Facile Synthesis of Nitrogen‐Doped Nanographenes with Joined Nonhexagons via a Ring Expansion Strategy

Abstract

Synthetic methodology is considered a holy grail in both organic chemistry and materials science. Over the past few decades, researchers have explored graphene‐type molecules (or nanographenes) through classic Scholl oxidative cyclodehydrogenation. Despite the successes achieved with various nanographenes, the development of new methods to synthesize these highly desired molecules lags behind. Herein, we developed a facile and effective method to produce a series of nanographenes bearing nitrogen (N)‐doped pentagon‐heptagon pairs in acceptable yields. Modification of the heptagonal ring endowed the resultant nanographenes with tunable physicochemical properties; for instance, M9 exhibited both aggregation‐caused quenching and aggregation‐induced emission behavior. Most strikingly, novel nanographenes containing N‐doped pentagon‐octagon pairs were also obtained using the same synthetic strategy, demonstrating the superior versatility and efficiency of the proposed ring expansion method.

Nonalternant Nanographenes Containing N-Centered Cyclopenta[ef]heptalene and Aza[7]Helicene Units

“…In contrast to ideal hexagonal nanographenes, these curved π-systems exhibit important features, such as good solubility, chirality, antiaromaticity, and open-shell character. − However, despite these intriguing properties, the synthesis of negatively curved aromatics is still a challenging task due to high strain. In the past decade, with the development of synthetic methodologies and strategies, a variety of negatively curved nanocarbons containing heptagons, − octagons, − pentagon-heptagon pairs, , and pentagon-octagon pairs − have been studied by Itami, Miao, Campaña, Martín and other pioneers. The diversity of negatively curved molecular systems not only provides crucial properties for potential applications in the field of materials science but also produces useful molecular scaffolds for the design of functional π-systems.…”

A Geometrically Flexible Three-Dimensional Nanocarbon

“…Design strategies used in the construction of 3D nanocarbons include (1) introducing curvature in PAHs by embedding in them five-, seven-, and eight-membered rings, ,− (2) forming strained topologies, such as those present in macrocycles, ,− cages, ,, tubes, , and knots, (3) introducing steric congestion onto the edges of PAHs, − and (4) forming mechanically interlocked molecules. , The fusion of PAHs to 3D molecular cores, − such as spirobifluorene, triptycene, ,,,, and tetraphenylene, , also enables the construction of 3D nanocarbons by effectively organizing PAH segments in stereoscopic arrangements. 3D nanocarbons featuring stereoscopic atomic arrangements present good candidates to accommodate shape-complementary guest molecules.…”

Using pyrrolizine-fused bipolar PAHs as a new strategy towards efficient red and NIR emissive dyes

“…1, IIb). In a similar fashion, but with 8 H -benzo[3,4][1,2]azaborinino[5,6,1- jk ]carbazole-8-ol as a precursor, Luo and Liu 19 reported a route to compounds containing a 7-membered ring consisting of a combination of Suzuki coupling and Buchwald–Hartwig amination reactions, as demonstrated in Fig. 1, IIc.…”