葡萄糖苷特异性固相萃取固定相的合成、表征及应用

以马来酰亚胺基修饰凝胶载体,通过β-葡萄糖胺和2-亚氨基硫代烷盐酸盐将作为配基的β-葡萄糖脒连接到载体上,合成了一种葡萄糖苷特异性固相萃取固定相,并对其固相萃取性能进行了表征.该固定相对葡萄糖苷具有特异性识别,并成功用于固相萃取分离葡萄糖苷.     

反相液相色谱中固定相和流动相对柱相比的贡献

依据柱相比的热力学定义和反相液相色谱中溶质的计量置换保留理论(the stoichiometric dispheement heory of solute for retention，SDT-R)，对反相液相色谱中固定相和流动相性质、温度对柱相比的影响进行了研究。结果表明：固定相的种类和配基的疏水性对柱相比影响较大，而流动相中有机溶剂的种类，特别是脂肪酸作为置换剂时，对柱相比的影响更大，而柱相比受温度的影响较小。此外，通过用27种小分子溶质对柱相比的测定，其logI和Z良好的线性关系，进一步证明柱相比是一个与溶质性质无关的常数。     

Morphological studies of a hydrogen-bonded LC polymer obtained by photopolymerization in LC solvents

Anisotropic morphologies and the phase behaviour of a hydrogen-bonded LC polymer obtained by photopolymerization in two kinds of LC solvent are discussed. The hydrogen-bonded LC monomer, 4-(6-acryloyloxyhexyloxy) benzoic acid (A6OBA), was photopolymerized in 4-cyano-4′-hexyloxybiphenyl (6OCB) and in 4-cyano-4′-undecyloxybiphenyl (11OCB), which show a nematic phase and a smectic A phase, respectively. After photo-polymerization, the LC media were removed by extraction and the pure polymer was observed by scanning electron microscopy. SEM images showed that the polymer possessed fibrous morphology with a fibre diameter of a few micrometers, based on polymerization-induced phase separation. The overall geometries reflected typical LC characteristics such as schlieren and focal-conic fan textures. It was found that the hydrogen bond between benzoic acid groups in the monomer was rigid enough to fix the anisotropic phase-separated structure forming during the early stage of phase separation; however, it could not permanently maintain the fibre structure due to dissociation at elevated temperature. X-ray measurements revealed that a well developed layer structure of the hydrogen-bonded mesogen existed in the polymer obtained from the smectic phase of 11OCB, whereas a polymer layer structure could develop only partially from the nematic phase of 6OCB.     

亲水有机相-含盐水两相体系的形成机理与分相能力

亲水有机相-含盐水两相体系的形成机理与分相能力;亲水有机相;含盐水相;两相体系;分相机理;分相能力     

Oxadiazole-based unsymmetrical chiral liquid crystal dimers: synthesis and mesomorphic properties

The synthesis and liquid crystalline properties of novel chiral Schiff's base dimers containing the 1,3,4-oxadiazole ring are reported. The length of the terminal S-alkyl chain has been varied. All the compounds synthesised were thermally stable and exhibited enantiotropic mesomorphism, showing either SmC*–SmA–TGB–N*–BP or SmC*–SmA phase sequence.     

Cholesterol-based dimeric liquid crystals: synthesis,mesomorphic behaviour of frustrated phases and DFT study

Chiral unsymmetrical dimeric liquid crystals consisting of a cholesterol moiety as chiral entity and a substituted salicylidene imine core (with the substituent being butyl or fluoro or chloro group) interconnected through an even methylene spacer have been synthesised and their mesomorphic properties are characterised. All the dimers exhibit enantiotropic mesophases. The butyl homologue exhibited N* phase only, the fluoro- and chloro-substituted compound exhibited frustrated blue phases (BPs), N* phase and SmC* or twisted grain boundary (TGB) phases. The occurrence of a fluid frustrated phase, the BP, in particular, observed in compounds with a polar moiety and bent optimised conformation by density functional theory (DFT) study, indicates the importance of polar structures and bent shape of the compounds. Theoretical calculation was performed in order to study the optimised conformation, polarity and electron density distribution of the synthesised cholesterol derivatives using DFT. Time-dependent density functional theory (TD-DFT) calculation also had been carried out to investigate the absorption spectra and HOMO–LUMO energies. The experimental and theoretical absorption spectra are also presented.     

