Estimate of benzene-triphenylene and triphenylene-triphenylene interactions: A topic relevant to columnar discotic liquid crystals

The interaction potential energy of several benzene-triphenylene and triphenylene-triphenylene dimer arrangements has been calculated by a Moller-Plesset second order perturbation theory with a suitably modified 6-31G* basis set. This approach, already tested and successfully employed on the benzene dimer, is presently shown to reproduce, with a level of accuracy comparable to other computationally affordable methods, the interaction potential energy of a few representative configurations of naphthalene dimer, for which high-level ab initio reference data exist. Thus, the method has been confidently applied to the interaction energy computation of the above-mentioned more complex dimers, for which high-level ab initio calculations are yet unfeasible. Comparisons have been made with the results obtained with an empirical force field and, as regards the benzene-triphenylene dimer, also with a dispersion corrected DFT method. The computed set of data may contribute to comprehending how aromatic interactions evolve with the ring size, a subject of general interest and particularly relevant to the field of columnar discotic liquid crystals, where the central cores of the mesogenic molecules often consist of triphenylene or triphenylene-derived units. In this case, attention has been paid to the determination of the favorable relative disposition of the monomers when the aromatic planes are parallel to each other, which is requisite information for their potential use as organic semiconductors.