The Effect of Dispersion on the Structure of Diphenyl Ether Aggregates.

Dispersion interactions can play an important role in understanding unusual binding behaviors. This is illustrated by a systematic study of the structural preferences of diphenyl ether (DPE)-alcohol aggregates, for which OH⋅⋅⋅O-bound or OH⋅⋅⋅π-bound isomers can be formed. The investigation was performed through a multi-spectroscopic approach including IR/UV and microwave methods, combined with a detailed theoretical analysis. The resulting solvent-size-dependent trend for the structural preference turns out to be counter-intuitive: the hydrogen-bonded OH⋅⋅⋅O structures become more stable for larger alcohols, which are expected to be stronger dispersion energy donors and thus should prefer an OH⋅⋅⋅π arrangement. Dispersion interactions in combination with the twisting of the ether upon solvent aggregation are key for understanding this preference.