Surface-induced chirality in a self-assembled monolayer of discotic liquid crystal

We report the observation by scanning tunneling microscopy of the emergence of chirality through the self-assembly into monolayers of nonchiral discotic liquid crystals, hexakis-2,3,6,7,10,11-alkyloxytriphenylene. on the nonchiral surface of highly oriented pyrolitic graphite. A chiral ordering transition appears when increasing the triangular aspect ratio of the molecules, through the tuning of alkoxy-side-chain length. The mechanism of this symmetry breaking, which involves steric hindrance, superlattice formation, and conformational mobility, can be understood in the light of a simple frustrated triangular Ising net. [S0031-9007(98)05401-5].