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@ARTICLE{Veroutis:888670,
      author       = {Veroutis, Emmanouil and Merz, Steffen and Eichel,
                      Rüdiger-A. and Granwehr, Josef},
      title        = {{I}ntra- and inter-molecular interactions in choline-based
                      ionic liquids studied by 1{D} and 2{D} {NMR}},
      journal      = {Journal of molecular liquids},
      volume       = {322},
      issn         = {0167-7322},
      address      = {New York, NY [u.a.]},
      publisher    = {Elsevier},
      reportid     = {FZJ-2020-05105},
      pages        = {114934 -},
      year         = {2021},
      abstract     = {Choline acetate [Ch]$^+$[OAc]$^−$ and choline
                      trifluoroacetate [Ch]$^+$[TFA]$^−$ mixed with 30 wt\%
                      H$_2$O have been characterized by variable temperature 1D
                      and 2D 1H/19F NMR. It was found that the cation, anion and
                      water molecules participate in a strong local H-bond
                      network, but there was no evidence for the formation of
                      large clusters of ions. Weaker association effects were
                      observed for the trifluoroacetate than for the acetate,
                      originating from the higher anion acidity of TFA. Rotational
                      correlation times, which were extracted by temperature
                      dependent spin–lattice relaxation measurements, indicated
                      that cations, anions and H$_2$O exhibit collective
                      reorientation even at room temperature. At the same time, no
                      significant long-range correlations in the translational
                      motion of the ions could be observed from PFG diffusion
                      measurements. Moreover, 1D and 2D NOE experiments showed
                      that both ions share close proximity to water molecules for
                      a period on the order of 0.2 s at room temperature. It is
                      deduced that the ions exist in a solvent-shared ion pair
                      (SIP) configuration, with strongly correlated short-range
                      dynamics between the choline cation and the H$_2$O
                      molecules, indicating a similar behavior of these ILs to a
                      deep eutectic solvent with water as Lewis acid. A reason for
                      this observation, which is supported by a high entropy term
                      in the activation process particularly at low temperatures,
                      could be a fairly static configuration with water near the
                      –N(CH$_3$)$_3$ center of the choline, and relaxation
                      caused by pseudorotation due to reordering of the H-bond
                      network.},
      cin          = {IEK-9},
      ddc          = {540},
      cid          = {I:(DE-Juel1)IEK-9-20110218},
      pnm          = {131 - Electrochemical Storage (POF3-131) / 1223 - Batteries
                      in Application (POF4-122)},
      pid          = {G:(DE-HGF)POF3-131 / G:(DE-HGF)POF4-1223},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000610834000099},
      doi          = {10.1016/j.molliq.2020.114934},
      url          = {https://juser.fz-juelich.de/record/888670},
}