On-surface interchain coupling and skeletal rearrangement of indenofluorene polymers

On-surface synthesis serves as a powerful approach to construct π-conjugated carbon nanostructures that are not accessible by conventional wet chemistry. Nevertheless, this method has been limited by the types and numbers of available on-surface transformations. While the majority of successful cases exploit thermally triggered dehalogenative carbon–carbon coupling and cyclodehydrogenation, rearrangement of appropriate functional moieties has received limited research attention. In a recent work, we describe the unprecedented interchain coupling and thermally induced skeleton rearrangement of (dihydro)indeno[2,1-b]fluorene (IF) polymers on an Au(111) surface under ultrahigh vacuum conditions, leading to different ladder polymers as well as fully fused graphene nanoribbon segments containing pentagonal and heptagonal rings. Au-coordinated nanoribbons are also observed. All structures are unambiguously characterized by high-resolution scanning probe microscopy. The results provide an avenue to fabricating a wider variety of π-conjugated polymers and carbon nanostructures comprising nonhexagonal rings as well as rarely explored organometallic nanoribbons. This record contains data of the calculations that support our results.

表面合成法作为一种强大的构建π共轭碳纳米结构的方法，这些结构通过传统的湿化学方法难以获得。然而，此方法受到了可用的表面转化类型和数量的限制。尽管大多数成功的案例利用了热触发的脱卤素碳-碳偶联和环己氢化反应，但适当官能团的重排却鲜有研究关注。在近期的研究中，我们描述了在超高压真空条件下，于金（111）表面进行的（二氢）茚苯并[2,1-b]芴（IF）聚合物前所未有的链间偶联和热诱导骨架重排，从而得到不同的梯形聚合物以及包含五边形和七边形环的完全熔融石墨烯纳米带段。同时，还观察到了金配位的纳米带。所有结构均通过高分辨率扫描探针显微镜得到了明确的表征。这些结果为制备更广泛的π共轭聚合物和包含非六边形环的碳纳米结构，以及鲜有探索的有机金属纳米带提供了新的途径。本记录包含了支持我们结果的计算数据。