Acenes comprise an important class of organic semiconducting materials. As graphene nanoribbons of ultimate width, they are valuable atom-precise model systems for studying the properties of this form of nanoscale carbon materials. Heptacene is the smallest member of the acene series that could only be studied under matrix isolation conditions. Its existence in bulk had never been positively confirmed, despite efforts dating back more than 70 years. We report that the reduction of 7,16-heptacenequinone produces a mixture of two diheptacene molecules. The diheptacenes undergo thermal cleavage to heptacene at high temperatures in the solid state. Monitoring this cycloreversion by solid state 13C cross-polarized magic angle spinning NMR reveals that solid heptacene has a half-life time of several weeks at room temperature. The diheptacenes are valuable precursors for generating films of heptacene by vapor phase deposition that can be studied below or at room temperature.

中文翻译：

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七苯：溶液、固态和薄膜中的表征

并苯包括一类重要的有机半导体材料。作为具有极限宽度的石墨烯纳米带，它们是用于研究这种形式的纳米级碳材料的性质的宝贵的原子级精确模型系统。七苯是并苯系列中最小的成员，只能在基质分离条件下进行研究。尽管已有 70 多年的努力，但它的批量存在从未得到肯定。我们报告说 7,16-七苯醌的还原会产生两个二七苯分子的混合物。二七苯在固态下在高温下经历热裂解成七苯。通过固态 13C 交叉极化魔角旋转 NMR 监测这种环逆转显示，固体七苯在室温下的半衰期为数周。