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Raman spectra of acetonitrile in imidazolium ionic liquids
Author(s) -
Garcia Humberto C.,
de Oliveira Luiz F. C.,
Nicolau Bruno G.,
Ribeiro Mauro C. C.
Publication year - 2010
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.2628
Subject(s) - ionic liquid , raman spectroscopy , acetonitrile , chemistry , ionic bonding , alkyl , polarity (international relations) , ion , molecule , analytical chemistry (journal) , inorganic chemistry , organic chemistry , biochemistry , physics , optics , cell , catalysis
Raman spectra of dilute solutions of acetonitrile in ionic liquids reveal the characteristic features of ionic liquids' polarity. This is accomplished by investigating the Raman bandshape of the ν (CN) band, corresponding to the CN stretching mode of CH 3 CN, which is a very sensitive probe of the local environment. The amphiphilic nature of the CH 3 CN molecule allows us to observe the effect of electron pair acceptor and electron pair donor characteristics on ionic liquids. It has been found that the overall polarity of nine different ionic liquids based on 1‐alkyl‐3‐methylimidazolium cations is more dependent on the anion than cation. The observed wavenumber shift of the ν (CN) band of CH 3 CN in ionic liquids containing alkylsulfate anions agrees with the significant different values previously measured for the dielectric constant of these ionic liquids. The conclusions obtained from the analysis of the ν (CN) band were corroborated by the analysis of the symmetric ν 1 (CD 3 ) stretching mode of deuterated acetonitrile in different ionic liquids. Copyright © 2010 John Wiley & Sons, Ltd.