| Summary: | 碩士 === 大同大學 === 化學工程學系(所) === 100 === In this study, we introduced the alkyl alkynyl group by Sonogashira coupling reaction, benzoyloxy group and (R)-2-octyloxyl tail into the salicylaldimine core to investigate the mesomorphic properties of salicylaldimine molecules. This works are divided into four sections. The first section is to introduce the alkyl alkynyl into the salicylaldimine core to obtain alkyl alkynyl salicylaldimine molecules. The second series of compounds could be obtained by introducing a benzyloxyl group to extend the conjuation of the alkyl alkynyl salicylaldimine molecules. We introduced (R)-2-octyloxyl tail into the first section of salicylaldimine molecules to obtain the third series of chiral salicylaldimine molecules. The fourth section of salicylaldimine molecules consist of the alkyl alkynyl group, benzoyloxy group and (R)-2-octyloxyl tail were synthesized. In the first section of the compounds, compound C10YOCn (n = 5-7) with shorter alkoxy chain length in the arylamine moiety show only SmA phase. When this alkoxy chain is increased (n = 8-12, 14), unidentified SmX1 phase appear besides SmA phase. However, when alkoxy chain length is further extended, compound C10YOCn (n = 16, 18) show the N and unidentified SmX2 phases. Compound C10YOCn (n = 8) show wider temperature range of the SmC phase (49.8 °C).
The second section of the compounds, C10YCBOC10 in which both alkyl alkynyl and benzoyloxy group are incorporated into the salicylaldimine core, exhibit wider temperature range of nematic phase(130°C).
The third section of the compounds, C10YOC8* show no any mesophase. Another compounds, C8*YOC10, is a liquid at room temperature.
The fourth section of the compound, CmYCBOC8* (m = 6-10) display the N*, SmA* and SmCA* mesophases. Compound CmYCBOC8*(m = 6-7) exhibit frustrated TGBA* phase, and the SmCA* phase still e at room temperature.
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