title: Thermotropic properties and molecular packing of discotic tristriazolotriazines with rigid substituents.
abstract: Tristriazolotriazines with a threefold dialkoxyaryl substitution have been prepared by Huisgen reaction of cyanuric chloride and the corresponding tetrazoles. Although these dyes show a negative or inverted solvatochromism of the UV/Vis absorption, their fluorescence is strongly positive solvatochromic. These discotic fluorophores are also emissive in their solid state and in their broad liquid-crystalline mesophase. The structural study indicates that the thermotropic properties and organization of these systems can be well tuned by the steric demand of the aryl groups. Depending on the substituents, the compounds showed either a pure crystalline phase or a highly complex helical superstructure with a characteristic liquid-crystalline phase at elevated temperatures. Changing the steric demand of the attached aryls allowed controlling the discs arrangement within the columnar helix, which is of great importance for the molecular orbital overlap.
authors.affiliation: Institute for Organic Chemistry, Johannes Gutenberg University Mainz, Duesbergweg 10-14, 55099 Mainz (Germany), Fax: (+49) 6131-39-25338.
authors.forename: Thorsten
authors.initials: T
authors.lastname: Rieth
authors.forename: Tomasz
authors.initials: T
authors.lastname: Marszalek
authors.forename: Wojciech
authors.initials: W
authors.lastname: Pisula
authors.forename: Heiner
authors.initials: H
authors.lastname: Detert
keywords: X-ray scattering; fluorescence; helical superstructures; liquid crystals; mesophases