| Summary: | 碩士 === 國立高雄師範大學 === 化學系 === 88 === Two new diastereomeric alcohols, 2(S)-[2(S)-methylhexoxy]propanol (11) and 2(S)-[2(R)-methylhexoxy]propanol (12), were synthesized and characterized in this thesis. From them, two new liquid crystal compounds, 4-{2(S)-[2(S)-methylhexoxy]propylcarbonyl}phenyl 4-(4-n-decoxy)phenylbenzoate(16) and 4-{2(S)-[2(R)-methylhexoxy]propylcarbonyl}phenyl 4-(4-n-decoxy)phenylbenzoate(17), were prepared and their physical properties studied. The difference of the 1H NMR spectrum between 16 and 17 is the chemical shift at the methylene group between two chiral centers. The pattern of 16 is positioned between that of 17.
The results indicate that the new chiral alcohols 11 and 12 are helpful for the formation of SC* phase. Both compounds 16 and 17 are FLCs and have a very broad mesophase range, ca. 114℃ wide. Their liquid crystal phase sequence is K－SI*－SC*－SA－I. The SC* phase temperature range of 16 is 72℃ wide while that of 17 is 47℃ wide. The PS value is 24 nC/cm2 for 16 and 15 nC/cm2 for 17. According to Boulder’s model the compound 16 should have a higher PS value than that of 17 and this is proved by the experimental results.
The study of Gray et al.29 ever indicate the compound 14a has no mesophase. But we found not only 14a but 14b and 14c do have mesophases. Their liquid crystal sequence is K－S？－SC－SA－I.
In addition, the semi-empirical calculations of FLCs show that the conformation difference of FLCs and the difference of elecrto-optical properties might have some correlation.
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