Highly Ordered Columnar Superlattice Nanostructures by Thermotropic Self-assembly of Tripheylene-based Discotics

A series of triphenylene esters with two ester groups at 2,3-, 2,7-, 2,6- and 3,6- substituent positions was successfully synthesized and fully investigated. Their self-assembly properties were exhaustively examined by DSC, POM, 1DXRD, 2DXRD, SAXS, TEM methods together with EDM, ESP calculations. It was unexpected that 3,6-substituted triphenylene ester formed an uncommonly helical hexagonal columnar superlattice structure made up of 91 right-handed helixes with a pitch of 60.3A. Its helical superlattice structure was further studied by transmission electron microscopy and found that the scale was at nanometer. Ultimately, the bipolar charge carrier mobility was measured by time-of-flight method at the order up to 10-1 cm2V-1s-1. The formation of this helical superlattice nanostructure which was firstly reported by us no doubt improved their electronic properties and made them more attractive in organic electronics.