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

Research output: Contribution to journalJournal article

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.
Original languageEnglish
JournalThe Journal of Physical Chemistry Part B: Condensed Matter, Materials, Surfaces, Interfaces & Biophysical
Volume120
Pages (from-to)11279-11286
Number of pages8
ISSN1520-6106
DOIs
Publication statusPublished - 12 Oct 2016

Keywords

  • Ionic liquid
  • Infra red
  • proton transfer
  • NMR
  • DFT calculations
  • rheology
  • synthesis

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