Empa, Swiss Federal Laboratories for Material Science and Technology, 8600, Dübendorf, Switzerland.
Graduate School of Materials Science, Nara Institute of Science and Technology (NAIST), 8916-5 Takayama-cho, Ikoma, 630-0192, Japan.
Nat Commun. 2019 Feb 20;10(1):861. doi: 10.1038/s41467-019-08650-y.
Acenes are an important class of polycyclic aromatic hydrocarbons which have recently gained exceptional attention due to their potential as functional organic semiconductors. Fundamentally, they are important systems to study the convergence of physico-chemical properties of all-carbon sp-frameworks in the one-dimensional limit; and by virtue of having a zigzag edge topology they also provide a fertile playground to explore magnetism in graphenic nanostructures. The study of larger acenes is thus imperative from both a fundamental and applied perspective, but their synthesis via traditional solution-chemistry route is hindered by their poor solubility and high reactivity. Here, we demonstrate the on-surface formation of heptacene and nonacene, via visible-light-induced photo-dissociation of α-bisdiketone precursors on an Au(111) substrate under ultra-high vacuum conditions. Through combined scanning tunneling microscopy/spectroscopy and non-contact atomic force microscopy investigations, together with state-of-the-art first principles calculations, we provide insight into the chemical and electronic structure of these elusive compounds.
并五苯是多环芳烃的一个重要类别，由于其作为功能有机半导体的潜力，最近引起了极大的关注。从根本上说，它们是研究一维极限下全碳 sp 骨架物理化学性质趋同的重要体系；并且由于具有锯齿状边缘拓扑结构，它们还为探索石墨烯纳米结构中的磁性提供了肥沃的游乐场。因此，从基础和应用的角度来看，研究更大的并五苯是必要的，但由于其溶解度差和反应性高，通过传统的溶液化学路线合成它们受到阻碍。在这里，我们通过在超真空条件下在 Au(111) 衬底上用可见光诱导 α-双二酮前体光解，证明了七并五苯和九并五苯的表面形成。通过结合扫描隧道显微镜/光谱学和非接触原子力显微镜研究以及最先进的第一性原理计算，我们深入了解了这些难以捉摸的化合物的化学和电子结构。
