共查询到20条相似文献,搜索用时 93 毫秒
1.
S. V. Blokhina A. V. Sharapova M. V. Ol’khovich 《Russian Journal of General Chemistry》2004,74(8):1201-1205
Thermodynamic characteristics of solution of n-alcohols in p-n-alkoxycynnamoyloxy-p-cyanoazobenzene liquid crystalline phases at infinite dilution are obtained. For each of the mesogens studied, the solubility of sorbates in the nematic phase is higher than in smectic. Increasing alkyl chain length in sorbates decreases their solubility in mesomorphic phases, whereas increasing alkyl chain length in liquid crystals exerts the opposite effect. The greater endothermic effect of solution of alcohols corresponds to higher entropy and positive deviations from ideality.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 8, 2004, pp. 1300–1305.Original Russian Text Copyright © 2004 by Blokhina, Sharapova, Olkhovich.This revised version was published online in April 2005 with a corrected cover date. 相似文献
2.
The sorption properties of supercooled smectic phases of homologues of the p-n-alkoxycinnamoyloxy-p-cyanoazobenzene series were studied by gas–liquid chromatography. Based on the system of universal retention indices, mesomorphic stationary phases were classified and the quality of the chromatographic separation was estimated. The increase in the selectivity of smectic phases with the use of the cooling mode was rationalized thermodynamically. 相似文献
3.
A series of new side-chain liquid crystalline polymers containing chenodiol residue derived from 24-[4′-hydroxybiphenyl-4-yl-4-(allyloxy)benzoyloxy]-3α,7α-di{n-[4′-(4-ethoxybenzoyloxy)biphenyl-4-yloxy]-n-oxoalkanoyloxy}-5β-cholane was designed and prepared. The chemical structures of the monomer and polymer were confirmed by Fourier transform
infrared and 1H NMR spectra. The mesomorphic properties of monomer and polymer were investigated by differential scanning calorimetry, thermogravimetric
analysis, polarizing optical microscopy, and X-ray diffraction. The side-chain liquid crystalline polymers revealed wide mesophase
temperature range and high thermal stability, and they showed nematic liquid crystalline phase. The influence of flexible
space group length on thermal properties and specific rotation was examined. 相似文献
4.
F. M. Samigullin S. F. Malatsion M. N. Rodnikova A. A. Syrbu N. S. Kucherepa 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2010,84(1):137-140
A unique viscometer of the CS rheometer viscometer class designed at the Kazan State University of Technology is used to measure
viscosities of two p-n-alkyloxybenzylidene-p-toluidines in the entire temperature range of the liquid crystalline state and transition into an isotropic liquid. The measured
shear stresses and flow rates are used to calculate shear rates and plot flow and viscosity curves. The liquid crystalline
phase and isotropic liquid are demonstrated to possess Newtonian viscosity, whose viscous flow activation parameters are calculated
in the temperature range under study. The results are discussed from the standpoint of intermolecular interactions and structural
details of the liquid crystalline phase. 相似文献
5.
Frank Marken Alastair N. Blythe Jay D. Wadhawan Richard G. Compton Steven D. Bull Robin T. Aplin Stephen G. Davies 《Journal of Solid State Electrochemistry》2001,5(1):17-22
The effect of the structure of the organic precursor molecule on the electroinsertion of anions and on the formation of materials
in the ionic liquid state is compared for three compounds, para-N, N, N′, N′-tetrahexylphenylenediamine (p-THPD), meta-N, N, N′, N′-tetrahexylphenylene diamine (m-THPD), and para-N, N, N′, N′-tetrakis(6-methoxyhexyl)phenylenediamine (p-TMHPD), by characterising their condensed phase voltammetric properties in aqueous media. The electrochemically driven anion
insertion in p-THPD and p-TMHPD in the presence of ClO4
−, F−, Cl−, Br−, I−, and SO4
2− is shown to be extremely sensitive to structure. The introduction of the methoxy end groups in p-TMHPD causes (1) a considerable shift to more negative electroinsertion potentials, (2) a less stable response which upon
continuous cycling decreases, and (3) considerably lower anion selectivity. For the insertion of sulfate, only p-TMHPD yields an electrochemical response which is shown to be consistent with insertion of the dianion SO4
2−. The electrochemical oxidation of a deposit of m-THPD is accompanied by anion insertion and a chemical reaction step in an EC-type electrochemical process. The product of
the chemical step is electrochemically active and results in a new reversible electroinsertion process. Starting materials
and products of the microdroplet reactions are characterised by Maldi-TOF mass spectrometry and a reaction mechanism based
on condensed phase polymerisation is proposed.
