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首页> 外文期刊>Chemistry: A European journal >Probing molecular wires: Synthesis, structural, and electronic study of donor-acceptor assemblies exhibiting long-range electron transfer
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Probing molecular wires: Synthesis, structural, and electronic study of donor-acceptor assemblies exhibiting long-range electron transfer

机译：探测分子线：表现出远距离电子转移的供体-受体组装体的合成，结构和电子研究

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A series of donor-acceptor arrays (C-60-oligo-PPV-exTTF; 16-20) incorporating pi-conjugated oligo(phenylenevinylene) wires (oligo-PPV) of different length between pi-extended tetrathiafulvalene (exTTF) as electron donor and C-60 as electron acceptor has been prepared by multistep convergent synthetic approaches. The electronic interactions between the three electroactive species present in 16-20 were investigated by UV-visible spectroscopy and cyclic voltammetry (CV). Our studies clearly show that, although the C-60 units are connected to the exTTF donors through a pi-conjugated oligo-PPV framework, no significant electronic interactions are observed in the ground state. Interestingly, photoinduced electron-transfer processes over distances of up to 50 A afford highly stabilized radical ion pairs. The measured lifetimes for the photogenerated charge-separated states are in the range of hundreds of nanoseconds (similar to 500 ns) in benzonitrile, regardless of the oligomer length (i.e., from the monomer to the pentamer). A different lifetime (4.35 Vs) is observed for the heptamer-containing array. This difference in lifetime has been accounted for by the loss of planarity of the oPPV moiety that increases with the wire length, as established by semi-empirical (PM3) theoretical calculations carried out with 19 and 20. The charge recombination dynamics reveal a very low attenuation factor (beta = 0.01 +/- 0.005 angstrom(-1)). This value, as well as the strong electron coupling (V similar to 5.5cm(-1)) between the donor and the acceptor units, clearly reveals a nanowire behavior for the pi-conjugated oligomer, which paves the way for applications in nanotechnology.
机译：一系列供体-受体阵列（C-60-oligo-PPV-exTTF; 16-20），在pi延伸的四硫富富瓦烯（exTTF）之间引入了不同长度的pi共轭低聚（亚苯基亚乙烯基）线（oligo-PPV），作为电子供体通过多步收敛合成方法制备了C-60作为电子受体。通过紫外可见光谱和循环伏安法（CV）研究了16-20中存在的三种电活性物质之间的电子相互作用。我们的研究清楚地表明，尽管C-60单元通过pi共轭的寡聚PPV骨架与exTTF供体相连，但在基态中未观察到明显的电子相互作用。有趣的是，在高达50 A的距离上进行光诱导的电子转移过程可提供高度稳定的自由基离子对。不论低聚物的长度（即从单体到五聚体）如何，光生电荷分离态在苯甲腈中测得的寿命在数百纳秒（约500 ns）的范围内。对于含七聚体的阵列，观察到不同的寿命（4.35 Vs）。寿命的这种差异是由oPPV部分的平面度随线长增加而造成的，这是通过对19和20进行的半经验（PM3）理论计算确定的。电荷重组动力学显示出非常低的衰减系数（β= 0.01 +/- 0.005埃（-1））。该值，以及供体和受体单元之间的强电子耦合（V类似于5.5cm（-1）），清楚地揭示了pi共轭低聚物的纳米线行为，这为纳米技术的应用铺平了道路。

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