Synthesis and Structural Elucidation of Bisdibenzocorannulene in Multiple Redox States

Abstract

We report an anti-folded bowl-shaped bisdibenzocorannulene (BDBC)f eaturing an ew chair-cyclohexane-like hexagon as abridge of two dibenzocorannulene moieties.The neutral compound showed multiple redox-active properties and could be converted to the corresponding redox states through chemical reduction or oxidation.C hemical reduction of BDBC by stoichiometric addition of metallic potassium in the presence of [18]crown-6 ether,p rovided ar adical anion BDBCC À and adianion BDBC 2À ,respectively;while chemical oxidation by silver hexafluoroantimonate(V), converted the neutral compound to an open-shell singlet diradical dication (BDBCCC) 2+ .T he structural consequences of both electronreduction and oxidation were closely related to the release of ring-strain of the bowl-shaped p-scaffold and imposed steric hindrance of the hexagonal bridge.I na ddition, the unusual open-shell nature of the dication could mainly be attributed to the changing of localized antiaromaticity in the closed-shell structure to delocalized character in the biradical, and thus the emergence of weakly bonded p-electrons.

Redox‐Active Hydrocarbons: Isolation and Structural Determination of Cationic States toward Advanced Response Systems

“…In addition, delocalization of a charge over an extended π‐conjugation is effective for the synthesis and isolation of charged species as stable entities with carbon‐centered ions. Indeed, aromatic hydrocarbons are known to exhibit unique electrochemical and spectroscopic properties based on their π‐conjugated systems, and several systems capable of redox interconversion between neutral and cationic (anionic) states have been reported by effectively stabilizing the charged state by embedding heteroatoms or introducing heteroatom‐substituents into the π‐skeleton [21–32] . On the other hand, since it is difficult to stabilize such charged species without heteroatoms, the development of pure hydrocarbon‐based redox systems is challenging from the viewpoint of the stability of cationic (anionic) species.…”

“…Indeed, aromatic hydrocarbons are known to exhibit unique electrochemical and spectroscopic properties based on their π-conjugated systems, and several systems capable of redox interconversion between neutral and cationic (anionic) states have been reported by effectively stabilizing the charged state by embedding heteroatoms or introducing heteroatom-substituents into the π-skeleton. [21][22][23][24][25][26][27][28][29][30][31][32] On the other hand, since it is difficult to stabilize such charged species without heteroatoms, the development of pure hydrocarbonbased redox systems is challenging from the viewpoint of the stability of cationic (anionic) species. In general, even though the incorporation of heteroatoms is an effective method for stabilizing charged species and modulating the electronic properties of organic molecules, the potential instability of bonds between carbon and heteroatoms in the neutral state may reduce fatigue resistance in organic electronic applications.…”

Synthesis, electronic properties, and self-assembly of an alkylated dibenzo(biscorannulene)

“…Accordingly, molecules of 1 adopt antiand syn-geometries depending on the conformation of each corannulene unit. 7,32 Zero-point-corrected energy values from DFT simulations under vacuum predict a negligible energy difference between the conformers (0.1 kcal mol −1 ). A variabletemperature (VT) 1 H NMR spectroscopic study of 1 in CD 2 Cl 2 from −90 °C to 20 °C showed that the peak intensities weaken upon lowering the temperature (Fig.…”

“…1b). 27,32 Various interaction modes are expected for both geometries, including interdigitated structures, parallel-stacked structures, and stacked structures with a lateral shift (Fig. 1c).…”

“…Another biscorannulene bridged by a benzene ring adopts multi-step redox states through chemical oxidation and reduction. 32 The synthesis and properties of biscorannulenes bridged by anthracene or more extended π-units have also been reported. [33][34][35] Further extended systems with egg-box-shaped nanographene structures have been produced very recently via the electrochemical polycondensation of corannulene.…”