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  • 1
    Electronic Resource
    Electronic Resource
    High resolution NMR in cholesteric medium: visualization of enantiomers (1989)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 111 (1989), S. 8294-8296 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja00203a049
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  • 2
    Electronic Resource
    Electronic Resource
    Caracteristiques spectroscopiques de la vibration nuOH des polychlorophenols a 1'etat solide
    Amsterdam : Elsevier
    Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy Section 39 (1983), S. 677-688 
    Details
    ISSN: 0584-8539
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0584-8539(83)80111-1
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  • 3
    Electronic Resource
    Electronic Resource
    Structural studies of ideal organic-inorganic nanocomposites by high resolution diffractometry and NMR spectroscopy techniques (1999)
    Springer
    Journal of materials science 34 (1999), S. 5945-5953 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Hybrid organic-inorganic materials, silica-poly(ethylene glycol) (PEG) blends, were prepared by the sol-gel process from mixtures of tetraethoxysilane and PEG of low molecular mass. The synthesis scheme (acidic [HCl] or nucleophilic [NH4F] catalysis) influences the structure of these materials and consequently their properties. Two different methods were used to investigate the structure of these blends: a) X-ray diffraction techniques; b) 29Si NMR spectroscopy. A new x-ray diffractometry technique identifies precise interference functions and radial distribution functions of these blends. The comparison of predicted radial distribution functions of the Bell and Dean's physical model refined by Gaskell with the radial distribution function obtained from this technique is implemented to identify the structure of these blends. Analysis by amorphography has identified the existence of SiO2 silica grains and provides only about the positional disorder of these grains in continuum random network. The NMR spectroscopy discriminates the different silicon sites and demonstrates the changes of the morphology and structure when the nature of the catalyst is modified. These results indicate that the structure of non-crystalline SiO2 aggregates inside nanocomposites differs from fused glass by their compositional disorders. These nanocomposites could be described as an agglomerate of SiO2 objects with the pores filled by disordered polymer chains. When these materials are obtained under acidic conditions, the polymer chains are linked to the SiO2 grains forming an ideal composite.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004711709642
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    New chemically bonded liquid crystal for high-performance liquid chromatography: Synthesis, characterization and chromatographic behaviour (1998)
    Springer
    Chromatographia 48 (1998), S. 823-829 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography (CLC) ; Bonded liquid-crystal stationary phase (BLC) ; Transition temperature ; Normal- and reversed-phase modes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new bonded liquid-crystal stationary phase has been developed for high-performance liquid chromatography. The method includes the synthesis of 4-(4-carboxybenzyloxy)-3-methyl-2-dodecyloxy-4′-(2-(4′-dodecyloxybenzyl)-ethylene-azobenzene (ALC) which reacts with LiChrospher Si 100 NH2 to give the bonded stationary phase (denoted BLC). Characterization of ALC and the BLC were performed by differential scanning calorimetry (DSC), proton NMR, solid-state13C NMR and elemental analysis. The specific surface area of the BLC was determined by BET. The chromatographic behaviour of the BLC was investigated in both normal-and reversed-phase modes. As a normal phase, a temperature transition is found in the 315–330 K range which leads to remarkable analytical properties. The retention factors of phenanthrene and anthracene increased when the temperature was increased from below to above the transition temperature. In the reversed-phase mode, the behaviour of the BLC seemed more complex, two temperature transitions being apparent. Separation of xylene and diethylbenzene isomers was possible at temperatures above the temperature range of the transitions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467655
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  • 5
    Electronic Resource
    Electronic Resource
    Investigation of thermal and analytical properties of two nematic liquid crystals by gas chromatography (1995)
    Springer
    Chromatographia 40 (1995), S. 581-586 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Liquid crystals ; Internal and external NO2 compounds ; Transition temperature ; Analytical properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Thermal and analytical properties of two liquid crystals containing internal [2-nitro, 3-methyl 4-(4-heptylbenzoyloxy) 4′-methylazobenzene] and external NO2 [2,3-dimethyl 4-(4-heptylbenzoyloxy) 4′-nitroazobenzene] have been investigated by gas chromatography. Transitions temperatures are determined by inverse gas chromatography using standard columns. Good agreement with values determined by differential scanning calorimetry are found. Analytical capabilities of the two liquid crystals are shown in glass capillary columns. Compared to examples in the literature, the crystals used separated different kinds of solutes. In addition, high molecular mass solutes were eluted at relatively low temperatures. Typical separations are observed for hydrocarbon positional isomers, aromatic hydrocarbons, geometric isomers, and volatile aroma compounds. Comparison between the performance of internal and external, NO2-liquid crystals is made.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02290272
