Petrusevich Elizaveta F, Reis Heribert, Ośmiałowski Borys, Jacquemin Denis, Luis Josep M, Zaleśny Robert
Faculty of Chemistry, Wroclaw University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland.
Institute of Computational Chemistry and Catalysis and Department of Chemistry, University of Girona, Campus de Montilivi, 17003, Girona, Catalonia, Spain.
Phys Chem Chem Phys. 2024 May 1;26(17):13239-13250. doi: 10.1039/d4cp01089b.
We synthesized a series of four parent -ketoiminate organoboron complexes and performed spectroscopic studies using both experimental and computational techniques. We studied how benzannulation influences the vibronic structure of the UV/Vis absorption bands with a focus on the bright lowest-energy π → π* electronic excitation. Theoretical simulations, accounting for inhomogeneous broadening effects using different embedding schemes, allowed gaining in-depth insights into the observed differences in band shapes induced by structural modifications. We observed huge variations in the distributions of vibronic transitions depending on the position of benzannulation. By and large, the harmonic approximation combined with the adiabatic hessian model delivers qualitatively correct band shapes for the one-photon absorption spectra, except in one case. We also assessed the importance of non-Condon effects (accounted for by the linear term in Herzberg-Teller expansion of the dipole moment) for S → S band shapes. It turned out that non-Condon contributions have no effect on the band shape in one-photon absorption spectra. In contrast, these effects significantly change the Franck-Condon band shapes of the two-photon absorption spectra. For one of the studied organoboron complexes we also performed a preliminary exploration of mechanical anharmonicity, resulting in an increase of the intensity of the 0-0 transition, which improves the agreement with the experimental data compared to the harmonic model.
我们合成了一系列四种母体 - 酮亚胺有机硼配合物，并使用实验和计算技术进行了光谱研究。我们研究了苯并环化如何影响紫外/可见吸收带的振动电子结构，重点关注明亮的最低能量π→π*电子激发。理论模拟使用不同的嵌入方案考虑了非均匀展宽效应，从而能够深入了解由结构修饰引起的观察到的能带形状差异。我们观察到振动电子跃迁的分布因苯并环化的位置而异。总体而言，除了一种情况外，谐波近似与绝热 Hessian 模型为单光子吸收光谱提供了定性正确的能带形状。我们还评估了非康登效应（由偶极矩的 Herzberg - Teller 展开中的线性项考虑）对 S→S 能带形状的重要性。结果表明，非康登贡献对单光子吸收光谱的能带形状没有影响。相比之下，这些效应显著改变了双光子吸收光谱的弗兰克 - 康登能带形状。对于其中一种研究的有机硼配合物，我们还对机械非谐性进行了初步探索，结果导致 0 - 0 跃迁强度增加，与谐波模型相比，这改善了与实验数据的一致性。
