電子與能量傳遞在矽基聚合物與有機無機混合材料之研究

Electron Transfer and Energy Transfer in Silicon-Bridged Copolymers and Hybrid Materials

陳志賢(Chih-Hsien Chen)

指導教授 ： 陸天堯

國立臺灣大學/理學院/化學研究所/博士(2009年)

https://doi.org/10.6342/NTU.2009.01434

摘要

設計並合成以矽烷基為間隔之芳香基聚合物用以研究光誘發電子傳遞反應。在此共聚高分子中，電子傳遞予體與受體有機發色團被矽烷基分隔並交錯排列。合成的方法是以銠金屬催化矽氫化反應得到聚合物。光誘發電子傳遞速率被發現與反應自由能有關，其符合Marcus理論對電子傳遞速率與反應自由能之關係的預測。值得注意的是，在電子分離的過程中即可發現反轉點(inverted region)的存在，並且，電子分離與電子再結合兩個步驟具有相同的重組能量(reorganization energy)與電子耦合(electronic coupling)。此共聚高分子中，矽烷基可保持電子傳遞予體與受體間具有一定的距離，而且，其可避免擴散作用的影響並確保此為分子內反應過程。此外，在某些聚合物中發現具有兩個螢光特徵峰。利用溶劑致變色方法得知此兩個螢光特徵峰分別是來自受體發色團本身的螢光與電子再結合過程所放出的螢光。此性質可能受到電子傳遞反應自由能與溶劑極性的影響。
在有機無機混合材料中，將兩個至三個有機發色團以不同比例組合在一起以研究分子間的能量傳遞與電子傳遞過程。螢光光譜顯示入射光能量可由能量傳遞予體傳送至能量傳遞受體。並且，受體有機發色團的螢光強度隨著予體莫耳比例的增加而增強。此即為天線效應。而由時間解析螢光光譜則可估計能量傳遞速率與效益。此外，改變不同的有機發色團亦可發現電子傳遞反應。當在有機無機混合材料中加入電子傳遞予體，相對應的受體有機發色團其螢光被淬滅。並且隨著予體莫耳比例的增加，受體的螢光強度愈弱。此結果說明了光誘發電子傳遞反應的發生，並且利用時間解析光譜亦可證實此結論。有機發色團間的能量傳遞與電子傳遞過程被證明可於此有機無機混合材料中進行。

關鍵字

能量傳遞 ； 電子傳遞 ； 聚合物 ； 有機無機混合材料

並列摘要

Silylene spaced copolymers for photoinduced electron transfer studies have been designed and synthesized. The donor and acceptor chromophores in these copolymers are arranged in alternating manner separated by silylene moieties. These copolymers are prepared by rhodium catalyzed hydrosilylation reactions. The rates of photoinduced electron transfer are found to be dependent on the free energy differences of the photoinduced electron transfer reactions between the donor and acceptor. The rates of the reactions follow the Marcus theory nicely. Notably, the inverted region is observed in forward electron transfer processes. Besides, the forward and backward electron transfer processes might be governed by the same electronic coupling and reorganization energy. The confined distance between donor and acceptor chromophores via silylene spacer might avoid the diffusion control limitation of electron transfer, and maintained the intramolecular process. Moreover, dual fluorescence is observed in certain copolymers, and the solvatochromic measurements show that the dual fluorescence may consist of local emission of acceptor chromophores and emission from charge recombination. The occurrence of dual fluorescence may be governed by free energy change of electron transfer reaction and environment polarity.
The hybrid materials consisting of two to three covalently bound organic chromophores at different ratios are conveniently synthesized and fabricated. The energy transfer and electron transfer processes within these hybrid materials have been studied. The fluorescence spectra reveal the occurrence of energy transfer from donor to acceptor chromophores, and the light-harvesting ability of these hybrid materials increased with increasing the molar fraction of donor chromophore. Time-resolved fluorescence experiments are employed to elucidate the average rates and efficiencies of energy transfer in these organic inorganic hybrid systems.
The photoinduced electron transfer processes are also investigated in these hybrid materials. The fluorescence quenching of the acceptor chromophores is observed in the presence of the electron donor chromophores, and the fluorescence intensities are decreased with increasing molar concentration of the donor moiety. The results indicate the occurrence of photoinduced electron transfer in hybrid materials, and that is confirmed by time-resolved fluorescence spectroscopy. The hybrid materials have been shown to provide antenna effect to facilitate energy transfer and allow the occurrence of electron transfer between chromophores

