On-Surface Precise Synthesis of Non-Hexagonal Ring-Embedded Graphene Nanoribbons

Graphene nanoribbons (GNRs), as quasi-one-dimensional carbon nanostructures, combine the exceptional properties of graphene with tunable bandgaps. The incorporation of periodic non-hexagonal ring motifs into GNR frameworks offers an effective approach to significantly tailor their electronic and magnetic properties. However, synthesis of GNRs incorporating non-hexagonal rings remains challenging, due to the thermodynamic instability compared to their hexagonal counterparts. Advancements in on-surface synthesis and in-situ characterization techniques have emerged as powerful methods for the atomically precise fabrication of novel carbon nanostructures. In this review, we comprehensively summarize the recent progress in on-surface synthesis of non-hexagonal ring-embedded GNRs via sophisticated design of precursors and optimized reaction pathways. This review aims to provide insights into strategies for constructing carbon polygons into nanostructures via surface-mediated chemical reactions, thereby enabling their multifunctional applications in electronics and spintronics.