臺灣博碩士論文加值系統

本研究目的是在於探討旋光性末端烷鏈部分對於液晶相之影響。以化合物4-(4-Hydroxyphenyl)benzoic acid (R0) 為起始物合成出六個具有不同碳數之旋光性尾鏈結構以探討化合物不同結構的旋光烷鏈與液晶相的關係。
第一部分是探討具燕尾旋光性化合物的旋光末端烷鏈不同形成I(m=1), I(m=2) 和 I(m=3) 在羥基與酯基中間具有分子內氫鍵的作用。我們發現系列I在降溫過程中僅有膽固醇液晶相(N*)。其中，I(m=2)具有最寬廣的膽固醇溫度範圍(29.1°C) 。

第二部分是具旋光性T字形分子化合物，II (n=5, m=2) T5 and II (n=5, m=3) T7 在降溫過程中顯示 Iso.-SmA*-Cr. 的相順序而其他化合物則不具有液晶相。在此部分中，我們發現在升溫或者降溫過程中系列II或者當非旋光碳鏈為10 (n=10) 時不具有液晶相。 T5 和 T7 在降溫過程中都有層列型A相(SmA*)出現。 其中， T5 的層列型液晶相(SmA*)具有較寬廣溫度範圍(46.4°C)。

第三部分是研究旋光性燕尾化合物I(m=2) 與具旋光性分子的S811、N821和E821進行摻混。具旋光性分子的結構如下圖所示，為了探討旋光性分子在旋光性燕尾化合物上的影響與其形成的液晶相。

在這一系列的混合液晶，S811的比例並沒有直接影響TGBA*的生成。另一方面，N821和E821對於TGBA*的生成的影響是明顯的。尤其是當摻混比例介於10%到20%之間，當比例為80 % I (m=2)和20 % E821時所生成的TGBA*具有最寬廣的溫度範圍(11.8°C)。

當摻混N821或E821時，膽固醇液晶相溫度範圍會隨著摻混比例增加而被壓縮。相反地，層列型液晶相(SmA*)的溫度範圍會隨著摻混比例增加而變廣。

The aim of the research work was intended to study the effect of terminal chiral chain moiety on the mesophases. By means of compound, 4-(4-Hydroxyphenyl)benzoic acid (R0) as building block, six homologous series of liquid crystal materials comprised of different chiral chains were synthesized for investigating the correlation between the chemical structure of chiral tails and mesomorphic properties.
The first part is to investigate the effect of lengthening the terminal chain on the formation of mesogenic phase for the chiral swallow-tailed compounds I(m=1-3) possessing intramolecular hydrogen bonding between the hydroxyl and ester group. Series of I only have cholesteric LC (N*) phase in cooling process. I(m=2) have the widest temperature range as large as 29.1°C.

Second part is the chiral T-shaped compounds, II (n=5, m=2) T5 and II (n=5, m=3) T7 display enantiotropic mesophases of Iso., SmA* and Cr. phases whereas the other compounds have no mesophases in cooling process. An increasing chiral chain length (m) or the spacer length between cyano-biphenyl moiety and phenyl core (n) don’t obviously affect on the formation of mesogenic phase for these compounds. In addition, when the length of the chiral swallow-tailed chain is shorter or the spacer length bwtween cyano-biphenyl moiety and phenyl core is longer, these T-shaped molecules exhibits no mesophase. Only T5 and T7 have SmA* phase in cooling process. Compound T5 exhibits the wider temperature range of SmA* as large as 46.4°C.

The third part of the work is to prepare binary mixtures of chiral swallow-tailed compound I(m=2) and chiral dopants S811, N821 and E821 which were synthesized by our laboratory. The structures of chiral dopants are shown below, in order to investigate the effect of chiral dopants upon the chiral swallow-tailed compounds I(m=1-3) on the formation of mesogenic phase.

