Fjord-Edge Graphene Nanoribbons with Site-Specific Nitrogen Substitution

The synthesis of graphene nanoribbons (GNRs) that contain site-specifically substituted backbone heteroatoms is one of the essential goals that must be achieved in order to control the electronic properties of these next generation organic materials. We have exploited our recently reported solid-state topochemical polymerization/cyclization-aromatization strategy to convert the simple 1,4-bis­(3-pyridyl)­butadiynes 3a,b into the fjord-edge nitrogen-doped graphene nanoribbon structures 1a,b (fjord-edge N2[8]­GNRs). Structural assignments are confirmed by CP/MAS 13C NMR, Raman, and XPS spectroscopy. The fjord-edge N2[8]­GNRs 1a,b are promising precursors for the novel backbone nitrogen-substituted N2[8]AGNRs 2a,b. Geometry and band calculations on N2[8]AGNR 2c indicate that this class of nanoribbons should have unusual bonding topology and metallicity.含有骨架特定位点掺杂杂原子的石墨烯纳米带（graphene nanoribbons, GNRs）的合成，是调控这类下一代有机材料电子特性必须达成的核心目标之一。我们依托近期报道的固态拓扑化学聚合/环化-芳构化策略，将简单的1,4-二(3-吡啶基)丁二炔3a、b转化为峡湾边缘氮掺杂石墨烯纳米带结构1a、b（峡湾边缘N₂[8]GNRs）。通过交叉极化/魔角旋转13C核磁共振（CP/MAS ¹³C NMR）、拉曼光谱以及X射线光电子能谱（X-ray Photoelectron Spectroscopy, XPS）的表征，确认了产物的结构归属。峡湾边缘N₂[8]GNRs 1a、b是制备新型骨架氮掺杂N₂[8]扶手椅型石墨烯纳米带（armchair graphene nanoribbons, AGNRs）2a、b的极具应用前景的前驱体。对N₂[8]AGNR 2c开展的几何结构与能带计算表明，该类纳米带具备独特的键合拓扑结构与金属导电性。