Effect of alkyloxy substituents on mesomorphic and photophysical properties of star-shaped tristriazolotriazines

Two series of tristriazolotriazine (TTT) derivatives with different length of aliphatic substituents have been synthesised in order to study the influence of peripheral substitution on mesomorphism and fluorescent properties of these star-shaped compounds. Homologues with methoxy and alkyloxy substituents (series 1) are non-mesogenic, in contrast to homologues with two alkyloxy substituents (series 2) exhibiting columnar mesophase. The results obtained by quantum-chemical calculations for the monomers and dimers of non-mesogenic TTT series and their comparison with truxenone derivatives having identical substituents made it possible to establish the reasons that deprive series 1 of mesogenity. Compounds of both TTT series possess good solubility in organic solvents and capable of specific interactions with solvents in the ground and excited states. They form fluorescenting floating layers and thin films. An analysis of the fluorescence spectra showed a high potential for their application, in particular, in the field of molecular sensing and precise non-invasive control.