A Comparative Analytical Study of Two New Liquid Crystals Used as Stationary Phases in GC

Benalia, Mokhtar; Badjah‐Hadj‐Ahmed, Ahmed Yacine; Djedid, Mebrouk; Meklati, B. Y.; Al-Dujaili, Ammar H.; Ferkous, Fouad

doi:10.1365/s10337-007-0345-0

Cited by 6 publications

(15 citation statements)

References 28 publications

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“…These phases can either be monomeric [4] or polymeric [5] , the latter being more thermally stable. Elsewhere, the physical and chemical properties of liquid crystal polymers have been studied by various analytical techniques [6,7] . The retention mechanism on this kind of stationary phases is complex and temperature dependent.…”

Section: Introductionmentioning

confidence: 99%

Gas Chromatographic Separation of Isomeric Phenols by Schiff`s Base Liquid Crystalline Stationary Phases

Hammza¹

2013

JNUS

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The chromatographic behaviour of liquid crystalline compounds 4-(propyloxybenzylidene)-4`-p-aminoazobenzene (1) and 4-(butyloxybenz--ylidene)-4`-p-aminoazobenzene (2) as stationary phases for the separation of cresol isomers was investigated. These isomers were analysed on 4-(propyloxybenzylidene)-4`-p-aminoazobenzene within a nematic range of 142-153° C with a temperature interval of 5° C. Better peak resolution was at a column temperature of 147° C. The analysis was repeated on a and 4-(butyloxybenzylidene)-4`-p-aminoazobenzene column at a nematic temperature of 176° C, which represented the end of the nematic range, and gave the optimum peak resolution. It was found that isomer better separation was obtained at 20% loading for both liquid crystal materials. Other columns of different liquid crystalline percentages (15% and 25%) were used. A chromatogram with unoverlapped peaks was only obtained in both cases at 20% column loading. The order of elution isomers under the applied chromatographic conditions is discussed. The separation of these isomers is also discussed on the basis of stereo chemical conformations.

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Section: Introductionmentioning

confidence: 99%

Gas Chromatographic Separation of Isomeric Phenols by Schiff`s Base Liquid Crystalline Stationary Phases

Hammza¹

2013

JNUS

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“…There has been also much interest in the synthesis and characterization of compounds containing 1,3,4-oxadiazole unit owing to their interesting unique properties, such as liquid crystalline and nonlinear optical properties, as well as their applications in other fields [5][6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Synthesis, Spectroscopic Characterization and Powder XRD Study of 4-(5-(Ethylthio)-1,3,4-Oxadiazole-2-yl) Aniline

Ghanem¹

2015

AJAC

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Abstract:In order to investigate the separation mechanism of liquid crystals stationary phases based on an oxadiazole moiety, new 1,3,4-oxadiazole derivative as side mesogenic arm in liquid crystals was prepared, and its structural spectroscopic data were studied in this paper. A powerful indication about the relationship between molecular structure and alignment properties is described. Such information is indispensable for the design and synthesis new liquid crystals stationary phases of high separation efficiency.

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“…Methods for the preparation of LCs and their utilisation as stationary phases in gas chromatography columns have been developed [8][9][10][11][12][13][14][15][16]. In his work, Benalia et al [12] compared the gas chromatographic behaviour of three monomeric LCs that have the same basic structure (1,3,4-oxadiazole ring) but have different substituents.…”

Section: Introductionmentioning

confidence: 99%

“…In his work, Benalia et al [12] compared the gas chromatographic behaviour of three monomeric LCs that have the same basic structure (1,3,4-oxadiazole ring) but have different substituents. Results established that this kind of nematic LCs when used as stationary phases in gas chromatography have an efficacy of separating isomers.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis and powder X-ray diffraction of new Schiff-base liquid crystal

Ghanem

Al-Hariri

2013

Liquid Crystals Today

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Liquid crystals (LCs) are soft materials that combine the fluidity of disordered liquids and the long-range orientational or positional order of crystalline solids, along one or two directions of space. A search for better stationary phases, including highly selective ones, is an important trend in chromatography development. Among the stationary phases under investigation are LC stationary phases that have been recently generated much interest. A variety of isomeric molecules were separated with high accuracy. Successfully, X-ray scattering is widely used to investigate and characterise the microscopic structure of most LCs. In this paper, a new liquid crystalline material that can be used potentially as stationary phase in gas chromatography was synthesised and characterised by means of nuclear magnetic resonance (NMR), infrared (IR) spectra, elemental analysis and X-ray diffraction.Keywords: liquid crystalline; Schiff base; nematic; X-ray diffraction; gas chromatography Introduction Liquid crystals (LCs) or mesophases are intermediate states of condensed matter; they combine long-range positional or orientational order along some directions of space (like in a crystal) and liquid-like disorder along other directions [1]. The most commonly obtained liquid crystalline phases are those with organic molecules or in solutions of surfactants.Presently, LCs can be divided into two categories: thermotropic and lyotropic according to the principal means of destroying the order in the parent solid state, probably thermotropic LC is the most widely studied category. Thermotropic LCs are formed by varying the temperature of the compounds and can be further classified as nematic (N) and smectic (S m ) structures [2,3].Since 1974, a number of studies have been centred on liquid crystalline materials with anisotropic properties. In particular, nematic LC materials based on Schiff base core have attracted considerable interest due to their unique solvent properties and potential applications in gas chromatography [4,5,[8][9][10][11][12][13][14][15][16].Increasing attention has been focused on important pollutants and phenols introduced into the environment through the discharge of industrial waste and the decomposition of various pesticides and herbicides [5][6][7]. The determination of substituted phenol isomers by ordinary stationary phases presents some difficulties, since these isomers have similar boiling points and polarities.A stationary phase able to separate on a basis other than boiling point or polarity is essential. Several studies have centred on liquid crystalline

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A Comparative Analytical Study of Two New Liquid Crystals Used as Stationary Phases in GC

Cited by 6 publications

References 28 publications

Gas Chromatographic Separation of Isomeric Phenols by Schiff`s Base Liquid Crystalline Stationary Phases

Gas Chromatographic Separation of Isomeric Phenols by Schiff`s Base Liquid Crystalline Stationary Phases

Synthesis, Spectroscopic Characterization and Powder XRD Study of 4-(5-(Ethylthio)-1,3,4-Oxadiazole-2-yl) Aniline

Synthesis and powder X-ray diffraction of new Schiff-base liquid crystal

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