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  • 學位論文

一、以C4-對稱釩酸鹽中心之四聚簇狀體,作為增效式陰離子之篩選及其在向列相液晶中的不對稱放大轉譯作用二、杯[4]芳烴之N-亞柳胺基酸衍生之掌性氧釩錯合物催化α-羥基苯乙酸芐酯進行不對稱氧化反應

Anion Recognition by Asymmetric Amplified Transcription of Vanadyl Quardruplexes in Nematic LC and Application of Calix[4]arene-based Chiral Oxidovanadium(V) Methoxides in Asymmetric Oxidation

指導教授 : 陳建添
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摘要


於單體氧釩錯合物亞柳胺基模板的C(5)位置接上向列相液晶分子的片段,將此手性氧釩單體與鋰的偏釩酸鹽增效式自組裝,以鋰離子鉗合之四聚簇狀體與不同陰離子的正二價鉛金屬鹽類進行置換反應,可合成出一系列陰離子配基之鉛離子鉗合的C4-對稱釩酸鹽四聚簇狀體。並透過陰離子的配位能力不同,來進行陰離子間的置換反應,且能做為鹵素離子 ( I-> Br-> Cl-)的特殊篩選傳送。將這些不同陰離子配基的鉛離子四聚簇狀體以1 wt%摻雜於E7液晶主層材料中,利用 Grandjean-Cano楔形槽法,以偏光顯微鏡觀察螺距的變化。當陰離子的配位結構相似,則路易士鹼性越小會造成鉛離子較酸,而與周圍配位的羰基鍵長縮短,使四聚簇狀體的底盤較為擴張,導致螺旋扭張力增加 (ClO4- > CH3SO3-;CF3COO-> CH3COO-> NO3-;Cl- > Br-> I-),其螺距大小差異能夠不對稱手性放大至0.6-27.5 m。且旋轉扭張力 (Y軸)會與鹵素離子的電負度 (X軸)呈現一線性關係。 此外我們也合成出杯[4]芳烴與四個亞柳胺基酸衍生之手性氧釩錯合物結合的新型催化劑,應用於α-羥基苯乙酸芐酯之光學對拆離的不對稱空氣型氧化反應。以1-氯苯為溶劑在50 ℃下反應,當轉換率為45 %時,可得到75 % ee選擇因子可高達52。

並列摘要


A tailor-designed vanadyl methoxides bearing p-heptoxyphenyl group at the C5 position of the salicylidene template was synthesized and then subjected to LiVO3 to form loosely bound, Li+-encapsulated quadruplexes. Quadruplexes bearing encapsulated Pb(II) ion, topped with five different anion ligands can be synthesized by dynamic metal-ion specific swapping with different Pb(II) salts. And NO3- ligand could be replaced by other anions due to different binding ability. The chiral tetrameric vanadyl(V) cluster complex allows for efficient halogen anion specific transport. These cluster complexes were utilized as chiral dopants (1 wt%) to nematic LC materials. A systematic survey on the changes of helical pitch was performed and determined by Grandjean method in wedge cells viewed under polarized microscope. It was found that anion with similar geometries, with decreasing in Lewis basicity of the couter anion, the four lower rim regions of the resulting cluster (i.e, the four p-heptoxyphenyl groups) getting farther, thus inducing more helical twisting to the nematic LC phase. This information can be asymmetrically amplified to 0.6-27.5 m pitch change in LC phase. A linear correlation was found between the induced helical pitch (Y-axis) and the electronegativity of halide anion (X-axis) was established. Besides, we have prepared a new type of calix[4]arene-based chiral oxidovanadium (V) complexes, which was utilized for asymmetric aerobic oxidation and kinetic resolution of benzyl α-hydroxy-phenyl-acetate. The best results of the resolved alcohol we obtained was 75 % ee at 45 % conversion, when the reaction was performed in chlorobenzene 50 ℃.

並列關鍵字

無資料

參考文獻


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