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  • 6
    Electronic Resource
    Electronic Resource
    High resolution NMR in solids; A simple and improved ‘magic angle’ probe design for conventional small gap 13C FT spectrometers (1981)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 16 (1981), S. 85-89 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mechanical and electronic design of a ‘magic angle’ NMR probe is described. This probe can be incorporated in a conventional small gap 13C FT spectrometer, without any hardware or software change, to obtain high resolution 13C NMR spectra on organic solids. A simple way of tuning the homogeneity and adjusting the angle is also proposed. Illustrative experimental results on various types of molecular crystals with different molecular mobilities, a clathrate compound and a polymer are discussed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270160204
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  • 7
    Electronic Resource
    Electronic Resource
    Influence of the lateral alkoxy chain length on the gas chromatographic properties of five liquid crystals (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 379-384 
    Details
    ISSN: 0935-6304
    Keywords: Capillary gas Chromatography ; Relative retention time ; Liquid Crystal ; Alkoxy lateral chain ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The gas Chromatographic properties of five laterally substituted liquid crystals are the subject of a comparative study. These liquid crystals belong to the homologous series: 2-alkoxy-3-methyl-4-(4-ethoxybenzoyl-oxy)-4′-(4-trans-n-pentyclcyclohexanecarboxyloxy) azobenzene, referred to as ALn, where n, the carbon number in the lateral alkoxy chain, is equal to 4, 6, 8, 10, or 12 carbon atoms. Their thermal properties were established by differential scanning calorimetry (DSC). It appears that the introduction of a lateral alkoxy chain affects the nematic temperature range which decreases when the carbon number increases. The chromatographic separation abilities of AL4, AL6, AL8, AL10, and AL12 were studied using capillary glass columns. The five liquid cystals are efficient before and after solid-nematic or nematic-liquid transitions; however, the plate numbers are higher in the nematic state. Interesting analytical properties were noted in various fields: iisomeric separation of alkanes, aromatics, polyaromatics, volatile aroma compounds, and cis and trans isomers. However, the chain length does not exert any great influence on the separation abilities.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200707
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  • 8
    Electronic Resource
    Electronic Resource
    Gas chromatographic study of the thermal and analytical properties of a nematic luquid crystal and its cupric complex (1995)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 18 (1995), S. 304-308 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Nematic liquid crystal ; Cupric complex ; Transition temperatures ; Analytical performance ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The nematic compound N-4-(2′-(4″-dodecyloxybenzoyloxy)-4′-do-decyloxy)azobenzenyl-4-dodecyloxysalicylideneimine, known as LH, and its cupric complex, bis[N-4-(2′-(4″-dodecyloxybenzoyloxy)-4′-dodecyloxy)azobenzenyl-4-dodecyloxysalicylidene]iminato of copper (II), known as CuL2 have been used as stationary phases for gas chromatography. The thermal properties of LH and CuL2 have been determined with conventional metal columns, using n-alkanes as solute probes. Plots of In V0g against 1/T clearly show the temperature transitions of LH and CuL2. The analytical capabilities of the two stationary phases were established by use of 25 m glass capillary columns. Satisfactory separations were obtained for positional hydrocarbon and halocarbon isomers, aromatic and polyaromatic compounds, and volatile essential oil constitutents.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240180508
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  • 9
    Electronic Resource
    Electronic Resource
    Mapping of motional heterogeneity in organic-inorganic nanocomposite gels (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 34 (1996), S. 2533-2542 
    Details
    ISSN: 0887-6266
    Keywords: organic-inorganic nanocomposites ; sol-gel ; poly(ethyleneoxide) ; EPR ; NMR ; molecular and macromolecular dynamics ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Organic-inorganic nanocomposite gels comprising poly(ethyleneoxide) chains grafted between silica particles have been studied by electron paramagnetic and nuclear magnetic resonances. Motional heterogeneity has been investigated as a function of gelation and drying by paramagnetic probes dissolved in the organic phase or grafted onto the inorganic nodes. The organic phase exhibits marked variations in dynamic behavior with the liquid-like mobility of the polymer chains strongly hindered at the silica nodes. The conclusions of the EPR study are confirmed by liquid- and solid-state carbon-13 NMR measurements. © 1996 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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