湖南科技学院Jiang qing团队报道了一种动力学稳定的二蒽并[2,3-a:3',2'-h]-s-茚并茂——具有三重基态的稳定Kekulé二自由基多环烃。相关研究成果于2024年12月12日发表在国际顶尖学术期刊《德国应用化学》。

高自旋多环烃（PHs）在有机自旋电子学和有机磁体中具有巨大的潜力。然而，由于其极高的反应性，它们的合成非常具有挑战性。

该文中，研究人员报告了二蒽并[2,3-a:3'，2'-h]-s-茚并茂的动力学阻断衍生物（1）的成功合成和分离，该衍生物代表了KekuléPH的一种罕见的持久三重态二自由基。其三重态基态通过电子顺磁共振和超导量子干涉器件测量得到了明确证实。其结构也通过X射线晶体学分析得到了明确证实，其电子性质通过实验和理论计算得到了系统研究。

关键的设计原理是扩展π共轭，以实现键合相互作用的减少和未配对电子之间交换相互作用的增加，这对于获得稳定的三重态基态至关重要。由于动力学阻断，1在环境条件下具有合理的稳定性，半衰期为64小时。它具有窄的HOMO-LUMO能隙，并表现出两性氧化还原行为。值得注意的是，它的二价和二价离子表现出封闭的壳层基态和近红外吸收，其结构通过X射线晶体学分析得到鉴定。

该项研究将为设计和合成具有高自旋多重性的新型稳定PHs提供新的思路。

附：英文原文

Title: A Kinetically Stabilized Dianthraceno[2,3-a:3',2'-h]-s-indacene: Stable Kekulé Diradical Polycyclic Hydrocarbon with Triplet Ground State

Author: Qing Jiang, Lei Wang, Haipeng Wei, Yuchen Peng, Guangyan Xu, Zhaoyang Li, Pengfei Liu, Zhenni Hu, Weiwei Niu, Yifan Chen, Hui Tang, Wangdong Zeng, Guangwu Li

Issue&Volume: 2024-12-12

Abstract: High-spin polycyclic hydrocarbons (PHs) hold significant potential in organic spintronics and organic magnets. However, their synthesis is very challenging due to their extremely high reactivity. Herein, we report the successful synthesis and isolation of a kinetically blocked derivative (1) of dianthraceno[2,3-a:3',2'-h]-s-indacene, which represents a rare persistent triplet diradical of a Kekulé PH. Its triplet ground state was unambiguously confirmed by electron paramagnetic resonance and superconducting quantum interference device measurements. Its structure was also unequivocally confirmed through X-ray crystallographic analysis, and its electronic properties were systematically investigated by both experiments and theoretical calculations. The key design principle is to extend the π-conjugation for achieving the decrease of the bonding interaction and the increase of the exchange interaction between unpaired electrons, which are essential for accessing the stable triplet ground state. Due to kinetic blocking, 1 shows a reasonable stability with a half-life time of 64 h under ambient conditions. It has a narrow HOMO–LUMO energy gap and displays amphoteric redox behavior. Notably, its dication and dianion exhibit a closed-shell ground state and near-infrared absorption, and the structures were identified by X-ray crystallographic analysis. This study will shed new light on the design and synthesis of novel stable PHs with high-spin multiplicity.

DOI: 10.1002/anie.202422994

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202422994