Preorganised effects of a tetramesogenic supermolecule on supramolecular assembly in the liquid crystalline phases

After preparing a homologous series of tetrameric mesogenic compounds in which two U-shaped molecules were connected via a rigid benzene derivative or a flexible alkyl chain, we investigated their phase transition behaviour using optical microscopy, differential scanning calorimetry and X-ray diffraction analysis. The compounds possessing an alkyl spacer as the central group exhibited nematic and smectic A phases just as the corresponding U-shaped molecule did. The compound possessing a 1,2-benzene unit as the connecting group showed nematic and smectic A phases, although the compound possessing a 1,3-benzene unit exhibited only an anticlinic smectic C phase. Structure–property relations of the liquid crystalline tetramers are interpreted in terms of preorganised effects of the four mesogenic units.     

Time‐Resolved Phase Transitions of the Nanocrystalline Cubic to Submicron Monoclinic Phase in Zirconia

The nanocrystalline cubic, tetragonal, and submicron monoclinic phases of pure zirconia were prepared by thermal decomposition of carbonate and hydroxide precursors. The crystallization and isothermal phase transformations of the oxide were studied using high temperature X‐ray diffraction, X‐ray diffraction and Raman spectra of quenched samples. Cubic zirconia formed first, and then progressively transformed to tetragonal and monoclinic phases at temperatures as low as 320°C. The cubic, tetragonal, and monoclinic phases for ZrO₂ were found to be distinct functions of crystallite size, indicating the nanocrystalline nature of these phases. They were found to exist within critical size ranges of 50 to 140 Å, 100 to 220 Å and 190 to 420 Å (±5 Å), respectively. Thus, as the crystallites grow during annealing, they first transform from cubic to tetragonal and then from tetragonal to monoclinic at critical sizes. The classical Avrami equation for nucleation and growth was applied to the tetragonal to monoclinic phase transition.     

Phase equilibria in the GeSe2-SnTe system

Journal of Thermal Analysis and Calorimetry - The phase diagram of the system GeSe2-SnTe is studied by means of X-ray diffraction, differential thermal and measurements of the microhardness and the...     

Physical properties of two systems with induced antiferroelectric phase

Two ferroelectric three‐ring chiral esters, one with a partially fluorinated alkyl chain and another with a cyano terminal group, were mixed with a structurally similar compound having an alkyl terminal chain. In their mixtures an antiferroelectric phase was induced. The phase behaviour, spontaneous polarisation, tilt angle, smectic layer spacing and helical pitch of both systems were determined. The mechanism of the induction of an antiferroelectric phase is different in both cases, with highly tilted phases in former system and less tilted phases in the latter.     

BaB2O4—CdO和BaB2O4—ZnO二元系相图的研究

本文用差热分析和X射线衍射方法测定了BaB_2O_4-CdO和BaB_2O_4-ZnO二元系相图。在BaB_2O_4-CdO体系中存在着一新化合物BaCdB_2O_5,在785±3℃同成份熔化。在BaB_2O_4-ZnO体系中,由包晶反应形成一新化合物BaZn_3B_2O_7,反应温度为903±3℃。在富BaB_2O_4区形成一个宽的低温相BaB_2O_4固溶区。研究结果表明,用Zn~(2 )替代BaB_2O_4中Ba~(2 )形成固溶体,不能将高温相BaB_2O_4稳定到室温,证实了“经验函数关系式”的预测结果。     

Obituary: Professor Frank M. Leslie FRS (1935-2000)

