The introduction of different functional groups at the periphery chains of discotic liquid crystals is a general strategy for the design and synthesis of new promising mesomorphic materials. Starting from triphenylene 2,3-dicarboxylic acid and anhydride, two kinds of triazole-modified triphenylene 2,3-dicarboxylic esters and 2,3-dicarboxyimides were synthesized via nucleophilic substitution and subsequent Cu-catalyzed azide-alkyne click reactions. Thermogravimetric analysis (TGA) measurements indicated that the prepared precursors and desired compounds exhibit good thermal stability with the temperatures of 5% weight loss in the range of 274~389 ℃. The thermal behavior and mesomorphism of these compounds were studied by differential scanning calorimetry (DSC), polarised optical microscopy (POM) and variable temperature X-ray diffraction (XRD) experiments. With the exceptions of esters 3a and 3b, which both show a single crystalline phase with a rather high melting temperature, the key precursors (2 and 5) and two triazole-modified imides (6a and 6b) all exhibit enantiotropic hexagonal columnar phase. Besides, the prepared triazole-bridged imide dimer 10 is a room temperature liquid crystalline material and has a wider mesophase range of 173 ℃ from 8 ℃ up to 181 ℃. XRD confirmed the existence of two columnar mesophases with different degrees of order in dimer 10, unambiguously characterized as Col_h1 and Col_h2. Due to the triazole moieties, additionally, all the triazole-modified esters and imides can form organogels in some organic solvents. Notably dimer 10 exhibits strong gelation ability in 1,2-dichloroethane or 1,4-dioxane with a very low critical gel concentration (1 mg/mL). In comparation, the precursor compounds 2 and 5, which do not possess any triazole ring in structure show no tendency to gelate, indicating that the strong dipole-dipole and π-π interactions between the triazole rings play an important role in the formation of the gel. Thus triazole-modified triphenylene 2,3-dicarboxyimides represent an interesting example of molecules exhibiting both liquid crystalline and gelling properties. This investigation sheds light on the potential applicability of the triazole-modified triphenylene 2,3-dicarboxyimides as promising multifunctional materials.

Key words: discotic liquid crystal, self-assembly, organogels, triphenylene 2,3-dicarboxylic ester, triphenylene 2,3-dicar- boxyimide, 1,2,3-triazole