| 摘要: | 在系列一中成功合成出以tetraketonates Ia-3b為配位基，與boron diflouride (BF2)形成其錯合物1a-BF2－3b-BF2，其中僅配位基化合物3b無液晶性質，而其他配位基化合物皆具有液晶相，且化合物2a-BF2, 3a-BF2, 3b-BF2經偏光紋理圖與X-粉末射線繞射實驗結果判定為Colh盤狀液晶。化合物Ia-3b, 1a-BF2－3b-BF2 (n = 12)以紫外光/可見光光譜、螢光光譜及固態螢光光譜探討該分子的光學性質，並可從結果得之增加推電子基的烷氧基數目與從tetraketonates形成含雙BF2錯合物時皆使最大放光波長紅移。化合物2a-BF2, 3a-BF2, 3b-BF2為目前少見含雙BF2結構之盤狀液晶，且3a-BF2, 3b-BF2為室溫液晶。
在系列二中成功合成出以吡啶為中心硬核且各含有兩個吡唑(pyrazole)及異唑(isoxazole)之對稱同雜環衍生化合物2a’-3b’’，本實驗藉由引入雜環系統、改變分子軟硬端比例、改變位向等來觀察以上因素對化合物液晶行為的影響。經偏光紋理圖與X-粉末射線繞射實驗結果能判定含有異唑(isoxazole)的化合物2a’, 3a’及含有吡唑(pyrazole)的化合物2a’’, 3a’’皆有Colh盤狀液晶的出現，而改變位向的化合物2b’-3b’’皆無液晶相出現。化合物2a’-3b’ (n = 12)以紫外光/可見光光譜、螢光光譜探討該分子的光學性質，並可從結果得知對位的化合物2a’, 3a’之最大放光波長較鄰位化合物2b’, 3b’紅移，因其共軛長度較長，故最大放光波長紅移。;Complexes containing boron diflouride (BF2) have been paid much attention during the past years. Many known boron diflouride complexes, widely investigated as fluorescent materials showed potential applications in many areas; such as biological imaging, molecular probes, electroluminescent devices, photosensitizers and others. However, only a few examples were reported among mesogenic applications.
In the first part, six new series of bis-(boron diflouride) complexes 1a-BF2－3b-BF2 derived from substituted tetraketonates Ia-3b were successfully synthesized. All of the substituted tetraketonates were mesogenic except for compound 3b. Results appeared that 2a-BF2, 3a-BF2, 3b-BF2 were enantiotropic columnar mesophase by polarized optical microscope (POM) and powder X-ray diffraction.The optical properties of compounds Ia-3b, 1a-BF2－3b-BF2 (n = 12) were investigated by UV-Vis spectroscopy, fluorescence spectroscopy and solid-state fluorescence spectroscopy. Results appeared that increasing the number of electron-donating groups and chelating bis-(boron diflouride) complexes from substituted tetraketonates might cause redshift. To our best knowledge, there are rare examples of columnar bis(BF2) complexes.
More and more liquid-crystalline compounds nowadays containing five-membered heterocycles are the subject of much investigation. These heterocyclic structures generally incorporated of such electronegative atoms (S, O or N atom) often resulted in a reduced or lowering symmetry for the overall molecules or/and a stronger polar induction. Quite a few examples, including pyrazoles, isoxazoles, 1,3,4-oxadiazoles, and others have been prepared and investigated in our laboratory. Most of them formed smectic phases whereas, only a few of them exhibited columnar phases.
In the second part, four series of symmetrically heterocyclic derivative compound 2a’-3b’’ with a pyridine hard core, pyrazole and isoxazole were successfully synthesized. The research introduced a heterocyclic ring system and changed the aspect ratio, the orientation to observe the influence of the above factors on the behavior of the mesogenic compounds. Results appeared that 2a’, 3a’, 2a’’, 3a’’ were enantiotropic columnar mesophase by polarized optical microscope (POM) and powder X-ray diffraction. The optical properties of compounds 2a’-3b’ (n = 12) were investigated by UV-Vis spectroscopy, fluorescence spectroscopy. Results appeared that the maximum emission wavelength of compounds 2a’, 3a’ at para position were found to be higher than the compounds at meta position due to their longer conjugated length. |
