Empa, Swiss Federal Laboratories for Materials Science and Technology, nanotech@surfaces Laboratory , 8600 Dübendorf , Switzerland.
Max Planck Institute for Polymer Research , 55128 Mainz , Germany.
J Am Chem Soc. 2018 Mar 14;140(10):3532-3536. doi: 10.1021/jacs.8b00587. Epub 2018 Feb 28.
On-surface synthesis is a successful approach to the creation of carbon-based nanostructures that cannot be obtained via standard solution chemistry. In this framework, we have established a novel synthetic pathway to one-dimensional conjugated polymers composed of indenofluorene units. Our concept is based on the use of ortho-methyl groups on a poly( para-phenylene) backbone. In this situation, surface-assisted oxidative ring closure between a methyl and the neighboring aryl moiety gives rise to a five-membered ring. The atomically precise structures and electronic properties of the obtained indenofluorene polymers have been unambiguously characterized by STM, nc-AFM, and STS, supported by theoretical calculations. This unprecedented synthetic protocol can potentially be extended to other polyphenylenes and eventually graphene nanoribbons, to incorporate five-membered rings at desired positions for the fine-tuning of electronic properties.
表面合成是一种成功的方法，可以创造出无法通过标准溶液化学方法获得的碳基纳米结构。在这个框架中，我们建立了一种新的合成方法，用于合成由茚并芴单元组成的一维共轭聚合物。我们的概念基于在聚对苯撑（para-phenylene）主链上使用邻甲基基团。在这种情况下，甲基和相邻芳基部分之间的表面辅助氧化环合会产生一个五元环。通过 STM、nc-AFM 和 STS 以及理论计算的支持，明确地表征了所得到的茚并芴聚合物的原子精确结构和电子性质。这种前所未有的合成方案有可能扩展到其他聚苯撑，并最终扩展到石墨烯纳米带，以便在所需位置引入五元环，以精细调整电子性质。
