Computational studies of π–π interactions in dimers of heterosubstituted sumanenes

A computational study of dimers of heterosubstituted sumanenes has been carried out using a dispersion-corrected density functional theory method. In the heterosubstituted systems, the three bridging CH 2 groups of sumanene have been replaced by O, NH, and S. For each dimer system, two motifs, staggered and eclipsed forms, were considered. The most stable geometry was the staggered stacked concave–convex motif where one monomer was rotated by 60° from the eclipsed configuration. The calculated binding energies and equilibrium distances of the staggered concave–convex dimers are predicted to be 20.1 kcal/mol and 3.7 Å for the parent sumanene molecule, 17.4 kcal/mol and 3.8 Å, 12.3 kcal/mol and 3.7 Å, and 16.6 kcal/mol and 3.7 Å for the NH-, O-, and S-substituted analogs, respectively. The binding energies of the dimers have been analyzed in terms of dipole–dipole contributions, dispersion contributions, and C–H···π interactions.