Theoretical Study on Singlet Fission in Aromatic Diaza s-Indacene Dimers,The Journal of Physical Chemistry A

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Theoretical Study on Singlet Fission in Aromatic Diaza s-Indacene Dimers
The Journal of Physical Chemistry A ( IF 2.7 ) Pub Date : 2021-04-09 , DOI: 10.1021/acs.jpca.0c11598
Takanori Nagami ₁ , Ryota Sugimori ₁ , Ryota Sakai ₁ , Kenji Okada ₁ , Masayoshi Nakano _{1,

2,

3,

4,

5}

Affiliation

We theoretically show that diaza (N₂)-substitution to s-indacene with 4n π-electrons, by which the number of π-electrons in N₂-s-indacene amounts to 4n+2, is a new strategy to design efficient singlet fission (SF) molecules. By N₂-substitution, the diradical character and the exchange integral are found to be tuned moderately, leading to satisfying the excitation energy level matching condition for SF with a large triplet excitation energy. On the basis of the effective electronic coupling related to the SF rate, we explore the optimal slip-stack dimer packings for fast SF. Their underlying mechanisms are well understood from the odd-electron density, resonance structure, and frontier orbital distribution, as the functions of the N₂-substituted positions. Furthermore, aromaticities of N₂-s-indacenes are evaluated explicitly on the basis of the magnetically induced current. Although N₂-s-indacenes display strengths of aromaticities similar to that of anthracene, a local decrease in aromaticity is found to correlate to the spatial feature of diradical character, i.e., odd-electron density. The present findings not only newly propose N₂-s-indacenes as feasible SF molecules but also contribute to comprehending the interplay between aromaticity and diradical electronic structures contributing to SF.

中文翻译：

在芳香二氮杂上单线裂变理论研究小号-Indacene二聚体

我们理论上表明，二氮杂（N ₂）3'-取代到小号-indacene与4- Ñ π电子，通过该π电子的N的数量₂ -小号-indacene达4 Ñ 2，是一种新的策略，以设计有效的单峰裂变（SF）分子。由N ₂-取代基，双自由基特性和交换积分被适度地调谐，从而满足具有大三重态激发能的SF的激发能级匹配条件。在与SF率相关的有效电子耦合的基础上，我们探索了用于快速SF的最佳滑动堆叠二聚体填料。根据N ₂取代位置的功能，从奇数电子密度，共振结构和前沿轨道分布可以很好地理解其基本机理。此外，将N芳香性₂ -小号-indacenes被磁感应电流的基础上明确地评价。虽然N ₂ - s-茚二酮显示出与蒽相似的芳香性强度，发现芳香性的局部降低与双自由基特征的空间特征即奇电子密度相关。本发明的发现不仅新提出Ñ ₂ -小号-indacenes可行SF分子，但也有助于理解芳香和促进SF双自由基的电子结构之间的相互作用。

更新日期：2021-04-29

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