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首页> 外文期刊>Chemistry: A European journal >Conformationally controlled electron delocalization in n-type rods: Synthesis, structure, and optical, electrochemical, and spectroelectrochemical properties of dicyanocyclophanes
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Conformationally controlled electron delocalization in n-type rods: Synthesis, structure, and optical, electrochemical, and spectroelectrochemical properties of dicyanocyclophanes

机译：n型棒中的构象控制电子离域：双氰基环烷的合成，结构以及光学，电化学和光谱电化学性质

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摘要

A series of dicyanobiphenylcyclophanes 1-6 with various π-backbone conformations and characteristic n-type semiconductor properties is presented. Their synthesis, optical, structural, electrochemical, spectroelectrochemical, and packing properties are investigated. The X-ray crystal structures of all n-type rods allow the systematic correlation of structural features with physical properties. In addition, the results are supported by quantum mechanical calculations based on density functional theory. A two-step reduction process is observed for all n-type rods, in which the first step is reversible. The potential gap between the reduction processes depends linearly on the cos~2 value of the torsion angle ψ between the π-systems. Similarly, optical absorption spectroscopy shows that the vertical excitation energy of the conjugation band correlates with the cos~2 value of the torsion angle ψ. These correlations demonstrate that the fixed intramolecular torsion angle ψ is the dominant factor determining the extent of electron delocalization in these model compounds, and that the angle ψ measured in the solid-state structure is a good proxy for the molecular conformation in solution. Spectroelectrochemical investigations demonstrate that conformational rigidity is maintained even in the radical anion form. In particular, the absorption bands corresponding to the SOMO-LUMO+i transitions are shifted bathochromically, whereas the absorption bands corresponding to the HOMO-SOMO transition are shifted hypsochromically with increasing torsion angle ψ.
机译：提出了一系列具有各种π骨架构型和特征性n型半导体特性的二氰基联苯环基1-6。研究了它们的合成，光学，结构，电化学，光谱电化学和堆积特性。所有n型棒的X射线晶体结构都可以使结构特征与物理性质进行系统的关联。另外，这些结果得到了基于密度泛函理论的量子力学计算的支持。对于所有n型杆，观察到两步还原过程，其中第一步是可逆的。还原过程之间的电位差线性地取决于π系统之间的扭转角ψ的cos〜2值。类似地，光学吸收光谱表明，共轭带的垂直激发能与扭转角ψ的cos〜2值相关。这些相关性表明，固定的分子内扭转角ψ是决定这些模型化合物中电子离域程度的主要因素，并且在固态结构中测量的角ψ可以很好地替代溶液中的分子构象。光谱电化学研究表明，即使在自由基阴离子形式下，构象刚性也得以保持。尤其是，与SOMO-LUMO + 1跃迁相对应的吸收谱带发生红移，而与HOMO-SOMO跃迁相对应的吸收谱带则随着扭角ψ的增加而向蓝移。

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