Due its complementary absorptions in the range of 450 and 600 nm, an energy‐donating hexaaryl‐subporphyrazine has been linked to a pentacene dimer, which acts primarily as an energy acceptor and secondarily as a singlet fission enabler. In the corresponding conjugate, efficient intramolecular Förster resonance energy transfer (i‐FRET) is the modus operandi to transfer energy from the subporphyrazine to the pentacene dimer. Upon energy transfer, the pentacene dimer undergoes intramolecular singlet fission (i‐SF), that is, converting the singlet excited state, via an intermediate state, into a pair of correlated triplet excited states. Solvatochromic fluorescence of the subporphyrazine is a key feature of this system and features a red‐shift as large as 20 nm in polar media. Solvent is thus used to modulate spectral overlap between the fluorescence of subporphyrazine and absorption of the pentacene dimer, which controls the Förster rate constant, on one hand, and the triplet quantum yield, on the other hand. The optimum spectral overlap is realized in xylene, leading to Förster rate constant of 3.52×10¹¹ s⁻¹ and a triplet quantum yield of 171 % ±10 %. In short, the solvent polarity dependence, which is a unique feature of subporphyrazines, is decisive in terms of adjusting spectral overlap, ensuring a sizable Förster rate constant, and maximizing triplet quantum yields. Uniquely, this optimization can be achieved without a need for synthetic modification of the subporphyrazine donor.

中文翻译：

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通过溶剂极性控制亚四氮杂并五苯共轭物中的分子内福斯特共振能量转移和单线态裂变

由于其在 450 和 600 nm 范围内的互补吸收，提供能量的六芳基亚紫菜嗪已与并五苯二聚体连接，该二聚体主要充当能量受体，其次充当单线态裂变促进剂。在相应的缀合物中，有效的分子内福斯特共振能量转移（i-FRET）是将能量从亚紫菜嗪转移到并五苯二聚体的操作方式。在能量转移时，并五苯二聚体经历分子内单线裂变（i-SF），即将单线激发态通过中间态转化为一对相关的三线激发态。亚紫菜嗪的溶剂致变色荧光是该系统的一个关键特征，在极性介质中红移高达 20 nm。因此，溶剂用于调节亚紫菜嗪的荧光和并五苯二聚体的吸收之间的光谱重叠，一方面控制福斯特速率常数，另一方面控制三线态量子产率。在二甲苯中实现了最佳光谱重叠，导致福斯特速率常数为3.52×10 ¹¹  s ^-1和三重态量子产率为171 % ±10 %。简而言之，溶剂极性依赖性是亚紫菜嗪的独特特征，对于调整光谱重叠、确保相当大的福斯特速率常数和最大化三重态量子产率而言具有决定性作用。独特的是，这种优化无需对亚紫菜嗪供体进行合成修饰即可实现。