Hexagonal high pressure phase of copper(I)tetraiodomercurate (Cu2HgI4)

Summary Using a high pressure X-ray camera Cu₂HgI₄ was subjected at room temperature to pressures up to about 8 GPa. A hexagonal high pressure phase (a=8.28 (2) Å,c=3.40 (0) Å, space group P lm,Z=1) could be detected. This phase shows a reversible transformation with pressure hysteresis. The transition occurs at 7 GPa when the pressure is increased but at 6 GPa when the pressure is decreased.

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Hexagonale Hochdruckphase von Kupfer(I)tetraiodomercurat (Cu₂HgI₄)

Zusammenfassung Cu₂HgI₄ wurde in einer Hochdruckkamera bei Raumtemperatur mit einem Druck bis zu 8 GPa belastet. Dabei bildete sich eine hexagonale Hochdruckmodifikation (a=8.28 (2) Å,c=3.40 (0) Å, Raumgruppe P lm,Z=1). Für diese Phase wurde eine reversible Umwandlung mit Druckhysterese festgestellt. Mit steigendem Druck findet die Umwandlung bei 7 GPa mit sinkendem Druck jedoch bei 6 GPa statt.

     

Clathrate formation in binary aqueous systems with CH2Cl2, CHCl3 and CCl4 at high pressures

P,T,X phase diagrams of the CH₂Cl₂-H₂O, the CHCl₃-H₂O and the CCl₄-H₂) systems have been studied by DTA in the pressure range 10^–3 to 5.0 kbar. Under pressure the cubic structure II (CS-II) hydrates forming in all the systems are replaced by hydrates with the composition M·7.3 H₂O whose stoichiometry and positive dT/dP values of melting lead us to believe that they are CS-I hydrates.In the CH₂Cl₂ and CHCl₃ systems the nonvariant point coordinates of the hydrate transformationQ ₂ ^h (l₁h17h7l₂, where l₁ and l₂ are liquid phases abundant in water and hydrate former, respectively, h₁₇ and h₇ are hydrates with hydrate numbers 17 and 7, respectively) areP = 0.6 kbar, T = –1.5°C andP =2.65 kbar,T = –10.5°C, respectively. In the CCl₄ system the 4-phaseQ ₃ ^h point (l₁h₁₇h₇s, where s is crystalline CCl₄) has coordinatesP = 0.75 kbar and T = 0.4°C.The main obstacle of the present study, the very slow achievement of equilibrium, has been eliminated by adding small amounts (0.25% by mass) of surfactants followed by ultrasonic mixing. We have shown that this accelerates the achievement of equilibrium without changing its position.     

New amides fromSpilanthes oleracea

In addition to the well known affinin [=spilanthol, (2E,6Z,8E)-deca-2,6,8-trienoic acid isobutylamide (1)], the corresponding 2-methyl-butylamide (2), and two new acetylenic alkamides were isolated fromSpilanthes oleracea L. by reversed phase medium pressure chromatography: (Z)-non-2-en-6,8-diynoic acid isobutylamide (3) and (Z)-dec-2-en-6,8-diynoic acid isobutylamide (4). The structures and their stereochemistries were elucidated by¹H-NMR,¹³C-NMR (2 and3), MS, UV, IR, and CD (2). The chemotaxonomic significance of the distribution of alkamides within theCompositae tribeHeliantheae is briefly discussed.

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Neue Amide ausSpilanthes oleracea (Kurze Mitteilung)

Zusammenfassung AusSpilanthes oleracea wurden neben dem seit langem bekannten Affinin [=Spilanthol, (2E,6Z,8E)-Deca-2,6,8-triensäureisobutylamid (1)] durch Umkehrphasen-Mitteldruckchromatographie das entsprechende 2-Methylbutylamid (2) und zwei neue acetylenische Alkamide isoliert: (Z)-Non-2-en-6,8-diinsäure-isobutylamid (3) und (Z)-Dec-2-en-6,8-diinsäure-isobutylamid (4). Die Strukturen und deren Stereochemie wurden mittels¹H-NMR,¹³C-NMR (2 und3), MS, UV, IR und CD (2) aufgeklärt. Die chemotaxonomische Bedeutung der Verbreitung von Alkamiden innerhalb der Compositen-TribusHeliantheae wird kurz diskutiert.

     

Double Pore Silica Gel Monolith Applied to Liquid Chromatography

Silica gels retaining double pore structure in the size ranges of micrometer and nanometer have been applied to the rod-shaped monolithic column for liquid chromatography. The macropore structure was designed by controlling the phase separation process induced by the hydrolysis and polycondensation of alkoxysilane, whereas the mesopore structure was tailored by the solvent exchange treatments on wet gels. The size exclusion chromatograms on polystyrene standards exhibited almost similar features for octadecyl-modified rod and conventional packed beads columns. The dependence of plate height on the velocity of mobile phase determined for amylbenzene was by far weaker in the rod column than in the packed beads column, suggesting that additional geometrical factors should be considered in describing the separation mechanism in the rod column.     

手性丙烯酸酯液晶原位光聚合反应

手性丙烯酸酯液晶原位光聚合反应何流，张树范，金顺子，漆宗能，王佛松（中国科学院化学研究所北京１０００８０）关键词手性丙烯酸酯，原位光聚合，双折射，近晶相手性侧链液晶高分子显示近晶Ｓ！相，具有铁电性，在光电功能材料和非线性光学材料方面有潜在的应用前景’...     

