Jiang Qing, Wang Lei, Wei Haipeng, Peng Yuchen, Xu Guangyan, Li Zhaoyang, Liu Pengfei, Hu Zhenni, Niu Weiwei, Chen Yifan, Tang Hui, Zeng Wangdong, Li Guangwu
College of Chemistry and Bioengineering, Hunan University of Science and Engineering, Yongzhou, 425100, China.
Center of Single-Molecule Sciences, Institute of Modern Optics, Tianjin Key Laboratory of Micro-Scale Optical Information Science and Technology, College of Electronic Information and Optical Engineering, Nankai University, 38 Tongyan Road, Jinnan District, Tianjin, 300350, China.
Angew Chem Int Ed Engl. 2025 Mar 17;64(12):e202422994. doi: 10.1002/anie.202422994. Epub 2024 Dec 20.
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.
高自旋多环烃（PHs）在有机自旋电子学和有机磁体领域具有巨大潜力。然而，由于其极高的反应活性，它们的合成极具挑战性。在此，我们报告了二蒽并[2,3-a : 3',2'-h]-s-茚并四烯动力学受阻衍生物（1）的成功合成与分离，该衍生物代表了一种罕见的具有凯库勒结构的持久性三线态双自由基PH。通过电子顺磁共振和超导量子干涉装置测量明确证实了其三线态基态。通过X射线晶体学分析也明确证实了其结构，并通过实验和理论计算系统地研究了其电子性质。关键设计原则是扩展π共轭，以实现键合相互作用的降低和未成对电子之间交换相互作用的增加，这对于获得稳定的三线态基态至关重要。由于动力学受阻，1在环境条件下表现出合理的稳定性，半衰期为64小时。它具有较窄的HOMO-LUMO能隙，并表现出两性氧化还原行为。值得注意的是，其二价阳离子和二价阴离子表现出闭壳基态和近红外吸收，并且通过X射线晶体学分析确定了其结构。这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。