Received: 15 November 1999 / Accepted: 2 December 1999 相似文献
6.
G. Giraudi Claudio Baggiani Antonella Cosmaro Emilio Santià Adriano Vanni 《Fresenius' Journal of Analytical Chemistry》1998,360(2):235-240
A very selective polyclonal antiserum against 1,1,1-trichloro-2,2-bis-(4-chlorophenyl)-ethane (p,p′-DDT) was obtained by a careful choice of the haptenic structure (2,2-bis(4-chlorophenyl)-ethanol hemisuccinate). This hapten
was conjugated to BSA to prepare the immunogen. The effects of different types of solid phases on the equilibrium reaction
between the hapten on solid phase and the polyclonal antiserum were evaluated to obtain a fine tuning of the antiserum performances
in terms of specificity for p,p′-DDT and sensitivity to low levels of this pesticide. The calibration curves obtained show that it is possible to set up
a sensitive assay for p,p′-DDT, employing a p,p′-dichlorodiphenylacetic acid-based solid phase, with a detection limit of 0.12 ng/mL and a working range of about 0.21–40
ng/mL. Selectivity towards several p,p′-DDT-related substances was good (o,p-DDT 17%, p,p′-DDD 1.2% o,p-DDD 6.3%, p,p′-DDE 6.7%).
Received: 4 November 1996 / Revised: 9 June 1997 / Accepted: 16 June 1997 相似文献
7.
Aránzazu Martínez-Gómez Ernesto Pérez Antonio Bello 《Colloid and polymer science》2010,288(8):859-867
The phase transitions and the orientational behavior of liquid crystalline poly(triethylene glycol p,p′-bibenzoate) have been studied. The real-time synchrotron diffraction results indicate that, on cooling from the isotropic
melt, an orthogonal SmA mesophase is formed first, and later it is transformed into a tilted SmC mesophase. However, the SmA
mesophase is stable in a rather wide temperature interval, and the transformation into the SmC phase occurs at temperatures
close to the glass transition, so that not very high tilting angles are attained. The uniaxial deformation of the SmC mesophase
indicates that usual parallel orientation of the molecular axes in relation to the stretching direction is obtained at high
strain rates, while anomalous perpendicular orientation occurs at low deformation rates, with the smectic layers aligned with
the stretching direction and the molecular axes almost perpendicular. A mixture of the two types of orientation is observed
at intermediate rates, with rather interesting features. 相似文献
8.
V. F. Chuvaev M. N. Rodnikova A. A. Syrbu S. A. Syrbu 《Russian Journal of Inorganic Chemistry》2009,54(11):1793-1797
A sample of 4′-(octyloxy)-4-cyanobiphenyl (8OCB) was studied in the temperature range −60–80°C by wide-line 1H NMR. The line shapes, half-widths, and second moments were determined. For the smectic phase of 8OCB, the relaxation times
T
1 and T
2, the correlation time τc, and the degree of order were estimated. The 1H NMR spectral patterns and characteristics were found to be quite different for the crystalline, smectic, and nematic phases
of 8OCB, which makes it possible to reliably identify the corresponding transitions and assess the molecular dynamics and
molecular order of a structure. The temperature ranges, stability conditions, and other characteristics of the liquid crystalline
phases that form on heating 8OCB were determined. 相似文献
9.
Liquid crystalline(LC) polymers with a shish-kebab-type moiety on their cross-conjugated(p-phenylene)s-poly(p-phenylenevinylene) s main chains were synthesized through Gilch polymerization in order to develop a kind of polymers available for linearly polarized white-light-emitting from single chain.In this system,the 2,5-bis(4’-alkoxyphenyl)benzene as the "kebabs" connects with poly(p-phenylenevinylene)(PPV) main chain backbone using its molecular gravity center and the PPV as the "shish" or "skewer"(the "shish-kebab").The polymers possess desirable properties such as excellent solubility and liquid crystalline properties.To drop the "kebabs" of the 2,5-bis(4’-alkoxyphenyl)benzene into the orientation microgroove of aligned polyimide film,not only the "shish" of polymer main chain can be aligned by the virtue of orientation of "kebabs" but also the uniform cross-conjugated structure between the "kebabs" and "shish" can be broken. Then,the alignment of the polymer main chain showed yellow light emission and was also accompanied by orientation of the LC side chains showing blue light emission,this gave rise to a notable linearly polarized white fluorescence. 相似文献
10.
