| 摘要: | 於近期的文獻中，含 BF2 之錯合物與多雜環系統被廣泛的合成與討論，BF2 complexes 因其特殊的光物理性質，在生物顯影、分子探針、發光材料、光感應器…等領域具有發展性，然而目前在液晶領域的例子為少數，且多數含 BF2 之液晶結構多為單、雙 BF2 配位，而三 BF2 配位至今未有文獻報導；雜環結構之組成常含有如：硫、氧、氮等陰電性大的原子，常可改變分子極性並產生donor-acceptor interaction，而此性質可能會影響液晶相行為。有鑑於本人所屬的實驗室所製備的含雜環結構實例，如：pyrazoles, isoxazoles, 1, 3, 4-oxadiazoles 等等，多呈現桿狀液晶，本論文探討含雜環結構之盤狀液晶的製備。
因此本研究以 1,3,5-三甲基苯三羧酸酯 (Trimethyl 1,3,5-benzenetricarboxylate) 作為核心，以 hexaketonates 連接外圍含苯環結構之烷氧長碳鏈合成配位基 2，並進而以 BF2 配位形成錯合物 1，以及合成 tris- pyrazole 及 tris- isoxazole 的相同雜環 3c 及 4c。其中化合物 1b, 2b, 1c, 4c 經偏光紋理圖與粉末 X-射線繞射實驗結果判定皆為 Colh 盤狀液晶，化合物 3c 經判定為 Colr 盤狀液晶。
為探討化合物的光物理性質，從紫外光/可見光光譜、螢光光譜結果得知：化合物 1a-1c 的最大放射波長較為紅移，且隨著烷氧鏈數目越多，放光波長也越為紅移。
;During the past years, borondifluoride (BF2) complexes and heterocyclic rings have been continuously reported. Many known borondifluoride complexes as fluorescent materials applied in many areas; such as biological imagings, molecular probes, electroluminescent devices, photosensitizers and others were prepared and investigated. However, among them only a few examples were truly mesogenic. Most of examples of BF2 complexes on mesogenic are mono- and bis(borondifluoride) complexes. In this thesis, we propose a study on tris(boron difluoride) mesogens. As heterocyclic structures are generally incorporated of electronegative atoms S, O and N, heterocyclic rings can change molecular polarity and leads to donor-acceptor interactions within the molecules. And these properties can further affect the mesophase behavior. Quite a few examples, including pyrazoles, isoxazoles, 1, 3, 4-oxadiazoles, and others have been prepared and investigated in our laboratory. Most of them were formed smectic phases, whereas only a few of them exhibited columnar phases.
In this work, a new series of columnar borondifluoride complexes, containing trimethyl 1,3,5-benzenetricarboxylate as a central core substituted with three β-diketonate with three, six and nine terminal alkoxy groups and is described. All compounds were characterized by 1H and 13C NMR spectroscopy, polarized optical microscope (POM) and differential scanning calorimeter (DSC), and their structures were confirmed by X-ray diffraction (XRD) methods. Compounds 2b, 4c and 1b-c formed hexagonal columnar phases. Compounds 3c formed rectangular columnar phases. The photophysical properties of compounds 1-4 (n = 8) were investigated by UV-vis spectroscopy, fluorescence spectroscopy. Results appeared that the maximum emission wavelength of compounds 1 were found to be higher than the compounds 2 because BF2 is a strong electron acceptor which enhance donor acceptor charge transfer effect. |
