Photoinduced non-adiabatic energy transfer pathways in dendrimer building blocks
Photoinduced non-adiabatic energy transfer pathways in dendrimer building blocks
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DOI：
10.1063/1.5086680
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发表时间：
2019-03-28
影响因子：
4.4
通讯作者：
Fernandez-Alberti, S.
中科院分区：
文献类型：
--
作者：
Freixas, V. M.;Ondarse-Alvarez, D.;Fernandez-Alberti, S.
在光捕获树枝状聚合物中的分子内能量转移的效率由其具有高度有序的明确定义的结构决定。光激发后，通过空间和通过键的能量转移机制可以发生，涉及矢量激子迁移不同的生色团在树枝状聚合物高度支化的结构。它们固有的分子内能量梯度取决于多个发色单元是如何组装的，取决于它们的相互连接、空间距离和取向。在这里，我们比较了光诱导非绝热分子动力学模拟上进行的一组不同的组合的链连接的树枝状大分子的积木组成的两个，三个，和四个环的线性聚亚苯基发色团单元。计算进行了最近开发的从头多克隆时间依赖非绝热基础上实施的多构型Escherfest（MCE）的方法。尽管在短时间的弛豫途径和不同的初始激子本地化的差异，在较长的时间尺度，电子弛豫速率和激子最终的再分布是非常相似的所有组合。与之前考虑的由两个构建块组成的系统不同，对于较大的3块系统，我们观察到克隆引起的波函数的分叉是重要的。在这项工作中考虑的所有系统中，在几百飞秒的时间尺度下，克隆增强了电子能量弛豫，与没有克隆的MCE方法相比，提高了13%。因此，准确描述量子效应是必不可少的理解的能量交换在树枝状聚合物在短期和长期的时间尺度。(C)2019年作者。
The efficiency of the intramolecular energy transfer in light harvesting dendrimers is determined by their well-defined architecture with high degree of order. After photoexcitation, through-space and through-bond energy transfer mechanisms can take place, involving vectorial exciton migration among different chromophores within dendrimer highly branched structures. Their inherent intramolecular energy gradient depends on how the multiple chromophoric units have been assembled, subject to their inter-connects, spatial distances, and orientations. Herein, we compare the photoinduced nonadiabatic molecular dynamics simulations performed on a set of different combinations of a chain of linked dendrimer building blocks composed of two-, three-, and four-ring linear polyphenylene chromophoric units. The calculations are performed with the recently developed ab initio multiple cloning-time dependent diabatic basis implementation of the Multiconfigurational Ehrenfest (MCE) approach. Despite differences in short time relaxation pathways and different initial exciton localization, at longer time scales, electronic relaxation rates and exciton final redistributions are very similar for all combinations. Unlike the systems composed of two building blocks, considered previously, for the larger 3 block systems here we observe that bifurcation of the wave function accounted by cloning is important. In all the systems considered in this work, at the time scale of few hundreds of femtoseconds, cloning enhances the electronic energy relaxation by similar to 13% compared to that of the MCE method without cloning. Thus, accurate description of quantum effects is essential for understanding of the energy exchange in dendrimers both at short and long time scales. (C) 2019 Author(s).