Zhi Qiang Shi Ning Ning Ji Ren Gao Zhao Ji Kun Li Zhi Feng Li 《Structural chemistry》2011,22(1):225-233
Two new copper(II) complexes, [Cu(p-FBA)2(2,2′-bpy)]·(H2O) (1) and [Cu(p-FBA)(2,2′-bpy)2]·(p-FBA)2 (2) {p-FBA = p-fluorobenzoic acid, 2,2′-bpy = 2,2′-bipyridine} have been obtained from an identical starting mixture using temperature as
the only independent variable and characterized by X-ray single crystal diffraction as well as with infrared spectroscopy,
elemental analysis, and thermogravimetric analysis. The results reveal that 1 has 1D infinite chain structure formed by O–H···O hydrogen bonds, while 2 features a 0D structure. Additionally, there exist C–H···O hydrogen bonds and π–π stacking interactions in 1, forming 2D supramolecular structure. Furthermore, density functional theory (DFT) calculations of the structures, stabilities,
orbital energies, composition characteristics of some frontier molecular orbitals and Mulliken charge distributions of the
[Cu(p-FBA)2(2,2′-bpy)] of 1 and [Cu(p-FBA)(2,2′-bpy)2]+ cation of 2 were performed by means of Gaussian 03W package and taking B3LYP/lanl2dz basis set. 相似文献
11.
Viorel Cîrcu Ana S. Mocanu Constantin Roşu Doina Manaila-Maximean Florea Dumitraşcu 《Journal of Thermal Analysis and Calorimetry》2012,107(3):877-886
A series of ortho-metallated palladium(II) complexes with two dimeric liquid crystals Schiff base (methoxy and decyloxy as terminal groups)
as cyclometallated ligands and N-aryl-N′-benzoyl thiourea derivatives as co-ligands were prepared and investigated for their liquid crystalline properties. Their
structures were assigned based on elemental analysis, FT-IR and 1H NMR spectroscopy while the thermal behaviour was investigated by differential scanning calorimetry and polarising optical
microscopy. The complexes with Schiff base ligand bearing methoxy group as terminal group show extensive decomposition during
melting while the complexes with Schiff base having decyloxy group as terminal group show monotropic nematic phases, with
the mesophase stability strongly related to the type of N-aryl-N′-benzoyl thiourea derivative used. Their liquid crystalline properties are compared with their analogues having N,N-dialkyl-N′-benzoyl thiourea as co-ligands which were reported previously. One of the latter complexes was also investigated by thermally
stimulated depolarisation currents method while the optical transmission was recorded simultaneously. The thermally stimulated
depolarisation currents and optical transmission spectra confirmed the previous observation regarding the phase transition
temperatures. The current intensity–applied voltage dependencies of this complex were investigated by specific electrical
measurements. 相似文献
12.
A series of optically active thiadiazole Schiff's bases were prepared and their liquid crystalline properties were studied. Chirality was achieved by introducing an asymmetric carbon atom into the alkoxy group. Thus, 2-(p -active-alkoxyphenyl-imine)-5-(p-n-alkoxy)phenyl-1,3,4-thiadiazoles were synthesized. Their structures were characterized using elemental analysis, and IR, 1H NMR and mass spectroscopies; their thermal properties were determined using DSC and polarized light microscopy. All the compounds are enantiotropic liquid crystals, and most of them exhibited both chiral smectic C* and cholesteric mesophases. Only one of them did not show a smectic C* phase. 相似文献
13.
Takamitsu Otake Yoshie Aoyagi Takashi Yarita Masahiko Numata 《Analytical and bioanalytical chemistry》2010,397(6):2569-2577
Fish certified reference material (CRM), NMIJ CRM 7404-a, for the analysis of polychlorinated biphenyls (PCBs) and organochlorine
pesticides (OCPs) was developed by the National Metrology Institute of Japan, part of the National Institute of Advanced Industrial
Science and Technology. Fish samples (Japanese seabass) used for the preparation of the CRM were collected from Tokyo Bay,
and the edible part was freeze-dried, pulverized, sieved, homogenized, and sterilized by γ-irradiation. This sample is in
the form of a powder comprising approximately 10 g stored in a brown glass bottle. The certification was carried out using
multiple analytical methods such as pressurized liquid extraction, Soxhlet extraction, saponification, and homogenization
to ensure the reliability of analytical results; the certified values of target PCBs (PCB 28, PCB 70, PCB 105, PCB 153, and
PCB 170) and OCPs (trans-nonachlor, dieldrin, p,p′-DDE, p,p′-DDT, and p,p′-DDD) were 1.05–14.0 μg kg−1 and 1.57–18.0 μg kg−1 for PCBs and OCPs, respectively. This is the first fish powder CRM in which PCBs and OCPs were determined by isotope dilution
mass spectrometry. 相似文献
14.
