The synthesis of C3‐symmetrical tristriazolotriazines with conjugated arms and lateral alkoxy side chains was performed by a threefold condensation of cyanuric chloride with tetrazoles. Conjugated π segments include phenyl, tolane, and its phenylethynyl‐elongated homologue. Disclike and a dendritic molecule have been obtained, and two compounds with a 3,4,5‐tris(octyloxy) substitution form broad thermotropic mesophases. The linear optical properties, solvatochromism of the fluorescence, acidochromism, and the two‐photon absorption efficiency of selected compounds are reported.

Star-shaped discotic liquid crystals with columnar superstructures constitute ah ighly interesting class of organic materials. Phenyl-substituted tris [1,2,4]triazolo- [1,3,5]triazine, prepared by aH uisgen reaction of phenyltetrazole and cyanuric chloride, represents an excellent core for discotic liquid crystals (DLCs). The thermals tability is not perfect, at temperatures above the clearing point, as uccessive threefold isomerization leads to a highly planar, C 3 -symmetrical isomer,w hich mainly differs in the orientation of the aryl substituents to the centre of the molecule.Anew class of discotic liquid crystals has been obtained:E quipped with peripheral alkoxyc hains both isomers can form broad thermotropic mesophases. The optical, thermal,a nd physical properties were investigated by polarized optical microscopy,d ifferentials canning calorimetry,w ide-angle X-ray scattering, UV/Vis absorption and fluorescence spectroscopic measurements. The thermotropic properties are decisively affected by the molecular structure of the isomers, isomerisation leads to higher meltingp oints but also the loss or even gain of mesomorphism is observed.Organic p-conjugated systems, small molecules [1] and polymers, [2] are of great interest for sensing, optical and electronic applications.[3] The group of discotic liquid crystals (DLC) offers the additional feature of self-organization, often as ac olumnar arrangement resulting in anisotropic properties, for example, one-dimensional charge transport in the liquid-crystalline phase.[4] Typical DLCs consist of electron-rich polycyclic aromatic units,f or example, triphenylene or hexabenzocoronene, [5] whereas DLCs with an electron deficientc orea re rather scarce.[6] One of the youngest members of this group is the tris[1,2,4]triazolo-[1,3,5]triazine (TTT), at etracyclic, nitrogenrich, and C 3 -symmetrical analogue of triphenylene. The first TTT,t riphenyl-TTT 1 (R i = H), hasb een prepared by Huisgen, [7] its shape is at etracyclic plane with three phenylr ings sticking out of the bays. To avoid steric compression,t he substituents are twisted out of the plane with dihedral angles up to 808. [8,9] In 2008, Gallardo [8,10] and Glang [11] recognizedt he suitability of the TTT as ac ore for discotic liquid crystals. These propellers (e.g. 1b-1h)w ith six to nine alkoxy groups on the outer rim can form broad mesophases. Polarized optical microscopy (POM) revealed the characteristic textures of ac olumnar phase and wide and small-angle X-ray diffraction (WAXS and SAXS, respectively) on pre-orientated filaments confirmed ah exagonal arrangement of the columns in the mesophase and complex helical superstructures in the solid state. [12] All these TTTs with a 'tangential' orientation (t-TTT) of the alkoxyphenyl substituents wereo btained by the Huisgen route. An independent access to TTTsw as reported by Ta rtakovsky [13] in 2005:t hermocyclization of three 5-chloro-3-phenyl-1,2,4-triazole molecules resulted in a C 3 -symmetrical triphenyl tristriazolotriazine (2,R ...

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.

Tristriazolotriazines with a threefold 3,5-dialkoxyphenyl substitution were prepared from the corresponding phenyltetrazoles and cyanuric chloride. These star-shaped compounds are discotic liquid crystals that form broad and stable thermotropic mesophases. The thermal behaviour was studied by DSC and polarizing optical microscopy. An increasing length of the side chains reduces the phase transition temperatures, this effect is more pronounced for the crystalline to mesophase transition than for the clearing temperature. XRD on an oriented sample revealed a hexagonal columnar structure for the mesophase. All TTTs emit a strong fluorescence in the UV-violet region.

Tristriazolotriazines (TTTs) with a threefold alkoxyphenyl substitution were prepared and studied by DSC, polarized optical microscopy (POM) and X-ray scattering. Six pentyloxy chains are sufficient to induce liquid-crystalline behavior in these star-shaped compounds. Thermotropic properties of TTTs with varying substitution patterns and a periphery of linear chains of different lengths, branching in the chain and swallow-tails, are compared. Generally, these disks display broad and stable thermotropic mesophases, with the tangential TTT being superior to the radial isomer. The structure–property relationships of the number of alkyl chains, their position, length and structure were studied.