Quarteranthene is predicted to manifest nontrivial edge states as the competition from the hybridization of localized frontier states and the Coulomb repulsion between valence electrons, which hosts much research potential in memory, spintronic devices fabrication, and quantum computation. The fabrication of ribbon‐like structures with up‐mentioned edge states, such as chiral graphene nanoribbon, possesses a high significance in the topological phase transition investigation. However, the synthesis of chiral graphene nanoribbon is limited in reactive substrate or with the edge‐brominated precursor. Here, the fabrication of quarteranthene and its chiral graphene nanoribbon segment on Au(111) substrate is reported. A combined bond‐resolved scanning tunneling microscopy, noncontact atomic force microscopy characterization, and corresponding density functional theory calculations confirm the chemical structure of fabricated products on the Au(111) substrate. The detailed analysis of the laterally extended products reveals that the lateral‐extended structures are acquired via the linkage of the hydrocarbon quarter‐anthryl. In addition, several strategies are used to modulate the yield of quarteranthene and its lateral‐extended products. These findings provide a new insight into the lateral extension strategy on metal substrates and provide another possible fabrication strategy of chiral graphene nanoribbons on the relative inert Au(111) substrate.

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Exploring the effect of porphin tautomerism on the regioselectivity of its derivatives is a big challenge, which is significant for the development and application of porphyrin drugs. In this work, we demonstrate the regioselectivity of 2H-diphenylporphyrin (H2-DPP) in the planarization reaction on Au(111) and Ag(111) substrates. H2-DPP monomer forms two configurations (anti- and syn-) via a dehydrogenation coupling, between which the yield of the anti-configuration exceeds 90%. Using high-resolution scanning tunneling microscopy, we visualize the reaction processes from the H2-DPP monomer to the final two planar products. Combined with DFT calculations of the potential reaction pathway and comparative experiments on Au(111) and Ag(111) substrates. Using M-DPP (M = Cu and Fe), we confirm that the regioselectivity of H2-DPP is derived from the reaction energy barrier during the cyclodehydrogenation reaction of different tautomers. This work reveals the regioselectivity mechanism of H2-DPP on the atomic scale, which holds great significance for understanding the chemical conversion process of organic macrocyclic molecules.

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