Metalation is an effective strategy for tuning the optical, magnetic, and other physical properties of porphyrins, which play an important role in material synthesis and biological activities. Multiple aromatic ring-fused structures (ARFSs) can be formed by cyclodehydrogenation from a single porphyrin compound. Understanding the various bonding forms and bond strengths of aromatic allotropes with metals remains as an intriguing area. The role of ARFSs in porphyrin metalation is yet unknown. Herein, we demonstrate highly selective metalation of porphyrin enabled by the distinctive ARFSs derived from a single precursor on Ag(111). ARFS-A is self-metalated with a high yield (∼100%) on Ag(111), setting one Ag atom in its molecular central cavity. ARFS-B is barely metalated until full molecular desorption from the substrate. The selectivity is attributed to the differences in metalation energy barriers originated from the different dehydrocyclization structures and adsorption configurations of porphyrin allotropes on the surface. By exposing the relationship between the ring-fused structures and porphyrin metalation, this work offers insights into how to design aromatic ring-fused porphyrins structurally and shows how to control the occurrence and selectivity of porphyrin metalation.

中文翻译：

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通过独特的芳环稠合结构实现卟啉的高选择性金属化

金属化是调节卟啉光学、磁性和其他物理性质的有效策略，在材料合成和生物活性中发挥着重要作用。多个芳环稠合结构（ARFS）可以通过单一卟啉化合物的环化脱氢形成。了解芳香族同素异形体与金属的各种键合形式和键合强度仍然是一个有趣的领域。 ARFS 在卟啉金属化中的作用尚不清楚。在此，我们证明了卟啉的高选择性金属化是通过源自 Ag(111) 上单一前体的独特 ARFS 实现的。 ARFS-A 在 Ag(111) 上以高产率 (∼100%) 自金属化，在其分子中心空腔中设置一个 Ag 原子。 ARFS-B 在分子从基材完全解吸之前几乎没有金属化。选择性归因于金属化能垒的差异，这些差异源于表面上卟啉同素异形体的不同脱氢环化结构和吸附构型。通过揭示稠环结构与卟啉金属化之间的关系，这项工作为如何从结构上设计芳环稠合卟啉提供了见解，并展示了如何控制卟啉金属化的发生和选择性。