Structure of 1-alkyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl) amide ionic liquids with linear, branched, and cyclic alkyl groups

Hemant K. Kashyap, Cherry S. Santos, N. Sanjeeva Murthy, Jeevapani J. Hettige, Kijana Kerr, Sharon Ramati, Jinhee Gwon, Masao Gohdo, Sharon I. Lall-Ramnarine, James F. Wishart, Claudio J. Margulis, Edward W. Castner

Research output: Contribution to journalArticlepeer-review

104 Scopus citations

Abstract

X-ray scattering and molecular dynamics simulations have been carried out to investigate structural differences and similarities in the condensed phase between pyrrolidinium-based ionic liquids paired with the bis(trifluoromethylsulfonyl)amide (NTf2-) anion where the cationic tail is linear, branched, or cyclic. This is important in light of the charge and polarity type alternations that have recently been shown to be present in the case of liquids with cations of moderately long linear tails. For this study, we have chosen to use the 1-alkyl-1-methylpyrrolidinium, Pyrr 1,n+ with n = 5 or 7, as systems with linear tails, 1-(2-ethylhexyl)-1-methylpyrrolidinium, Pyrr1,EtHx+, as a system with a branched tail, and 1-(cyclohexylmethyl)-1-methylpyrrolidinium, Pyrr1,ChxMe+, as a system with a cyclic tail. We put these results into context by comparing these data with recently published results for the Pyrr1,n+/NTf2- ionic liquids with n = 4, 6, 8, and 10.1,2 General methods for interpreting the structure function S(q) in terms of q-dependent natural partitionings are described. This allows for an in-depth analysis of the scattering data based on molecular dynamics (MD) trajectories that highlight the effect of modifying the cationic tail.

Original languageAmerican English
Pages (from-to)15328-15337
Number of pages10
JournalJournal of Physical Chemistry B
Volume117
Issue number49
DOIs
StatePublished - Dec 12 2013

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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