Investigating the Nonradiative Decay Pathway in the Excited State of Silepin Derivatives: A Study with Second-Order Multireference Perturbation Wavefunction Theory
Investigating the Nonradiative Decay Pathway in the Excited State of Silepin Derivatives: A Study with Second-Order Multireference Perturbation Wavefunction Theory
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DOI：
10.1021/acs.jpca.0c08738
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发表时间：
2021-01-08
影响因子：
2.9
通讯作者：
Yanai, Takeshi
中科院分区：
文献类型：
--
作者：
Inai, Naoto;Yokogawa, Daisuke;Yanai, Takeshi
荧光有机分子的荧光量子产率是一种重要的分子性质，在各种应用中都需要对其进行调谐。对于荧光量子产率的计算估计，非辐射衰变速率常数的理论预测已成为一个吸引人的研究课题。热激活非辐射衰变的速率常数与光反应的活化能有关，因此，量子化学计算中激发态势能的准确性和可靠性至关重要。在本研究中，我们用二阶多参考微扰波函数理论研究了1，1-二甲基二苯并[b，f]silepin衍生物通过锥形交点(CI)的热激活衰变。在S-1状态下达到CI几何构型的计算活化能与实验测定的荧光量子产率之间的关联表明，西平类药物是通过中心C-C键扭曲触发的CI进行非辐射衰变的。用多参考微扰理论对过渡态进行几何优化，大大降低了估算的活化能。我们的计算合理地预测了光激发1，1-二甲基二苯并[b，f]silepin的激活自由能。采用合适的量子化学方法得到的能量分布和几何构型的优化对于可靠地估算速率常数和荧光量子产率起着至关重要的作用。
The fluorescence quantum yield for fluorescent organic molecules is an important molecular property, and tuning it up is desired for various applications. For the computational estimation of the fluorescence quantum yield, the theoretical prediction of the nonradiative decay rate constant has become an attractive subject of study. The rate constant of thermally activated nonradiative decay is related to the activation energy in the photoreaction; thus, the accuracy and reliability of the excited-state potential energies in the quantum chemical computation are critical. In this study, we employed a second-order multireference perturbation wave-function theory for studying the thermally activated decay via conical intersection (CI) of 1,1-dimethyldibenzo[b,f]silepin derivatives. The correlation between the computed activation energy to reach the CI geometry in the S-1 state and the experimentally determined fluorescence quantum yield implied that silepins nonradiatively decay via the CI triggered by the twisting of the central C-C bond. Geometry optimization of the transition state using multireference perturbation theory drastically reduced the estimated activation energy. Our computation gave reasonable predictions of the activation free energies of photoexcited 1,1-dimethyldibenzo[b,f]silepin. The energy profiles and geometry optimizations using proper quantum chemical methods played a critical role in reliable estimation of the rate constant and fluorescence quantum yield.