The synthesis of five new cholesteryl-based monomers (M-1?M-5) and the corresponding smectic comb-like polymers containing cholesteryl groups (P-1?P-5) is presented. The chemical structures were characterised by FT-IR, 1H NMR and elemental analyses. The specific optical rotations were evaluated with a polarimeter. The phase behaviour was investigated by polarising optical microscopy, differential scanning calorimetry, thermogravimetric analysis, and X-ray diffraction. The specific optical rotation values of these monomers and polymers with the same number of phenyl rings and terminal groups were nearly equal; however, they decreased with increasing the aryl numbers in the mesogenic core. The monomers M-1?M-5 showed oily streak and focal conic optical textures, or finger print textures characteristic of the chiral nematic phase. The polymers P-1?P-5 showed the smectic A phase. The melting, clearing, and glass transition temperatures increased, and the mesophase temperature ranges widened with increasing the aryl number in the mesogenic core. However, although the molecular structures of M-4 and M-5 were similar to those of M-3, namely their mesogenic cores contained three phenyl rings, their phase behaviour differed considerably, and T _m and T _i of M-4 and M-5 were less than those of M-3. In addition, M-4 and M-5 showed a clear glass transition similar to the polymer. Furthermore, the ester linkage bond and aryl arrangement in the mesogenic core also affected the phase behaviour.     

Synthesis,structure and properties of new chiral liquid crystalline monomers and homopolysiloxanes containing menthyl groups

The synthesis is described of four new chiral liquid crystalline monomers (M₂–M₅ ) and their corresponding side‐chain homopolysiloxanes (P₂–P₅ ) containing menthyl groups. Chemical structures were characterised using FT‐IR or ¹H NMR spectra, and specific optical rotations were evaluated with a polarimeter. The phase behaviour and mesomorphic properties of the new compounds were investigated by differential scanning calorimetry, thermogravimetric analysis, polarising optical microscopy, UV/visible/NIR spectrocopy and X‐ray diffraction. The monomers and homopolymers with more aryl segments showed noticeably lower specific optical rotation value. The monomers M₂–M₅ formed a cholesteric or blue phase when a flexible spacer was inserted between the rigid mesogenic core and the terminal menthyl groups by reducing the steric effect. M₂–M₅ revealed enantiotropic cholesteric phase. Moreover, M₂ also exhibited a monotropic smectic A (SmA) phase, and M₄ also exhibited a cubic blue phase on cooling. The selective reflection of light shifted to the long wavelength region with increasing rigidity of the mesogenic core for M₂–M₅ . P₂–P₅ exhibited SmA phases, and the mesogenic moieties were ordered in smectic orientation with their centres of gravity in planes. Melting or glass transition temperature and the clearing temperature increased, and the mesophase temperature range widened with increasing rigidity of the mesogenic core.     

Extensively Reversible Thermal Transformations of a Bistable,Fluorescence‐Switchable Molecular Solid: Entry into Functional Molecular Phase‐Change Materials

Functional phase‐change materials (PCMs) are conspicuously absent among molecular materials in which the various attributes of inorganic solids have been realized. While organic PCMs are primarily limited to thermal storage systems, the amorphous–crystalline transformation of materials like Ge‐Sb‐Te find use in advanced applications such as information storage. Reversible amorphous–crystalline transformations in molecular solids require a subtle balance between robust supramolecular assembly and flexible structural elements. We report novel diaminodicyanoquinodimethanes that achieve this transformation by interlinked helical assemblies coupled with conformationally flexible alkoxyalkyl chains. They exhibit highly reversible thermal transformations between bistable (crystalline/amorphous) forms, along with a prominent switching of the fluorescence emission energy and intensity.     

