五苯荑衍生之分子馬達

Abstract

近年來，化學家嘗試增加工作的精準度與效率從而以原子層級建構出分子機械，此種分子可以利用外部施加能量來仿效如巨觀世界中的機械運轉模式。本論文的研究過程中，我們嘗試以先前本實驗室研究具五苯荑之分子剎車為基底，進一步發展出分子馬達而合成出E-1及Z-2分子。經由DFT理論計算指出，經由外部施加電壓，E-1在中性態與自由基陰離子態之間的轉換，可以控制五苯荑分子與茚酮所連接的碳‒碳單鍵旋轉方向。而在Z-2的研究中，合成並純化出具有光學活性的五苯荑前驅物為最困難的議題，經利用(R)-BINOL為掌性輔助基，可以分離純化出具有光活性的五苯荑前驅物，進而成功的合成出Z-2分子。Z-2的單方向旋轉特性則是利用混參於5CB液晶分子中，並在裝備有偏光鏡的光學顯微鏡下觀察其在受光照射後，是否能改變液晶分子的排列。

For more precise and efficient work, chemists have been trying to synthesize molecular machines that perform quasi-mechanical motion by adding external stimuli. Here, we tried to synthesize two Brownian molecular motors E-1 and Z-2 which are based on one of our previous molecular brakes containing pentiptycene scaffold. In the case of E-1, the DFT-derived rotational potential energy surfaces (RPES) for the neutral and radical anion states are distinct, which suggests that the pulsating ratchet mechanism can be applied in performing directional rotations about the exocyclic C‒C bond with electrical energy. For Z-2, the most challenging issue is to obtain optically pure pentiptycene precursor. (R)-BINOL was used as a chiral auxiliary for the purpose. The unidirectional rotation of Z-2 was performed in doped 1 wt% of Z-2 in 5CB. A preliminary test shows that the texture of nematic liquid crystal is not affected by Z-2.