Cerdá Jesús, Calbo Joaquín, Ortí Enrique, Aragó Juan
Instituto de Ciencia Molecular (ICMol), Universidad de Valencia, Catedrático José Beltrán 2, Paterna 46980, Spain.
J Phys Chem A. 2021 Nov 25;125(46):9982-9994. doi: 10.1021/acs.jpca.1c05740. Epub 2021 Nov 12.
The kinetics of the nonradiative photoinduced processes (charge-separation and charge-recombination) experimented in solution by a supramolecular complex formed by an electron-donating bowl-shaped truxene-tetrathiafulvalene (truxTTF) derivative and an electron-accepting fullerene fragment (hemifullerene, CH) has been theoretically investigated. The truxTTF·CH heterodimer shows a complex decay mechanism after photoexcitation with the participation of several low-lying excited states of different nature (local and charge-transfer excitations) all close in energy. In this scenario, the absolute rate constants for all of the plausible charge-separation (CS) and charge-recombination (CR) channels have been successfully estimated using the Marcus-Levich-Jortner (MLJ) rate expression, electronic structure calculations, and a multistate diabatization method. The outcomes suggest that for a reasonable estimate of the CS and CR rate constants, it is necessary to include the following: (i) optimally tuned long-range (LC) corrected density functionals, to predict a correct energy ordering of the low-lying excited states; (ii) multistate effects, to account for the electronic couplings; and (iii) environmental solvent effects, to provide a proper stabilization of the charge-transfer excited states and accurate external reorganization energies. The predicted rate constants have been incorporated in a simple but insightful kinetic model that allows estimating global CS and CR rate constants in line with the most generalized three-state model used for the CS and CR processes. The values computed for the global CS and CR rates of the donor-acceptor truxTTF·CH supramolecular complex are found to be in good agreement with the experimental values.
通过理论研究了一种由供电子的碗状并四苯 - 四硫富瓦烯（truxTTF）衍生物和受电子的富勒烯片段（半富勒烯，CH）形成的超分子配合物在溶液中进行的非辐射光诱导过程（电荷分离和电荷复合）的动力学。truxTTF·CH异二聚体在光激发后显示出复杂的衰减机制，涉及几个能量相近的不同性质的低激发态（局域激发和电荷转移激发）的参与。在这种情况下，使用马库斯 - 列维奇 - 约尔特纳（MLJ）速率表达式、电子结构计算和多态绝热化方法成功估计了所有可能的电荷分离（CS）和电荷复合（CR）通道的绝对速率常数。结果表明，为了合理估计CS和CR速率常数，有必要考虑以下因素：（i）优化调整的长程（LC）校正密度泛函，以预测低激发态的正确能量排序；（ii）多态效应，以考虑电子耦合；（iii）环境溶剂效应，以提供电荷转移激发态的适当稳定和准确的外部重组能。预测的速率常数已纳入一个简单但有洞察力的动力学模型，该模型允许根据用于CS和CR过程的最广义三态模型估计全局CS和CR速率常数。供体 - 受体truxTTF·CH超分子配合物的全局CS和CR速率的计算值与实验值吻合良好。
