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首页> 外文期刊>Photochemical & photobiological sciences: the official journal of the European Photochemistry Association and the European Society for Photobiology >The use of dendrimers as high-performance shells for round-trip energy transfer: efficient trans-cis photoisomerization from an excited triplet state produced within a dendrimer shell
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The use of dendrimers as high-performance shells for round-trip energy transfer: efficient trans-cis photoisomerization from an excited triplet state produced within a dendrimer shell

机译：将树枝状聚合物用作往返能量转移的高性能外壳：从树枝状聚合物外壳中产生的激发三重态有效地进行反式顺式光异构化

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A series of stilbene-cored poly(benzyl ether) dendrimers with benzophenone peripheries were synthesized and their photophysical and photochemical properties were studied. Fluorescence studies revealed that singlet-singlet energy transfer (SSET) from the stilbene core to the benzophenone units took place efficiently in dendrimers of all generations. Similarly, phosphorescence and time-resolved spectroscopic measurements indicated efficient triplet-triplet energy transfer (TTET) from the benzophenone periphery to the stilbene core. Upon excitation at 310 nm, the stilbene core isomerizes via an energy round trip within the dendrimer shell. The quantum yields for the energy round trip (Φ_(ERT)), denned as the product of the quantum yields of SSET, intersystem crossing, and TTET (Φ_(ERT) = Φ_(SS)Φ_(isc)Φ_(TT)), were extremely high for all generations—99%, 95% and 94% for G1, G2, and G3, respectively—which means that the excitation energy of the dendrimer core was transferred to the dendrimer periphery and back to the core almost quantitatively. The quantum yield for photoisomerization of G1-G3 via an energy round trip was higher than for other stilbene-cored dendrimers, which mainly isomerize from the excited singlet state. Photostability in the dendrimers was also demonstrated and discussed.
机译：合成了一系列具有二苯甲酮周边的以sti为核的聚（苄基醚）树枝状大分子，并研究了它们的光物理和光化学性质。荧光研究表明，从二苯乙烯核到二苯甲酮单元的单重态-单态能量转移（SSET）在各代树状聚合物中均有效发生。类似地，磷光和时间分辨光谱测量表明从三苯甲酮外围到二苯乙烯核的有效三重态-三重态-三重态能量转移（TTET）。在310 nm激发后，二苯乙烯核通过树枝状聚合物壳内的能量往返异构化。能量往返行程（Φ_（ERT））的量子产率定义为SSET，系统间交叉和TTET的量子产率的乘积（Φ_（ERT）=Φ_（SS）Φ_（isc）Φ_（TT）） ，对于所有代来说都是极高的-G1，G2和G3分别为99％，95％和94％，这意味着树枝状聚合物核的激发能几乎定量地转移到树枝状聚合物的外围并转移回核。 G1-G3通过能量往返进行光异构化的量子产率高于其他以1,2-二苯乙烯为中心的树枝状大分子，后者主要从激发的单重态异构化。树枝状聚合物的光稳定性也得到了证明和讨论。

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