Synergetic Role of Conformational Flexibility and Electronic Coupling for Quantitative Intramolecular Singlet Fission
Synergetic Role of Conformational Flexibility and Electronic Coupling for Quantitative Intramolecular Singlet Fission
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DOI：
10.1021/acs.jpcc.1c04734
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发表时间：
2021-08-13
影响因子：
3.7
通讯作者：
Hasobe, Taku
中科院分区：
文献类型：
--
作者：
Nakamura, Shunta;Sakai, Hayato;Hasobe, Taku
我们提出了一种新的分子二聚体的设计概念，通过分子内单线态裂变来定量的单个三重态产率（Phi(T)）。我们合成了一系列由不同苯基连接剂桥接的四烯（Tc）二聚体，重点研究了其构象柔韧性和电子耦合。在瞬态吸收测量中，具有较弱电子耦合和较大构象柔韧性的4,4'-联苯桥接Tc二聚体在高激发能下的定量Phi(T): 196 +/- 12%。此外，解耦自旋与构象变化直接表征了时间分辨电子顺磁共振。通过自旋-自旋交换耦合的大小揭示了几何变化和电子局域化对三重态解离的强烈相互作用。因此，明确了构象柔韧性和电子耦合在定量Phi(T)中的协同作用。
We present a novel design concept of molecular dimers for quantitative individual triplet yield (Phi(T)) through intramolecular singlet fission. We synthesized a series of tetracene (Tc) dimers bridged by different phenylene-based linkers, focusing on the conformational flexibility in addition to the electronic coupling. In transient absorption measurements, a 4,4'-biphenyl-bridged Tc dimer with weaker electronic coupling and larger conformational flexibility exhibited the quantitative Phi(T): 196 +/- 12% at high excitation energy. Moreover, decoupled spins associated with conformational change were directly characterized by time-resolved electron paramagnetic resonance. Strong interplay of the geometry change and electronic localization was revealed on the triplet pair dissociation through magnitudes of spin-spin exchange couplings. Thus, a synergetic role of conformational flexibility and electronic coupling in quantitative Phi(T) was clarified.