Knippenberg S, Bohnwagner M V, Harbach P H P, Dreuw A
Laboratoire de chimie physique théorique, Département de Chimie B6c, Université de Liége , B-4000 Liége, Belgium.
J Phys Chem A. 2015 Feb 26;119(8):1323-31. doi: 10.1021/acs.jpca.5b00637. Epub 2015 Feb 12.
The absorption spectrum of a representative BisBODIPY molecule is investigated using high-level quantum chemical methodology; the results are compared with experimental data. The S1 and S2 excited states are examined in detail to illuminate and to understand the electronic coupling between them. With the help of model systems in which the distance between the BODIPY monomers is increased or in which the dihedral angle between the subunits is changed, the electronic coupling is quantified, and its influence on energetics and oscillator strengths is highlighted. For the explanation of the experimental spectrum, orbital interaction effects are found to be important. Because of the large experimental Stokes shift of BisBODIPY, the nature of the emissive state is investigated and found to remain C2 symmetric as the ground state, and no localization of the excitation on one BODIPY subunit occurs. The excitonic coupling is in BisBODIPY still larger than the geometry relaxation energy, which explains the absence of a pseudo-Jahn-Teller effect.
使用高级量子化学方法研究了一种代表性双硼二吡咯（BisBODIPY）分子的吸收光谱；并将结果与实验数据进行了比较。详细研究了S1和S2激发态，以阐明和理解它们之间的电子耦合。借助于双硼二吡咯单体之间距离增加或亚基之间二面角改变的模型系统，对电子耦合进行了量化，并突出了其对能量学和振子强度的影响。为了解释实验光谱，发现轨道相互作用效应很重要。由于双硼二吡咯的实验斯托克斯位移较大，对发射态的性质进行了研究，发现其仍与基态一样保持C2对称性，且激发没有定域在一个双硼二吡咯亚基上。双硼二吡咯中的激子耦合仍然大于几何弛豫能，这解释了不存在赝 Jahn-Teller 效应的原因。
