A Dipleiadiene‐Embedded Aromatic Saddle Consisting of 86 Carbon Atoms

Abstract

This study presents a new type of negatively curved nanographene (C H ) that contains an unprecedented pattern of heptagons. A tert-butylated derivative of C H was successfully synthesized using tetrabenzodipleiadiene as a key building block. This synthesis involved a ring expansion reaction as a key step to form the seven-membered rings in the framework of tetrabenzodipleiadiene. The single-crystal structure reveals a saddle-shaped molecule with a highly bent naphthalene moiety at the center of the polycyclic backbone. As found from the DFT calculations, this aromatic saddle is flexible at room temperature and has a saddle-shaped geometry as the dominant conformation. The DFT calculations along with experimental results show that the attachment of t-butyl groups to the central tetrabenzodipleiadiene moiety of nanographene C H can stabilize the saddle conformation and make this nanographene less flexible.

Construction of Polycyclic π‐Conjugated Systems Incorporating an Azulene Unit Following the Oxidation of 1,8‐Diphenyl‐9,10‐bis(phenylethynyl)phenanthrene

“…Unlike alternant π‐conjugated systems, the non‐alternant structure of azulene contributes to the construction of peculiar π‐conjugated systems . In addition to the electronic perturbations of the alternant π‐conjugated systems, many three‐dimensional nanocarbon structures with curvature have been proposed by embedding pentagons or heptagons in the hexagonal honeycomb lattice . Thus, the embedding of an azulene core into alternant PAHs could change both the molecular geometry and the electronic properties of the original PAHs.…”

“…[19][20][21][22][23][24][25][26] In addition to the electronic perturbations of the alternant p-conjugated systems, many three-dimensional nanocarbon structuresw ith curvature have been proposed by embedding pentagons or heptagonsi nt he hexagonal honeycomb lattice. [5,[27][28][29][30][31] Thus, the embedding of an azulenec ore into alternant PAHs could change both the molecular geometry and the electronicp roperties of the originalP AHs. Despite recenti nterest in the structural and electronic perturbations from the incorporationo fo ne or more azuleneu nit(s)i nto pconjugated systems, [32][33][34] the development of ar elatively simple and efficient method to construct azulene-embedded PAHs remains av ery challenging issue due to the limited number of synthetic methodologies.…”

Synthetic Applications of Oxidative Aromatic Coupling—From Biphenols to Nanographenes

“…The dipleiadiene‐embedded PAH‐saddle 194 contains two seven‐membered rings embedded within two fused [7]circulene moieties (Figure ). Its synthesis has been realized by Miao and co‐workers in high yields using FeCl 3 and DDQ as oxidants . The same group also synthesized other heptagon‐containing saddle‐shaped PAHs using intramolecular oxidative coupling in key steps …”

“…Its synthesis has been realized by Miao and co-workers in high yields using FeCl 3 and DDQ as oxidants. [207] Thesame group also synthesized other heptagoncontaining saddle-shaped PA Hs using intramolecular oxidative coupling in key steps. [208,209] Kuck, Chow,a nd co-workers have utilized the DDQ/ TfOH oxidative system for the synthesis of molecules 195 a (Figure 15).…”

A Highly Warped Heptagon‐Containing sp2 Carbon Scaffold via Vinylnaphthyl π‐Extension

“…[5,6] Synthetic strategies for curved, heptagon-containing sp 2 carbon structures most often utilize intramolecular oxidative C À H/C À Hcouplings [7] or Pd-catalyzed C À H/C À Xcouplings [8] of prearranged aromatic units as key steps.O ther recent approaches involve heptagonal ketone precursors, [9] which can in turn be made by cyclotrimerization [10] or ring expansion. [11] Intermolecular coupling routes are less commonly encountered, but are promising in terms of generalizing reactivity. [12] Recently our group has reported afacile one-pot synthetic approach for PA Hs bearing embedded borinic acid moieties using simple alkene precursors.…”