) Å for (1), a=9.9142(7), b=18.570(1) and c=8.4920(5) Å for (2) and a=9.8038(2), b=18.2453(2) and c=8.4106(1) Å for (3), with Z=8 in the three phases. An X-ray diffraction study reveals that the crystal structure is composed of a three-dimensional skeleton formed by [MO₅F] and [MO₄F₂] (M=Fe, Co and Ni) octahedra and [HPO₃] tetrahedra, partially substituted by [PO₄] tetrahedra in phase (1). The IR spectra show the vibrational modes of the water molecules and those of the (HPO₃)²⁻ tetrahedral oxoanions. The thermal study indicates that the limit of thermal stability of these phases is 195 °C for (1) and 315 °C for (2) and (3). The electronic absorption spectroscopy shows the characteristic bands of the Fe(II), Co(II) and Ni(II) high-spin cations in slightly distorted octahedral geometry. Magnetic measurements indicate the existence of global antiferromagnetic interactions between the metallic centers with a ferromagnetic transition in the three compounds at 28, 14 and 21 K for (1), (2) and (3), respectively. Compound (1) exhibits a hysteresis loop with remnant magnetization and coercive field values of 0.72 emu/mol and 880 Oe, respectively.     

Oxygen deficiency and phase transitions in SrCo1– x – y Fe x Cr y O3–δ ( x =0.10–0.40, y =0–0.05)

Oxygen-deficient phases based on perovskite-like strontium cobaltites-ferrites are promising mixed conductors for high-temperature electrochemical applications. The p(O₂)-T-δ diagrams for the oxide systems SrCo_{1– x – y} Fe _x Cr _y O_{3– δ} (x=0.10–0.40; y=0–0.05) were studied at 500–1000 °C in the oxygen pressure range from 10^–5 to 0.21 atm using the coulometric titration technique and thermogravimetric analysis. Stability limits of the cubic perovskite phases having a high oxygen ionic conductivity were evaluated as functions of temperature, oxygen partial pressure and oxygen nonstoichiometry. It was found that doping with chromium and increasing the iron content in SrCo(Fe,Cr)O_{3– δ} both lead to a considerable enlargement of the cubic perovskite phase existence domain towards lower temperatures and reduced oxygen pressures. Electronic Publication     

High-efficient calculation of the interaction energies between dissimilar double layers for Na2SO4-type asymmetric electrolytes at y 0 > y d > 0

Several rapidly convergent series for highly efficient calculation of the interaction energies between dissimilar double layers for Na₂SO₄-type electrolytes at y ₀ > y _d > 0 are derived, the accurate numerical results are given, and several approximate expressions are obtained for y ₀ ≪ 1. The number of the series terms required to obtain the interaction energies with six significant digits via the use of the series derived is no more than 2 when the dimensionless surface potential of double layers y ₀ ≤ 20. The interaction energies between dissimilar double layers for NaCl-or Na₂SO₄-type electrolytes are remarkably affected by the value of y _d,, but the interaction energies for Na₂SO₄-type electrolytes are hardly affected by the value of y ₀. The present results can also be applied to CaCl₂-type electrolytes at y ₀ < y _d < 0. The text was submitted by the authors in English.     

A conjecture for some partial differential operators on L 2( R n)

OnX =L ²(R ⁿ), letQ = (Q ₁,Q ₂,…,Q _n) andP = (P ₁,P ₂, …,P _n) be the operators given by (Q _jf) (x) =x _jf(x),P _j = - i∂/∂x _j. For anyC ^∞ functionh:R ⁿ →R putH ₀ =h(P) andH =H ₀ + (1 +Q ²)^-δ, where δ > 1/2. By the method of scattering theory we prove thatH _ac, the absolutely continuous part ofH is unitarily equivalent toH ₀ when (a)n = 1 and (b) forn ≥ 2, whenh is in a large class of polynomials. It is conjectured that the results are true for any polynomialh. We use the techniques of Enss’ method and the idea of bound states for momentum.     

