Anion and ether group influence in protic guanidinium ionic liquids
Daniel Rauber, Frederik Philippi, Julian Becker, Josef Zapp, Bernd Morgenstern, Björn Kuttich, Tobias Kraus, Rolf Hempelmann, Patricia A. Hunt, Tom Welton, Christopher W. M. Kay
Abstract
N chemical shifts. Using anions from acids with lower proton affinity leads to proton localization on the cation as evident from NMR spectra and self-diffusion coefficients. In contrast, proton exchange was evident in ionic liquids with triflate and trifluoroacetate anions. Using imide-type anions and ether side groups decreases glass transitions as well as fragility, and accelerated dynamics significantly. In case of the ether guanidinium ionic liquids, the conformation of the side chain adopts a curled structure as the result of dispersion interactions, while the alkyl chains prefer a linear arrangement.