Molecule and molecular ion structures of triphenylene, fluoro-triphenylene and hydroxy-triphenylene have been studied at the level of B3LYP/6-31G**, and their most stable configurations were obtained. On the basis of the most stable geometries, the relationship of the total energy with rotation degrees and intermolecular distances between the dimer have been calculated, and the lowest energy point was obtained. Based on the semiclassical model of the charge transfer, electric charge transfer constants of the triphenylene and hydroxy-triphenylene have been studied. Introduction of fluorine and hydroxy groups made the positive charge transfer reduced clearly, but had little effect on negative charge transfer.

Key words: triphenylene, charge transfer, discotic liquid crystal