The charge‐transfer complex trans‐STB–TCNQF4

In the crystal structure of the title charge‐transfer complex, namely trans‐stilbene–2,2′‐(2,3,5,6‐tetra­fluoro­benzene‐1,4‐diyl­idene)­propane­di­nitrile (1/1) (trans‐STB–TCNQF₄), C₁₄H₁₂·C₁₂F₄N₄, the planar STB and TCNQF₄ mol­ecules are stacked alternately. The structure is not isostructural with that of STB–TCNQ. No anomaly was found in the displacement parameters of any atoms, while the bond length of the central C=C moiety was shorter than the corresponding bond in ethyl­ene. This suggests that the central C=C moiety of the STB mol­ecule vibrates with a large amplitude, similar to the case in free STB and STB–TCNQ.     

q-deformed Circular Operators

In this paper, q-deformed circularity of an operator in a Hilbert space is introduced and investigated. In particular, the q-deformed circularity of a weighted shift is characterized by an integer, which is uniquely determined by the operator. It is shown that that the spectrum of a q-deformed circular weighted shift is the whole complex plane.     

An Inherently Chiral Au24 Framework with Double‐Helical Hexagold Strands

2,3‐bis(diphenylphosphino)butane enantiomers (chiraphos, L) used as chiral auxiliaries results in the preferential formation of an unprecedented Au₂₄ framework with inherent chirality. The crystal structure of [Au₂₄L₆Cl₄]²⁺ ( 1 ) has a square antiprism‐like octagold core twinned by two helicene‐like hexagold motifs, where the inherent chirality is associated with the helical arrangement. The clusters carrying (R,R)‐ and (S,S)‐ diphosphines had right‐ and left‐handed strands, respectively. Circular dichroism spectra showed peaks in the visible to near‐IR region, some of which did not coincide with absorption bands, suggesting the enantiomeric Au₂₄ frameworks possess unique chiroptical properties. The Au₂₄ frameworks were thermally robust, which could be attributed to the superatomic concept (18 e^? system) and the steric constraint effects of the bridging ligand units.     

聚乙烯醇中的紫外偏振线性聚炔分子

本文通过研究共轭线性碳链分子，聚炔H(C≡C)_nH (n=5∽7)的电子吸收带，设计了适用于UV的光偏振膜. 激光烧蚀的聚炔分子被分散在聚乙烯醇膜中. 结构各向异性的性质使得多炔分子的UV吸收跃迁偶极子与分子轴平行，并且吸收仅发生在沿着分子轴具有电子矢量幅度的电磁波上. 多炔分子在固体聚乙烯醇膜中作为特定波长入射光的偏振分量之一的选择性吸收剂. 使用可旋转的偏振UV光研究包含聚炔分子的拉伸聚乙烯醇膜的吸收强度的角度依赖性，并根据线性二向色性理论中有序参数进行分析.     

Radiation Chemical Studies of Protein Reactions: Effect of Amino Acids and Vitamins on the Breaking of Secondary Bonding in Protein

The radiation protective effect of the breaking of secondary bonding in protein was examined with such amino acids as disodium inosine-5′ -monophosphate and disodium guanosine-5′ -monophosphate and vitamins such as thiamine and λ-ascorbic acid. The behavior of the viscosity change closely resembles that found with the sodium 1-glutamate as shown by a similar dependence on concentration.     

Simple determination of betamethasone and chloramphenicol in a pharmaceutical preparation using a short monolithic column coupled to a sequential injection system

This contribution describes the use of a new separation method based on a reversed-phase sequential injection chromatography (SIC) technique for simultaneous determination of chloramphenicol and betamethasone in pharmaceutical eye drops. A short monolithic column coupled with a sequential injection analysis (SIA) system enabled separation of two compounds in one step. A Chromolith Flash RP-18e, 25 x 4.6 mm column with a 5 mm precolumn (Merck, Germany) and a FIA1ab 3000 system (USA) with a 6-port selection valve and 5 mL syringe were used for sequential injection chromatographic separations in this study. The mobile phase used was acetonitrile-water (30:80, v/v), flow rate 0.48 mL/min; UV detection was at two wavelengths, i.e., 241 and 278 nm (absorption maxima of betamethasone and chloramphenicol, respectively). The basic validation parameters showed good results: linearity of determination for both compounds including internal standard (propylparaben) >0.999; repeatability of determination (RSD) in the range 0.8-1.7% at two different concentration levels, and detection limits in the range 0.5-1.0 mg/mL. The chromatographic resolution between compound peaks was greater than 2.1 and the analysis time was less than 8 min under optimal conditions. The developed sequential injection chromatography method was compared with the HPLC method and was found to be applicable for routine analysis of active compounds in pharmaceutical preparations.     

Phase changes of CO2 hydrate under high pressure and low temperature

High pressure and low temperature experiments with CO(2) hydrate were performed using diamond anvil cells and a helium-refrigeration cryostat in the pressure and temperature range of 0.2-3.0 GPa and 280-80 K, respectively. In situ x-ray diffractometry revealed that the phase boundary between CO(2) hydrate and water+CO(2) extended below the 280 K reported previously, toward a higher pressure and low temperature region. The results also showed the existence of a new high pressure phase above approximately 0.6 GPa and below 1.0 GPa at which the hydrate decomposed to dry ice and ice VI. In addition, in the lower temperature region of structure I, a small and abrupt lattice expansion was observed at approximately 210 K with decreasing temperature under fixed pressures. The expansion was accompanied by a release of water content from the sI structure as ice Ih, which indicates an increased cage occupancy. A similar lattice expansion was also described in another clathrate, SiO(2) clathrate, under high pressure. Such expansion with increasing cage occupancy might be a common manner to stabilize the clathrate structures under high pressure and low temperature.     

Densities and Viscosities of Tris(acetylacetonato)cobalt(III) Complex Solutions in Various Solvents

The densities and the viscosities of tris(acetylacetonato)cobalt(III) solutions in acetonitrile, dichloromethane, chloroform, tetrachloromethane, benzene, toluene, ethylbenzene, and p-xylene were measured in the dilute concentration regions at several temperatures ranging from 278 to 313 K under ambient pressure. The partial molar volumes of the solvents and solute were calculated. They are independent of concentration and increase slightly as the temperature increases. The viscosity A- and B-coefficients of the Jones-Dole equation were obtained. The A-coefficients were found to be zero within experimental error. The B-coefficients are positive and decrease as the temperature increases. Thermodynamic quantities of activation for viscous flow were calculated on the basis of Eyring’s viscosity equation. From the quantities obtained in this study, along with some information from the literature, it is suggested that structure-making interactions occur between the segments of the complex and the solvent molecules. These interactions include electrostatic interactions between the local charge on the complex and the dipole moment of the solvent in solutions of acetonitrile and dichloromethane, interlocking packing interactions along C ₃-axis of the complex with solvent in solutions of chloroform and tetrachloromethane, and π-electron interactions between the chelate ring of the complex and the solvent in solutions of benzene, toluene, ethylbenzene, and p-xylene.