Institut für Physik, Universität Rostock, D-18051 Rostock, Germany.
Phys Chem Chem Phys. 2011 Oct 21;13(39):17649-57. doi: 10.1039/c1cp21624d. Epub 2011 Sep 7.
Perylene bisimides (PBIs) are excellent dyes and versatile building blocks for supramolecular structures. Only recently have PBIs been shown to depict absorption characteristics of J-aggregates. We apply electronic structure calculations and femtosecond pump-probe spectroscopy to the monomeric, bay-substituted building-block of a PBI aggregate in dichloromethane to investigate its electronically excited states in order to provide the ingredients for the description of excitons in the aggregates and their annihilation processes. The PBI S(1)←S(0) absorption spectrum and the S(1)→S(0) emission spectrum have been assigned based on time-dependent Density Functional Theory calculations for the geometry-optimized electronic ground state and excited state structures in the gas phase. The monomeric absorption spectrum contains a strong transition at 580 nm and a broad shoulder between 575-500 nm, both features are attributed to a vibrational progression with an effective vibrational mode of 1415 cm(-1) whose major contributing vibrational normal modes are breathing modes of the perylene body. The effective vibrational mode of the emission spectrum is characterized by a frequency of 1369 cm(-1), whose major contributing vibrational normal modes are characterized by perylene and phenol (bay-substituent) CH bendings. The S(n)←S(1) excited state absorption spectrum is assigned based on Multi-Reference Configuration Interaction methodology. Here, we identify three transitions which give rise to two broad experimental features, one being located between 500 and 600 nm and the other one ranging from 650 to 750 nm.
并苯二酰亚胺（PBIs）是出色的染料，也是超分子结构的多功能构建模块。直到最近，人们才发现 PBIs 具有 J-聚集体的吸收特性。我们应用电子结构计算和飞秒泵浦探测光谱学，研究了二氯甲烷中 PBI 聚集体的单体、苯并取代构建基块的电子激发态，以提供描述聚集体中激子及其湮灭过程的成分。基于气相中几何优化电子基态和激发态结构的含时密度泛函理论计算，对 PBI S(1)←S(0)吸收光谱和 S(1)→S(0)发射光谱进行了归属。单体吸收光谱在 580nm 处有一个很强的跃迁，在 575-500nm 之间有一个宽肩，这两个特征都归因于一个具有 1415cm(-1)有效振动模式的振动级联，其主要贡献的振动正则模式是并苯主体的呼吸模式。发射光谱的有效振动模式的特征频率为 1369cm(-1)，其主要贡献的振动正则模式由并苯和苯酚（苯并取代基）的 CH 弯曲组成。基于多参考组态相互作用方法，对 S(n)←S(1)激发态吸收光谱进行了归属。在这里，我们确定了三个跃迁，它们产生了两个宽的实验特征，一个位于 500nm 到 600nm 之间，另一个位于 650nm 到 750nm 之间。