Debasis Das S. A. Ansari P. K. Mohapatra G. Mary K. Radhakrishnan S. C. Tripathi V. K. Manchnada 《Journal of Radioanalytical and Nuclear Chemistry》2011,287(1):293-298
Ion-chromatography (IC) as well as high performance liquid chromatography (HPLC) techniques have been used as analytical tools
for the separation and estimation of some of the relevant metal ions present in the high level liquid waste (HLLW). IC was
applied for the estimation of alkali and alkali earth metal ions, viz. Na, Cs, Ba and Sr using methane sulphonic acid as the
eluent on a cation exchange column. On the other hand, dynamically modified (with sodium salt of n-octane sulphonic acid) reverse phase HPLC was followed for the estimation of lanthanides viz. La, Pr, Nd and Sm using α-hydroxy
isobutyric acid as the eluent on a C-18 column. Sample acidity of 0.01 M HNO3 was optimized for best analytical results. The interferences of one group of metal ions on the quantification of the other
group of metal ions were studied. The solvent extraction data (distribution coefficient data) of Na, Cs, Sr, Ba, La, Pr, Nd
and Sm from their mixture was obtained by analyses of the aqueous samples before and after extraction with extractants used
for actinide partitioning, viz., octyl(phenyl)N,N-diisobutyl carbamoyl methylene phosphine oxide (CMPO), N,N′-dimethyl-N,N′-dibutyl tetradecyl malonamide (DMDBTDMA) and N,N,N′,N′-tetraoctyl diglycolamide (TODGA). The solvent extraction data obtained by IC/HPLC techniques was compared with those obtained
by ICP-AES technique. A good agreement between the results of the two techniques validated the present analytical method. 相似文献
15.
E. A. Krasnov V. A. Raldugin I. V. Shilova E. Yu. Avdeeva 《Chemistry of Natural Compounds》2006,42(2):148-151
A chromatographically inseparable crystalline mixture of the previously undescribed quercetin-4′-O-β-galactopyranoside and the known quercetin-3-O-β-glucopyranoside (isoquercitrin) in a 7:5 ratio was isolated from the extract of the aerial part of Filipendula ulmaria (L.) Maxim.
__________
Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 122–124, March–April, 2006. 相似文献
16.
Linbo Gong Shuling Gong Haiqing Dong Chunlei Zhang Yuanyin Chen 《Frontiers of Chemistry in China》2007,2(3):292-295
The reaction of 4′-hydroxy-4-methyl azobenzene (1) and 1,6-dibromohexane afforded 6-bromo-1-((4-((4-met hylphenyl)azo)phenyl)oxy)hexane (2), which further reacted with p-tert-butylcalix[4]arene to give the calix[4]arene derivative (3) whose lower rim had been modified by the azobenzene photochromic group. The structure of 3 was characterized by 1H-nuclear magnetic resonance (NMR) and electrospray ionization-mass spectrometry (ESI-MS). The fluorescence intensity of compound
3 was two to four times higher than that of compounds 1 and 2 as the azobenzene group concentration in the range of 1.6 × 10−5 to 8.0 × 10−4 mol/L, indicating that the fluorescence quantum yield of the azobenzene group had been improved through being attached to
the calix[4]arene skeleton. The liquid crystalline behavior of compound 3 was studied by polarized microscopy (POM) and differential scan calorimeter (DSC). Compound 3 exhibited the enchased texture of a smectic liquid crystal from 209.4°C to 219.5°C on heating, while 2 exhibited a liquid crystalline phase from 87.4 to 83.2°C on cooling. It was found that the calix[4]arene skeleton was a good
platform for conformation immobilization of azobenzene photochromic group and the formation of liquid crystalline.
Translated from Chinese Journal of Applied Chemistry, 2006, 23(9): 1023–1026 [译自: 应用化学] 相似文献
17.
