Modeling solvation effects on absorption and fluorescence spectra of indole in aqueous solution
Modeling solvation effects on absorption and fluorescence spectra of indole in aqueous solution
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DOI：
10.1063/5.0038342
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发表时间：
2021-02-14
影响因子：
4.4
通讯作者：
Matsika, Spiridoula
中科院分区：
文献类型：
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作者：
Abou-Hatab, Salsabil;Carnevale, Vincenzo;Matsika, Spiridoula
对溶液中分子的光谱进行建模是一个挑战，因此重要的是了解哪种溶剂化效应(即溶质和溶剂分子之间的静电、相互极化和氢键相互作用)对于再现吸收光谱和荧光光谱的各种特征至关重要，并确定一个充分的理论模型，以最小的计算成本准确地捕捉这些影响。在这项研究中，我们使用各种隐式和显式的溶剂化模型，如与不可极化和可极化力场耦合的分子动力学，以及Car-Parrinello分子动力学，来模拟吲哚在水溶液中的吸收光谱和荧光光谱。用单激发和双激发耦合的团簇运动方程结合有效碎片势来计算水分子的激发态，我们发现这是在量子理论的高水平上模拟大的溶质-溶剂团簇的一种有效的计算方法。我们发现，与其他溶剂化效应相比，模拟互极化是准确再现溶液中吲哚吸收光谱的峰位和谱线形状的主要因素。我们深入分析了不同的溶剂化模型对导致吸收光谱特征的电子激发态的影响。建立荧光模型更具挑战性，因为即使是正确的发射状态也很难再现，而且需要重新评估力场参数。
Modeling the optical spectra of molecules in solution presents a challenge, so it is important to understand which of the solvation effects (i.e., electrostatics, mutual polarization, and hydrogen bonding interactions between solute and solvent molecules) are crucial in reproducing the various features of the absorption and fluorescence spectra and to identify a sufficient theoretical model that accurately captures these effects with minimal computational cost. In this study, we use various implicit and explicit solvation models, such as molecular dynamics coupled with non-polarizable and polarizable force fields, as well as Car-Parrinello molecular dynamics, to model the absorption and fluorescence spectra of indole in aqueous solution. The excited states are computed using the equation of motion coupled cluster with single and double excitations combined with the effective fragment potential to represent water molecules, which we found to be a computationally efficient approach for modeling large solute-solvent clusters at a high level of quantum theory. We find that modeling mutual polarization, compared to other solvation effects, is a dominating factor for accurately reproducing the position of the peaks and spectral line shape of the absorption spectrum of indole in solution. We present an in-depth analysis of the influence that different solvation models have on the electronic excited states responsible for the features of the absorption spectra. Modeling fluorescence is more challenging since it is hard to reproduce even the correct emitting state, and force field parameters need to be re-evaluated.