The Effect of Dispersion on the Structure of Diphenyl Ether Aggregates

• Published in: Angewandte Chemie International Edition 2018-07, Vol.57 (30), p.9534-9537
• Main Authors: Dietrich, Fabian, Bernhard, Dominic, Fatima, Mariyam, Pérez, Cristóbal, Schnell, Melanie, Gerhards, Markus
• Format: Article
• Language: English
• Subjects: Aggregates; Alcohols; Diphenyl ether; Dispersion; Infrared radiation; Isomers; molecular complexes; non-covalent interactions; Preferences; rotational spectroscopy; Theoretical analysis; Twisting; vibrational spectroscopy
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201801842

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. In the balance: The critical balance of two hydrogen bonding motifs is discussed by looking at a series of aggregates between diphenyl ether and water or different alcohols. Unexpected structural preferences were observed and explained by calculations, in which different energy contributions, including dispersion, were extracted. For the experimental investigations, combined IR/UV and microwave spectroscopy were performed.