Asymmetric oxadiazole mesogens as candidates for low-temperature biaxial nematics |
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| Authors: | N A Zafiropoulos Wenbin Lin T J Dingemans S J Picken |
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| Institution: | 1. Department of Chemistry , University of North Carolina , Chapel Hill, NC, 27599-3290, USA;2. Delft University of Technology, Faculty of Aerospace Engineering , Kluyverweg 1, 2629 HS Delft, The Netherlands;3. Delft University of Technology, TNW, Section Nanostructured Materials , Julianalaan 136, 2628 BL Delft, The Netherlands |
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| Abstract: | We report the synthesis and properties of a homologous series of asymmetric, mesogenic derivatives of 2,5-bis-(p-hydroxyphenyl)-1,3,4-oxadiazole (ODBP). Benzyloxy (BnO-), alkoxy benzoate ester derivatives BnO-ODBP-Ph-O-C n , where n?=?4, 5, 6, 7, 8, 9, 12, were studied by 2H-NMR, X-ray diffraction and polarising microscopy in order to ascertain if the lower temperature nematic phases exhibited biaxiality. Deuterium nuclear magnetic resonance (NMR) of labelled probes in these asymmetric mesogens does not show evidence of biaxiality. The absence of biaxiality is discussed in terms of the statistical non-linearity of these asymmetric ODBP mesogens. |
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| Keywords: | biaxial nematics oxadiazole derivatives structure-property relationship |
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