series of 1,3,5-benzenetrisamide derivatives with three hexaalkoxytriphenylene pendant groups were prepared, in which the triphenylene groups are connected to the central 1,3,5-benzenetrisamide core through a flexible spacer. The length of this spacer, as well as the size of the ortho-substituent at the triphenylene core, influences the columnar packing of these molecules. All compounds show liquid crystalline behavior with high isotropization temperatures. Different columnar hexagonal phases (Colh, Colhp, Colobl and Colr) have been identified using optical polarization microscopy, differential scanning calorimetry and X-ray diffraction. A chiral 1,3,5-benzenetrisamide derivative forms columnar stacks with a single helical sense, both in an apolar solvent and in a film, as observed by circular dichroism studies. Pulse radiolysis time-resolved microwave conductivity (PR-TRMC) studies show that the high ordering in a Colhp phase results in high charge carrier mobilities. On the other hand, the highest mobility was observed for the chiral compound, which has a Colr ordering.
- liquid-crystalline materials
- charge-carrier mobility
- resolved microwave conductivity
- helical supramolecular polymers
- crowded aromatics
Paraschiv, I., de Lange, K., Giesbers, M., van Lagen, B., Grozema, F. C., Abellon, R. D., Siebbeles, L. D. A., Sudhölter, E. J. R., Zuilhof, H., & Marcelis, A. T. M. (2008). Hydrogen-bond stabilized columnar discotic benzenetrisamides with pendant triphenylene groups. Journal of Materials Chemistry, 18, 5475-5481. https://doi.org/10.1039/b805283b