Wen Lingbo, Cao Xian, Lee Seokwon, Xu Ling, Rao Yutao, Kang Seongsoo, Kim Dongho, Osuka Atsuhiro, Song Jianxin
Key Laboratory of Chemical Biology and Traditional Chinese Medicine, Ministry of Educational of China, Key Laboratory of the Assembly and Application of Organic Functional Molecules of Hunan Province College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha, 410081, China.
Spetroscopy Laboratory for Functional π-Electron Systems and Department of Chemistry, Yonsei University, Seoul, 03722, Korea.
Commun Chem. 2023 Feb 9;6(1):25. doi: 10.1038/s42004-023-00822-8.
Symmetry-breaking charge transfer is one of the key process in photosynthetic reaction centers and specific artificial optoelectronic devices such as dye-sensitized solar cells. Here we report the synthesis of aromatic-bridged BF-smaragdyrin dimers, meso-free BF-smaragdyrin, and its meso-meso-linked BF-smaragdyrin dimer. The decays of S-states of these dimers are accelerated with an increase in solvent polarity and a decrease in the distance between the two BF-smaragdyrin units, suggesting symmetry-breaking charge transfer. The fluorescence lifetimes of the dimers become shortened in polar solvents. However, ultrafast transient absorption spectroscopy do not detect charge-separated ion pairs. On the basis of these results, we conclude that the decays of the excited states of the BF-smaragdyrin dimers are accelerated by solvation-induced symmetry-breaking charge transfer, depending on the degree of the electronic interaction between the smaragdryin units as a rare case for porphyrinoids. The degree of charge transfer is larger for dimers with larger electronic interactions.
对称破缺电荷转移是光合反应中心以及特定人工光电器件（如染料敏化太阳能电池）中的关键过程之一。在此，我们报告了芳香桥连的BF-绿宝石卟啉二聚体、中位无取代的BF-绿宝石卟啉及其中位-中位连接的BF-绿宝石卟啉二聚体的合成。随着溶剂极性的增加以及两个BF-绿宝石卟啉单元之间距离的减小，这些二聚体的S态衰变加速，表明存在对称破缺电荷转移。二聚体的荧光寿命在极性溶剂中会缩短。然而，超快瞬态吸收光谱未检测到电荷分离离子对。基于这些结果，我们得出结论，BF-绿宝石卟啉二聚体激发态的衰变是由溶剂化诱导的对称破缺电荷转移加速的，这取决于绿宝石卟啉单元之间电子相互作用的程度，这在卟啉类化合物中是一种罕见情况。对于具有较大电子相互作用的二聚体，电荷转移程度更大。
