|Titolo||Structure and vibrational features of the protic ionic liquid 1,8-diazabicyclo[5.4.0]-undec-7-ene-8-ium bis(trifluoromethanesulfonyl)amide, [DBUH][TFSI]|
|Tipo di pubblicazione||Articolo su Rivista peer-reviewed|
|Anno di Pubblicazione||2021|
|Autori||Triolo, A., Paolone A., Sarra A., Trequattrini F., Palumbo O., Appetecchi Giovanni Battista, F. Celso Lo, Chater P., and Russina O.|
|Rivista||Journal of Molecular Liquids|
|Parole chiave||Amides, Bis(trifluoromethane sulfonyl)imide, DFT calculation, Far-ir spectroscopy, Hydrogen, Hydrogen bonds, Ionic liquids, IR-spectroscopy, molecular dynamics, Neutralisation, Protic ionic liquids, Strongest acid, Structure features, Vibrational features, X -ray scattering, X ray scattering|
The Protic Ionic Liquid (PIL) formed by neutralization of the super-strong base 1,7-diazabicyclo[5.4.0]undec-7-ene (DBU) with the super-strong acid bis(trifluoromethanesulfonyl)-imide (TFSI), indicated as [DBUH][TFSI], has been investigated. Its chemical physical properties and structural features have been explored using a synergy of experimental and computational tools. Molecular Dynamics-rationalised X-ray diffraction patterns highlight the major role played by hydrogen bonding (HB) in affecting morphology in this PIL. A comparison between HB features in this and in related PILs has been presented, on the base of far-IR experiments and DFT analysis. Indications of a weaker HB interaction in [DBUH][TFSI] in comparison with [DBUH][TfO], consistently with their ΔpKa difference, have been observed and rationalised in terms of geometrical properties of the main conformers contributing to the experimental spectra. In the liquid phase of [DBUH][TFSI] a particularly large conformational disorder is observed and the corresponding large dispersion of the frequencies of the HB stretching modes leads to a broad absorption band without a well defined peak. On the contrary, well detectable HB related absorptions are observable in the solid phase of [DBUH][TFSI] and at all temperatures in [DBU][TfO], where less configurational disorder occurs. © 2021 Elsevier B.V.
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