In this series binary mixtures, the ratio of S811 don’t directly influence the formation of TGBA* phase. On the other hand, compound I(m=2) doped with N821 and E821 for the formation of TGBA* phase is apparent. Especially, when the ratio of dopants between 10% and 20%, such as the proportion of 80 % I (m=2) and 20 % E821 has the widest temperature range of TGBA* phase in this series.
When the dopant is N821 or E821, the temperature range of N* phase is depressed as the dopant increases. Conversely, the temperature range of SmA* phase is increased as the dopant increases.

ACKNOWLEDGEMENTS I
ABSTRACT II
中文摘要 V
TABLE OF CONTENTS VIII
LIST OF SCHEME XI
LIST OF TABLES XII
LIST OF FIGURES XIII

CHAPTER 1 1
INTRODUCTION 1
1.1. Overview 1
1.2. Cholesteric (Ch) or chiral nematic (N＊) phase 3
1.3. Chiral smectic phases 5
1.3.1. Chiral smectic A phases (SmA*) 5
1.4. Frustrated phases 6
1.4.1. Twist grain boundary phase(TGB) 6
1.4.1.1The TGBA* phase 7
1.5. Motivation of study 11

CHAPTER 2 18
EXPERIMENTAL 18
2.1. Preparation of materials 18
2.1.1. Synthesis of Methyl-2-hydroxy-4-octyloxybezoate (C1) 21
2.1.2. Synthesis of Methyl-2-hydroxy-4-octyloxybezoic acid (C2) 22
2.1.3. Synthesis of Ethyl 11-bromoundecanoate (C10-L1) 23
2.1.4. Synthesis of Ethyl 11-[(4'-cyano-1,1'-biphenyl-4-yl)oxy]undecanoate (C10-L2).24
2.1.5. Synthesis of 11-[(4'-Cyano-1,1'-biphenyl-4-yl)oxy]undecanoic acid (C10-L3) 25
2.1.6.Synthesis of 4'-(methoxycarbonyloxy)biphenyl-4-carboxylic acid (R1) 26
2.1.7. Synthesis of (S)-1-isobutoxy-1-oxopropan-2-yl 4'-(methoxycarbonyloxy)
biphenyl-4-carboxylate R2(m=1) 27
2.1.8 Synthesis of (S)-1-isobutoxy-1-oxopropan-2-yl 4'-hydroxybiphenyl -4-carboxylate R3(m=1) 28
2.1.9 Synthesis of (S)-1-isobutoxy-1-oxopropan-2-yl 4'-(2-hydroxy-4-(octyloxy)
benzoyloxy)biphenyl-4-carboxylate I(m=1) 29
2.1.10 Synthesis of (S)-1-isobutoxy-1-oxopropan-2-yl 4'-(2-(6-(4'-cyanobiphenyl-4-yloxy)hexanoyloxy)-4-(octyloxy)benzoyloxy)biphenyl-4-carboxylate (T3) 31
2.2. Characterization of Materials 33
2.2.1. Chemical structure identification. 33
2.2.2. Masophase identification 33

CHAPTER 3 34
RESULTS AND DISSCUSSION 34
3.1. The Study of Mesomorphic Properties in I(m=1,2,3) 34
3.1.1. Chemical Structure Identifications 34
3.1.2. Optical microscopy observations and phase transition behaviors for compounds I (m=1, 2, 3) 40
3.1.3 Differential Scanning Calorimetry (DSC) 42

3.2. The Study of Mesomorphic Properties in chiral T-shaped semiflexible compounds 46
3.2.1. Chemical Structure Identifications 46
3.2.2. Optical microscopy observations and phase transition behaviors for compounds II、III and IV 51
3.2.3. Differential Scanning Calorimetry (DSC) 56

3.3. The study of binary mixtures on the formation of TGBA* phases 59
3.3.1. Optical microscopy observations and phase transition temperatures for the binary mixture I(m=2)/S811 60
3.3.2 Optical microscopy observations and phase transition temperatures for the binary mixture I(m=2)/N821 70
3.3.3 Optical microscopy observations and phase transition temperatures for the binary mixture I(m=2)/E821 80
3.3.4 Summary 90
CHAPTER 4 91
CONCLUSIONS 91
REFERENCES 93
Appendix 95

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