title: A Conformationally Stable Contorted Hexabenzoovalene.
abstract: Contorted two-dimensional aromatic molecules are fascinating synthetic targets because they are molecular "cutouts" of nonplanar graphene structures, fullerenes, or carbon nanotubes. In most cases, the curvature is introduced by the implementation of either five-, seven-, or eight-membered rings into the fused aromatic plane. Curvature can also be generated for two-dimensional systems consisting of six-membered rings exclusively, by the introduction of cove or fjord regions. The synthesis of a polycyclic aromatic hydrocarbon (PAH) that contains two peripheral triptycene units and six tert-butyl substituents is described. As a result of steric repulsion, the structure is highly contorted with two phenylene blades of the peripheral triptycene units oriented almost coplanar with respect to each other at a distance of 16 Å, as has been verified by single crystal X-ray diffraction. The conformation is stable in solution even at a temperature of 150 °C. Additionally, internal tert-butyl groups could be selectively removed, allowing a UV/Vis-spectroscopic comparison of two structures with the same π-system, but different degrees of contortion.
authors.affiliation: Organisch-Chemisches Institut, Ruprecht-Karls-Universität, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany.
authors.forename: Kevin
authors.initials: K
authors.lastname: Baumgärtner
authors.affiliation: Organisch-Chemisches Institut, Ruprecht-Karls-Universität, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany.|Institut für Organische Chemie, Universität Würzburg, Am Hubland, 97074, Würzburg, Germany.
authors.forename: Ana Lucia
authors.initials: AL
authors.lastname: Meza Chincha
authors.affiliation: Interdisziplinäres Zentrum für Wissenschaftliches Rechnen, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 205, 69120, Heidelberg, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Dreuw
authors.affiliation: Organisch-Chemisches Institut, Ruprecht-Karls-Universität, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Rominger
authors.affiliation: Organisch-Chemisches Institut, Ruprecht-Karls-Universität, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Mastalerz
keywords: X-ray diffraction; aromaticity; ovalenes; polycyclic aromatic hydrocarbons; triptycene