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Development of the dendrimer photochemistry and the reaction dynamics

树枝状聚合物光化学和反应动力学的发展

基本信息

批准号：
16350005
负责人：
ARAI Tatsuo
金额：
$ 10.11万
依托单位：
University of Tsukuba
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2005
项目状态：
已结题

项目摘要

(1)Photoisomerization mechanismA cross-linked 1,3,5-tristyrylbenzene dendrimer was synthesized to study the photochemical isomerization mechanism. On irradiation, cross-linked dendrimer isomerized with the quantum yields of 0.063, which was not very much different from that for a model compound (0.080), supporting a volume-conserving mechanism during the photochemical E-Z isomerization.(2)Whole structural change of the dendrimers triggered by photoisomerizaition at the core partThe conformational dynamics and the energy-releasing process of stilbene dendrimers upon photoexcitation in water are investigated by the time-resolved transient grating method. Whereas the energy relaxation and the conformational change are completed within 30 ns for the first generation, slower dynamics are observed for the second and the third generations.(3)Increasing the fluorescence quantum yield in dendronized chromophoreThe photochemical properties of a series of newly synthesized dendrimers, having a 2- … More (2'-hydroxyphenyl)-benzoxazole (HBO) core, were studied in benzene. In general, the quantum yield for fluorescence of HBO and its analogues was small, However, the fluorescence quantum yields were determined to be 0.022,0.030, and 0.038 for G0,G2, and G3 dendrimers, respectively, increasing in higher generation dendrimers.(4)Increasing the quantum yield for generation of singlet oxygen upon photoexcitation of dendronized stilbenesSince the excited singlet state of the core moiety in stilbene-cored dendrimers G1-G4 has ca.10-ns lifetime, oxygen quenched their excited singlet state producing the singlet oxygen. The efficiency of singlet oxygen production based on the quenching of the stilbene core is the highest in G4 stilbene dendrimer.(5)Self-assembly of chromophore using amphiphilic dendronsThe self-assembly of amphiphilic pyrene-cored poly(aryl ether) dendrimers has been studied. Pyrene excimer emission from the higher generation is observed in KOH aqueous solution at low concentration. The results indicate that the self-aggregation in higher generation dendrimer takes place more efficiently than in lower generation in aqueous solution. Less

（1）光致异构化机理本文合成了交联的1，3，5-三苯乙烯基苯树枝状大分子，研究了其光致异构化机理。在辐照下，交联的树枝状大分子异构化的量子产率为0.063，这是不是很大的不同，从模型化合物（0.080），支持体积守恒的机制，在光化学E-Z异构化。（2）树枝状大分子在光激发下的整体结构变化采用时间分辨瞬态光栅方法研究了二苯乙烯树枝状大分子在水中光激发下的构象动力学和能量释放过程。而第一代的能量弛豫和构象变化在30 ns内完成，第二代和第三代观察到较慢的动力学。（3）提高树枝化生色团的荧光量子产率 ...更多信息（2 '-羟基苯基）-苯并恶唑（HBO）核的合成。一般来说，HBO及其类似物的荧光量子产率较小，而G 0、G2和G3的荧光量子产率分别为0.022、0.030和0.038，随着代数的增加而增加。（4）增加了光激发二苯乙烯树枝状大分子时产生单线态氧的量子产率由于二苯乙烯树枝状大分子G1-G4中核心部分的激发单线态寿命约为10-ns，氧猝灭了它们的激发单线态，产生单线态氧。基于二苯乙烯核猝灭的单线态氧产生效率在G4二苯乙烯树枝状大分子中最高。（5）两亲性树枝自组装生色团研究了以芘为核的两亲性聚芳醚树枝状大分子的自组装。在低浓度KOH水溶液中观察到芘激基缔合物的高代发射。结果表明，在水溶液中，高代树枝状大分子的自聚集比低代树枝状大分子更有效。少