一种新型C_(18)酯型反相高效液相色谱填料的制备

发展了一种用于制备反相高效液相色谱填料的实用、经济的方法。以γ环氧丙基氧丙基三甲氧基硅烷为中间偶联试剂,将十八烷基脂肪酸键合至硅胶上。元素分析、色谱测试验证了该工艺的可行性和填料的反相色谱行为。     

Signatures for Coexistence of Monoclinic and Hexagonal Phases in GaTe Nanoflakes

The burgeoning two-dimensional (2D) layered materials provide a powerful strategy to realize efficient light-emitting devices. Among them, gallium telluride (GaTe) nanoflakes, showing strong photoluminescence (PL) emission from multilayer to bulk crystal, relax the stringent fabrication requirements of nanodevices. However, detailed knowledge on the optical properties of GaTe varies as layer thickness is still missing. Here we perform thickness-dependent PL and Raman spectra, as well as temperature-dependent PL spectra of GaTe nanoflakes. Spectral analysis reveals a spectroscopic signature for the coexistence of both the monoclinic and hexagonal phases in GaTe nanoflakes. To understand the experimental results, we propose a crystal structure where the hexagonal phase is on the top and bottom of nanoflakes while the monoclinic phase is in the middle of the nanoflakes. On the basis of temperature-dependent PL spectra, the optical gap of the hexagonal phase is determined to be 1.849 eV, which can only survive under temperature higher than 200 K with the increasing phonon population. Furthermore, the strength of exciton-phonon interaction of the hexagonal phase is estimated to be 1.24 meV/K. Our results prove the coexistence of dual crystalline phases in multilayer GaTe nanoflakes, which may provoke further exploration of phase transformation in GaTe materials, as well as new applications in 2D light-emitting diodes and heterostructure-based optoelectronics.     

Synthesis of novel nematic liquid crystals containing 3,3'-dimethyl-2,2'-bipyridyl

Liquid-crystalline 3,3′-dimethyl-2,2′-bipyridyl derivatives with long 4-(alkoxyphenyl)ethynyl (-C≡C-C₆H₄-OR) groups in the 5,5′-positions were synthesized by palladium-catalysed crosscoupling reactions. The compounds exhibit exclusively nematic behaviour; for example, the hexyl derivative showed a nematic phase over the temperature range 145.2–205.0°C. On increasing the length of the terminal chain, the transition temperatures were lowered; for example, the hexadecyl derivative was nematic in the range 117.0–126.8°C.     

Phase Equilibria in The System La2O3–K2O–P2O5

The ternary system La₂O₃–K₂O–P₂O₅ has been examined by thermal, X-ray, IR and microscopic methods. The existence of three double potassium-lanthanum phosphates, K₃La(PO₄)₂, KLa(PO₃)₄ and K₂La(PO₃)₅ has been confirmed, and the phase diagram of the ternary system La₂O₃–K₂O–P₂O₅ over the composition range LaPO₄–K₃PO₄–P₂O₅ has been determined. This revised version was published online in August 2006 with corrections to the Cover Date.     

Fe(NO3)3—C0(NH2)2—H2O体系在20℃及60℃的溶解度相图

三硝酸六尿素合铁〔Fe(N_2H_4CO)_6〕(NO_3)_3是一种含氮和铁的复合肥料。G.Malguori曾测定过硝酸铁在水中的溶解度,H.Kakinuma等都报道过尿素在水中的溶解度。对尿素——硝酸铁——水体系的溶解度相图,仅仅有等用多温法进行过研究。本文提供了尿素——硝酸铁——水体系在20℃和60℃两个温度下的溶解度相图数据,在65℃以上由于该三元     

Spectroscopic study of liquid crystalline N-[4-(4-n-alkoxybenzoyloxy)2-hydroxybenzylidene]hydroxyanilines

New homologous series of N-[4-(4-n-alkoxybenzoyloxy)-2-hydroxybenzylidene]hydroxyanilines were synthesized. All 4-hydroxyaniline derivatives exhibited a nematic phase, while 3-hydroxyaniline and 2-hydroxyaniline derivatives exhibited only a nematic phase as the terminal alkoxy group was lengthened. Infrared spectra suggest that the 4-hydroxyaniline derivatives form intermolecular hydrogen bonding of the single bridge type, while the 3-hydroxy and 2-hydroxy derivatives form the polymer type. The Raman band at around 1360 cm^-1 exhibited large differences in intensity among these derivatives. This can be explained by the effect of intermolecular or hydrogen bonding molecular conformation.