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.
|Tidsskrift||The Journal of Physical Chemistry Part B: Condensed Matter, Materials, Surfaces, Interfaces & Biophysical|
|Status||Udgivet - 12 okt. 2016|
- ionic liquid
- DFT calculations
- proton transfer
Hansen, P. E., Lund, T., Krake, J., Spanget-Larsen, J., & Hvidt, S. (2016). A Reinvestigation of the Ionic Liquid Diisopropylethylammonium Formate by NMR and DFT Methods. The Journal of Physical Chemistry Part B: Condensed Matter, Materials, Surfaces, Interfaces & Biophysical, 120, 11279-11286. https://doi.org/10.1021/acs.jpcb.6b08561