Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, M5S 3H6 Canada.
Phys Chem Chem Phys. 2010 Jul 21;12(27):7378-85. doi: 10.1039/c003496g. Epub 2010 Jun 12.
On the basis of time-dependent density functional theory (TD-DFT) calculations coupled to the polarizable continuum model (PCM) and single molecule spectroscopic studies, we provide a detailed investigation of excitation energy transfer within a model bi-chromophoric system where a perylene monoimide (PMI) donor is bridged to a terrylene diimide (TDI) acceptor through a ladder-type pentaphenylene (pPh) spacer. We find that the electronic excitation on the PMI donor significantly extends over the bridge giving rise to a partial charge transfer character and inducing a approximately 3-fold increase in the electronic interaction between the chromophores, which explains the failure of the Förster model in reproducing the observed energy migration rates when treating PMI as the donor. However, despite an increased charge transfer contribution in the effective donor state, the increase in solvent polarity is not accompanied by an enhancement in the electronic coupling between the subunits, which is rationalized from a detailed analysis of the excited-state wavefunctions.
基于含时密度泛函理论（TD-DFT）计算与极化连续模型（PCM）以及单分子光谱研究，我们对模型双发色团体系内的激发能量转移进行了详细研究，其中一个苝二酰亚胺（PMI）给体通过梯形五苯（pPh）间隔基桥接到一个三亚苯二酰亚胺（TDI）受体。我们发现 PMI 给体上的电子激发显著扩展到了桥接部分，导致部分电荷转移特性，并在发色团之间诱导了约 3 倍的电子相互作用增强，这解释了当将 PMI 视为给体时，福斯特模型在重现观察到的能量迁移率方面的失败。然而，尽管有效给体态中的电荷转移贡献增加，但溶剂极性的增加并没有伴随着亚基之间电子耦合的增强，这可以从对激发态波函数的详细分析中得到合理化解释。
