彎曲型分子於藍相液晶與氫鍵奈米複合液晶之研究

Abstract

彎曲型分子是具有非掌性的彎曲型結構，並以特殊的液晶相行為、分子雙軸性、自發極性，和超分子掌性等奇特的性質聞名。這些特別的結構和光電特性有導致大量應用的可能性。 因此，在第2章中四種具有線狀、環狀與籠狀矽氧烷末端基團之氫鍵彎曲型液晶分子（S1、P1、C4，和P8）被合成並加以研究，並揭示了形狀和限制效應在這些液晶中自組裝行為的影響。 此外，如在第3章所示，第一次的，鐵電和反鐵電液晶相經由C60/Si基之氫鍵彎曲型分子之合成與混摻（FIAx與FIIAx）而被誘導出並被報導。相對於純Si基之氫鍵彎曲型液晶，混摻物之自發極化值增加、相轉移溫度下降，與SmCP相的區間可被拓寬。與之前報導的Au/Si基之氫鍵彎曲型分子之混摻相比，本系統的C60含量比Au在混摻物中高的多，所以不失為一個有效的混合方法。 最後，在第4章，含1,3,4-oxadiazole的彎曲型分子被合成，其可以誘導出單組成且具有寬溫度區間的BPIII相（OXD7*和OXD5B7F*分別具有34和7 K的溫度範圍）。研究發現，高旋性（測量值）和分子雙軸性（計算值）是導致彎曲型分子產生BPIII重要的因素。

Bent-core molecules were of achiral bent-core structures and known as specific mesophasic behaviors, molecular biaxiality, spontaneous polarity, and supramolecular chirality. These special structural and electro-optical properties might lead to a lot of applications. Therefore, four hydrogen-bonded (H-bonded) bent-core complexes S1, P1, C4, and P8 with string-, ring-, and cage-like siloxane termini were synthesized and investigated in chapter 2 to reveal the shape and confinement effects of the terminal siloxane groups on the self-assembled behavior of molecular arrangements. In addition, as illustrated in chapter 3, ferroelectric and anti-ferroelectric mesophases were induced via hybrid (C60-based/Si-based) H-bonded bent core LCs, where the complexes (FIAx and FIIAx) are synthesized and reported for the first time. Not only the Ps values were increased, but also the transition temperatures and ranges of the SmCP phases could be reduced and extended respectively in contrasted to the Si-based H-bonded bent core LCs. Compared with reported Au-based/Si-based H-bonded bent core LCs, much higher contents of surface-modified C60 could be miscible in binary LC complexes indicating an effective hybrid method. Finally, in chapter 4, 1,3,4-oxadiazole–based bent core LCs inducing the broad ranged single-component BPIII phase (with ranges of 34 and 7 K for OXD7* and OXD5B7F*, respectively) were synthesized. It is found that HTPs (measured) and molecular biaxialities (calculated) were crucial for BPIII of bent core molecules.