以矽烷基為間隔之芳香基雙乙烯基高分子在能量轉移及手性光學轉移之研究

Energy Transfer and Chiroptical Transfer in Silylene-Spaced Divinylarene Copolymers

鄭彥如(Yen-Ju Cheng)

指導教授 ： 陸天堯

國立臺灣大學/理學院/化學研究所/博士(2004年)

https://doi.org/10.6342/NTU.2004.01592

摘要

利用銠催化的矽氫化反應，雙乙炔和雙矽氫化合物可以合成一系列有規則以矽為間隔並且交錯排列的芳香基雙乙烯基高分子 [(donor-SiMe2)n=1-3-(acceptor)-SiMe2]。藉由單體的精心設計，給體與受體在高分子中之比例可以被良好的控制。鎳催化雙硫縮醛化合物與格林納試劑偶合反應可以方便的得到乙烯基矽基醚，再經由LAH還原反應，得到相對應的矽基氫化合物。先經由Heck偶合反應再進行Sonogashira或Kumada-Corriu偶合反應可以合成雙給體的雙乙炔單體。三給體的雙乙炔單體則是經由矽氫化反應來合成。不同於大部份的雙聚合物，我們的合成策略提供了一個很有效的方法來建構有精確位置化學及重複規則排列的高分子聚合物。具有與高分子相同發光團的參考單體也被製備用以作為光物理性質的比較。矽基團在聚合物中除了扮演一絕緣體的角色也連接不同的發光團。當高分子中的發光團具有一定的共軛長度時，並無激發態錯合物的生成。光誘導的電子轉移在此聚合物系統並不重要。當激發波長在給體的在最大吸收時，在螢光光譜中並無觀察到從給體所放出的螢光，說明高分子內可以進行非常有效率且完全的能量轉移。此外，高分子也展現了光收成的能力，隨著增加能量給體對於受體的比例，聚合物中受體螢光的強度也隨之增強。在高分子中配對不同能量的給體與受體，當激發在紫外光區的波長時，經由能量轉移的機制可以調控得到不同顏色的可見光。此外含有三種不同共軛長度發光團的高分子也被成左漲X成，隨著共軛長度的增加，能量也隨之遞減，藉由此設計的能量梯度，可以進行連續的能量轉移。這些結果說明以矽烷基來建構含給體與受體的高分子擁有絕佳的結構來進行能量轉移與光收成。
另一方面，以矽為間隔的芳香基雙乙烯基之手性高分子也被設計與合成。聚集效應明顯扮演了重要的角色來說明此高分子在圓形二色性光譜的性質。在低濃度時，高分子鏈呈現不規則的構形因此無法誘導圓形二色性光譜產生訊號。然而在高濃度下，由圓形二色性光譜可以發現光學手性之誘導及轉移，混合實驗建議在聚集狀態下光學手性之轉移在高分子鏈內似乎較為重要。

關鍵字

Energy Transfer ； Silylene-Spaced ； Chiropitcal Transfer

並列摘要

A series of regioregular silylene-spaced alternating [(donor-SiMe2)n=1-3-(acceptor)-SiMe2] copolymers was synthesized by rhodium-catalyzed hydrosilylation of bis-alkynes with bis-silylhydrides. The ratio of donor to acceptor can be well controlled by appropriate design of the monomeric precursors. Bis-silylhydrides were prepared by nickel-catalyzed olefination of the corresponding aryl dithioacetals with Grignard reagent followed by LAH reduction. Two-donor bis-alkynes were obtained by Heck reaction followed by subsequent Sonogashira or Kumada-Corriu reaction. The synthesis of three-donor bis-alkyne was based on hydrosilylation of two different donor precursors. Unlike most copolymers, our strategy has furnished a powerful arsenal for the construction of copolymers with precise regiochemistry and repetitive units. Monomeric reference compounds having similar chromophore components were also prepared for photophysical comparison. The silylene moieties serve as insulating building block between chromophores. No excimer-like formation has been found in these types of polymers with relatively long conjugation chromophores. The effect of photoinduced electron transfer plays a negligible role in these polymeric systems. No emission coming from donor was observed in fluorescence spectra, illustrating that intrachain energy transfer is highly efficient along the polymeric chain. The polymers exhibit light-harvesting ability and the intensity of emission spectra are enhanced with the increasing number of donor to acceptor ratio. Upon excitation of these copolymers at UV wavelengths, versatile colors of light from acceptors via energy transfer can be accessed by incorporating well-designed

並列關鍵字

能量轉移 ； 手性光學轉移 ； 矽烷基為間隔

參考文獻

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