Li Donglin, Ohto Tatsuhiko, Nishiuchi Tomohiko, Takeuchi Shino, Nishide Yuki, Kimizuka Hajime, Kubo Takashi, Kawai Shigeki
Center for Basic Research on Materials, National Institute for Materials Science, Tsukuba 305-0047, Japan.
Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan.
ACS Nano. 2025 Oct 14;19(40):35825-35832. doi: 10.1021/acsnano.5c12424. Epub 2025 Oct 1.
On-surface synthesis became a powerful strategy to synthesize extended nanocarbon materials, such as oligomers and graphene nanoribbons, via C-C bond formation between small precursor molecules. However, the reverse reaction, namely, C-C bond cleavage, remains challenging due to the high activation barrier. Here, we present systematic fragmentation to individual units from tetra(9-anthryl)benzene oligomers, which were synthesized by Ullmann-type homocoupling on Au(111). The detailed mechanism of fragmentation was investigated with a combination of scanning tunneling microscopy and density functional theory calculations. We found that the Diels-Alder reaction between anthracene groups in the unit significantly lowers the activation barrier to cleave the C-C bond between the units in the oligomer. Our findings may offer an approach to disassemble oligomers in a controlled manner.
表面合成成为一种通过小分子前驱体分子之间形成C-C键来合成扩展纳米碳材料（如低聚物和石墨烯纳米带）的强大策略。然而，由于高活化能垒，逆反应（即C-C键断裂）仍然具有挑战性。在此，我们展示了对通过在Au(111)上进行乌尔曼型自偶联合成的四(9-蒽基)苯低聚物进行系统的单个单元碎片化过程。结合扫描隧道显微镜和密度泛函理论计算研究了碎片化的详细机制。我们发现单元中蒽基团之间的狄尔斯-阿尔德反应显著降低了低聚物中单元之间C-C键断裂的活化能垒。我们的发现可能提供一种以可控方式拆解低聚物的方法。
