Nanographenes and Graphene Nanoribbons as Multitalents of Present and Future Materials Science

Abstract

As cut-outs from a graphene sheet, nanographenes (NGs) and graphene nanoribbons (GNRs) are ideal cases with which to connect the world of molecules with that of bulk carbon materials. While various top-down approaches have been developed to produce such nanostructures in high yields, in the present perspective, precision structural control is emphasized for the length, width, and edge structures of NGs and GNRs achieved by modern solution and on-surface syntheses. Their structural possibilities have been further extended from “flatland” to the three-dimensional world, where chirality and handedness are the jewels in the crown. In addition to properties exhibited at the molecular level, self-assembly and thin-film structures cannot be neglected, which emphasizes the importance of processing techniques. With the rich toolkit of chemistry in hand, NGs and GNRs can be endowed with versatile properties and functions ranging from stimulated emission to spintronics and from bioimaging to energy storage, thus demonstrating their multitalents in present and future materials science.

Heteroatom-Doped [4]Triangulene: Facile Synthesis and Two-Dimensional On-Surface Self-Assemblies

“…The synthetic route to OBO-doped [4]triangulenes 1a and 1b is depicted in Scheme 1. 45 The corresponding precursors 3a and 3b were synthesized through a Suzuki coupling reaction of 1,3,5-tribromobenzene and two aryl boronic acids (2a and 2b) in 92% and 91% yields, respectively.…”

“…In addition, the superstructures of 1a show higher values of standard deviation on Au(111) surface (σ = 0.116 for phase I and 0.084 for phase II) than those on Ag(111) surface (σ = 0.030) and on Cu(111) surface (σ = 0.040), which is in accordance with the observations of more motifs on Au(111) surface. In summary, we have synthesized the unprecedented air-stable OBO-doped [4]triangulenes 1a and 1b. The structure of 1b is unambiguously determined by single-crystal X-ray analysis.…”

“…Figure 1. Chemical structures of[4]triangulene and the OBO-doped[4]triangulene reported in this work, as well as the schematic representations of their on-surface self-assembled behaviors.…”

“…Nanographenes (NGs), namely nanoscale graphene fragments, have been considered as next-generation semiconductors due to their potential in, for example, optoelectronics, bio-imaging, and energy storage. [1][2][3][4][5] Bottom-up fabrication of NGs is crucial for controlling their structures at the atomic level and precisely tuning their functions. During the past years, a large number of structurally well-defined NGs with various sizes and topological features have been synthesized in solution and on metal surfaces.…”

“…A variety of zigzag-edged triangular NGs, namely triangulenes, have been synthesized on metal surfaces recently, mainly displaying random distribution patterns on the substrate. 42 Toward extended 2D assemblies, oxygen-boron-oxygen (OBO) segments are incorporated into the three zigzag edges of [4]triangulene, leading to OBO-doped [4]triangulenes with high ambient stability. Importantly, highly ordered 2D selfassemblies driven by intermolecular C-H•••O hydrogen bonds are observed on different substrates, 43,44 and an interesting substrate-dependent assembly behavior is observed, thus demonstrating the great potential of OBO-doped triangulenes for constructing 2D functional materials.…”