High efficient calculation of the interaction energies between two double layers for CaCl2 type asymmetric electrolytes at y 0 > y d > 0

Several rapidly convergent series for the highly efficient calculation of the interaction energies between dissimilar double layers for CaCl₂ type electrolytes at y ₀ > y _d > 0 were derived. The accurate numeral results were given and several approximate expressions were obtained for y ₀ ≪ 1. The number of the series terms required to obtain the interaction energies with six significant digits is not more than 3 when the dimensionless surface potential of double layers y ₀ ≤ 20. The interaction energies between dissimilar double layers for Na₂SO₄ or CaCl₂ type electrolytes depend significantly on the y _d value, while the interaction energies for Na₂SO₄ type electrolytes is practically independent of y ₀. The present results can also be applied to Na₂SO₄ type electrolytes at y ₀ < y _d < 0. The text was submitted by the authors in English.     

Development and validation of an analytical methodology for the determination of p,p′-DDT, p,p′-DDE and p,p′-DDD in fish oil pills

An analytical methodology was proposed and validated to be applied to the determination of p,p′-DDT and its metabolites p,p′-DDE and p,p′-DDD in fish oil. The analytical procedure presented in this paper involves a single-step clean up process prior to the analysis. A solution of 1,2,3,4-tetrachloronaphtalene was used as internal standard.The analytical technique used was gas chromatography coupled to an electron capture detector. Details on the validation process are provided.The limits of detection ranged from 2.6 to 4.7 pg μL^− 1. The BCR 598 standard reference material (cod liver oil) was used to evaluate the performance of the methodology with satisfactory recoveries for all the compounds.The analytes were determined in three different fish oil pills sold in Spain as a supplementary vitamin support. The sum of p,p′-DDT and metabolites was from 13.2 to 51.3 ng g^− 1, the dominant compound being p,p′-DDE.     

New complex oxides of the A3n+3mA′nB3m+nO9m+6n family: Ba6A′Mn4O15 (A′=Mg, Ni)

Complex oxides Ba₆AMn₄O₁₅, where A=Mg (I) and Ni (II), belonging to the homologous series A_3n+3mA′_nB_3m+nO_9m+6n (n=1, m=1) were obtained by solid state reaction method from Ba carbonate and oxides MgO, NiO, MnO₂. Both new oxides are incommensurate. Their crystal structures were interpreted as composite ones with two subcells: a=10.042(3) Å, c₁=4.318(2) Å, c₂=2.565(1) Å, c₁/c₂=1.6834 for (I) and a=10.044(3) Å, c₁=4.308(2) Å, c₂=2.551(1) Å, c₁/c₂=1.6887 for (II). Magnetic susceptibility measurements in the range 2–850 K revealed antiferromagnetic correlations in Ba₆MgMn₄O₁₅ (T_N=7 K) and a pseudo-square-planar environment of some Ni²⁺ cations in Ba₆NiMn₄O₁₅.     

High-pressure structural evolution of a perovskite solid solution (La1−x,Ndx)GaO3

