The literature has seen a large increase in the number of new carbon‐based organic diradicals/diradicaloids in recent years. While a plethora of new and exciting structures have been created, there seemingly is a gap in knowledge of what fundamental electronic parameters are in play and thus how to rationally manipulate said parameters to “fine tune” the resultant diradical properties. Since 2014, the Haley group has been exploring methods to systematically alter the diradical character and the singlet‐triplet energy gap in said class of molecules. Our entrance into organic diradicals began with the π‐expansion of the benzene core of indeno[1,2‐b]fluorene up to the anthracene core of diindenoanthracene (DIAn). DIAn possessed moderate diradical character (y = 0.62) with a surprising level of stability (more than 2 months in solution). From this molecular blueprint for producing stable diradicals, the Haley lab has investigated how to fine tune diradical properties via structural changes in two key positions: (a) the length of the acene core and (b) thoughtful exchange of the outer arenes. With this strategy at our disposal, we can make large scale changes to the diradical character index and singlet‐triplet energy gap through changing the core length, and these properties can be further fine‐tuned in a series of closely related diradicals by careful exchange of the outer arenes utilizing the straightforward methods described in this mini‐review.

中文翻译：

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学习如何通过结构优化来微调双基性

近年来，文献中发现新的碳基有机双基/双基类化合物的数量大大增加。尽管已经创建了许多新的令人兴奋的结构，但似乎在了解哪些基本电子参数起作用以及如何合理地操纵所述参数以“微调”所得的双自由基特性的知识方面存在差距。自2014年以来，Haley小组一直在探索方法，以系统地改变上述分子类型的双自由基特征和单重态-三重态能隙。我们进入有机双自由基的过程是从茚并[1,2- b ]芴的苯核的π-扩展到二茚并蒽（DIAn）的蒽核的扩展。DIAN具有中等的激进性（y =0.62）的稳定性（在溶液中超过2个月）令人惊讶。从生产稳定的双基自由基的分子蓝图出发，海利实验室研究了如何通过两个关键位置的结构变化来微调双基自由基的性质：（a）并苯核的长度和（b）外芳烃的深思熟虑的交换。利用我们可以使用的这一策略，我们可以通过改变核心长度来大幅度地改变双自由基特性指数和单线态-三重态能隙，并且可以通过仔细地交换一系列的双自由基来进一步微调这些性质。外部竞技场利用此迷你审查中描述的简单方法。