本研究利用酯化反應合成一系列具有不同間隙長度和末端基團之光致變性化合物Nazo、Cazo 及Nstil 系列，在分子結構設計上導入不同的拉電子基NO2 或推電子基OCH3，以及不同的液晶核心azobenzene (N=N)基團或stilbene (C=C)衍生物，探討其分子結構與熱性質及光學性質的相關性。
本實驗合成的化合物以FT-IR、1H-NMR、13C-NMR 及EA 鑑定分子結構，以DSC 和POM 分析熱性質及液晶相種類，並使用UV-Vis 和PL 分析化合物之光學性質。在熱性質方面，本研究所合成的液晶分子均為互變型膽固醇液晶，Nazo、Cazo 及Nstil 系列最寬廣的液晶相轉移溫度分別為升溫的50.4、66.6 及69.6 oC 與降溫過程的78.8、78.2 及148.1 oC。在光學性
質方面，Nazo、Cazo 及Nstil 系列溶液態的最大UV/Vis 吸收波長分別在342~381、349~359 及354~378 nm，螢光波長則分別413~466、414~438及415~550 nm。Nstil 系列有較高的量子效率，約0.37~0.66。本研究中，我們使用UV-Vis 和1H-NMR 光譜來驗證光致變性化合物的光化學行為。光致變性化合物經由不同波長UV 光的照射使光致變性基團進行E-Z 光異構化反應或2+2 環化反應，達到可逆或不可逆的光化學反應。我們亦將所合成之光致變性化合物製作成液晶cells，經由改變溫度和照射UV 光來探討膽固醇型液晶螺旋距大小及反射波長位移等特性，結果發現提高液晶cells 溫度或照射UV 光皆會使選擇性光反射波長發生藍位移現象。本實驗研究所
製備之膽固醇型液晶光學cells，可應用在光調變儲存紀錄材料、不可逆數據記錄及可覆寫的數據儲存系統。

In this work, three series of novel cholesterol-based photochromic compounds, named as Nazo, Cazo, and Nstil series, containing various photochromic moieties, flexible spacer lengths and terminal groups using esterization reaction were designed and synthesized. Their structure-property relation of liquid crystals and the effect on E/Z photoisomerization were also investigated.
The chemical structures of the synthesized compounds were identified using FTIR, 1H-NMR, 13C-NMR, and EA analyzer. The thermal and optical properties of compounds were evaluated using DSC, POM, UV-Vis, and PL techniques. All mesophase of the synthesized compounds revealed enantiontropic cholesteroc liquid crystals with planar textures. The maxima absorption for Nazo, Cazo, and Nstil series are in the range of 342-381, 349-359, and 354-378 nm, respectively. Nstil series showed the maxima quantum
efficiencies in the range of 0.37~0.66. The increase of LC cell temperature and UV irradiation induced blue-shifts of the selective light reflection of cholesteric phases. Synthesized photochromic compounds containing N=N and C=C
segments revealed one reversible and one irreversible photochromic properties.Photochromic compounds with various photoisomerizable groups fabricated in this investigation could be used as irreversible image recording and rewritable data storage systems. The results of this investigation present significant scientific and practical contributions with respect to the development of unique functional photochromic materials.

目錄
摘要.....................................................................................................................I
Abstract.................................................................................................................II
致謝.................................................................................................................... III
目錄.................................................................................................................... III
表目錄...............................................................................................................VII
圖目錄............................................................................................................. VIII
Scheme ............................................................................................................ XIV
符號表.............................................................................................................. XV
第一章 緒論........................................................................................................ 1
1-1 前言......................................................................................................... 1
1-2 研究動機與方向..................................................................................... 2
第二章 原理與文獻回顧.................................................................................... 3
2-1 液晶簡介................................................................................................. 3
2-2 液晶的分子構造..................................................................................... 4
2-3 液晶的種類............................................................................................. 5
2-3-1 熱向型液晶的物理性質及光學異方性........................................ 8
2-4 光致變系統簡介................................................................................... 11
2-4-1 光變色材料之光變色機制.......................................................... 13
2-4-2 光致變反應................................................................................... 14
2-5 偶氮苯光致變型液晶高分子照光排列之效應.................................. 19
2-5-1 膽固醇型液晶之分子排列與光學特性...................................... 20
V
2-6 小分子膽固醇型液晶可逆性顏色儲存系統之簡介.......................... 22
2-7 膽固醇型液晶之應用........................................................................... 23
2-7-1 膽固醇型液晶可逆性顏色儲存系統之簡介.............................. 23
2-7-2 膽固醇型液晶濾光膜(color filter)............................................... 26
2-7-3 反射式膽固醇型液晶顯示器...................................................... 26
2-7-4 膽固醇型液晶反射式偏光板簡介(reflective polarizer) ............. 27
2-8 分子能階與光激發原理....................................................................... 28
2-8-1 分子間激發態................................................................................ 30
第三章 實驗部分.............................................................................................. 31
3-1 實驗藥品............................................................................................... 31
3-2 實驗與鑑定儀器................................................................................... 32
3-3 實驗步驟............................................................................................... 35
3-3-1 藥品純化....................................................................................... 35
3-3-1-1 CH2Cl2 溶劑之除水.................................................................. 35
3-3-2 光致變性化合物之合成.............................................................. 35
3-3-2-1 含NO2 系列偶氮苯化合物之合成 (Scheme 3-1) .................. 35
3-3-2-2 含OCH3 系列偶氮苯化合物之合成 (Scheme 3-1)................ 38
