Inter‐ and intramolecular aryl‐aryl‐interactions in partially fluorinated ethylenedioxy‐bridged bisarenes

Several ethylenedioxy-bridged bisarenes with a variety of type and number of aryl groups were synthesized to study non-co-va-lent dispersion-driven inter- and intramolecular aryl - aryl-interactions in the solid state and gas phase. Intramolecular interactions are pre-fe-rably found in the gas phase. DFT calculations of dispersion-cor-rec-ted energy scans for rotations around the ethy-lene-dioxy-bridge and optimized structures show larger inter-acting aromatic groups to in-crea-se the dispersion energy. Single molecule structures generally a-dopt folded conformations with short intramolecular aryl-aryl-con-tacts. Gas electron diffraction experiments were per-formed exem-pla-rily for 1-(pentafluorophenoxy)-2-(phenoxy)-ethane. A new pro-cedure for struc-ture refinement was developed to deal with the confor-ma-tional com-plexity of such molecules. The results are an experimental con-fir-ma-tion of the existence of folded conformations of this molecule with short -intramolecular aryl-aryl distances in the gas phase. Solid-state struc-tures are dominated by stret-ched structures with-out intra-mo-le-cular aryl - aryl-interactions but in-ter-actions with neigh--boring molecules.