The structural evolution with pressure of six perovskites in the system La_1−xNd_xGaO₃ with x=0.00, 0.06, 0.12, 0.20, 0.62 and 1.00 have been determined by single-crystal diffraction. At room pressure, all six samples have Pbnm symmetry. The room-pressure bulk moduli vary only slightly with composition, between K_0T=169(4) and 177(2) GPa, with . As pressure is increased there is significant compression of the octahedral Ga–O bonds, the tilts of the GaO₆ octahedra decrease and the structures evolve towards higher symmetry. At room conditions the average Ga–O bond length increases with increasing compositional parameter x. However, the GaO₆ become stiffer with increasing x; the Ga–O bonds thus become stiffer as they become longer. Bond strengths in the octahedra in perovskites are therefore not a simple function of bond lengths but depend also upon the extra-framework cation.Phase transitions to R-3c symmetry occur at 2.2 GPa in end-member LaGaO₃, at 5.5 GPa in the x=0.06 sample, at 7.8 GPa for x=0.12, and at 12 GPa for x=0.20. No evidence of the transition in the x=0.62 or 1.00 samples was found by X-ray diffraction to 9.4 or 8.0 GPa, respectively, or by Raman measurements of NdGaO₃ up to 16 GPa. The transition pressure therefore increases with increasing Nd content (increasing x) at approximately 0.45 GPa per 0.01 increment in x, at least up to x=0.20. Compression of the R-3c phase of LaGaO₃ above the transition results in no significant changes in the tilt angle of the octahedra. The structural behavior of all six samples at high pressures is the result of the GaO₆ octahedra being softer than the extra-framework (La, Nd)O₁₂ site. The results therefore demonstrate that the evolution of solid-solution perovskites at high pressures follow the same general principles recently elucidated for end-member compositions.     

Alkaloids ofFumaria vaillantii

FromFumaria vaillantii, collected in the Tashkent province, 18 alkaloids have been isolated of which N-methyladlumine with mp 198–199°C, []_D-45° (c 0.5; methanol) has proved to be new. Its structure has been established on the basis of spectral characteristics and a direct comparison withl-adlumine methiodide.Institute of the Chemistry of Plant Substances of the Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 602–604, September–October, 1981.     

New Quaternary Chalcogenides BaLnMQ3 (Ln = Rare Earth or Sc; M = Cu, Ag; Q= S, Se): II. Structure and Property Variation vs Rare-Earth Element

Some new quaternary compounds of the type BaLnMQ₃ (Ln = rare earth or Sc; M = Cu, Ag; Q = S, Se) have been synthesized by the reaction of the constituent binary chalcogenides and elements at 1000°C. The crystal structures of two of these compounds have been determined by single-crystal X-ray diffraction techniques and are isostructural. Crystal data: BaErCuS₃—space group D¹⁷_2h —Cmcm, M= 464.32, Z = 4 , a = 3.987(1), b = 13.377(3), c = 10.101(2) Å (T = 115 K), V = 538.7(4) ų, R_w (F²) = 0.095 for 848 observations and 24 variables, R(F) = 0.037 for 840 observations having F²₀ > 2σ (F²₀); BaYAgSe—space group D¹⁷_2h —Cmcm, M = 571.0, Z = 4, a = 4.239(1), b = 14.030(2), c = 10.636(2) Å (T = 115 K), V = 632.6(2) ų, R_w (F²) = 0.057 for 645 observations and 24 variables, R(F) = 0.023 for 595 observations having F²₀ > 2σ(F²₀). These two compounds adopt the layered KZrCuS₃ structure type. The layers, which are separated by Ba²⁺ ions, consist of edge-sharing octahedral chains and corner-sharing tetrahedral chains. The other compounds synthesized crystallize either with this same structure or with that of β-BaLaCuSe₃, a slightly distorted variation, which is isostructural with Eu₂CuS₃. The diffuse reflective UV-visible spectra of several of these compounds have been measured. From magnetic susceptibility measurements, both BaNdCuS₃ and BaGdCuS₃ show Curie-Weiss behavior, whereas BaCeCuS₃ and BaCeCuSe₃ show in addition temperature-independent paramagnetism.     

Steroid compounds ofErysimum XI. Sterols ofErysimum diffusum andE. cuspidatum

Summary It has been shown that the unsaponifiable fraction of the oil ofErysimum cuspidatum contains -sitosterol and campesterol, and the oil ofErysimum diffusum contains -sitosterol.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 821–823, November–December, 1977.     

