雙分子與氟取代藍相液晶之合成與研究

Abstract

本文實驗探討了雙液晶基液晶分子與含氟液晶分子，利用H1-NMR、EA、Mass作為結構鑑定。並以POM、DSC探討其液晶行為。我們成功合成出II-76R*CB與過去合成出的II-76*CB比較藍相溫寬與液晶行為；也合成出II-7FF6*CB之雙氟取代液晶分子；並合成出III-7*6CB共價鍵液晶分子與氫鍵分子III-7*6CB-H比較；也在II-7F6*CB與II-7FF6*CB液晶分子中摻雜Iso-(6OBA)2旋光分子，探討藍相之變化；也用分子模擬軟體HyperChem中的AM1半經驗式運算模擬液晶相關數據，尋找擁有藍相之液晶分子條件。在研究中我們發現，過大的twisting power無法有效誘導出藍相；分子的堆疊效果也會影響藍相的出現；對於以II-76CB為模型之雙液晶共價分子，分子長寬比在介於2.73-2.87之間與分子單位長度之dipole moment在介於0.23-0.26之間時，擁有藍相的機率很高。

We study liquid crystals consisting of dimers and fluorinated substitutional liquid crystal. The chemical structures of these compounds were characterized by H1-NMR, Elemental Analyzer and Fab-Mass , and the liquid crystalline phases and mesomorphic behavior of all compounds were identified from the result of POM and DSC. We synthesized II-76R*CB, compared with II-76*CB which was synthesized before, and II-7FF6*CB, double fluorine substituted liquid crystals. Furthermore, III-7*6CB composed of covalent bond was compared with III-7*6CB-H composed of H-bond. In addition, HyperChem is a sophisticated molecular modeling software. That’s why we used it with AM1 semi-empirical calculation to get the information from the compound we used. From the results of calculation, we found that blue phase liquid crystals show with high probability in the situation where aspect ratio of II-76CB like liquid crystals molecules is between 2.73-2.87 and dipole moment per length of liquid crystal molecule is between 0.23-0.26.