Dicyclohepta[ijkl,uvwx]rubicene with Two Pentagons and Two Heptagons as a Stable and Planar Non‐benzenoid Nanographene

Zhang, Xi‐Sha; Huang, Yan‐Ying; Zhang, Jing; Meng, Wei; Peng, Qian; Kong, Ruirui; Xiao, Zhenwei; Liu, Jie; Huang, Miaofei; Yi, Yuanping; Chen, Liangliang; Fan, Qingrui; Lin, Gufa; Liu, Zitong; Zhang, Guanxin; Jiang, Lang; Zhang, Deqing

doi:10.1002/anie.201914416

Cited by 93 publications

(68 citation statements)

References 64 publications

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“…Nucleus-independent chemical shift (NICS) calculations of NG 4 at the GIAO-B3LYP/6-311G (d,p) level ( Figure S36 ) 34 − 36 revealed negative values ranging from −3.41 to −26.88 ppm for all the benzene rings. In contrast, the two heptagons showed positive values of 15.12 and 16.76 ppm ( Figure 1 D), indicating their antiaromaticity, 37 , 38 which might also account for the upfield shift of proton 21 adjacent to a heptagon.…”

mentioning

confidence: 97%

Negatively Curved Nanographene with Heptagonal and [5]Helicene Units

Qiu

Asako

et al. 2020

J. Am. Chem. Soc.

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Negatively curved nanographene (NG) 4 , having two heptagons and a [5]helicene, was unexpectedly obtained by aryl rearrangement and stepwise cyclodehydrogenations. X-ray crystallography confirmed the saddle-shaped structures of intermediate 3 and NG 4 . The favorability of rearrangement over helicene formation following radical cation or arenium cation mechanisms is supported by theoretical calculations. NG 4 demonstrates a reversible mechanochromic color change and solid-state emission, presumably benefiting from its loose crystal packing. After resolution by chiral high-performance liquid chromatography, the circular dichroism spectra of enantiomers 4 -( P ) and 4 -( M ) were measured and showed moderate Cotton effects at 350 nm (|Δε| = 148 M –1 cm –1 ).

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confidence: 97%

Negatively Curved Nanographene with Heptagonal and [5]Helicene Units

Qiu

Asako

et al. 2020

J. Am. Chem. Soc.

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“…The aromaticity of such azulene moieties is typically lost due to structural distortions . But even if planarity prevails, such PAHs usually possess non‐ or anti‐aromatic “formal azulene“ units because of the dominant aromaticity of the surrounding benzenoid rings. This situation might be overcome by annulation of aromatic units onto the periphery of azulene at positions 1,8 and 3,4, which is, however, challenging because of a lack of synthetic methodologies (Figure ).…”

Section: Figurementioning

confidence: 99%

NIR‐Absorbing π‐Extended Azulene: Non‐Alternant Isomer of Terrylene Bisimide

2020

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The first planar π‐extended azulene that retains aromaticity of odd‐membered rings was synthesized by [3+3] peri‐annulation of two naphthalene imides at both long‐edge sides of azulene. Using bromination and subsequent nucleophilic substitution by methoxide and morpholine, selective functionalization of the π‐extended azulene was achieved. Whilst these new azulenes can be regarded as isomers of terrylene bisimide they exhibit entirely different properties, which include very narrow optical and electrochemical gaps. DFT, TD‐DFT, as well as nucleus‐independent chemical shift calculations were applied to explain the structural and functional properties of these new π scaffolds. Furthermore, X‐ray crystallography confirmed the planarity of the reported π‐scaffolds and aromaticity of their azulene moiety.

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“…Zhang 38 also independently achieved in-solution synthesis of highly fused azulene units via the Scholl cyclisation of ingeniously tailored precursors. Despite these pioneering works, there is still a lack of appropriate methods to construct highly condensed azulene clusters, structures that frequently appear in graphenes.…”

Section: Andmentioning

confidence: 99%

Helical Graphene Nanostructures Embedded with an Azulene Cluster

Yamaoka¹,

Ogawa²,

Takikawa³

et al. 2020

Preprint

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An azulene cluster is a structural defect of graphenes, and it alters the electronic, magnetic, and structural properties of graphenes and graphene nanoribbons. However, detailed experimental investigations of graphenes or graphene nanostructures embedded with an azulene cluster are limited because they are difficult to synthesise. Herein, azulene-embedded graphene nanostructures (AGNs) were synthesised by following a newly developed synthetic protocol. The nanostructures comprising pentagons, hexagons, and heptagons has three characteristic edges, viz., zigzag-, armchair-, and cove-type edges. Experimental and theoretical investigations of the properties of AGN revealed that the cove edge has stable helical chirality with a racemisation barrier of 29.2 kcal/mol, in contrast to normal cove-type edges that undergo rapid racemisation. The in-solution self-association behaviour and the structural, electronic, and electrochemical properties of AGN are also described in detail.

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Dicyclohepta[ijkl,uvwx]rubicene with Two Pentagons and Two Heptagons as a Stable and Planar Non‐benzenoid Nanographene

Cited by 93 publications

References 64 publications

Negatively Curved Nanographene with Heptagonal and [5]Helicene Units

Negatively Curved Nanographene with Heptagonal and [5]Helicene Units

NIR‐Absorbing π‐Extended Azulene: Non‐Alternant Isomer of Terrylene Bisimide

Helical Graphene Nanostructures Embedded with an Azulene Cluster

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