Evaluation of Cation-Anion Interaction Strength in Ionic Liquids

• Type: Article in International Scientific Journal
• Date: 2011

Authors

Ana M Fernandes (Author) Other; Marisa A A Rocha (Author) Other; Mara G Freire (Author) Other; Isabel M Marrucho (Author) Other; Joao A P Coutinho (Author) Other; Luis M N B F Santos (Author) FCUP

Journal

Title: Journal of Physical Chemistry B

Vol. 115 No. 24

Pages: 4033-4041

ISSN: 1520-6106

Publisher: American Chemical Society

Indexing

ISI Web of Knowledge - 208 Citations

Scopus - 215 Citations

Scientific classification

FOS: Natural sciences > Chemical sciences

Other information

Authenticus ID: P-002-SDP

DOI: 10.1021/jp201084x

Abstract (EN): Electrospray ionization mass spectrometry with variable collision induced dissociation of the isolated [(cation)(2)anion](+) and/or [(anion)(2)cation] ions of imidazolium-, pyridinium-, pyrrolidinium-, and piperidinium-based ionic liquids (Its) combined with a large set of anions, such as chloride, tetrafluoroborate, hexafluorophosphate, trifluoromethane-sulfonate, and bis[(trifluoromethyl)sulfonyl]imide, was used to carry out a systematic and comprehensive study on the ionic liquids relative interaction energies. The results are interpreted in terms of main influences derived from the structural characteristics of both anion and cation. On the basis of quantum chemical calculations, the effect of the anion upon the dissociation energies of the ionic liquid pair, and isolated [(cation)(2)anion](+) and/or [(anion)(2)cation](-) aggregates, were estimated and are in good agreement with the experimental data. Both experimental and computational results indicate an energetic differentiation between the cation and the anion to the ionic pair. Moreover, it was found that the quantum chemical calculations can describe the trend obtained for the electrostatic cation anion attraction potential. The impact of the cation anion interaction strengths in the surface tension of ionic liquids is further discussed. The surface tensions dependence on the cation alkyl chain length, and on the anion nature, follows an analogous pattern to that of the relative cation anion interaction energies determined by mass spectrometry.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 9