Direct observation of the intramolecular triplet-triplet energy transfer in poly(aryl ether) dendrimers.
Direct observation of the intramolecular triplet-triplet energy transfer in poly(aryl ether) dendrimers.
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DOI：
10.1021/jp055845h
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发表时间：
2006-02
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影响因子：
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通讯作者：
Jinping Chen;Shayu Li;Lu Zhang;Yingying Li;Jie Chen;Guoqiang Yang;Yi Li
中科院分区：
文献类型：
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作者：
Jinping Chen;Shayu Li;Lu Zhang;Yingying Li;Jie Chen;Guoqiang Yang;Yi Li
合成了一系列二苯甲酮（BP）和萘（NA）标记的聚（芳基醚）树枝状聚合物（BP-Gn-NA），第1-4代，并检查了它们的光物理性质。闪光光解表明 BP-Gn-NA 中的三重态能量可以从外围 BP 生色团转移到核心 NA 基团，效率约为 100%。室温下第 1-4 代的速率常数分别为 0.97、0.96、0.88 和 0.54，速率常数分别为 1.4x10(8)、1.2x10(8)、9.5x10(7) 和 1.3x10(7) s-1。 BP-Gn-NA的瞬态吸收光谱清楚地显示了三重态NA吸收的形成以及等吸光点为475 nm的三重态BP的衰减，这直接证明了三重态能量从外围BP发色团转移到核心NA基团。当 77 K 下选择性照射 BP-G1-NA 中的外围 BP 发色团时，观察到附着在焦点上的 NA 基团的磷光。三重态能量转移发生在 77 K 下，第 1-4 代的效率分别为 1.0、0.16、0.17 和 0.21。分子内三重态能量转移被认为主要通过空间机制进行。
A series of benzophenone (BP) and naphthalene (NA) labeled poly(aryl ether) dendrimers (BP-Gn-NA), generations 1-4, were synthesized, and their photophysical properties were examined. Flash photolysis demonstrates that the triplet energy in BP-Gn-NA can be transferred from the peripheral BP chromophores to the core NA group with the efficiencies of ca. 0.97, 0.96, 0.88, and 0.54 and with the rate constants of 1.4x10(8), 1.2x10(8), 9.5x10(7), and 1.3x10(7) s-1 at room temperature for generations 1-4, respectively. The transient absorption spectra of BP-Gn-NA show clearly the formation of the triplet NA absorption along with the decay of the triplet BP one with an isosbestic point at 475 nm, which gives direct evidence of the triplet energy transfer from the periphery BP chromphores to the core NA group. The phosphorescence of the NA group attached to the focal point was observed when the periphery BP chromophores were selectively irradiated in BP-G1-NA at 77 K. The triplet energy transfer occurs at 77 K with the efficiencies of 1.0, 0.16, 0.17, and 0.21 for generations 1-4, respectively. The intramolecular triplet energy transfer is proposed to proceed mainly via a through space mechanism.