以C4-對稱釩酸鹽中心之四聚簇狀體，作為增效式金屬離子之篩選及其在向列相液晶中的不對稱轉譯作用和手性放大

Metal-Ion Specific Recognition by Asymmetric Transcription and Amplification of Metal ion-encapsulated, Vanadyl Quardruplexes in Nematic LC

何日森(Jih-Sen Ho)

指導教授 ： 陳建添

國立清華大學/理學院/化學系/碩士(2012年)

摘要

我們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，並利用此單體與偏釩酸鹽增效式自組裝，並利用與四個單體上羥基鍵結力較弱的鋰離子，交換成其它金屬離子。將這些鉗合不同金屬離子之簇狀四聚體摻雜於 E7 液晶主層材料中，利用偏光顯微鏡下觀察其螺距變化。因為接在四聚簇狀體上的向列項液晶片段與 E7 主層材料結構相似，彼此之間 pi–pi 及偶極作用力強，所以 E7 液晶分子的螺旋排列方式對四聚簇狀體結構的改變非常靈敏。若鉗合離子的半徑越大，會造成四聚簇狀體底盤較為緊密；由 Li+ 到 Rb+ 之四聚簇狀體離子半徑越大，造成亞柳胺基上所接的四條向列項液晶片段的手臂越近，而導致螺旋扭張力逐漸下降。對於這些金屬離子 Rb+ (152 pm) > K+ (138 pm) > Ag+(115 pm) > Na+ (102 pm) > Li+ (76 pm)，離子半徑大約只相差 13-26 pm 的變化，但其螺距大小差異卻能夠不對稱手性放大至 1.3-2.1 um (或以 Grandjean-Cano 楔形槽測得之 Cano’s lines 差異為 39-76 um)，約十萬倍 (約三百萬倍)。旋轉扭張力 (Y軸) 與離子半徑 (X軸) 呈現線性關係。

關鍵字

C4-對稱釩酸鹽 ； 四聚簇狀體 ； 金屬離子篩選 ； 液晶 ； 手性放大

並列摘要

A tailor-designed vanadyl methoxide complex bearing p-heptoxyphenyl group (i.e., a nematic LC like fragment) at the C5 position of the salicylidene template was synthesized and then subjected to LiVO3-induced self assembly to form loosely bound, Li+-encapsulated quadruplexes. These cluster complexes were utilized as chiral dopants (1% by weight) to nematic LC materials. A systematic survey regarding the effect of the encapsulated metal ions within the alkali family and Ag+ on the changes of helical pitch was performed and determined by Grandjean method in wedge cells viewed under polarized microscopic scope. It was found that the twisting power or helical pitch induced by a chiral quadruplex dopant is very responsive to its modulable helical shape due to its π-π and dipole-dipole interactions with a nematic LC host. By increasing the size of the encapsulated metal ion from Li+ to Rb+ in the quadruplex by dynamic metal-ion specific swapping, its four lower rim regions of the resulting cluster (i.e, the four p-heptoxyphenyl groups) get closer, thus inducing less helical twisting to the nematic LC phase. Notably, the ion size change [Rb+ (152 pm) > K+ (138 pm) > Ag+(115 pm) > Na+ (102 pm) > Li+ (76 pm)] among the encapsulated metal ions is only around 13-26 pm. This information can be asymmetrically amplified to 1.3-2.1 um pitch change in LC phase. Therefore, the overall extent of amplification reaches 100000 times in terms of helical pitch change. A linear correlation between the induced helical pitch (Y-axis) and the ionic radius of a metal ion (X-axis) was established.

參考文獻

45.林雅慧 (2011)，誘導式自組裝生成C4-對稱釩酸鹽為中心之四聚簇狀體，作為增效式金屬離子之篩選傳送及不對稱催化劑，國立台灣師範大學化學系博士論文。

3.BurKhart, B. M.; Gassman, R. M.; Langs, D. A.; Pangborn, W. A.; Duax, W. L.; Pletnev, V. Biopolymers. 1999, 51, 129.

44.(a) Weng, S.-S.; Shen, M.-W.; Kao, J.-Q.; Munot, Y. S.; Chen, C.-T. Proc. Natl. Acad. Sci. U.S.A. 2006, 103, 3522. (b) Pawar, V. D.; Weng, S.-S.; Bettigeri, S.; Kao, J.-Q.; Chen, C.-T. J. Am. Chem. Soc. 2006,128, 6308.

4.Jani, P.; Enmmert, J.; Wohlgemuth, R. Biotech. J. 2008, 3, 202.

7.Lin, Y.-H.; Kuo, T.-S.; Chen, C.-T. J. Am. Chem. Soc. 2008, 130, 12842.