Approximate formulae for calculation of the integral òT0Tmexp(-E/RT)dT

Summary In this paper two approximate formulae have been developed for calculation of the integral ò^T₀T^mexp(-E/RT)dT by using integration-by-parts approaches. They are in the following forms: I(m,T) = (RT^m+2)/(E+(m+2)RT)exp(-E/RT) I(m,T) = (RT^m+2)/(E+(m+2)(0.00099441E+0.93695599RT)exp(-E/RT) The validity of the two formulae has been confirmed and their accuracies have been tested with data from numerical calculating. In contrast to existing other integral methods, both the present approaches are simply used, accurate, and can be used for arbitrary values of m.     

Sesquiterpene lactones ofLigularia macrophylla andL. thomsonii

Summary From the roots ofLigularia macrophylla D. C. Prodr. we have isolated a new sesquiterpene lactone ligolide with the composition C₁₆H₂₂O₄, for which the structure of 10-hydroxy-6-methoxyeremophilan-7-olide is proposed. From the same plant and fromL. thomsonii (Clark) Pojark. we have isolated and identified furoeremophilan-14, 6-olide, -sitosterol, and hydrocarbons with the compositions C₁₁H₁₈ and C₁₁H₃₆.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Tashkent Pharmaceutical Institute. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 742–745, November–December, 1976.     

Applications of Raman-based techniques to on-site and in-vivo analysis

Raman-based technologies have proved to be excellent tools for on-site and in-vivo analysis, due to the non-invasive nature of their detection, their capability of providing structure information, their high tolerance to aqueous samples, the ultra-sensitivity of surface-enhanced Raman scattering (SERS) and resonance Raman scattering (RRS), the high spatial resolution of tip-enhanced Raman scattering (TERS), and the ultrashort spectra-acquisition time for coherent anti-Stokes Raman scattering (CARS) and stimulated Raman scattering (SRS).In this review, we highlight the recent success of Raman-based technologies in various applications, including:

• (1) 

  on-site surface analysis and chemical-reaction monitoring;

• (2) 

  on-site identification of cultural objects, archeological studies and planetary science;

• (3) 

  in-vivo analysis of cells and microorganisms;

• (4) 

  in-vivo diagnosis inside human and animal bodies;

• (5) 

  in-vivo fast Raman imaging and mapping;

• (6) 

  the study of SERS processes; and,

• (7) 

  assessment of nanomaterial safety.

     

Phytoecdysteroids ofRhaponticum carthamoides

From the roots with rhizomes of the plantRhaponticum carthamoides Willd) Iljin Compositae), in addition to integristerone A, ecdysterone, polypodin B, 2-deoxyecdysterone, and 24(28)-dehydromakisterone A, we have isolated the new compounds ecdysteron3–2,3-monoacetonide (I), ecdysterone 20,22-monoacetonide (II)) and rhapisterone (III): I — C₃₀H₄₈O₇, mp 232–233° (ethyl acetate-methanol) [] _D ²⁰ +56.4±2° (c 0.0; methanol); II — C₃₀H₄₈O₇, mp 227–229° (ethyl acetate-methanol), [] _D ²⁰ +60.1±2° (c 1.3; methanol); III — C₂₉H₄₈O₇, mp, 241–242° (ethyl acetate-methanol), [] _D ²⁰ +30±2° (c 0.1; dioxane). The structure of (III) was established on the basis of spectral characteristics as 2, 3, 14, 20R, 22R, 23-5-stigmast-7-en-6-one. Details of the PMR, mass, and IR spectra of all the compounds and of the CD of rhapisterone are given.Institute of the Chemistry of Plant Substances of the Uzbek SSR Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 681–684, September–October, 1987.     

Cardenolides ofCoronilla glauca andC. scorpioides

The cardenolide glycosides glucocorotoxigenin, scorpioside, and coronillobioside and a new compound which has been called glucocoroglaucigenin have been isolated from the seeds ofCoronilla glauca L. for the first time. The new glycoside has the structure of 3-(-D-glucopyranosyloxy)-14,19-dihydroxy-5-card-20(22)-enolide. This glycoside has also been isolated from the seeds ofC. scorpioides.Khar'kov Pharmaceutical Institute. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 676–679, September–October, 1985.