The alternation effect in ionic liquid homologous series

Gabriela Adamová, José N. Canongia Lopes*, Luís Paulo N Rebelo, Luís M N B Santos, Kenneth R. Seddon, Karina Shimizu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

31 Citations (Scopus)


A recent report on a density odd-even alternation effect in a homologous series of ionic liquids (alkyltrioctylphosphonium chlorides, with the linear alkyl group ranging from ethyl to decyl) led to the detection of a similar trend in another ionic liquid family based on a different cation (1-alkyl-3- methylimidazolium). Ab initio calculations and Molecular Dynamics simulations of the corresponding ions confirmed that the charge distribution along the alkyl side chains and the conformations adopted by them are not the direct cause of the odd-even effect. The simulations also showed that all cation side chains tend to adopt transoid conformations that pack head-to-head in the liquid phase. Such types of conformations/packing lead to odd-even alternation effects on properties involving solid phases of different molecular compounds containing linear alkyl chains. The surprising results obtained for the ionic liquid series enabled us to unveil similar trends in the liquid phases of linear alkanes and alkanols via the application of a simple corresponding states principle. 

Original languageEnglish
Pages (from-to)4033-4038
Number of pages6
JournalPhysical Chemistry Chemical Physics
Issue number9
Early online date07 Jan 2014
Publication statusPublished - 07 Mar 2014

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry


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