Theoretical Insights into the Excited State Decays of a Donor–Acceptor Dyad: Is the Twisted and Rehybridized Intramolecular Charge-Transfer State Involved?
Theoretical Insights into the Excited State Decays of a Donor–Acceptor Dyad: Is the Twisted and Rehybridized Intramolecular Charge-Transfer State Involved?
复制标题
对供体-受体二元组的激发态衰变的理论见解：是否涉及扭曲和重新杂化的分子内电荷转移态？
DOI：
10.1021/acs.jpcb.0c02455
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发表时间：
2020
影响因子：
3.3
通讯作者：
Panwang Zhou
中科院分区：
文献类型：
--
作者：
Zhangrong Lou;Xiaoyan Zhou;Zhe Tang;Panwang Zhou
扭曲的分子内电荷转移被提出并被广泛接受来解释有机分子的激发态动力学。最近，在超快时间分辨光谱的基础上，提出了一种称为“扭曲和再杂化的分子内电荷转移”的新状态来解释含炔间隔的苯胺-三氮电子供体-受体二元体的激发态动力学。然而，激发态衰变路径上几何构型的变化仍然未知。在本研究中，通过优化施主-受主双体的激发态几何结构和沿扭角的势能表面扫描，我们成功地重现了时间分辨红外吸收光谱中实验观察到的谱带。我们的计算结果表明，不涉及再杂化过程，只形成了扭曲的分子内电荷转移态。此外，我们还在施主-受体二体的基态和第一激发态之间找到了一个最小能量锥形交点，该交点很容易到达，与施主-受体二体的初级非辐射衰变路径相对应。最小能量锥交的能量与溶剂有关，并与实验观察到的与溶剂有关的激发态寿命一致。
The twisted intramolecular charge transfer has been proposed for a number of years and widely accepted to explain the excited-state dynamics of organic molecules. Recently, a new state termed as “twisted and rehybridized intramolecular charge transfer” has been proposed to explain the excited-state dynamics of an aniline–triazine electron donor–acceptor dyad with an alkyne spacer based on ultrafast time-resolved spectroscopy. However, the change of the geometries along the excited-state decay pathway remains unknown. In this study, by optimization of the excited-state geometry of the donor–acceptor dyad and potential energy surface scan along the twisting angle, we successfully reproduce the experimentally observed band in time-resolved infrared absorption spectroscopy. Our calculation results demonstrated that the rehybridization process is not involved and only the twisted intramolecular charge transfer state is formed. Moreover, we located a minimum energy conical intersection between the ground and first excited-state of the donor–acceptor dyad, which is easily reached and corresponding to the primary nonradiative decay pathway of the donor–acceptor dyad. The energy of minimum energy conical intersection is solvent-dependent and consistent with the experimentally observed solvent-dependent lifetime of excited state.