Institut für Organische Chemie, Universität Tübingen , Auf der Morgenstelle 18, 72076 Tübingen, Germany.
Flux Research Institute LLC , 11444 Rothschild Place, Dublin, California 94568, United States.
J Am Chem Soc. 2017 Mar 29;139(12):4435-4442. doi: 10.1021/jacs.6b13212. Epub 2017 Mar 20.
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 C 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.
并苯由一类重要的有机半导体材料组成。作为最窄的石墨烯纳米带，它们是研究这种形式的纳米级碳材料性质的有价值的原子精确模型系统。并五苯是并苯系列中最小的成员，只能在基质隔离条件下进行研究。尽管早在 70 多年前就已经进行了研究，但它在块体中的存在从未得到过肯定。我们报告称，7,16-并五苯醌的还原会产生两种二并五苯分子的混合物。在固态下，二并五苯在高温下发生热裂解，生成并五苯。通过固态 C 交叉极化魔角旋转 NMR 对这种闭环反应进行监测，表明固态并五苯在室温下的半衰期为数周。二并五苯是通过气相沉积生成并五苯薄膜的有价值的前体，这些薄膜可以在低于或室温下进行研究。
