Heterocyclic pyridine-based liquid crystals: synthesis and mesomorphic properties |
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| Authors: | Lay-Khoon Ong Guan-Yeow Yeap Hong-Cheu Lin |
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| Affiliation: | 1. Lee Kong Chian Faculty of Engineering &2. Science, Universiti Tunku Abdul Rahman, Kuala Lumpur, Malaysia;3. Liquid Crystal Research Laboratory, School of Chemical Sciences, Universiti Sains Malaysia, Minden, Malaysia;4. Department of Materials Science &5. Engineering, National Chiao Tung University, Hsinchu, Taiwan, ROC |
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| Abstract: | A series of new calamitic liquid crystals, 4-{[(pyridin-4-yl)methylidene]amino}phenyl 4-alkoxybenzoates comprising a heterocyclic (pyridine) and two phenyl rings core system, terminal alkoxy chain, imine and ester linkers were synthesised and characterised. This series consists of nine members wherein the members differ by the length of alkoxy chain (CnH2n+1O–, where n = 2, 4, 6, 8, 10, 12, 14, 16, 18). Spectral analysis results were in accordance with the expected structure. Their thermotropic behaviours were studied by using differential scanning calorimetry, optical polarising microscopy and powder X-ray diffraction techniques. A single mesophase (nematic) was observed for the first three members of the series (n = 2, 4 and 6). As the alkoxy chain increased to n = 8 and n = 10, the nematic phase appeared together with an additional smectic A (SmA) phase. When moving from n = 12 until the highest members (n = 18), the nematic phase disappeared and these compounds only exhibited a single mesophase (SmA). |
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| Keywords: | Pyridine nematic smectic A enantiotropic |
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