title: Crowded Star Mesogens: Guest-Controlled Stability of Mesophases from Unconventional Liquid-Crystal Molecules.
abstract: The molecular design of crowded hexasubstituted star mesogens based on a benzene core and alternating substitution with oligo(phenylenevinylene) arms and aryl units generates free space between the conjugated arm scaffolds. Various arylcarboxy building blocks, decorated with alkoxy chains, have been incorporated in the void by mixing, hydrogen bonding or covalent bonds to the aryl groups. The mesogens assemble in columnar stacks ranging from soft crystals to rectangular and hexagonal columnar liquid crystals, revealed by polarized optical microscopy, differential scanning calorimetry, X-ray scattering and modelling. The stability of the mesophases is crucially influenced by the binding mode of the arylcarboxy guest building blocks. The origin of the variation in clearing temperature is unravelled by modelling, cohesive energy density considerations and solid-state NMR spectroscopy. The control over the transition temperature is important for the formation of aligned thin films and thus for potential applications.
authors.affiliation: Institute of Organic Chemistry & Center for Nanosystems Chemistry, University of Würzburg, Am Hubland, 97074, Würzburg, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Lehmann
authors.affiliation: Institute of Organic Chemistry & Center for Nanosystems Chemistry, University of Würzburg, Am Hubland, 97074, Würzburg, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Maier
authors.affiliation: Institute of Organic Chemistry & Center for Nanosystems Chemistry, University of Würzburg, Am Hubland, 97074, Würzburg, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Grüne
authors.affiliation: Institute of Organic Chemistry & Center for Nanosystems Chemistry, University of Würzburg, Am Hubland, 97074, Würzburg, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Hügel
keywords: X-ray scattering; host-guest systems; liquid crystals; nanosegregation; star mesogens