Mediating Reductive Charge Shift Reactions in Electron Transport Chains,Journal of the American Chemical Society

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Mediating Reductive Charge Shift Reactions in Electron Transport Chains
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2017-11-17 00:00:00 , DOI: 10.1021/jacs.7b08670
Maximilian Wolf ₁ , Carmen Villegas ₂ , Olga Trukhina _{3,

4} , Juan Luis Delgado _{5,

6} , Tomás Torres _{3,

4,

7} , Nazario Martín _{2,

4} , Timothy Clark ₈ , Dirk M. Guldi ₁

Affiliation

We report the synthesis of a full-fledged family of covalent electron donor–acceptor₁–acceptor₂ conjugates and their charge-transfer characterization by means of advanced photophysical assays. By virtue of variable excited state energies and electron donor strengths, either Zn(II)Porphyrins or Zn(II)Phthalocyanines were linked to different electron-transport chains featuring pairs of electron accepting fullerenes, that is, C₆₀ and C₇₀. In this way, a fine-tuned redox gradient is established to power a unidirectional, long-range charge transport from the excited-state electron donor via a transient C₆₀^•– toward C₇₀^•–. This strategy helps minimize energy losses in the reductive, short-range charge shift from C₆₀ to C₇₀. At the forefront of our investigations are excited-state dynamics deduced from femtosecond transient absorption spectroscopic measurements and subsequent computational deconvolution of the transient absorption spectra. These provide evidence for cascades of short-range charge-transfer processes, including reductive charge shift reactions between the two electron-accepting fullerenes, and for kinetics that are influenced by the nature and length of the respective spacer. Of key importance is the postulate of a mediating state in the charge-shift reaction at weak electronic couplings. Our results point to an intimate relationship between triplet–triplet energy transfer and charge transfer.

中文翻译：

介导电子传输链中的还原性电荷转移反应

我们报告了完整的共价电子供体-受体_1-受体₂结合物家族的合成，以及通过先进的光物理测定法对其电荷转移进行了表征。凭借可变的激发态能量和电子给体强度，Zn（II）卟啉或Zn（II）酞菁被连接到以成对的电子接受富勒烯（即C ₆₀和C ₇₀）为特征的不同电子传输链上。这样，建立了一个微调的氧化还原梯度，以驱动单向的，从激发态电子供体通过瞬态C ₆₀^•–向C ₇₀^•–进行长距离电荷迁移。。这种策略有助于最大程度地减少从C ₆₀到C ₇₀的还原性短程电荷转移中的能量损失。我们研究的最前沿是从飞秒瞬态吸收光谱测量结果和瞬态吸收光谱的后续计算反卷积推导的激发态动力学。这些为短程电荷转移过程的级联提供了证据，包括两个电子接受富勒烯之间的还原性电荷转移反应，以及受各自间隔基的性质和长度影响的动力学。至关重要的是假设在弱电子耦合下电荷转移反应中的介导态。我们的结果表明三重态-三重态能量转移和电荷转移之间存在密切的关系。

更新日期：2017-11-19

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