Authors:	Tober, Natalie Rieth, Thorsten Lehmann, Matthias Detert, Heiner
Title:	Synthesis, thermal, and optical properties of tris(5-aryl-1,3,4-oxadiazol-2-yl)-1,3,5-triazines, new star-shaped fluorescent discotic liquid crystals
Online publication date:	31-May-2022
Year of first publication:	2019
Language:	english
Abstract:	The synthesis of tris(aryloxadiazolyl)triazines (TOTs), C3-symmetrical star-shaped mesogenes with a 1,3,5-triazine center, 5-phenyl-1,3,4-oxadiazole arms, and various peripheral alkoxy side chains is reported. Threefold Huisgen reaction on a central triazine tricarboxylic acid and suitable aryltetrazoles yields the title compounds. Selected analogues with a benzene center are included in this study and allow for an evaluation of the impact of the central unit on the physical properties. Thermal (differential scanning calorimetry, DSC; polarization optical microscopy, POM), optical (UV/Vis, fluorescence), electric (time of flight, TOF), and structural (single crystal; wide-angle X-ray scattering, WAXS) properties of these compounds were investigated. The modification of alkoxy chain length and substitution pattern allows for a tuning of the physical properties. TOTs emit blue to yellow light, depending on conjugation length, donor–acceptor substitution, and solvent polarity, whereas concentration quenches and aggregation enhances the emission. The width of the mesophases is typically around ΔT=100–150 K but can even exceed 220 K. Polarization optical microscopy and X-ray diffraction on oriented filaments reveal that TOTs are highly ordered liquid crystals (LCs) with long-range hexagonal columnar structure.
DDC:	540 Chemie 540 Chemistry and allied sciences
Institution:	Johannes Gutenberg-Universität Mainz
Department:	FB 09 Chemie, Pharmazie u. Geowissensch.
Place:	Mainz
ROR:	https://ror.org/023b0x485
DOI:	http://doi.org/10.25358/openscience-7055
Version:	Published version
Publication type:	Zeitschriftenaufsatz
License:	CC BY-NC-ND
Information on rights of use:	https://creativecommons.org/licenses/by-nc-nd/4.0/
Journal:	Chemistry - a European journal 25 67
Pages or article number:	15295 15304
Publisher:	Wiley-VCH
Publisher place:	Weinheim
Issue date:	2019
ISSN:	1521-3765
Publisher DOI:	10.1002/chem.201902975
Appears in collections:	JGU-Publikationen