On-Surface Synthesis of Chlorinated Narrow Graphene Nanoribbon Organometallic Hybrids

Abstract

Graphene nanoribbons (GNRs) and their derivatives attract growing attention due to their excellent electronic and magnetic properties as well as the fine-tuning of such properties that can be obtained by heteroatom substitution and/or edge morphology modification. Here, we introduce graphene nanoribbon derivatives—organometallic hybrids with gold atoms incorporated between the carbon skeleton and side Cl atoms. We show that narrow chlorinated 5-AGNROHs (armchair graphene nanoribbon organometallic hybrids) can be fabricated by on-surface polymerization with omission of the cyclodehydrogenation reaction by a proper choice of tailored molecular precursors. Finally, we describe a route to exchange chlorine atoms connected through gold atoms to the carbon skeleton by hydrogen atom treatment. This is achieved directly on the surface, resulting in perfect unsubstituted hydrogen-terminated GNRs. This will be beneficial in the molecule on-surface processing when the preparation of final unsubstituted hydrocarbon structure is desired.

Substrate-Modulated Synthesis of Metal–Organic Hybrids by Tunable Multiple Aryl–Metal Bonds

“…One main contribution of the interactions between nanoribbons 2 is the abundant Cl···Cl halogen bonding which directs the parallel packing of 2 . The coadsorbed bromine atoms exhibit a lower adsorption height and self-assemble into random networks and clusters in the darker regions on Au(111) surfaces without forming other chemical species (Figure S1), which has proven to obstruct the growth of longer gold–organic nanoribbons . A closer look at the nanoribbons 2 with high-resolution STM and nc-AFM imaging (Figure d,g) reveals the nonplanar geometry of 2 arising from the steric hindrance of the adjacent Cl atoms in the bay -regions.…”

“…The coadsorbed bromine atoms exhibit a lower adsorption height and self-assemble into random networks and clusters in the darker regions on Au(111) surfaces without forming other chemical species (Figure S1), which has proven to obstruct the growth of longer gold−organic nanoribbons. 39 A closer look at the nanoribbons 2 with high-resolution STM and nc-AFM imaging (Figure 1d,g) reveals the nonplanar geometry of 2 arising from the steric hindrance of the adjacent Cl atoms in the bay-regions. As a result, the higher Cl atoms of the twisted molecular units appear as the bright protrusions in the STM and nc-AFM images, whereas the low-lying perylene backbones and gold adatoms become invisible in the constantheight nc-AFM image.…”

“…Consequently, the backbone of nanoribbons 4 turns into the same as the 5-AGNR. 39 The reduced distance between the repeating units makes the cavities at the edges of 4 insufficient for the adsorption of Br atoms.…”

“…One year later, the same group reported another type of gold–organic nanoribbons with peri -aryl–Au bonds . These two bonding motifs have proven to be versatile tools to afford unprecedented 1D MOHs, − whereas 2D MOHs constructed solely by multiple aryl–metal bonds remain elusive.…”

Evolution of the Topological Energy Band in Graphene Nanoribbons

“…By the rational design of molecular precursors and the catalytic surfaces, a large number of GNRs with atomic-scale control on their edges, widths, and chemical compositions have been realized through surface-assisted reactions. − In this work, we focus on a seven-carbon-atom wide armchair GNR with staggered edge extensions (7-AGNR- S (1,3)), chemical structure displayed in Figure e), which was recently demonstrated to have topologically derived bands originating from the 1D superlattice of topological junctions along the longitudinal GNR axis . We have experimentally demonstrated the evolution of the topological band of 7-AGNR- S (1,3) by probing GNRs having a single topological junction, dimerized junctions, and GNRs with multiple coupled junctions.…”