Triphenylene based discotic liquid crystals as self-assembled monolayers

A side chain w-thiol substituted triphenylene derivative was synthesised to investigate self-organisation of the triphenylene head group within a self-assembled monolayer (SAM). Scanning tunneling microscopy (STM) was used to characterise the ordering within the monolayer and the mesogenic head groups were found to orient with the discotic plane normal to the substrate forming columnar structures with the principal axis in plane of the monolayer. The overall degree of ordering within the monolayer and the persistence length of the columnar structures was increased by insertion of the SAM into trinitrofluorenone (TNF) solution. By altering the imaging parameters, the STM tip could be used to perturb the ordering in the monolayer and subsequent re-annealing of some of the columns was observed on a time scale of about a minute.