Synthesis of terminally substituted stilbene-tolane liquid crystals

Methods for synthesizing substituted alkyl and fluoro stilbene-tolane (PTPDP) liquid crystal materials are presented. These compounds show a slightly higher birefringence than the analogous bistolanes, but higher melting points and heats of fusion. Potential applications of these compounds for optical communications and displays are discussed.     

Fluorine-containing triphenylenes. Liquid crystalline properties and surface ordering

The synthesis and liquid crystalline properties of two novel series of triphenylenes with 4 or 5 pentafuoropentyloxy tails and 1 or 2 alkoxy tails of varying length are reported. All compounds form wide-range hexagonal columnar phases. The isotropisation temperatures and the corresponding enthalpy changes for the compounds with 4 or 5 fluorinated tails are higher than for the compounds with 6 alkoxy tails, and also higher than for compounds with 6 fluorinated tails. These results indicate that the best ordering is obtained for compounds with a mix of fluorinated and non-fluorinated tails. With increasing length of the alkyl tails in HAT compounds with 4 or 5 fluoroalkoxy tails, the isotropisation temperatures decrease and the d-spacings as observed by XRD increase. All fluoro-containing compounds have a strong tendency for spontaneous homeotropic alignment on surfaces, both hydrophilic and hydrophobic.     

An improved set of mndo parameters for sulfur

The MNDO parameters for sulfur have been reoptimized. Calculations for a number of sulfur compounds indicate a very significant improvement. Inclusion of d AOs failed to correct the errors for compounds of sulfur in its higher valence states. Since d AOs are not included, the calculations are still confined to compounds of divalent sulfur.     

Analysis of organic compounds of water-in-crude oil emulsions separated by microwave heating using comprehensive two-dimensional gas chromatography and time-of-flight mass spectrometry

In this work the higher peak capacity and resolution of comprehensive two-dimensional gas chromatography (GCxGC) has been successfully applied, for the first time, to tentatively identify several polar organic compounds of organic extracts of aqueous phases resulting from microwave demulsification process of water-in-crude oil emulsions. Results have shown that higher temperatures and longer exposure time to microwave irradiation produced water phases with a wider variety of polar organic compounds. The microwave process showed to be suitable for the extraction of several polar compounds classes of petroleum. The proposed microwave extraction method and GCxGC identification of polar compounds of petroleum samples are of practical interest for the petrochemical industry due to corrosion and related problems associated with these polar compounds in refinery equipments. The GCxGC/time-of-flight MS technique shows to be very important in the total separation of different classes of compounds and allows the identification of many compounds in these classes.     

The dependence of the fluorescence properties, laser properties and photochemical stability of aromatic compounds on the molecular symmetry

It is known that the spectral properties of organic compounds are, to a large extent, determined by the molecular symmetry. Numerous articles and monographs have been devoted to this problem. However, the influence of the molecular symmetry on fluorescence and, hence, laser parameters has not been fully investigated. In this paper, the fluorescence and laser properties of 20 aromatic compounds are experimentally studied at room temperature. The compounds studied are arranged in family-related pi-structure pairs. In each pair, even-numbered compounds belong to a higher symmetry group than odd-numbered compounds due to symmetrical substitution. All main fluorescence parameters such as quantum yield, gamma, decay time, tauf, fluorescence rate constant, k(f) (Einstein coefficient, A), and intersystem crossing rate constant, kST, are measured or calculated. It has been found that for most of the symmetrically substituted molecules, the value of kST decreases, sometimes very significantly. For example, the transition from 9-phenylanthracene (C2 symmetry) to 9,10-diphenylanthracene (D2 symmetry) is accompanied by an 18-fold decrease in the value of kST. This phenomenon is explained by the fact that, in a molecule of higher symmetry, not all triplet states mix with the fluorescing S1 state. It is also found that the symmetry of a molecule greatly affects laser parameters such as the threshold of laser action and the photochemical stability of a laser solution. It is observed that the threshold for even-numbered compounds is much lower and the photochemical stability, in most cases, is much higher than for odd-numbered compounds. These phenomena are discussed and explained.     

