Stable radicals are challenging to prepare due to their intrinsic high reactivity. Herein, three trisphenolamine radicals were readily synthesized and exhibited unexpected thermal/electrochemical stability and semiconductor property. These three nitroxide radicals could be considered as a class of aromatized nitro groups or HNO₃ derivatives. The closed-shell nitro-like and open-shell nitroxide resonance structure contribute to their outstanding stability. Furthermore, the tunable ground states, extremely low band gap and p-type charge transport properties were systematically investigated. More importantly, the work presents the concept of aromatic inorganic acid radical (AIAR) and aggregation-induced radical (AIR) mechanism to understand the intrinsic structure-property relationship of these radicals. In addition, we provide a novel strategy for the design of stable and low bandgap radicals for organic electronics, magnetics, spintronics, etc.

中文翻译：

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芳香族无机酸基

稳定的自由基由于其固有的高反应活性而难以制备。在此，三个三酚胺基很容易合成，并表现出出乎意料的热/电化学稳定性和半导体性能。这三个氮氧化物自由基可被视为一类芳香化的硝基或HNO ₃衍生品。闭壳类硝基和开壳型一氧化氮共振结构有助于其出色的稳定性。此外，系统地研究了可调基态，极低的带隙和p型电荷传输性能。更重要的是，该工作提出了芳香族无机酸自由基（AIAR）和聚集诱导自由基（AIR）机理的概念，以了解这些自由基的内在结构与性质之间的关系。此外，我们为有机电子，磁性，自旋电子等的稳定和低带隙自由基设计提供了一种新颖的策略。