Bis(9-Boraphenanthrene) and Its Stable Biradical
Bis(9-Boraphenanthrene) and Its Stable Biradical
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Bis(9-Boraphenanthrene)及其稳定的双自由基
DOI：
10.1021/jacs.3c07236
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发表时间：
2023
影响因子：
15
通讯作者：
Gilliard, Robert J.
中科院分区：
文献类型：
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作者：
Sarkar, Samir Kumar;Hollister, Kimberly K.;Molino, Andrew;Obi, Akachukwu D.;Deng, Chun-Lin;Tra, Bi Youan;Stewart, Brennan M.;Dickie, Diane A.;Wilson, David J.;Gilliard, Robert J.
多环芳烃框架的选择性和位点特异性硼掺杂通常引起氧化还原和/或物理性质，这是不容易获得的类似的全碳系统。在本文中，我们报告了配体介导的对硼菲闭壳层和开壳层电子态的控制，这导致了中性双（9-硼菲）（2-3）及其相应的双自由基（4）的第一个结构表征的例子。值得注意的是，化合物2和3显示出来自9-硼菲单元顶部-醌二甲烷的分子内电荷转移吸收，由于激发态共轭增强（ESCE）而在溶液中显示出双（红移）发射。此外，虽然硼为中心的单价自由基是普遍存在的，biradical 4代表了一种罕见的类型的开壳层单线态化合物与95%的双自由基字符，其中最高的任何报道的硼为基础的多环物种与两个自由基网站。
Selective and site-specific boron-doping of polycyclic aromatic hydrocarbon frameworks often give rise to redox and/or photophysical properties that are not easily accessible with the analogous all-carbon systems. Herein, we report ligand-mediated control of boraphenanthrene closed- and open-shell electronic states, which has led to the first structurally characterized examples of neutral bis(9-boraphenanthrene) (2–3) and its corresponding biradical (4). Notably, compounds2and3show intramolecular charge transfer absorption from the 9-boraphenanthrene units top-quinodimethane, exhibiting dual (red-shifted) emission in solution due to excited state conjugation enhancement (ESCE). Moreover, while boron-centered monoradicals are ubiquitous, biradical4represents a rare type of open-shell singlet compound with 95% biradical character, among the highest of any reported boron-based polycyclic species with two radical sites.