Effect of analyte properties on the kinetic performance of liquid chromatographic separations

Advances in modern high-performance liquid chromatography (HPLC) have led to increased interest in the comparison of the ultimate performance limits of methodologies aimed at increasing the resolving power per unit time. Kinetic plot-based methods have proven invaluable in facilitating such evaluations. However, in bridging the gap between fundamental comparisons and the eventual practical applicability of kinetic performance data, the effect of analyte properties have thus far largely been neglected. Using pharmaceutical compounds as representative real-life analytes, it is demonstrated that noteworthy differences in the optimal kinetic performance of a chromatographic system are observed compared to data for common test compounds. For a given stationary phase particle size, higher optimal- and maximum plate numbers, corresponding to increased analysis times, are measured for pharmaceutical compounds. Moreover, it is found that the optimal particle size/maximum pressure combination depends on the analyte under investigation, with the beneficial range of efficiencies for small particles shifted towards higher plate numbers for drug molecules. It is further demonstrated that the pH of the mobile phase plays a crucial role in determining the kinetic performance of pharmaceutical compounds. These data clearly indicate that data for test compounds do not reflect the performance attainable for pharmaceutical compounds and highlights the importance of using real-life samples to perform kinetic evaluations.     

Adhesives and compounds in manufacture of electronic mechanisms

The general properties of adhesives and compounds for electronic articles are described that were elaborated by the company: TK-1 adhesive with elevated thermal conductivity; TEK-type adhesives that demonstrate higher elasticity and adhesion ability; TK-8-type all-purpose adhesives; MS-type, single-packed, thermally stable glues for long storage; electrically conductive adhesives; TPK-1 and TPK-2 magnetic adhesives and TPK-3 nonmagnetic adhesive; and some compounds, e.g., epoxide molding compositions. The functionality of all adhesives and compounds presented were tested for weather factors, including elevated humidity, higher and lower temperatures, thermal cycles, effects of vibrations for both pilot samples, and final articles of electronic mechanisms.     

Determination of nucleotides, nucleosides and nucleobases in cells of different complexity by reversed-phase and ion-pair high-performance liquid chromatography

Procedures are presented for the analysis of profiles of purine and pyridine compounds in human and rabbit red blood cells by reversed-phase high-performance liquid chromatography and in Ehrlich ascites tumour cells of mouse by ion-pair high-performance liquid chromatography. These compounds are present in rabbit erythrocytes in higher concentrations than in human blood cells, and in rabbit reticulocytes the concentration of purine compounds is still higher. During glucose-free incubation, human red cells accumulate adenosine and adenine in the presence of coformycin owing to the inhibition of adenosine and AMP deamination. Ehrlich ascites tumour cells lose major portions of purine mono-, di- and triphosphates between the seventh and eleventh day after inoculation into mouse peritoneal cavities.     

The synthesis and properties of fluoro-substituted analogues of 4-butyl-4′-[(4-butylphenyl)ethynyl]biphenyls

The synthesis of 4-butyl-4′-[(4-butyl-2,6-difluorophenyl)ethynyl]biphenyl and its higher fluorinated analogues is presented and discussed. Correlations between molecular structure and mesomorphic properties for presented compounds as well as other known from the literature analogues have been drawn. The dielectric study of four synthesised compounds and their mixtures are presented and discussed. Trifluoro-substituted analogues are trade off between low dielectric anisotropy of difluorinated compounds and lower clearing points of tetrafluorinated ones.     

I-Line光刻胶材料的研究进展

酚醛树脂-重氮萘醌正型光刻胶由于其优异的光刻性能,在g-line(436 nm)、i-line(365 nm)光刻中被广泛使用.g-line光刻胶胶、i-line光刻胶,两者虽然都是用线型酚醛树脂做成膜树脂,重氮萘醌型酯化物作感光剂,但当曝光波长从g-line发展到i-line时,为适应对应的曝光波长以及对高分辨率的追求,酚醛树脂及感光剂的微观结构均有变化.在i-line光刻胶中,酚醛树脂的邻-邻'相连程度高,感光剂酯化度高,重氮萘醌基团间的间距远.溶解促进剂是i-line光刻胶的一个重要组分,本文对其也进行了介绍.     

