Rotational signatures of dispersive stacking in the formation of aromatic dimers

The aggregation of aromatic species is dictated by inter‐ and intramolecular forces. Not only is characterizing these forces in aromatic growth important for understanding grain formation in the interstellar medium, but it is also imperative to comprehend biological functions. We report a combined rotational spectroscopic and quantum‐chemical study on three structurally related aromatic homo‐dimers to analyse the influence of structural flexibility and the presence of heteroatoms on dimer formation. The dimers are comprised of diphenylether, dibenzofuran, and fluorene. The obtained structural information shows clear similarities between the dimers despite their qualitatively different molecular interactions. All dimers are dominated by dispersion interactions such as CH‐π or π‐π, but the dibenzofuran dimer is also influenced by repulsion between the free electron pairs of the oxygen atoms and the π clouds. This study lays the groundwork for understanding the first steps of molecular aggregation in systems with aromatic residues.

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