Chemical synthesis typically yields the most thermodynamically stable ordered arrangement, a principle also governing surface synthesis on an atomically level two-dimensional (2D) surface, fostering the creation of structured 2D formations. The linear connection arising from energetically stable chemical bonding precludes the generation of a 2D random network comprised of one-dimensional (1D) convoluted stripes through on-surface synthesis. Nonetheless, we underscored that on-surface synthesis possesses the capability not solely to fashion a 2D ordered linear network but also to fabricate a winding 2D network employing a precursor with a soft ring and intermediate state bonding within the Ullmann reaction. Here, on-surface synthesis was exhibited on Cu(111) employing a 2D self-assembled monolayer array of 4,4′,5,5′-tetrabromodibenzo[18]crown-6 ether (BrCR) precursors. These precursors were purposefully structured, with a crown ether ring at the core and Br atoms positioned at the head and tail ends, facilitating preferential connections along the elongated axis to foster a 1D stripe configuration. We illustrate how adjustments in the quantities of the intermediate state, serving as a primary linkage, can yield a labyrinthine, convoluted winding 2D network of stripes. The progression of growth, underlying mechanisms, and electronic structures were scrutinized using an ultrahigh vacuum low-temperature scanning tunneling microscopy and spectroscopy (STM/STS) setup combined with density functional theory (DFT) calculations. This experimental evidence opens a novel functionality in leveraging on-surface synthesis for the formation of a 2D random network. This discovery holds promise as a pioneering constituent in the construction of a ring host supramolecule, augmenting its capability to ensnare guest atoms, molecules, or ions.

中文翻译：

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Cu(111)表面冠醚中间体乌尔曼耦合设计二维条纹缠绕网络


化学合成通常会产生热力学最稳定的有序排列，这一原理也控制着原子级二维 (2D) 表面上的表面合成，从而促进结构化 2D 结构的创建。由能量稳定的化学键合产生的线性连接阻止了通过表面合成生成由一维 (1D) 卷积条纹组成的 2D 随机网络。尽管如此，我们强调，表面合成不仅具有形成二维有序线性网络的能力，而且还能够利用乌尔曼反应中具有软环和中间态键合的前体来制造缠绕的二维网络。在这里，采用 4,4',5,5'-四溴二苯并[18]冠-6 醚 (BrCR) 前体的二维自组装单层阵列在 Cu(111) 上进行表面合成。这些前体是有目的地结构化的，其核心是冠醚环，而溴原子位于头端和尾端，促进沿细长轴的优先连接，以形成一维条纹结构。我们说明了作为主要链接的中间状态数量的调整如何产生迷宫般的、盘旋的二维条纹网络。使用超高真空低温扫描隧道显微镜和光谱学 (STM/STS) 设置与密度泛函理论 (DFT) 计算相结合，对生长过程、潜在机制和电子结构进行了仔细检查。这一实验证据开启了利用表面合成形成二维随机网络的新功能。 这一发现有望成为构建环主体超分子的开创性成分，增强其捕获客体原子、分子或离子的能力。