3-3-2-3 含NO2 系列stilbene 化合物之合成 (Scheme 3-2) ................ 41
3-4 玻璃片的清洗及空cell 的製作........................................................... 45
3-4-1 玻璃的清洗................................................................................... 45
3-4-2 水平配向(homogeneous alignment)基板製作............................ 46
3-4-3 水平配向之液晶sample 製作..................................................... 46
3-5 光穿透度的測量................................................................................... 46
第四章 結果與討論........................................................................................ 48
4-1 化合物結構之鑑定.............................................................................. 48
VI
4-2 化合物之元素分析............................................................................... 51
4-3 化合物之熱性質、液晶相及光學活性性質之探討.......................... 52
4-3-1 化合物之熱性質及液晶相之探討.............................................. 52
4-3-2 光致變性化合物之比旋光度量測.............................................. 56
4-4 光致變性化合物之光化學性質探討................................................... 56
4-4-1 光致變性化合物之吸收光譜....................................................... 56
4-4-2 光致變性化合物之發光性質探討.............................................. 63
4-4-2-1 發光性質之濃度效應探討....................................................... 63
4-4-2-2 發光性質之疊圖比較............................................................... 64
4-4-2-3 發光團於good/non-solvent 混合溶劑之自組裝行為探討..... 68
4-5 膽固醇液晶選擇性光反射之探討....................................................... 68
4-5-1 選擇性光反射之溫度效應探討................................................... 69
4-5-2 選擇性光反射之光化學異構化性質探討................................... 70
第五章 結論.................................................................................................... 112
參考文獻.......................................................................................................... 113

表目錄
Table 4-1 Results of elemental analysis for the photochromic compounds........ 52
Table 4-2 Thermal properties of photochromic compounds............................... 55
Table 4-3 UV-Vis absorption of chiral photochromic compounds. .................... 59
Table 4-4 Optical properties of photochromic compounds................................. 65
Table 4-5 Light reflection of photochromic compounds. ................................... 71

圖目錄
Figure 2-1 Phase transition of compounds on temperature................................... 3
Figure 2-2 Dependence of intermolecular force on temperature with general
compounds and liquid crystal compounds. ......................................... 4
Figure 2-3 Basic structure of liquid crystals. ........................................................ 4
Figure 2-4 Classification of thermotropic liquid crystals. .................................... 7
Figure 2-5 Nematic liquid crystals........................................................................ 7
Figure 2-6 Molecular orientation of cholesteric liquid crystal. ............................ 9
Figure 2-7Anisotropic properties of nematic liquid crystals. ............................... 9
Figure 2-8 Energy vectors of light. ..................................................................... 11
Figure 2- 9 Indicatrix of an optically uniaxial material: (a) positive sign of
birefringence (ne- no> 0); (b) negative sign of birefringence (ne- no<
0). ...................................................................................................... 11
Figure 2-10 Photochromism between two forms................................................ 13
Figure 2-11 Energy-level diagrams of photochromic materials. ........................ 14
Figure 2-12 Chemical structure and colorful pattern of chiral cinnamate
derivative. ....................................................................................... 18
Figure 2-13 Photoreactions of the photochromic spiropyrans and diarylethenes
under UV light. ............................................................................... 19
Figure 2-14 Three types of molecular reorientation of photochromic liquid
crystal polymers irradiated with linearly polarized light. .............. 20
Figure 2-15 Liquid crystals in the cholesteric phase reflect incident white light
selectively, provided that the incident light has a wavelength
satisfying the Bragg condition........................................................ 22
Figure 2-16 Thermally induced change in selective light reflection of cholesteric
liquid crystal on various temperature. ............................................ 23
IX
Figure 2-17 Photograph of a cholesteric solid film sandwiched between two
plastic films. The characters are recorded using a thermal head
printer that heats the sample to the isotropic temperature. Changing
the voltage applied to the thermal head controls the color of the
recorded characters. ........................................................................ 24
Figure 2-18 Photographs of the cholesteric solid films recorded using a
photochemical mode and a scheme of the recording process. ....... 25
Figure 2-19 A photograph of the super-cooled solid films of a mixture. (a)
Samples with mesh images, and (b) a sample with letters of the
alphabet. The mask used has a transmittance of 0%, 10%, and 25%
at top, middle, and bottom “NIMC” characters, respectively. ....... 25
Figure 2-20 (a) Chemical structures of cholesterol-based chiral nematic phase,
and (b) the corresponding light reflection and pattern. [39] ............. 26
Figure 2-21 Basic principle of reflective cholesteric liquid crystalline display. 27
Figure 2-22 Basic principle of cholesteric liquid crystal reflective polarizer..... 28
Figure 2-23 Schematic representation of energy level........................................ 29
Figure 3-1 Selective light reflection cell forming process.................................. 47
Figure 3-2 Experimental setup for investigation of transmittance of sample cells.