Liquid-Crystalline copolymers and polymer blends containing electron donor and acceptor groups: Effects of mesogenic structures on the smectic phase and the miscibility

Side-chain liquid-crystalline copolymers and polymer blends containing an electron-donating (carbazolylmethylene)aniline group and electron-accepting nitrophenyl groups with various central linking groups between aromatic groups in the mesogenic units, i.e., N?CH, CH?CH, N?N, and COO, were prepared to examine effects of the mesogenic structure on thermal behaviours. The most remarkable effects of the central linking group on the thermal properties and the miscibility were observed for the polymer blends. The 1:1 miscible polymer blends were prepared from the electron-donating polymer containing (carbazolylmethylene)aniline group (PM6C_z) and the electron-accepting polymers with similar central linking groups, i.e., N?CH, CH?CH, and N?N. For example, the 1: 1 polymer blend of PM6C_z and the electron-accepting polymer containing the nitrostilbene group induced a smectic phase from 73 to 207°C. This isotropic temperature was 46°C higher than the calculated value (161°C) based on the composition without the electron donor-acceptor interaction. On the other hand, the 1: 1 polymer blend of PM6C_z and the electron-accepting polymer containing the nitrophenylbenzoate group showed phase separation. Thus, the remarkable thermal stability and the miscibility of the polymer blends containing the electron donor and acceptor groups might be caused by planar structures between the mesogenic side groups which have similar central linking groups through the electron donor-acceptor interaction. A similar tendency was seen for copolymers and binary mixtures of both low-molecular-weight compounds containing the same mesogenic groups. © 1995 John Wiley & Sons, Inc.     

Enthalpies of Phase Transitions and Heat Capacity of TbCl3 and Compounds Formed in TbCl3–MCl Systems (M=K, Rb, Cs)

The molar enthalpies of the solid–solid and solid–liquid phase transitions were determined by differential scanning calorimetry for pure TbCl₃ and KTb₂Cl₇, RbTb₂Cl₇, CsTb₂Cl₇, K₃TbCl₆, Rb₃TbCl₆ and Cs₃TbCl₆ compounds. Both types of compounds, i.e. M₃TbCl₆ and MTb₂Cl₇ (M=K, Rb, Cs) melt congruently and show additionally a solid–solid phase transition with a corresponding enthalpy Δ_trs H ⁰ of 6.1, 7.6 and 7.0 kJ mol^–1 for potassium, rubidium and caesium M₃TbCl₆ compounds andΔ_trs H ⁰ of 17.1 (rubidium) and of 12.1 and 10.9 kJ mol^–1 (caesium) for MTb₂Cl₇ compounds, respectively. The enthalpies of fusion were measured for all the above compounds with the exception of Rb₃TbCl₆ and Cs₃TbCl₆. The heat capacities of the solid and liquid compounds have been determined by differential scanning calorimetry (DSC) in the temperature range 300–1100 K. The experimental heat capacity strongly increases in the vicinity of a phase transition, but varies smoothly in the temperature ranges excluding these transformations. C _p data were fitted by an equation, which provided a satisfactory representation up to the temperatures of C _p discontinuity. The measured heat capacities were checked for consistency by calculating the enthalpy of formation of the liquid phase, which had been previously measured. The results obtained agreed satisfactorily with these experimental data. This revised version was published online in August 2006 with corrections to the Cover Date.     

Structure and Phase Transitions of SnP2O7

SnP₂O₇ is a member of the ZrP₂O₇ family of materials, several of which show unusual thermal expansion behavior over certain temperature ranges and which show a number of displacive phase transitions on cooling from high temperature. Here we describe the structural properties of SnP₂O₇ from 100 to 1243 K as determined by X-ray and neutron powder diffraction. These studies reveal that SnP₂O₇ shows two phase transitions in this temperature range. At room temperature the material has a pseudo-cubic 3×3×3× superstructure. Electron diffraction studies show that the symmetry of this structure is P2₁3 or lower. On warming to ∼560 K it undergoes a phase transition to a structure in which the subcell reflections show a triclinic distortion; above 830 K the subcell reflections show a rhombohedral distortion. Significant hysteresis in cell parameters is observed between heating and cooling. The structure of SnP₂O₇ is discussed with references to other members of the AM₂O₇ family of materials.     

Ni添加对0.4Zr0.1V1.1Mn0.5Cr0.1合金的相结构和电化学性能的影响

本文通过XRD、SEM、EDS研究了Ti_0.4Zr_0.1V_1.1Mn_0.5Cr_0.1Ni_x(x=0，0.2，0.4，0.6，0.8)合金的相结构和电化学性能。该合金系由BCC结构的V基固溶体主相和六方结构的C14 Laves第二相组成，Ni能够促进第二相的生成，Ni含量的增加导致了各相中的化学组成和晶格参数的变化，并通过电化学方法研究了Ni含量对_0.4Zr_0.1V_1.1Mn_0.5Cr_0.1合金电极的最大放电容量、自放电性能、高倍率放电性能、循环稳定性能等的影响。     

Binary solid-liquid phase diagram of the two diastereomer racemates of triglycidyl isocyanurate (TGIC)

Triglycidyl isocyanurate [2451-62-9] as a trifunctional epoxy monomer is mostly used as curing agent. It exists in the form of two diastereomer racemates according to the configuration of the three chiral carbon atoms in the molecule, i.e. beta- or RRR/SSS and alpha- or RRS/SSR. The binary solid-liquid phase diagram of the two diastereomer racemates has been determined by differential scanning calorimetry (DSC). The two diastereomer racemates have different crystalline structures and are physical mixtures with an eutectic phase diagram. The eutectic mixture melts at 92.3 ± 1.0 °C and has alpha-TGIC content of 93.44% by mass or mole. With the help of the phase diagram the ratio of the two diastereomer racemates in TGIC may be determined. The binary phase diagram shows that beta-TGIC can be separated with efficiency from the mixture and may serve for enantiomer synthesis of high optical activity giving rise to the development of novel polymers.