1,4-二(苯并噁唑-1',3'-基-2')苯衍生物的合成及其物理性能研究

合成了1,4-二(苯并(口恶)唑-1′,3′-基-2′)苯衍生物13种化合物。测定了它们的熔点、红外光谱、紫外吸收光谱、荧光发射光谱、荧光量子产率、荧光寿命和激光性能。     

Synthesis of higher alicyclic compounds from thiophene derivatives

A new method is proposed for the synthesis of higher alicyclic compounds in which bi- and tricyclic molecules possessing the thiophene ring are desulphurized with the aid of Raney nickel New routes to many-membered bi- and tricyclic compounds possessing the thiophene ring have been developed, based on acyloin condensation and intramolecular acylation and alkylation.     

Solar and supplemental UV-B radiation effects in lemon peel UV-B-absorbing compound content-seasonal variations

Effects of solar and supplemental UV-B radiation on UV-B-absorbing compounds and malondialdehyde (MDA) accumulations in the peel of lemons collected in summer and winter were analyzed. UV-B-absorbing compounds were higher in flavedo than in albedo tissue in both seasons; however, the highest values were observed in summer. These compounds were also higher in outer than in inner flavedo surface. Lemons were categorized as sun-, semisun- and shaded-lemon according to localization inside the tree canopy. Depending on-tree localization UV-B-absorbing compounds were higher in flavedo of sun-lemon than in semisun- and shaded-lemon. Supplementary UV-B radiation (22 kJ m(-2) day(-1) UV-BBE) induced UV-B-absorbing compound synthesis in on-tree and postharvest lemons. Two minutes of supplemental UV-B irradiation in summer lemons produced a strong increment (300%) of UV-B-absorbing compound content, whereas in winter lemons a slight increase (30%) was observed only after 3 min of irradiation. By contrast, UV-B-absorbing compound accumulation was not observed in albedo. MDA accumulation showed approximately a similar trend of UV-B-absorbing compounds. According to our results, solar UV-B was not required for UV-B-absorbing compound accumulation in lemon peel. Relationships between UV-B-absorbing compounds, MDA, reactive oxygen species and pathogen protection are also discussed.     

Hidden active information in a random compound library: extraction using a pseudo-structure-activity relationship model

We propose a hypothesis that "a model of active compound can be provided by integrating information of compounds high-ranked by docking simulation of a random compound library". In our hypothesis, the inclusion of true active compounds in the high-ranked compound is not necessary. We regard the high-ranked compounds as being pseudo-active compounds. As a method to embody our hypothesis, we introduce a pseudo-structure-activity relationship (PSAR) model. Although the PSAR model is the same as a quantitative structure activity relationship (QSAR) model, in terms of statistical methodology, the implications of the training data are different. Known active compounds (ligands) are used as training data in the QSAR model, whereas the pseudo-active compounds are used in the PSAR model. In this study, Random Forest was used as a machine-learning algorithm. From tests for four functionally different targets, estrogen receptor antagonist (ER), thymidine kinase (TK), thrombin, and acetylcholine esterase (AChE), using five scoring functions, we obtained three conclusions: (1) the PSAR models significantly gave higher percentages of known ligands found than random sampling, and these results are sufficient to support our hypothesis; (2) the PSAR models gave higher percentages of known ligands found than normal scoring by scoring function, and these results demonstrate the practical usefulness of the PSAR model; and (3) the PSAR model can assess compounds failed in the docking simulation. Note that PSAR and QSAR models are used in different situations; the advantage of the PSAR model emerges when no ligand is available as training data or when one wants to find novel types of ligands, whereas the QSAR model is effective for finding compounds similar to known ligands when the ligands are already known.     

DEHYDROCHLORINATION OF α-CHLORO SULFONES WITH KOH-T-BUOH: KINETIC VS EQUILIBRIUM CONTROL OF THE FORMATION OF α, β-UNSATURATED SULFONES AND THE β-T-BUTOXY AND β-HYDROXY MICHAEL ADDUCTS

Abstract

Inorganic sulfur compounds are used by microorganisms (bacteria, fungi, algae) and plants for assimilation, i.e. biosynthesis of sulfur-containing cell constituents.

Quantitatively, within the biogeochemical cycle of sulfur the utilization of inorganic sulfur compounds in bacterial energy metabolism, i.e. dissimilatory sulfur utilization, is of far higher importance. Reduced sulfur compounds serve as electron donors for photosynthesis and respiration, whereas inorganic sulfur compounds of oxidation levels above sulfide serve as electron donors in anaerobic respiration as well as in fermentation. In still other bacteria reduced sulfur compounds act as protective agents against hydrogen peroxide.     

