A Dipleiadiene‐Embedded Aromatic Saddle Consisting of 86 Carbon Atoms

Abstract

This study presents a new type of negatively curved nanographene (C86H32) that contains an unprecedented pattern of heptagons. A tert‐butylated derivative of C86H32 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 C86H32 can stabilize the saddle conformation and make this nanographene less flexible.

Ring‐Expanding Rearrangement of Benzo‐Fused Tris‐Cycloheptenylenes towards Nonplanar Polycyclic Aromatic Hydrocarbons

“…In recent years, several negatively curved PAHs containing heptagons have been reported [1a,b,e,6a,b,e,g,7a,b,15] . They exhibited improved solubility and enhanced fluorescence in the solid state resulting from nonplanarity of their polycyclic backbones [7c,16] .…”

Fuller-Rylenes: Cross-Dimensional Molecular Carbons

“…[1][2][3] The most attractive feature of SMCs is the diversity of their topological structures, which include zero-dimensional (0D)-fullerenes, 1D-carbon nanotubes, and 2D-nanographenes with positive or negative curvatures. [4][5][6][7][8][9][10][11] Although the focused investigations of various SMCs have changed the perceptions of organic and materials scientists considerably, the atom-precise synthesis of cross-dimensional molecular carbons, such as fullerene/nanographene hybrids, remains a formidable challenge. [12][13][14][15] Favorably, the discovery of the first molecular allotrope of carbon, the fullerene, provided a fascinating carbon skeleton for endo-and exohedral chemical modifications.…”

Photo- and Thermal Interconversion of Multiconfigurational Strained Hydrocarbons Exhibiting Completely Switchable Oxidation to Stable Dicationic Dyes

“…Extended -conjugated molecules have been widely investigated for their unique physical properties that can be modified by proper molecular design. In particular, much attention has been focused on sterically congested and/or curved polycyclic aromatic hydrocarbons (PAHs) [1][2][3][4][5][6][7][8][9][10][11][12][13][14] as well as cyclic -conjugated molecules like cycloparaphenylenes [15][16][17][18][19][20][21] and carbon nanobelts. [22][23][24] These highly strained molecules are potential candidates with special characteristic features that are not found in normal compounds.…”

“…Within such compounds, curved structures for PAHs are efficiently induced by incorporating mediumsized rings, such as seven-membered rings, which impart molecular strain and distortion. 3,4,7,8,10,11,13 For example, we recently reported that highly strained hydrocarbons could be generated by connecting two dibenzocycloheptatriene units with a C-C bond, in which a sevenmembered ring is a key structure to induce severe strain to give a hyper covalent bond with a C-C single bond length beyond 1.8 Å. 25 Such an elongated bond can be cleaved upon two-electron oxidation to give the corresponding stable dication [dynamic redox (dyrex) behavior] to exhibit electrochromic behavior.…”