排序方式: 共有9条查询结果,搜索用时 15 毫秒
1
1.
2.
Summary The comparative gas chromatographic behavior has been investigated for two new liquid-crystal stationary phases, 2-(3-chlorobenzyloxy)-3-hexanoxy-4-(4-chlorobenzoyloxy)-4′-(4-methylbenzoyloxy)azobenzene
(denoted 3-Cl) and 2-(3-methylbenzyloxy)-3-hexanoxy-4-(4-chlorobenzoyloxy)-4′-(4-methylbenzoyloxy)azobenzene (denoted 3-CH3). The structures of the main core of the two liquid crystals are the same but they differ by lateral aromatic branch— 3-chlorobenzyloxy
and 3-methylbenzoyloxy. Their thermal properties were established by use of differential scanning calorimetry (DSC) and their
chromatographic separation properties by use of glass capillary columns. Interesting analytical performance was obtained in
the separation of isomeric aromatic compounds, polyaromatic compounds, volatile aroma compounds, andcis andtrans isomers. Separation efficiency was higher for 3-Cl, especially for volatile aroma compounds, light aromatic compounds, and
polyaromatic compounds, although the phases were similar in otherways. 相似文献
3.
Fatiha Athman Mohamed Dahmane Soulimane Boudah Moulay-Hassane Guermouche Jean Pierre Bayle Saïd Sebih 《Chromatographia》2009,70(3-4):503-510
Comparative gas chromatographic applications of two new liquid crystals were investigated. The characterization of the two mesogenic compounds was performed with 1H NMR and mass spectrometry. The thermal properties were established by differential scanning calorimetry. The optical characterization of the liquid crystal was made by using polarizing optical microscopy. The chromatographic separation abilities of the mesogenic compounds were studied using fused silica capillary columns. Interesting analytical performances were obtained notably in the separation of volatile aroma compounds and derivatives phenols. 相似文献
4.
Effect of the chain length on the thermal and analytical properties of laterally biforked nematogens
Mohamed Dahmane Fatiha Athman Saïd Sebih Moulay-Hassane Guermouche Jean-Pierre Bayle Soulimane Boudah 《Journal of chromatography. A》2010,1217(42):6562-6568
Three laterally substituted liquid crystals were synthesized in order to investigate the effect of a lateral biforked chain on the thermal and analytical properties. The mesogenic molecules have the same core containing four aromatic rings connected by two ester and one diazo linkages, they differ by the length of one chain within the lateral biforked substituent. The phase transition temperatures were obtained by polarized light microscopy and differential scanning calorimetry (DSC). The clearing temperature and the nematic range decrease with increasing length of the lateral biforked chain. The stationary phases derived from these nematogens provide excellent resolution of various classes of compounds, including aromatic hydrocarbons (AH), substituted benzenes, polycyclic aromatic hydrocarbons (PAH), phenols and volatile organic compounds (VOC) present in the essential oils. The selectivities of the stationary phases were found to decrease according to the length of the side chain. 相似文献
5.
Sahel Fatma Sebih Fatiha Bellahouel Salima Bengueddach Abdelkader Hamacha Rachida 《Research on Chemical Intermediates》2020,46(1):133-148
Research on Chemical Intermediates - Low-cost Al-MCM-41 and Al-SBA-15 mesoporous materials are successfully synthesized from bentonite as silicon and aluminum sources instead of laboratory reagents... 相似文献
6.
Bélaïdi D Sebih S Boudah S Guermouche MH Bayle JP 《Journal of chromatography. A》2005,1087(1-2):52-56
Comparative gas chromatographic applications of two new liquid crystals called LCa and LCb and their equimolar mixture LC(a+b) were investigated. The thermal properties of LCa, LCb and LC(a+b) were established with differential scanning calorimetry (DSC) and polarizing microscopy. Differential scanning calorimetry of LC(a+b) showed that the melting or clearing temperature was intermediate between the corresponding temperatures of the pure compounds. Polarizing microscopy showed that the liquid crystal phase of A + B was nematic. The chromatographic separation abilities LCa, LCb and LC(a+b) were studied using fused silica capillary columns. Interesting analytical performances were obtained: isomeric separation of aromatics, polyaromatics, phenols. 相似文献
7.
Ferroukhi O Guermouche S Sebih S Guermouche MH Berdagué P Bayle JP 《Journal of chromatography. A》2002,971(1-2):87-94
A new bonded liquid crystal stationary phase (2OC12) for high-performance liquid chromatography was studied. It resulted from coupling of LiChrospher Si 100 NH2 and a mesogenic carboxylic acid, 4-(4-(4-(3,4-didoceyloxystyrenyl)phenyl-diazenyl)phenyloxy-methylene) benzoic acid (ILC). ILC was characterized with proton NMR and differential scanning calorimetry, while 2OC12 was characterized by solid state 13C NMR and elemental analysis. 2OC12 surface area was determined by the BET method. The chromatographic behaviour of 2OC12 was investigated under both normal- and reversed-phase conditions. The plots of ln k against 1/T showed transition temperatures at 325 and 337 K. Polyaromatic hydrocarbons (PAHs) were separated using hexane, isooctane or hexane-chloroform. Above the transition temperatures, the bonded material exhibited a liquid crystal-like behaviour: (i) the plate number N was always highest possible, and (ii) the more retained the solute the more elongated it was (anthracene is eluted after phenanthrene, chrysene before tetracene, pentacene after dibenzo-a,h-anthracene). Using acetonitrile/water (60/40), reversed-phase data of aromatic hydrocarbons are similar (highest values of N, better resolution below than during the transitions). 相似文献
8.
9.
Mohamed Dahmane Fatiha Athman Saïd Sebih Moulay-Hassane Guermouche Jean-Pierre Bayle Soulimane Boudah 《Chromatographia》2009,70(3-4):489-495
Two related novel liquid crystals used as gas chromatographic stationary phases were evaluated for their analytical properties and separation capabilities, 2-(1-ethyloctyloxy)-4-(4′-(4-butoxybenzoyloxy)-benzoyloxy)-4′-ethyl-azobenzene (LCC) and azo-(4-ethylbenzyl)-3-(2-(1-ethyloctyloxy)-4-(4-(4-butyloxybenzoyloxy)benzoyloxy)pyridino (LCN). The thermal properties of LCC and LCN were established with differential scanning calorimetry and polarizing microscopy. The comparative study of the retention behavior for the both liquid crystals was also reported. The study of the chromatographic performance of a column coated with liquid crystals in the solid, nematic and liquid state was done using a series of appropriate solutes. The mesogenic compounds exhibit interesting separation for some positional and geometrical isomers in aromatic hydrocarbons, phenols, volatile aromatic compounds and polyaromatic hydrocarbons. 相似文献
1