1036711-65-5Relevant articles and documents
Star-shaped oligobenzoates: Non-conventional mesogens forming columnar helical mesophases
Lehmann, Matthias,Jahr, Michael,Donnio, Bertrand,Graf, Robert,Gemming, Sibylle,Popov, Igor
experimental part, p. 3562 - 3576 (2009/05/07)
Star-shaped mesogens with a phloroglucinol or a trimesic acid core and oligobenzoate arms with up to five repeating units have been synthesised. These non-conventional mesogens form various columnar mesophases over a broad temperature range. The liquid-crystal phases were characterised by optical microscopy, differential scanning calorimetry, X-ray diffraction, dilatometry and solid-state NMR spectroscopy. In addition to the high-tem-perature hexagonal columnar phases, the columnar self-assemblies undulate upon cooling and consequently form higher-ordered body-centred orthorhombic columnar 3D structures. A model of Es-shaped folded conformershelically displaced along the columns is proposed. Helical preorganisation in the hexagonal phase precedes the transition to the low-temperature phases. Space filling and nano-segregation compete in the self-organisation process, thus aliphatic chains and the polar oligobenzoate scaffold are not perfectly separated in these star-shaped mesogens.