Biphenylene network: A nonbenzenoid carbon allotrope

Abstract

The quest for planar sp2-hybridized carbon allotropes other than graphene, such as graphenylene and biphenylene networks, has stimulated substantial research efforts because of the materials’ predicted mechanical, electronic, and transport properties. However, their syntheses remain challenging given the lack of reliable protocols for generating nonhexagonal rings during the in-plane tiling of carbon atoms. We report the bottom-up growth of an ultraflat biphenylene network with periodically arranged four-, six-, and eight-membered rings of sp2-hybridized carbon atoms through an on-surface interpolymer dehydrofluorination (HF-zipping) reaction. The characterization of this biphenylene network by scanning probe methods reveals that it is metallic rather than a dielectric. We expect the interpolymer HF-zipping method to complement the toolbox for the synthesis of other nonbenzenoid carbon allotropes.

Spectroscopic Evidence of New Low-Dimensional Planar Carbon Allotropes Based on Biphenylene via On-Surface Ullmann Coupling

“…Finally, at 515 • C, no Br 3d signal was detected and the C-Br shoulder was almost completely absent, indicating a polymeric network was formed (see Figure S3 for preliminary STM result). We note that the C 1s PE line profile here was similar to other 2D carbon allotropes such as graphene [17] or BPN [8]. The geometry of the system was investigated by means of the Near-Edge X-ray Absorption Fine Structure (NEXAFS) at the C K-edge.…”

“…However, compared to the extensive theoretical modelling, limited experimental success was achieved to form large area frameworks. Just very recently, Qitang Fan et al successfully synthesized, for the first time, a biphenylene network (BPN) [8], a nonbenzenoid carbon allotrope based on biphenylene (Figure 1c). The detailed morphology and electronic properties were characterized, showing that BPN has metallic electronic properties, clarifying the theoretical debate about the dielectric or metallic properties of BPN [2,9,10].…”

On‐Surface Synthesis of Porphyrin‐Complex Multi‐Block Co‐Oligomers by Defluorinative Coupling

“…[4] Particularly, since the successful synthesis of graphene nanoribbons (GNRs) [5] by combining with the subsequent cyclodehydrogenation, [6] the dehalogenative coupling reaction became popular. [7] Furthermore, such products allowed us to investigate the electronic, [8] mechanical, [9] and spintronics properties [10] as well as to demonstrate the electroluminescence. [11] Taking advantage of different reaction temperatures required for each CÀ X bond cleavage, a stepwise synthesis could be performed if more than two kinds of halogen atoms were substituted to precursor molecules.…”

Elasticity Boundary-Value Problems for Straight Wedge Disclinations. A Review on Methods and Results

“…In last decade, pseudo-graphenes -planar graphene allotropes with periodically distributed disclinations, attracted special attention of researchers [189,60,61]. A remarkable fact on pseudo-graphenes is that they fist predicted only theoretically were recently experimentally synthesized [190].…”