Diethyl 3,3′-di-tert-butyl-4,4′-dimethyl-2,2′-bipyrrole-5,5′-dicarboxylate was synthesized in four steps from ethyl 3,5-dimethyl-1H-pyrrole-2-carboxylate. The CH2 hydrogens of the ethyl ester groups of the former are diastereotopic in the 1H-NMR, consistent with axial chirality of the bipyrrole and restricted rotation about the 2,2′-bipyrrole bond, due to the
tert-butyl groups. An X-ray structure of the crystalline target compound shows the pyrrole rings are twisted out of coplanarity
by 84.5°. 相似文献
18.
Danuta Pentak W. W. Su?kowski Anna Su?kowska 《Journal of Thermal Analysis and Calorimetry》2008,93(2):471-477
Transmission electron micrographs (TEM) showed that liposome vesicles prepared from DL-α-phosphatidylcholine dimyristoyl (1,2-ditetradecanoyl-rac-glycerol-3-phosphocholine) (DMPC) by the modified reverse-phase
evaporation method (mREV) were spherical in shape and in majority of them were less than 100 nm in diameter. Differential
scanning calorimetry (DSC) method was used to determine the influence of cholesterol content and pH of Tris-HCl buffer used
for the preparation of liposomes on the temperature of phase transition T
C of phospholipids which form the investigated liposome vesicles. The use of DSC method made it possible to determine not only
the temperature of the main phase transition of phospholipids but also the temperature of the phospholipid phase transition
from the tilted gel phase(L
β′) to the ripple gel phase(P
β′). The results were compared with those obtained with EPR study. EPR study was carried out in the temperature range from 284
to 310 K i.e. below and above the phase transition temperature T
C of DMPC. On the basis of EPR spectra of spin marker 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) incorporated into the liposome,
the values of parameters f were determined. Hence TEMPO can be used to observe the change in partition between aqueous and fluid lipid regions. The
change in the relative values of f determined for DMPC as a function of temperature shows that this phospholipid undergoes a transition from a ‘gel phase’ to
a lamellar smectic liquid crystalline phase in the presence of excess water. The EPR study of TEMPO allowed us to determine
the transition temperature T
C. The results were compared with those obtained with DSC method. 相似文献
19.
Thermal decomposition of 2,4,6-trimethylphenyl and (+)-2′-methoxy-1,1′-binaphthalen-2-yl (4-methylphenylsulfonyl)azidimidocarbonates
in the presence of norbornene, methyl acrylate, and camphene was studied. (+)-2′-Methoxy-1,1′-binaphthalen-2-yl (4-methylphenylsulfonyl)azidimidocarbonate
reacted with norbornene to give (+)-exo-2′-methoxy-1,1′-binaphthalen-2-yl N-(4-methylphenylsulfonyl)-3-azatricyclo-[3.2.1.02,4]octane-3-carboximidoate, while in the reaction with methyl acrylate a mixture of stereoisomeric methyl 1-[(2′-methoxy-1,1′-binaphthalen-2-yloxy)(4-methylphenylsulfonylimino)methyl]aziridine-2-carboxylates
was obtained. The reaction of 2,4,6-trimethylphenyl (4-methylphenylsulfonyl)azidimidocarbonate with (−)-camphene involved
insertion of intermediate nitrene into the exocyclic double bond with formation of 2,4,6-trimethylphenyl N-(3,3-dimethylbicyclo[2.2.1]heptan-2-ylidenemethyl)-N′-(4-methylphenylsulfonyl)-imidocarbamate as a 3: 1 mixture of E,E and E,Z diastereoisomers in good yield.
Published in Russian in Zhurnal Organicheskoi Khimii, 2008, Vol. 44, No. 10, pp. 1495–1500.
The text was submitted by the authors in English. 相似文献
20.
A solid-phase extraction methodology, followed by high-performance liquid chromatography (HPLC) quantification with UV absorbance
detection (λ=267 nm), was developed in order to study the stability of 3′-azido-3′-deoxy-5′-O-isonicotinoylthymidine (AZT-Iso), a novel derivative of the antiretroviral AZT, in different matrixes. The half-lives (t
1/2) for AZT-Iso were 1.19, 1.13 and 0.30 h for human, rat and rabbit plasma, respectively, and 14.91 and 25.49 h for potassium
phosphate buffer (pH 7.4) and human serum albumin solution, respectively. The HPLC method proved to be selective, sensitive
and accurate. Good recovery, linearity and precision were achieved using p-fluorophenol as an internal standard. The validity of this method was tested using synthetic mixtures of the intact drug
with its decomposition products. In conclusion, the method presented is applicable to in vivo pharmacokinetics studies of
AZT-Iso in rats. 相似文献