The odd alternant hydrocarbon phenalenyl (PLY) can exist in three different forms, a closed-shell cation, an open-shell radical, and a closed-shell anion, using its nonbonding molecular orbital (NBMO). The chemistry of PLY-based molecules began more than five decades ago, and so far, the progress has mainly involved the open-shell neutral radical state. Over the last two decades, we have witnessed the evolution of a range of PLY-based radicals generating an array of multifunctional materials. However, it has been admitted that the practical applications of PLY radicals are greatly challenged by the low stability of the open-shell (radical) state.

中文翻译：

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探索闭壳阳离子苯甲醛：从催化到自旋电子

利用其非键合分子轨道（NBMO），奇数交替的烃菲吩烯基（PLY）可以三种不同的形式存在，即闭壳阳离子，开壳自由基和闭壳阴离子。基于PLY的分子的化学作用始于五十多年前，到目前为止，进展主要涉及开壳中性自由基状态。在过去的二十年中，我们目睹了一系列基于PLY的自由基的进化，这些自由基产生了多种多功能材料。然而，已经认识到，PLY自由基的实际应用受到开壳（自由基）态的低稳定性的极大挑战。