Extension of Non‐alternant Nanographenes Containing Nitrogen‐Doped Stone‐Thrower‐Wales Defects

Abstract

Non‐alternant topologies have attracted considerable attention due to their unique physiochemical characteristics in recent years. Here, three novel topological nanographenes molecular models of nitrogen‐doped Stone–Thrower–Wales (S–T–W) defects were achieved through intramolecular direct arylation. Their chemical structures were unambiguously elucidated by single‐crystal analysis. Among them, threefold intramolecular direct arylation compound (C42H21N) is the largest nanographene bearing a N‐doped non‐alternant topology to date, in which the non‐benzenoid rings account for 83 % of the total molecular skeleton. The absorption maxima of this compound was located in the near‐infrared region with a long tail up to 900 nm, which was much longer than those reported for similarly sized N‐doped nanographene with six‐membered rings (C40H15N). In addition, the electronic energy gaps of these series compounds clearly decreased with the introduction of non‐alternant topologies (from 2.27 eV to 1.50 eV). It is noteworthy that C42H21N possesses such a low energy gap (Egopt=1.40 eV; Egcv=1.50 eV), yet is highly stable under ambient conditions. Our work reported herein demonstrates that the non‐alternant topology could significantly influence the electronic configurations of nanocarbons, where the introduction of a non‐alternanting topology may be an effective way to narrow the energy gap without extending the molecular π‐conjugation.

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

“…Notably, CPH-3 showed an intense absorption at 406 nm with an ε up to 1.14×10 5 M –1 cm –1 . In contrast to other pentagon- and heptagon-containing π-systems with no or weak fluorescence, , these three compounds were emissive in solution (Figure b). In particular, the quantum yield was measured to be 0.32 for CPH-3 , which is much higher than that of its carbonaceous analog (Φ F = 0.09, compound C in Figure S7).…”

Sequential annulation of bidentate diamines for modular access to N-fused/helical/spiro-carbazole scaffolds

“…6,7 On the other hand, hexagonal and heptagonal ring-fused Czs also showed appealing optical and electronic properties (Scheme 1b). 8 Besides these material-oriented syntheses based on Pd-catalysis, 8 Dong 9 and Zeng 10 independently reported two typical synthetic methodologies for the synthesis of a [5,6]-fused Cz skeleton through Ir( iii )/Rh( iii )-catalysed double C–H annulation of 2-aryl indoles and diazo compounds. Despite these seminal methodologies for building π-extended Czs, general, cheap, and modular tools for the assembly of five/six/seven-membered ring-fused Czs at N sites are still scarce and should be developed.…”

Gold‐Catalyzed 1,2‐Aryl Shift and Double Alkyne Benzannulation

“…[33][34][35] Taking advantage of this new chemical space, enabled by a multicomponent reaction leading to 1,4-dihydropyrrolo[3,2-b]pyrroles (DHPPs) [36,37] we hypothesized that it could be possible to obtain πexpanded DHPPs possessing fused five-and seven-membered rings. [38][39][40] Assessing this hypothesis requires DHPPs possessing arylethynylaryl substituents at positions 1 and 4 which could undergo double alkyne benzannulation forming two 7-membered rings (Figure 1d, Figure 2).…”