锂离子电池有机硅电解液

有机硅电解液具有优良的热稳定性、低可燃性、无毒性、高电导率和高分解电压等优点,近年来成为了锂离子电池新型电解液的研究热点。本文综述了有机硅电解液的研究进展,重点介绍了聚醚有机硅电解液的设计合成、物理化学性能、与电解质盐和电极材料的匹配性关系及其在电池中的性能表现;简述了有机硅功能化电解液添加剂的研究进展,如成膜添加剂、阻燃添加剂、吸酸吸水添加剂等;最后对有机硅电解液的进一步研究趋势和应用前景进行了展望。     

Literature-based generation of hypotheses on chemical composition using database co-occurrence of chemical compounds

Candidates for identification of unknown constituents in a sample to be chemically analyzed are hypothetical. It is proposed to generate these hypotheses according to the co-occurrence of different chemical compounds with a known sample constituent in the chemical literature. The efficiency of the co-occurrence approach for predicting chemical compositions was tested for 67 impurities in 17 chemical/pharmaceutical products. The relative co-occurrence of impurity compounds and these products in the Chemical Abstracts Service database was evaluated and compared with corresponding values for several reference groups of probability sampled compounds from the literature. Almost all impurities (97%) and only < or = 8% randomly sampled compounds co-occurred with these chemical products. Mean and median values of relative co-occurrence for impurities are much higher than those of probability sampled compounds which co-occurred with the products. For the combination of impurities and the probability sample of 396 interfering compounds, the power to predict the chemical composition using the highest co-occurrences is 0.49-0.59. The co-occurrence value can also be considered as an "empiric" indicator of chemical similarity useful to generate new hypotheses on relationships both between compounds and between compounds and their properties.     

The relationship between the connectivity indices and the thermodynamic parameters describing the interaction of fatty acid methyl esters with polar and nonpolar stationary phases

Summary The relationships between the connectivity indices — easily calculated from the molecular structure of the compounds — and the partial molar free energies of solution are investigated for the methyl esters of 39 saturated (normal and branched) mono- and polyunsaturated higher fatty acids on a nonpolar (SE-30) and polar (SILAR 5CP) phase. The prediction of the ΔG values seems possible for any compound assuming that data for standard compounds are available. The relationship may be generally useful for the thermodynamic evaluation of nonspecific interactions of compounds with the stationary phases.     

异喹啉类化合物抑制肥大细胞脱颗粒活性的3D-QSAR研究

对一组抑制肥大细胞脱颗粒的异喹啉类化合物的活性及毒性进行了3D-QSAR研究,采用距离比较法(DISCO)得到了它们的药效团模型,通过选择不同的叠合方式,建立了相关性很好的比较分子力场分析(CoMFA)模型,其交叉验证参数R^2~cv分别为0.654和0.662,非交叉验证的相关系数分别为0.990与0.983,通过查阅统计量F表,表明活性及毒性模型的置信度都大于99%,显示模型具有较强的预测能力,并在此基础上进行了新活性先导化合物的设计,得到了预测活性高以及预测毒性低的新结构,合成实验正在进行之中。     

Characterization of oligomeric compounds in secondary organic aerosol using liquid chromatography coupled to electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry

The components of secondary organic aerosols (SOAs) generated from the gas‐phase ozonolysis of two C₁₀H₁₆‐terpenes (α‐pinene; sabinene) and a cyclic C₆H₁₀ alkene (cyclohexene) were characterized by the use of a Fourier transform ion cyclotron mass spectrometer equipped with an electrospray ionization source operated in the negative ion mode. Reversed‐phase high‐performance liquid chromatography was used to achieve chromatographic separation of highly oxidized organic compounds. In addition to the well‐known group of low molecular weight oxidation products (monomers; e.g. dicarboxylic acids), higher molecular weight compounds (dimers) were also detected and their exact elemental compositions were determined. In order to provide additional information for the structural elucidation of these compounds, collision‐induced dissociation was applied. Based on the MS/MS spectra, two higher molecular weight products are proposed to be an ester and a peroxide. Molecular formulae calculated from the exact masses show that the SOA‐compounds are heavily oxidized and this information creates the background to a discussion of potential reaction pathways for the formation of higher molecular weight compounds. Copyright © 2009 John Wiley & Sons, Ltd.