A Reinvestigation of the Ionic Liquid Diisopropylethylammonium Formate by NMR and DFT Methods

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Abstract

The complex between diisopropylethylamine (DIPEA) and formic acid has been reinvestigated. Mixing the compounds in the ratio 1:1 leads to a phase separation in which the upper phase is DIPEA, the lower phase is the “ionic liquid” named DIPEF. A combined NMR and DFT study shows that the lower phase primarily is formic acid:formate and diisopropyl-ammonium ions in the ratio 2:1 (acid:base) plus the formic acid dimer. Addition of more acid leads to more and more of the acid dimer. The proton transfer in the system is 65-80%. The structural picture presented in this paper is very different from that presented elsewhere. However, the present picture should be considered using acids and bases with a pKa difference less than 8. The formic acid content in the DIPEF ionic liquid causes desorption of the dye-sensitized solar cell (DSC) dye N719 from the photo anode and DIPEF is therefore not a suitable electrolyte for DSCs.
OriginalsprogEngelsk
TidsskriftThe Journal of Physical Chemistry Part B: Condensed Matter, Materials, Surfaces, Interfaces & Biophysical
Vol/bind120
Sider (fra-til)11279-11286
Antal sider8
ISSN1520-6106
DOI
StatusUdgivet - 12 okt. 2016

Emneord

  • ionic liquid
  • NMR
  • rheology
  • DFT calculations
  • synthesis
  • proton transfer

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