On-surface synthesis has been widely used for the precise fabrication of surface-supported covalently bonded nanostructures. Here, we report on tuning the on-surface synthesis of graphene nanoribbons by noncovalent intermolecular interactions on Au(111) surfaces. By introducing noncovalent intermolecular interactions with the companion molecules (dianhydride derivative), intramolecular cyclodehydrogenation of nonplanar precursor molecules (bianthryl derivative) are promoted at 200 °C, with the monomers interlinked by gold atoms instead of the formation of polyanthrylene. By adjusting the deposition sequence of precursor and companion molecules, conjugated graphene nanoribbons can be finally obtained at a temperature of 240 °C, much lower than the synthesis procedures without companion molecules. Density functional theory calculations indicate that intermolecular interactions result in a dramatic shrinkage of the torsional angle between the adjacent anthryl groups of the precursor molecule, aiding the cyclodehydrogenation process. Our work demonstrates an intermolecular strategy for controllable fabrication of covalently bonded nanostructures by on-surface synthesis.

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通过非共价分子间相互作用调节石墨烯纳米带的表面合成

表面合成已被广泛用于表面支撑的共价键纳米结构的精确制造。在这里，我们报告关于通过Au（111）表面上的非共价分子间相互作用调节石墨烯纳米带的表面合成。通过与伴侣分子（二酐衍生物）引入非共价分子间相互作用，在200°C时，非平面前体分子（联蒽衍生物）的分子内环脱氢反应得以促进，单体通过金原子交联而不是形成聚蒽。通过调整前驱物和伴随分子的沉积顺序，可以在240°C的温度下最终获得共轭石墨烯纳米带，这比没有伴随分子的合成过程要低得多。密度泛函理论计算表明，分子间的相互作用导致前体分子的相邻蒽基之间的扭转角急剧减小，这有助于环脱氢过程。我们的工作证明了通过表面合成可控地制造共价键纳米结构的分子间策略。