奈米石墨烯 (Nanographenes) 材料 MHs 6-8 與 MHs 10 是由三個 [6]螺旋烴或三個 [7]螺旋烴次單元組成核心分子骨架，再以三個 [4]螺旋烴或 [5]螺旋烴在骨架外圍建構 π-共軛系統的六螺旋烴衍生物，而 MHs 9 則為九 [6]/[5]/[4]螺旋烴化合物。我們以 C3 對稱的炔類化合物 1-R1 (1,3,5-Tris[2-(arylethynyl)phenyl]benzene) 作為起始物，透過三鍵親電性碘合環反應得到三碘化合物 2-R1，再進一步與 2-溴苯甲酸衍生物 3-5 與 9-溴-10-菲羧酸 28，在鈀金屬的催化下進行合環，成功得到化合物 MHs 6-9，而六螺旋烴 MHs 10 則參考上述之合成方式，但目前 10-Et 的合成仍在努力嘗試當中。
根據 X-ray 單晶繞射的結果，MHs 6-8 為 C1 點群，立體組態為 (P,M,M,M,P,P)，而 MHs 9 則為 (P,P,P,M,M,M) 組態的 C3 對稱結構。經由 DFT 理論計算發現類似物 6-H 與 8-H 具有 12 種可能非鏡像異構物，其晶體結構與本篇 6-Et 及 8-Et 結果吻合，並且證實具有 (P,M,M,M,P,P) 組態的 C1-Ⅳ 對稱結構為最穩定的構形。反之，化合物 9-Et 中，具有 (P,P,P,M,M,M) 組態的 C3 對稱結構為能量最低的異構物。在本篇研究中，我們順利透過掌性高效液相層析儀，將 8-nBu 的鏡像異構物分離，進行動力學測試，其消旋活化能 (enantiomerization barrier) 為 31.2 kcal•mol-1，與理論計算結果相符。化合物 MHs 6-8 經由電化學及光物理性質探討發現延伸 π-共軛系統的合成策略對於 HOMO-LUMO 能階差並沒有顯著的改變，而 MHs 9 與 MHs 10 則有效地降低了光能隙，分別為 2.26 eV 與 2.12 eV。我們也進一步針對 8-nBu 的鏡像異構物進行旋光度及圓二色光譜的量測，深入研究其掌性光學性質。
關鍵字：
奈米石墨烯 / 六螺旋烴 / 鈀金屬催化合環 / 2-溴苯甲酸衍生物 / 消旋活化能

SUMMARY
Helicene-based nanographenes MHs 6-8 and MHs 10 were hexapole helically shaped π-conjugated polycyclic arenes, bearing three inner [6] or [7]helicene substructures as a core and three outer [4] or [5]helical moieties in a molecule framework. Furthermore, the most outstanding one was nonapole [6]/[5]/[4]helicenes MHs 9. In the thesis, we successfully obtained MHs 6-9 by two synthetic routes, starting from iodocyclization of C3-symmetric precursor 1-R1
to afford triiodo-substituted species 2-R1 and then underwent the palladium-catalyzed annulation with o-Bromoaryl carboxylic acids derivatives 3-5 and
28. However, with the optimal reaction conditions in hand, the result of the
decarboxylation coupling reaction of hexapole [7]/[4]helicene 10-Et was presumably inaccessible due to the low purity of triiodo-substituted precursor 53b and the steric hinderance caused by the naphthyl subunits of the structure.
In contrast to low symmetric MHs aforementioned, the stereochemistry of MHs 6-8
(P,M,M,M,P,P) with C1 symmetry was confirmed by single-crystal X-ray diffraction
analysis. C3-symmetric MHs 9 with (P,P,P,M,M,M) configuration was also proved by Xray. The crystallographic structures of 6-H and 8-H were identical to those of 6-Et and 8-Et. Among the possible 12 diastereomers, density functional theory (DFT) calculation identified C1-symmetric 6-H and 8-H with (P,M,M,M,P,P) as the most stable isomer, and C3-symmetric 9-Et with (P,P,P,M,M,M) configuration, however, was proved to be the most stable one. Both enantiomers of 8-nBu could be separated by chiral HPLC and the calculated racemization energy (ΔH‡ = 31.2 kcal·mol−1) was consistent with that experimentally obtained. The photophysical and electrochemical properties of MHs 6-8 showed that the extended π-conjugation did not remarkably influence the HOMO-LUMO gaps. Specific rotation and dissymmetry factor (gabs) of circular dichroism (CD) spectra were also investigated to make us gain insight into chiral optical properties.
Key words: Nanographenes, Hexapole Helicenes, Palladium-Catalyzed Annulation, oBromoaryl Carboxylic Acids Derivatives, Racemization Energy

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