Surface-confined synthesis is a promising approach to build complex molecular nanostructures including macrocycles. However, despite the recent advances in on-surface macrocyclization under ultrahigh vacuum, selective synthesis of monodisperse and multicomponent macrocycles remains a challenge. Here, we report on an on-surface formation of [6 + 6] Schiff-base macrocycles via dynamic covalent chemistry. The macrocycles form two-dimensional crystalline domains on the micrometer scale, enabled by dynamic conversion of open-chain oligomers into well-defined ∼3.0 nm hexagonal macrocycles. We further show that by tailoring the length of the alkyl substituents, it is possible to control which of three possible products-oligomers, macrocycles, or polymers-will form at the surface. In situ scanning tunneling microscopy imaging combined with density functional theory calculations and molecular dynamics simulations unravel the synergistic effect of surface confinement and solvent in leading to preferential on-surface macrocyclization.

中文翻译：

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通过动态共价化学进行表面限制的大环化。

表面限制合成是一种建立包括大环在内的复杂分子纳米结构的有前途的方法。然而，尽管最近在超高真空下进行表面大环化方面取得了进展，但是单分散和多组分大环化合物的选择性合成仍然是一个挑战。在这里，我们通过动态共价化学报告了[6 + 6] Schiff碱大环化合物的表面形成。大环形成微米级的二维晶域，这是通过将开链低聚物动态转​​化为定义明确的〜3.0 nm六角形大环而实现的。我们进一步表明，通过调整烷基取代基的长度，可以控制在表面上形成三种可能的产物（低聚物，大环或聚合物）中的哪一种。