Photoinduced electron-transfer processes along molecular wires based on phenylenevinylene oligomers: a quantum-chemical insight.
Photoinduced electron-transfer processes along molecular wires based on phenylenevinylene oligomers: a quantum-chemical insight.
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基于亚苯基乙烯低聚物的沿分子线的光诱导电子转移过程：量子化学见解。
DOI：
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发表时间：
2002
影响因子：
15
通讯作者：
J. Brédas
中科院分区：
文献类型：
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作者：
G. Pourtois;D. Beljonne;D. Beljonne;J. Cornil;J. Cornil;M. Ratner;J. Brédas;J. Brédas
应用量子化学技术模拟光诱导电荷从π-电子供体基团（并四苯，D）转移到π-电子受体部分（均苯四酸酰亚胺，A）的机制，由一个越来越大的桥（对苯撑亚乙烯基低聚物，B）分开。相关Hartree-Fock半经验方法被用来计算的四个主要参数控制的转移速率（k（RP））的框架中的Marcus-Jortner-Levich的形式主义：（i）之间的电子耦合的初始和最终状态;（ii）和（iii）的内部和外部的重组能量项;和（iv）的变化的自由吉布斯能。在这些化合物中，电荷转移通过两种竞争机制进行，相干（超交换）与非相干（桥介导）途径。虽然超交换是短桥的主要机制，但通过沿沿着亚苯基亚乙烯基链段跳跃的不相干转移在较长链中接管（对于约1000个碳原子）。三个亚苯基亚乙烯基重复单元）。研究了π共轭亚苯基亚乙烯桥的化学结构对电子性质和电荷转移速率的影响。
Quantum-chemical techniques are applied to model the mechanisms of photoinduced charge transfer from a pi-electron donating group (tetracene, D) to a pi-electron-acceptor moiety (pyromellitimide, A) separated by a bridge of increasing size (p-phenylenevinylene oligomers, B). Correlated Hartree-Fock semiempirical approaches are exploited to calculate the four main parameters controlling the transfer rate (k(RP)) in the framework of Marcus-Jortner-Levich's formalism: (i) the electronic coupling between the initial and final states; (ii) and (iii) the internal and external reorganization energy terms; and (iv) the variation of the free Gibbs energy. The charge transfer is shown to proceed in these compounds through two competing mechanisms, coherent (superexchange) versus incoherent (bridge-mediated) pathways. While superexchange is the dominant mechanism for short bridges, incoherent transfer through hopping along the phenylene vinylene segment takes over in longer chains (for ca. three phenylenevinylene repeat units). The influence of the chemical structure of the pi-conjugated phenylenevinylene bridge on the electronic properties and the rate of charge transfer is also investigated.