Synthesis and Properties of Pentiptycene-Derived Molecular Devices : Molecular Gear & Molecular Brake

五苯荑分子具有特殊剛硬、立體障礙大的三維立體結構，我們認為這樣的結構具有作為分子機械的潛力。本論文主要是合成新型的五苯荑衍生物，將之運用在分子齒輪與分子機械的系統中以做進一步的研究與性質討論。 第一部份分子齒輪系統中，我們利用帶有炔基的五苯荑衍生物6/9與鄰二碘苯進行Sonogashira偶合反應以得到化合物IBI/IBI-OMe。化合物IBI作為此系統的簡單模型；而化合物IBI-OMe的前驅物9具有對掌性異構物，使得IBI-OMe為具有多種光學異構物的複雜系統。根據一系列的變溫NMR模擬實驗搭配理論計算DFT (B3LYP/6-31G*//AM1)的輔佐，我們可以了解化合物IBI/IBI-OMe在室溫下的運動行為，除了一般的齒輪轉動外，還會經過在U形槽搖擺的運動過程。我們成功架構了一種新型的四葉片齒輪IBI與IBI-OMe，在室溫下IBI-OMe的滑動能量為18 kcal mol-1。 第二部分分子剎車系統中，我們合成了一系列具有雙邊甲氧基取代的五苯荑衍生物。我們成功的從雙取代五苯荑醌11(s)/11(a)進行官能化得到新型的五苯荑衍生物12(s)/12(a)、13(s)/13(a)、14(s)/14(a)、15(s)/15(a)、16(s)/16(a)。目標化合物B-OH及B-CO的合成與整個系統的性質量測還有待研究。Because of its unique rigid, bulky and three-dimensional structure, pentiptycene is a potential scaffold for the construction of molecular machines. This thesis reports the synthesis and properties of new pentiptycene derivatives as molecular gear and molecular brake systems. The target molecular gear system IBI/IBI-OMe was prepared from compound 6/9 by the Sonogashira reaction. Compound IBI serves as a model compound. The precursor of IBI-OMe is racemic mixture and thus IBI-OMe is a mixture of stereoisomers including diastereomers and phase isomers. On the basis of experimental and simulated variable temperature (VT) NMR spectra and DFT (B3LYP/6-31G*//AM1) calculations, we concluded that the pentiptycene rotation in IBI-OMe is correlated at room temperature, and we also observed the swing motion of one pentiptycene rotor in the U-shaped cavities of the other pentiptycene rotor. The experimental free energies ΔG‡ for gear slippage is 18 kcal mol-1 at 298 K. For the molecular brake system, middle-ring disubstituted pentiptycenes 12(s)/12(a), 13(s)/13(a), 14(s)/14(a), 15(s)/15(a), 16(s)/16(a) from the tetramethoxypentiptycene quinone 11(s)/11(a) have been prepared. They are the precursors for the target compound B-OH and B-CO