Kim Woojae, Nowak-Król Agnieszka, Hong Yongseok, Schlosser Felix, Würthner Frank, Kim Dongho
Department of Chemistry and Spectroscopy Laboratory for Functional π-Electronic Systems , Yonsei University , Seoul 03722 , Korea.
Institut für Organische Chemie and Center for Nanosystems Chemistry , Universität Würzburg , Am Hubland , 97074 Würzburg , Germany.
J Phys Chem Lett. 2019 Apr 18;10(8):1919-1927. doi: 10.1021/acs.jpclett.9b00357. Epub 2019 Apr 5.
Excimer, a configurational mixing between Frenkel exciton and charge-transfer resonance states, is typically regarded as a trap state that hinders desired energy or charge-transfer processes in artificial molecular assemblies. However, in recent days, the excimer has received much attention as a functional intermediate in the excited-state dynamics such as singlet fission or charge-separation processes. In this work, we show that the relative contribution to charge-transfer resonance of the excimer state in a bay-substituted perylene bisimide dimer cyclophane can be modulated by dielectric properties of the solvents employed. Solvent-dependent time-resolved fluorescence and absorption measurements reveal that an enhancement of charge-transfer resonance in the excimer state is reflected by incomplete symmetry-breaking charge-separation processes from the structurally relaxed excimer state by means of dipolar solvation processes in the high dielectric environment.
准分子是弗伦克尔激子与电荷转移共振态之间的一种构型混合，通常被视为一种陷阱态，会阻碍人工分子组装中所需的能量或电荷转移过程。然而，近年来，准分子作为激发态动力学（如单线态裂变或电荷分离过程）中的功能中间体受到了广泛关注。在这项工作中，我们表明，在所使用溶剂的介电性质作用下，海湾取代苝二酰亚胺二聚体环番中准分子态对电荷转移共振的相对贡献可以得到调节。溶剂依赖的时间分辨荧光和吸收测量结果表明，在高介电环境中，通过偶极溶剂化过程，从结构弛豫的准分子态发生不完全对称破缺电荷分离过程，这反映出准分子态中电荷转移共振的增强。
