雙甲氧化甲基取代之二芐環庚烷螺旋烯在液晶光學開關及有機發光材料之研究
Abstract
中文摘要
本篇論文合成了一系列雙甲氧化甲基取代（MOM）的二芐環庚烷(DBS)骨架之螺旋烯類化合物，並與本實驗室發展完整之螺旋烯系統在光物物理表現及光化學行為上作進一步的表現與討論。我們可由已知的X-ray結構得知當環硫化合物具R絕對立體化學時，在銅粉還原作用下可得相對應的M form螺旋烯化合物。同理，若環硫化合物為S form絕對立體化學則得P form螺旋烯化合物，我們可藉此來判斷螺旋烯之絕對立體化學。螺旋烯類化合物在照光下會由基態激發至激發態，中間雙鍵接受能量後失去其雙鍵特性，並以兩種形式躍降回基態，如下 :一、形成雙自由基時，經由失去雙鍵特性的中間單鍵來進行旋轉，而可得到光異構化的產物。本篇論文為以（10R,11R,P）MOM取代之DBS為上盤結構與下盤為7-Br-α-tetralone的螺旋烯化合物經由Toluene為溶劑在310nm照射下，我們可以得到幾乎是單一形式M form的異構化產物，且在甲苯的實驗中由光引導的非鏡像超越值（de %）也有102 %的優異表現。令人振奮的是，再次以254nm照射下可回到P form較多的光異構化產物，利用這樣的光異構化特性，我們可將之利用在液晶光學開關的掌性光學添加劑上。二、另一種途徑因為結構的環張力及轉動能障太大所以經由放光形式來釋能，而我們也設計不同立體結構及共軛性的下盤來調整其發光特性，本篇論文在MOM取代的內向萘環螺旋烯系統中有相當優異的螢光量子產率表現且其發光波長以相當接近綠光範圍，我們也將螺旋烯的光物理行為應用在有機發光材料的使用上。
在光化學行為表現上，我們還結合了本實驗時發展相當完整的釩金屬錯離子與（10R,11R,P）MOM取代之螺旋烯結合下，希望能透過錯離子與取代基上的氧能有coordination而改變其光切換選擇性。而我們在加入等當量VOCl2.2THF後，發現MOM-7-Br螺旋烯在光化學切換上確實有明顯的轉換，並在論文中討論其行為表現。
Abstract The triaryethene synthesis adopt helical shapes（ie helicenes）, due to the steric overlap of symmetrical upper-part (dibenzosuberane) and the unsymmetrical lower part(β-naphtholflavone,α-tetralone etc). The chirality of these helicenes are defined as P or M for right- or left-hand helical handness.We synthesized a series of MOM (Methoxy-methyl) -substituted helicenes, and designed different structure and conjugation of lower part to evaluate these effects on their photophysical properties and photochemistry behavior. By irradiation, the central double bond of the helicenes loose its’ double bond character and exhibits diradical character. It has been documented that the relaxation of the excited state to the ground state procceds through two pathways. First, planarization around the diradical unit with increasing ring strainand with concomitant rotation leading to the perpendecular excited state enroute to anotherphotostationary ground state. Therefore, upon receiving irradiation energy, the helicenes consume the energy by double-bond photoisomerization. In this thesis, we have synthesized (10R,11R,P) MOM-7-Br helicene as the target optical-switching material. It was irradiated in toluene at 310nm,the opposite, pseudoenantiomeric helicene(10R,11R, M)isomer was furnished almost exclusively. The switching process was found reversible. The original (10R,11R,P) isomer may be enriched by irradiating (10R,11R,M)-isomer at 254nmas evidenced by HPLC and CD analyses. As mentioned above, we can use this reversible progress to apply the helicenes as LC-optical switch. Secon, an alternative way to release energy was by fluorescent emission.By selection of a different kinds of lower part, we can tune the irradiation wavelength and MOM-substituted upper part help to increase the energy barrier to photoisomerization and thus increase the fluorescence quantum yield. We used these photophysical properties to apply in organic light emitting materials. Based on photochemical behaviors of chiral MOM-substituted hlicene. We added 1 equivalent V-complex to bind bothmethoxymethye oxygens. We can effect reversal of photoisomerization selectivities.
Abstract The triaryethene synthesis adopt helical shapes（ie helicenes）, due to the steric overlap of symmetrical upper-part (dibenzosuberane) and the unsymmetrical lower part(β-naphtholflavone,α-tetralone etc). The chirality of these helicenes are defined as P or M for right- or left-hand helical handness.We synthesized a series of MOM (Methoxy-methyl) -substituted helicenes, and designed different structure and conjugation of lower part to evaluate these effects on their photophysical properties and photochemistry behavior. By irradiation, the central double bond of the helicenes loose its’ double bond character and exhibits diradical character. It has been documented that the relaxation of the excited state to the ground state procceds through two pathways. First, planarization around the diradical unit with increasing ring strainand with concomitant rotation leading to the perpendecular excited state enroute to anotherphotostationary ground state. Therefore, upon receiving irradiation energy, the helicenes consume the energy by double-bond photoisomerization. In this thesis, we have synthesized (10R,11R,P) MOM-7-Br helicene as the target optical-switching material. It was irradiated in toluene at 310nm,the opposite, pseudoenantiomeric helicene(10R,11R, M)isomer was furnished almost exclusively. The switching process was found reversible. The original (10R,11R,P) isomer may be enriched by irradiating (10R,11R,M)-isomer at 254nmas evidenced by HPLC and CD analyses. As mentioned above, we can use this reversible progress to apply the helicenes as LC-optical switch. Secon, an alternative way to release energy was by fluorescent emission.By selection of a different kinds of lower part, we can tune the irradiation wavelength and MOM-substituted upper part help to increase the energy barrier to photoisomerization and thus increase the fluorescence quantum yield. We used these photophysical properties to apply in organic light emitting materials. Based on photochemical behaviors of chiral MOM-substituted hlicene. We added 1 equivalent V-complex to bind bothmethoxymethye oxygens. We can effect reversal of photoisomerization selectivities.