title: Pushing steric bias in the Scholl reaction to access liquid crystalline crown ethers.
abstract: Sterically congested o-terphenyl crown ethers with alkoxy substituents at the 2,3,4-position or 3,4,5-position were synthesized from the corresponding tetrabromodibenzo[15]crown-5 and the corresponding boronic acids or borolanes via Suzuki cross-coupling and subsequently cyclized to the corresponding triphenylenes utilizing the Scholl reaction. Both series of compounds were investigated by differential scanning calorimetry, polarizing optical microscopy, and X-ray diffraction (SAXS, WAXS) regarding their mesomorphic properties. While all but one of the 3,4,5-substituted derivatives displayed liquid crystalline behavior (Col(h) and Col(r)), only the 2,3,4-substituted triphenylene with the shortest alkoxy chains was liquid crystalline (Col(r)).
authors.affiliation: Institut für Organische Chemie, Universität Stuttgart , 70569 Stuttgart, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Wöhrle
authors.forename: Jochen
authors.initials: J
authors.lastname: Kirres
authors.forename: Martin
authors.initials: M
authors.lastname: Kaller
authors.forename: Markus
authors.initials: M
authors.lastname: Mansueto
authors.forename: Stefan
authors.initials: S
authors.lastname: Tussetschläger
authors.forename: Sabine
authors.initials: S
authors.lastname: Laschat