............................................................................................................................. 47
Figure 4-1-1 FT-IR spectra of compound 1, 2, and Nazo6................................. 72
Figure 4-1-2 1H-NMR spectrum of compound 1. ............................................... 72
Figure 4-1-3 1H-NMR spectrum of compound 2. ............................................... 73
Figure 4-1-4 1H-NMR spectrum of compound 3. ............................................... 73
Figure 4-1-5 1H-NMR spectrum of Nazo. .......................................................... 74
Figure 4-1-6 1H-NMR spectrum of Nazo6. ........................................................ 74
Figure 4-1-7 1H-NMR spectrum of Nazo11........................................................ 75
Figure 4-1-8 13C-NMR spectrum of Nazo6. ....................................................... 75
X
Figure 4-1-9 HMQC NMR spectrum of Nazo6.................................................. 76
Figure 4-1-10 COSY NMR spectrum of Nazo6. ................................................ 76
Figure 4-1-11 1H-NMR spectrum of Cazo. ........................................................ 77
Figure 4-1-12 1H-NMR spectrum of Cazo6. ...................................................... 77
Figure 4-1-13 1H-NMR spectrum of Cazo11...................................................... 78
Figure 4-1-14 1H-NMR spectrum of compound 7. ............................................. 78
Figure 4-1-15 1H-NMR spectrum of compound 8. ............................................. 79
Figure 4-1-16 1H-NMR spectrum of Nstil. ......................................................... 79
Figure 4-1-17 1H-NMR spectrum of Nstil6. ....................................................... 80
Figure 4-1-18 1H-NMR spectrum of Nstil11. ..................................................... 80
Figure 4-3-1 DSC thermogram of Nazo6 at a heating rate of 10 oC/min. .......... 81
Figure 4-3-2 DSC thermogram of Nazo11 at a heating rate of 10 oC/min.......... 81
Figure 4-3-3 DSC thermogram of Cazo6 at a heating rate of 10 oC/min. .......... 82
Figure 4-3-4 DSC thermogram of Cazo11 at a heating rate of 10 oC/min.......... 82
Figure 4-3-5 DSC thermogram of Nstil6 at a heating rate of 10 oC/min. ........... 83
Figure 4-3-6 DSC thermograma of Nstil11 at a heating rate of 10 oC/min. ....... 83
Figure 4-3-8 Polarized optical microscopic texture of Nazo6............................ 84
Figure 4-3-9 Polarized optical microscopic texture of Nazo11. ......................... 84
Figure 4-3-10 Polarized optical microscopic texture of Cazo6.......................... 85
Figure 4-3-11 Polarized optical microscopic texture of Nazo6. ......................... 85
Figure 4-3-12 Polarized optical microscopic texture of Nstil11......................... 86
Figure 4-4-1 (a) Variation of the UV-vis spectra of Nazo with various irradiation
times, and (b) stability of the UV-vis spectra of Nazo in the dark.
...................................................................................................... 87
Figure 4-4-2 (a) Variation of the UV-vis spectra of Nazo6 with various
irradiation times, and (b) stability of the UV-vis spectra of Nazo6
in the dark. .................................................................................... 88
XI
Figure 4-4-3 (a) Variation of the UV-vis spectra of Nazo11 with various
irradiation times, and (b) stability of the UV-vis spectra of Nazo11
in the dark...................................................................................... 89
Figure 4-4-4 (a) Variation of the UV-vis spectra of Cazo with various irradiation
times, and (b) stability of the UV-vis spectra of Cazo in the dark.
