A comparison of ferroelectric liquid crystals containing diastereomeric propionic acids derived from natural ethyl lactate |
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Authors: | Wen-Liang Tsai Tzu-Chi Lu Hong-Wei Liu Meng-Yen Tsai Chao-Ming Fu |
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Institution: | 1. Department of Chemistry, National Kaohsiung Normal University, 116 Ho-Ping 1st Road, Kaohsiung 802, Taiwan ROC;2. Department of Physics, National Kaohsiung Normal University, 116 Ho-Ping 1st Road, Kaohsiung 802, Taiwan ROC |
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Abstract: | Two diastereomeric carboxylic acids, 2(S)-2(R)-methylhexyloxy]propionic acid and 2(S)2(S)-methylhexyloxy]propionic acid, were prepared from ethyl (S)-lactate and (R)-1-iodo2-methylhexane or (S)-1-iodo-2-methylhexane in the presence of Ag2O. From these acids two liquid crystals, 2 and 3, whose configurations are (S, R) and (S, S) were synthesized and their liquid crystal properties investigated. Although both LCs have the same phase sequence Cr-SmC*-N*-I as well as a wide SmC* phase range, the influence of the relative stereochemistry on their physical properties is clear. The liquid crystal with (S, S)-configuration possesses better properties: lower SmC* phase transition temperature, wider SmC* phase range and higher Ps value. The Ps value difference between the ferroelectric LCs 2 and 3 (97 and 131nCcm-2, respectively, at Tc - T = 10°C) is unexpectedly large. The consideration, alone, of a zigzag conformation at the chiral molecular part of 2 and 3 is insufficient to explain such a difference. |
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