Pressure effects in a plastic columnar discotic triphenylene

Abstract

The effect of hydrostatic pressure on the structure of a plastic columnar discotic triphenylene has been investigated. The goal was to determine whether pressure can be used to modify electronic properties via changes in structural properties of columnar discotics to any significant extent. The findings are that (i) the intra‐ and inter‐columnar distances are reduced in a nearly isotropic fashion, (ii) that the crystal sizes are reduced and (iii) that a transition takes place from a more highly ordered plastic columnar to a less ordered hexagonal columnar state with increasing pressure. The induced decrease of the molecular distances, amounting to 6% for pressures up to 17 kbar, are clearly too small to induce an appreciable modification of the electronic structure and thus opto‐electronic properties.

Acknowledgements

We gratefully acknowledge the strong support of the Hasylab team with the X‐ray investigations (Dr F. Porsch). Financial support was provided by the Fonds of the Chemische Industrie.