利用銠金屬催化的矽氫化反應或鈀金屬催化的Heck反應可以合成一系列有規則以矽為間隔將不同發光團隔開並且交錯排列的芳香基高分子[(donor)-SiMe2-(acceptor)-SiMe2-]。以镍金屬催化硫縮醛芳香化合物與格林那試劑偶合反應可以方便的得到乙烯基矽基醚,再經由氫化鋁鋰還原反應,得到相對應的矽基氫化合物。不同於大部分的共聚合物,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。矽原子再高分子中扮演一絕緣體角色也連接不同的發光團。 在苯胺與蒽組成的共聚合物中,當激發波長在電子受體的最大吸收時,從螢光光譜中所觀察到的螢光強度明顯較電子給體不存在時小的多,說明高分子鏈中可以進行非常有效率的電子轉移。在進行金屬離子滴定後,高分子對特定離子具有不錯的選擇性,且螢光強度可增強數十倍。 另一方面,在聯苯和蒽的共聚合物中,聯苯做為能量給體,而蒽為能量受體,彼此的比例為一比一並且有規則地交替連接,當激發在給體的最大吸收波長時,由螢光發射光譜可以觀測到受體的螢光放射強度明顯較給體大的多,說明了高分子內可以非常有效率的進行能量轉移。 最後我們合成出包含三種不同發光團的高分子,我們可以觀察到連續的能量與電子轉移現象發生在高分子鏈中。在這個以矽烷基為間隔且交替排列的高分子系統中,成功得模擬植物體進行光合作用的機制。
A series of regioregular silylene-spaced alternating donor-acceptor arene copolymers [(donor)-SiMe2-(acceptor)-SiMe2-]n were synthesized by rhodium catalyzed hydrosilylation of bis-alkynes with bis-silylhydride or by palladium catalyzed Heck reaction of di-bromoarene with bis-vinylsilane. Vinylsilylhydrides were prepared by nickel-catalyzed olefination of the corresponding aryl dithioacetals with Grignard reagent followed by LAH reduction. Unlike most copolymers, our strategy has furnished a powerful arsenal for the construction of copolymers with precise regiochemistry and repetitive units. The silylene group serves as an insulating building block between chromophores. In the aniline and anthracene copolymer, efficient intrachain electron transfer between donor-acceptor chromophores is observed. On the other hand, in the biphenyl and anthracene copolymer, very weak intensity emission coming from donor is observed in fluorescence spectra, illustrating that energy transfer is highly efficient between the donor and the acceptor along the copolymer chain. In addition, the polymer composed of three different chromophores is synthesized, the sequential energy and electron transfer along the polymeric chain is also observed. In this three chromophores silyene-spaced copolymer system, we can successfully mimic the photosynthesis process in the green plants.
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