....................................................................................................... 90
Figure 4-4-5 (a) Variation of the UV-vis spectra of Cazo6 with various
irradiation times, and (b) stability of the UV-vis spectra of Cazo6
in the dark...................................................................................... 91
Figure 4-4-6 (a) Variation of the UV-vis spectra of Cazo11 with various
irradiation times, and (b) stability of the UV-vis spectra of Cazo11
in the dark...................................................................................... 92
Figure 4-4-7 (a) Dependence of 365 nm UV exposure on 1H-NMR spectra and
(b) schematic representation of photoisomerization of Nazo before
UV irradiation (initial condition) and then visible irradiation...... 93
Figure 4-4-8 (a) Dependence of 365 nm exposure on UV-vis spectra of Nstil
with various irradiation times, and then (b) recovering of
molecular structure exposure by 254 nm UV light....................... 94
Figure 4-4-9 (a) Dependence of 365 nm exposure on UV-vis spectra of Nstil6
with various irradiation times, and then (b) recovering of
molecular structure exposure by 254 nm UV light....................... 95
Figure 4-4-10 (a) Dependence of 365 nm exposure on UV-vis spectra of Nstil11
for 8 seconds, and then (b) recovering of molecular structure
exposure by 254 nm UV light..................................................... 96
Figure 4-4-11 (a) Dependence of 365 nm exposure on UV-vis spectra of Nstil11
for 44 minutes, and then (b) recovering of molecular structure
exposure by 254 nm UV light..................................................... 97
XII
Figure 4-4-12 Dependence of 365 nm UV light on 1H-NMR spectra of Nstil11.
...................................................................................................... 98
Figure 4-4-13 Concentration effect on (a) real and (b) normalized absorption
spectra of Nazo6. ......................................................................... 99
Figure 4-4-14 Concentration effect on (a) real and (b) normalized absorption
spectra of Cazo6. ....................................................................... 100
Figure 4-4 15 Concentration effect on (a) real and (b) normalized absorption
spectra of Nstil6. ........................................................................ 101
Figure 4-4-16 Concentration effect on (a) real and (b) normalized PL spectra of
Nazo6. ........................................................................................ 102
Figure 4-4-17 Concentration effect on (a) real and (b) normalized PL spectra of
Cazo6. ........................................................................................ 103
Figure 4-4-18 Concentration effect on (a) real and (b) normalized PL spectra of
Nstil6.......................................................................................... 104
Figure 4-4-19 Normalized Absorption and PL spectra of Nazo series. ............ 105
Figure 4-4-20 Normalized Absorption and PL spectra of Cazo series. ............ 105
Figure 4-4-21 Normalized Absorption and PL spectra of Nstil series.............. 106
Figure 4-4-22 Normalized Absorption and PL spectra of Nazo, Cazo, and Nstil.
.................................................................................................... 106
Figure 4-4-23 Normalized Absorption and PL spectra of Nazo6, Cazo6, and
Nstil6. ......................................................................................... 107
Figure 4-4-24 Normalized Absorption and PL spectra of Nazo11, Cazo11, and
Nstil11. ....................................................................................... 107
Figure 4-4-25 Photo images of Nstil series (a) without and (b) with UV 365 nm
exposures. .................................................................................. 108
Figure 4-4-26 Photo images of Nstil series after UV irradiation for (a) 90 and (b)
150 minutes................................................................................ 108
XIII
Figure 4-4-27 Dependence of solvent mixtures on PL spectra of Cazo6......... 109
Figure 4-5-1 Dependence of temperature on selective light reflection of (a)
Nazo6 and (b) Cazo6. .................................................................. 110
Figure 4-5-2 Dependence of UV light on selective light reflection of (a) Nazo6
and (b) Cazo6............................................................................... 111

Scheme
Scheme 2-1 Molecular structures of (a) tetracene and (b) β-TCDHN. [13].......... 12
Scheme 2-2 Photoisomerization of azobenzene derivatives. .............................. 15
Scheme 2-3 Photoreaction of stilbene................................................................. 16
Scheme 2-4 Reaction products of the different packing of cinnamic acid upon
irradiation. ........................................................................................................... 17
Scheme 2-5 Photoreaction of cinnamate derivatives. ......................................... 17
Scheme 3-1 Synthetic routes of photochromic compounds Nazo and Cazo series.
............................................................................................................................. 44
Scheme 3-2 Synthetic routes of photochromic compounds Nstil series............. 45
Scheme 4-1 Photoisomerization of azobenzene derivatives………...………...57
Scheme 4-2 Photoreaction of stilbene................................................................. 57

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