並列關鍵字

electron transfer ； energy transfer ； Marcus theory ； polymer ； hybrid materials

參考文獻

3. Choi, M.-S.; Yamazaki, T.; Yamazaki, I; Aida, T. Angew. Chem. Int. Ed. 2004, 43, 150.

4. (a) Kawa, M.; Fréchet, J. M. J.; Chem. Mater. 1998, 10, 286. (b) Adronov, A.; Gilat, S. L.; Fréchet, J. M. J.; Ohta, K.; Neuwahl, F. V. R.; Fleming, G. R. J. Am. Chem. Soc. 2000, 122, 1175. (c) Serin, J. M.; Brousmiche, D. W.; Fréchet, J. M. J. Chem. Comm. 2002, 2605. (d) Gilat, S. L.; Adronov, A.; Fréchet, J. M. J. Angew. Chem. Int. Ed. 1999, 38, 1422. (e) Adronov, A.; Fréchet, J. M. J. Chem. Comm. 2000, 1701.

5. (a) Devadoss, P.; Moore, J. S. J. Am. Chem. Soc. 1996, 118, 9635. (b) Melinger, J. S.; Pan, Y.; Kleiman, V. D.; Peng, Z.; Davis, B. L.; McMorrow, D.; Lu, M. J. Am. Chem. Soc. 2002, 124, 12002. (c) Mak, C. C.; Bampos, N.; Sanders, J. K. M. Angew. Chem. Int. Ed. 1998, 37, 3020. (d) Benites, M. R.; Johnson, T. E.; Weghorn, S.; Yu, L.; Rao, P. D.; Diers, J. R.; Yang, S. I.; Kirmaier, C.; Bocian, D. F.; Holten, D.; Lindsey, J. S. J. Mater. Chem. 2002, 12, 65. (e) Plevoets, M.; Vögtle F.; Cola, L. D.; Balzani, V. New J. Chem. 1999, 23, 63. (f) Stewart, G. M.; Fox, M. A. J. Am. Chem. Soc. 1996, 118, 4354. (g) Nantalaksakul, A.; Reddy, D. R.; Bardeen, C. J.; Thayumanavan, S. Photosynthesis Res. 2006, 87, 133.

6. (a) Choi, M.-S.; Aida, T.; Yamazaki, T.; Yamazaki, I. Angew. Chem. Int. Ed. 2001, 40, 3194. (b) Choi, M.-S.; Aida, T.; Yamazaki, T.; Yamazaki, I. Chem. Eur. J. 2002, 8, 2668. (c) Li, W.-S.; Kim, K. S.; Jiang, D.-L.; Tanaka, H.; Kawai, T.; Kwon, J. H.; Kim, D.; Aida, T. J. Am. Chem. Soc. 2006, 128, 10527. (d) Jiang, D.-L.; Aida, T. Nature 1997, 388, 454.

8. (a) Kimura, M.; Narikawa, H.; Ohta, K.; Hanabusa, K.; Shirai, H.; Kobayashi, N. Chem. Mater. 2002, 14, 2711. (b) Nakano, A.; Osuka, A.; Yamazaki, T.; Nishimura, Y.; Akimoto, S.; Yamazaki, I.; Itaya, A.; Murakami, M.; Miyasaka, H. Chem. Eur. J. 2001, 7, 3134. (c) Gust, D.; Moore, T. A.; Moore, A. L. Acc. Chem. Res. 2001, 34, 40. (d) Choi, M.-S.; Aida, T.; Yamazaki, T.; Yamazaki, I. Chem. Eur. J. 2002, 8, 2667. (e) Tomizaki,K.; Loewe, R. S.; Kirmaier, C.; Schwartz, J. K.; Retsek, J. L.; Bocian, D. F.; Holten, D.; Lindsey, J. S. J. Org. Chem. 2002, 67, 6519. (f) Kyushin, S.; Ikarugi, M.; Goto, M.; Hiratsuka, H.; Matsumoto, H. Organometallic 1996, 15, 1067. (g) Kwak, G.; Masuda, T. Macromolecules 2002, 35, 4138. (h) Duerr, B. F.; Chung, Y. S.; Czarnik, A. W. J .Org. Chem. 1988, 53, 2120. (i) Suzuki, H.; Satoh, S.; Kimata, Y.; Kuriyama, A. Chem. Lett. 1995, 451. (j) Haycock, R. A.; Yartsev, A.; Michelsen, U.; Sundström, V.; Hunter, C. A. Angew. Chem. Int. Ed. 2000, 39, 3616.