Parallel Polar Dimers in the Columnar Self-Assembly of Umbrella-Shaped Subphthalocyanine Mesogens

The self-assembly of umbrella-shaped mesogens is explored with subphthalocyanine cores and oligo(thienyl) arms with different lengths in the light of their application as light-harvesting and photoconducting materials. While the shortest arm derivatives self-assemble in a conventional columnar phase with a single mesogen as a repeating unit, the more extended derivatives generate dimers that pile up into liquid crystalline columns. In contrast to the antiparallel arrangement known from single crystals, the present mesogens align as parallel dimers in polar columnar phases as confirmed by X-ray scattering, experimental densities, dielectric spectroscopy, second harmonic generation, alignment, and conductivity studies. UV-vis and fluorescence spectroscopies reveal a broad absorption in the visible range and only weak emission of the Q-band. Thus, these light-collecting molecules forming strongly polar columnar mesophases are attractive for application in the area of photoconductive materials.

Automated summary

The self-assembly of umbrella-shaped mesogens with subphthalocyanine cores and oligo(thienyl) arms of different lengths was explored for their application as light-harvesting and photoconducting materials. The molecules form liquid crystalline columns in polar columnar phases, showing broad absorption in the visible range but weak emission of the Q-band. This makes them attractive for use in the field of photoconductive materials.