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首页> 外文学位 >Charge migration in supramolecular assemblies with multiple redox centers.
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Charge migration in supramolecular assemblies with multiple redox centers.

机译：具有多个氧化还原中心的超分子组装体中的电荷迁移。

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摘要

The relationship between molecular structure and charge migration within supramolecular assemblies containing multiple redox centers is the primary topic of this thesis. The supramolecular assemblies are comprised of molecules with favorable attributes for use in organic electronic and light-harvesting applications. The main techniques employed for the determination of charge migration are electron paramagnetic resonance (EPR) spectroscopy and electron nuclear double resonance (ENDOR) spectroscopy.;First, a series of zinc porphyrin arrays using meso-meso and meta-phenylene linkages comprised of dimers, tetramers, and a dodecameric ring were singly oxidized and intramolecular hole hopping between the porphyrin moieties was probed using EPR and ENDOR. Rapid hole hopping occurs between both porphyrins within both dimers, and among three porphyrins of the tetramers, and among 8-12 porphyrins in the dodecameric ring with rates > 107 s-1. These results show that hole hopping is rapid even though the meta-phenyl bridges and direct meso-meso linkages do not provide optimal electronic coupling between the porphyrins within these multi-porphyrin arrays.;Next, intramolecular electron hopping is explored within a series of synthetic DNA hairpins in which perylenediimides (PDIs) are cofacially stacked by incorporation into the DNA strands as base pair surrogates. Analysis of the EPR and ENDOR spectra of the singly reduced duplexes is consistent with electron delocalization over two sites in both dimers and the trimer and over three sites in the tetramer. These results demonstrate the potential of synthetic DNA scaffolds, readily obtainable using automated synthesis techniques, to promote large scale ordering and long distance charge transport in redox-active organic molecules.;Lastly, a series of linearly-linked PDI dimers and trimers were synthesized in which the PDI pi systems are oriented nearly orthogonal to one another. When the functional groups attached to the ends of the oligomers were chosen to make each PDI molecule electronically equivalent, the single electron in a mono-reduced sample hops between the PDI molecules with rates that significantly exceed 107 s-1. Rapid electron hopping between pairs of PDI molecules having orthogonal pi systems is unexpected and may expand the possible design motifs for organic electronic materials based on PDI.
机译：包含多个氧化还原中心的超分子组装体中分子结构与电荷迁移之间的关系是本论文的主要主题。超分子组装体由具有良好属性的分子组成，可用于有机电子和光收集应用。用于确定电荷迁移的主要技术是电子顺磁共振（EPR）光谱和电子核双共振（ENDOR）光谱。首先，使用由二聚体组成的中观和间亚苯基键连接一系列锌卟啉阵列，将四聚体和十二聚体环单独氧化，并使用EPR和ENDOR检测卟啉部分之间的分子内空穴跳跃。在两个二聚体中的两个卟啉之间，以及四聚体的三个卟啉之间，以及在十二聚体环中的8-12个卟啉之间，以> 107 s-1的速率发生快速跳孔。这些结果表明，即使间苯基桥键和直接的中观-内观键合不能在这些多卟啉阵列中的卟啉之间提供最佳的电子偶联，空穴跳跃也是快速的。接下来，在一系列合成中探索了分子内电子跳跃DNA发夹，其中per二酰亚胺（PDI）通过掺入到DNA链中作为碱基对替代物而共面堆叠。对单个还原的双链体的EPR和ENDOR光谱的分析与在二聚体和三聚体中两个位点以及四聚体中三个位点上的电子离域一致。这些结果证明了使用自动化合成技术容易获得的合成DNA支架在促进氧化还原活性有机分子中促进大规模有序化和长距离电荷迁移方面的潜力。最后，在此过程中合成了一系列线性连接的PDI二聚体和三聚体。 PDI pi系统的方向几乎彼此正交。选择连接到低聚物末端的官能团以使每个PDI分子电子等效时，单还原样品中的单个电子在PDI分子之间跳跃，跳变速率明显超过107 s-1。具有正交pi系统的PDI分子对之间的快速电子跳跃是出乎意料的，并且可能会扩展基于PDI的有机电子材料的可能设计图案。

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  • 作者

    Wilson, Thea Marika.;

  • 作者单位

    Northwestern University.;

  • 授予单位 Northwestern University.;
  • 学科 Chemistry Organic.;Chemistry Physical.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 115 p.
  • 总页数 115
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

  • 入库时间 2022-08-17 11:38:30

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