Acta Phys. -Chim. Sin. ›› 2009, Vol. 25 ›› Issue (06): 1185-1189.doi: 10.3866/PKU.WHXB20090628

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NMR Study on the Aggregation of [C4mim][BF4] in D2O and CDCl3

ZHAI Cui-Ping, LIU Xue-Jun, ZHAO Yang, WANG Jian-Ji   

  1. College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475001, Henan Province, P. R. China|School of Chemistry and Environmental Science, Henan Normal University, Xinxiang 453007, Henan Province, P. R. China
  • Received:2008-12-26 Revised:2009-03-11 Published:2009-06-05
  • Contact: ZHAI Cui-Ping


Aggregation behavior of the room temperature ionic liquid (IL) [C4mim][BF4] in D2O and CDCl3 was studied by the nuclear magnetic resonance (NMR) technique. Results indicated that proton chemical shifts for the cation of the IL shift downfield as the molar fraction of IL increases. These proton chemical shifts change rapidly at lower concentrations and level off at higher concentrations in D2O. Chemical shifts for H2 on the cation shift upfield. H4, H5, methyl and methylene protons next to the nitrogen of the cation shift downfield as the molar fraction of IL increases while the NMR signals for each proton changes in CDCl3. The critical aggregation concentration (CAC) and the aggregation number were determined by applying mass action theory to the concentration dependence of the 1H NMR chemical shifts. These results are discussed based on the interactions between the cation and the anion and those between the IL and the solvents.

Key words: NMR, Ionic liquid, D2O, CDCl3, Aggregation