Binding Energy of π-π Stacking Fluoranthene and Benzofluoranthene Derivatives Dimers: A Theoretical Study

Abstract

Soot Nanoparticles formation is assumed to be associated to dimerization, trimerization, and so on, of polycyclic aromatic hydrocarbons (PAH). Thus, structural properties of such a kind of molecules should be well understood in order to clarify the impact of these incipient soot nanoparticles on environment and health. In the present study, structural parameters of Fluoranthene C16H10 and Benzo-[a], [b], [j] and [k]-fluoranthene C20H12 are reported by quantum mechanics. Both Full Parallel Sandwich (FSP) and Partial Parallel Sandwich (PPS) conformations of these dimers have been considered. The calculated binding energies, corrected for BSSE by the counterpoise method, at different intermolecular distances have been fitted to a Morse potential. The equilibrium distances are predicted to be 3.7 Å for all the FPS dimers and from 3.4 to 3.6 Å for the PPS ones. The strongest binding energies are found in the range of 11 kcal/mol for all the FPS and for some of the PPS dimers. For the conformations with the same interacting cycles number, the binding energy varies from 6 to 11 kcal/mol. The structure of the dimer has an impact on the dispersion-type interactions.