如DNA般的雙股高分子

DNA-like Double Stranded Polymers

楊慧君(Hui-Chun Yang)

指導教授 ： 陸天堯

國立臺灣大學/工學院/高分子科學與工程學研究所/博士(2006年)

https://doi.org/10.6342/NTU.2006.00401

摘要

利用Grubbs-I催化的開環歧化反應，含二茂鐵之雙二環〔2.2.1〕庚烯骨架的衍生物可以合成一系列的雙股螺旋高分子。藉由單體的精心設計，雙股高分子具有一定的剛性，架橋於雙股之連接基團中的二茂鐵又使雙股高分子有一些柔軟性。另外，利用鹼基促進高分子的水解可得到相對高產率的二條單股高分子和連接基團，二羰酸二茂鐵。STM（Scanning Tunneling Microscopy）觀察雙股高分子得到螺旋狀（helical structure），超螺旋（supercoil）和梯狀（ladder）三種結構和理論計算的結果相符。雙股高分子和DNA的結構相似，它們有相似的寬度，每一段有相似的重覆單元的數量，雙股高分子的五環垂直於連接基團而且相鄰二個單體間也具有相似的距離，這些結果暗示著我們所合成的高分子是類似DNA 結構的雙股螺旋高分子。
另一方面，我們合成出一系列具手性的雙股高分子，由吸收光譜的藍位移證明高分子中存在發色團間的相互作用，由圓二色性光譜 (circular dichroism) 測量，各別單體和高分子的鏡向異構物的圓二色性性質，發現手性中心 (chiral center) 的取代基是主要影響手性單體和手性雙股高分子的圓二性光譜性質的主要因素，在一些例子當中，雙股高分子的圓二色性光譜強度大於手性單體，這些結果暗示著手性雙股高分子的螺旋性增加。

關鍵字

螺旋結構 ； 雙股高分子 ； 掃描式穿隧電子顯微鏡

並列摘要

The synthesis of a series of helical double strand polymers containing ferrocene moiety by ring opening metathesis polymerization (ROMP) of a bisnorbornene derivative is described.　Ferrocene moiety was incorporated as part of the linker since it has certain rigidity but is somewhat flexible. Base-promoted hydrolysis of this polymer affords the corresponding single stranded polymer and the linker, ferrocene-1,1’-dicarboxylic acid, in excellent yield. Three forms (helical, supercoil and ladder) of the polymer have been observed by STM and simulated by molecular mechanical and dynamical calculations. The polymer thus obtained resembles structurally to DNA by having similar width, number of monomeric units per pitch, five-membered rings in the polymeric frame, perpendicular linkers to the backbones, and similar spacing between neighboring monomeric units. These results suggest that the polymers may adopt our proposed DNA-like double stranded structures.
On the other hand, A series of chiral double stranded polymers were designed and synthesized. Between chromophores interaction may occur as evidenced by the blue shift of the absortion maximum. A pair of enantiomeric double stranded monomers and polymers was subjected to CD measurements. Substitute of chiral center may appear to be the pivotal factor to dictate the CD properties of chiral double stranded monomers and polymers. The CD intensity of chiral double stranded polymers is enhancement than monomers. These results suggest that the helixty of chiral double stranded polymers may increased.

並列關鍵字

Helical structuer ； Double stranded polymer ； STM

參考文獻

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