Liu Junzhi, Li Bo-Wei, Tan Yuan-Zhi, Giannakopoulos Angelos, Sanchez-Sanchez Carlos, Beljonne David, Ruffieux Pascal, Fasel Roman, Feng Xinliang, Müllen Klaus
†Max-Planck Institut für Polymerforschung, Ackermannweg 10, 55128, Mainz, Germany.
‡State Key Laboratory of Physical Chemistry of Solid Surfaces and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China.
J Am Chem Soc. 2015 May 13;137(18):6097-103. doi: 10.1021/jacs.5b03017. Epub 2015 May 4.
Graphene nanoribbons (GNRs), defined as nanometer-wide strips of graphene, have attracted increasing attention as promising candidates for next-generation semiconductors. Here, we demonstrate a bottom-up strategy toward novel low band gap GNRs (Eg = 1.70 eV) with a well-defined cove-type periphery both in solution and on a solid substrate surface with chrysene as the key monomer. Corresponding cyclized chrysene-based oligomers consisting of the dimer and tetramer are obtained via an Ullmann coupling followed by oxidative intramolecular cyclodehydrogenation in solution, and much higher GNR homologues via on-surface synthesis. These oligomers adopt nonplanar structures due to the steric repulsion between the two C-H bonds at the inner cove position. Characterizations by single crystal X-ray analysis, UV-vis absorption spectroscopy, NMR spectroscopy, and scanning tunneling microscopy (STM) are described. The interpretation is assisted by density functional theory (DFT) calculations.
石墨烯纳米带（GNRs）被定义为纳米宽度的石墨烯条带，作为下一代半导体的有前途的候选材料，已引起越来越多的关注。在这里，我们展示了一种自下而上的策略，以苊为关键单体，在溶液中和固体衬底表面制备具有明确凹型边缘的新型低带隙GNRs（Eg = 1.70 eV）。通过乌尔曼偶联，然后在溶液中进行氧化分子内环脱氢反应，得到由二聚体和四聚体组成的相应环化苊基低聚物，并通过表面合成得到更高的GNR同系物。由于内凹位置的两个C-H键之间的空间排斥，这些低聚物采用非平面结构。描述了通过单晶X射线分析、紫外可见吸收光谱、核磁共振光谱和扫描隧道显微镜（STM）进行的表征。通过密度泛函理论（DFT）计算辅助解释。
