Synthesis and optical behaviour of hydrogen-bonded liquid crystals based on a chiral pyridine derivative

Three series of cholesteryl-containing supramolecular hydrogen-bonded (H-bonded) liquid crystal (LC) complexes with different number of fluoro-substituent were synthesised and characterised. Cholesteryl isonicotinate as proton acceptor and 4-n-alkoxybenzoic acids with or without fluoro-substituent as proton donor had been mixed in tetrahydrofuran to obtain H-bonded LC complexes. The effect of lateral substitution and the length of terminal chain in the H-bonded precursors on the formation of the supramolecular complexes had been examined. It was found that the introduction of fluoro substituent on the induced mesogens could widen the molecular width and thus reduce the molecular aspect ratio of the complexes, therefore it could lead to compress the formation of the LCs. However, the fluoro substituent played a positive role in enhancing the intermolecular interactions and stabilising the H-bond structure of the complexes. The influence of terminal length on the mesogenic behaviours is also discussed. On increasing the spacer length, the clear point and the thermal range of induced mesophase-like cholesteric phase decreased, and an induced chiral smectic phase began to appear in some complexes with long terminal tails.     

Application of the photon's intrinsic flux to the 1s‐2p and 2p‐3d excitonic transitions in nanostructures

We have applied our two recent results [depending on its helicity photon carries a quantum flux of ± Φ ₀ = ± hc/e and the quantized magnetic fluxes through the electronic orbits of the Dirac hydrogen atom are given by: Φ (n,l,m_j) = (n‐l‐m_j)Φ₀) ] to the 1s‐2p and 2p‐3d excitonic transitions in nanostructures. It is shown that the flux changes for the non‐zero matrix elements in the 1s‐2p and 2p‐3d excitonic transitions is either ± Φ₀ or zero. The present result supports the previous results stated above. It is also shown that spin flip is possible in the 1s‐2p and 2p‐3d excitonic transitions.     

Syntheses, Crystal Structures, and Antimicrobial Activities of 3-Bromo-N'-(2-chloro-5-nitrobenzylidene)benzohydrazide and 3-Bromo-N'-(4-nitrobenzylidene)benzohydrazide

Two new hydrazone compounds, 3-bromo-N'-(2-chloro-5-nitrobenzylidene)-ben- zohydrazide 1 and 3-bromo-N'-(4-nitrobenzylidene)benzohydrazide 2, have been synthesized and characterized by elemental analysis, IR spectra, <'1>H NMR, and single-crystal X-ray diffraction.Compound 1 crystallizes in monoclinie, space group P2<,1>/c with a = 7.7924(10), b = 24.490(3), c =7.8989(9)(A),β = 94.987(6)°, V = 1501.7(3)(A)<'3>, Z = 4, R = 0.0345 and wR = 0.0739. Compound 2 crystallizes in monoclinic, space group P2<,1>/c with a = 7.4099(11), b = 24.868(4), c = 8.3255(12)(A),β= 112.796(8)°, V= 1414.3(4)(A)<'3>, Z = 4, R = 0.0744 and wR = 0.1912. Both compounds display E configurations with respect to the C=N double bonds. In the crystal structure of 1, molecules are linked through N-H…N and N-H…O hydrogen bonds, forming chains running along the c axis. In the crystal structure of 2, molecules are linked through N-H…O hydrogen bonds, forming chains running along the c axis. The preliminary antimicrobial activities were studied.     

Schnell-Methode zur Umsetzung von Kohlenwasserstoffen zu Wasserstoff für die Isotopenanalyse

Es wird eine weiterentwickeltes, isotopenanalytisches Verfahren zur probenchemischen Umsetzung von Kohlenwasserstoffen mit Chromium zu Wasserstoff bei 1300 K vorgestellt. Die erzielten Testergebnisse zeigen anhand der gemessenen δD-Werte, daβ Quarzöfen bei diesen Temperaturen noch keine die Isotopenmeβwerte beeinflussende Diffusion von Wasserstoff durch die Wandung zulassen. Auβerdem erfolgte die Reaktion nahezu spontan und vollständig, was die Methode zeitlich sehr effektiv macht.

A modified isotope analytical method is presented for the chemical reaction of hydrocarbons with chromium at 1300 K to form hydrogen. The test results obtained (i.e. the measured δD-values) show that at this temperature quartz heating tubes do not allow hydrogen to diffuse through the wail, which fact would influence the isotopic composition. Furthermore the reaction proceeds nearly spontaneously and quantitatively, which yields an effective method, especially with respect to time.     

Association and Shape of Molecules Using Free Length Theory

Abstract

Traditionally workers engaged in calculation of the ultrasonic velocity in liquid mixtures using Jacobson's Free Length Theory (FLT) arrive at the conclusion that the predictions of FLT produce large deviations when compared with experimental velocities. Such workers seemed to have ignored the necessity of incorporating two parameters in FLT as originally suggested by Jacobson himself: one, to account for the association, and the other, for the shape of the component molecules in the mixture. By introducing the association factor and deriving explicit expressions for different shapes of the molecules, the present work has demonstrated that FLT might be made to predict ultrasonic velocities in the mixtures better. Also this approach can very well be used to account for molecular associations and shapes.     

旋转滑动弧氩等离子体裂解甲烷制氢

采用切向气流和磁场协同驱动的旋转滑动弧氩等离子体,先通过光谱分析法计算了其电子温度和电子密度,了解其物理特性,将其应用于甲烷裂解制氢,研究了进气流量和CH_4/Ar比对反应效果的影响。结果表明,该滑动弧系统电子温度为1.0-2.0 e V,电子密度高达1015cm~(-3),是介于热与低温等离子体之间的一种等离子体形式,具有独特的物理特性,可以在达到较高反应效率的同时,保持较大的处理量;在CH_4裂解制氢实验中,CH_4转化率可达22.1%-70.2%,并随进气流量和CH_4/Ar比的增大均逐渐降低;H_2选择性为21.2%-61.2%,并随进气流量的增大先基本不变后有所增大,随CH_4/Ar比的增大逐渐降低;与应用于甲烷裂解的不同形式的低温等离子体对比(如微波、射频、介质阻挡放电等)可以发现,旋转滑动弧在获得较高甲烷转化率、较高H_2选择性和较低制氢能耗的同时,还可以保持较大的处理量,即进气流量可达6-20 L/min。