Study of the conductivity behavior of pyridinium-based ionic liquids

In this work, ionic conductivity data as a function of temperature in the pyridinium-based ionic liquids 1-butylpyridinium tetrafluoroborate, 1-butylpyridinium triflate, 1-butyl-2-methylpyridinium tetrafluoroborate, 1-butyl-3-methylpyridinium tetrafluoroborate, 1-butyl-4-methylpyridinium tetrafluoroborate, 1-butyl-3-methylpyridinium dicyanamide, and 1-octyl-3-methylpyridinium tetrafluoroborate, are reported. A comparison of results for this series of ionic liquids has been used to evaluate the influence of the ionic structural characteristic in this transport property. Temperature dependence of experimental values has been fitted by means of the Vogel-Fulcher-Tammann equation, and from their parameters, maximum conductivity and activation energy for conduction have been derived. From conductivity parameters and the glass transition temperature, a detailed analysis has been performed in fragility terms. Finally, the classical Walden rule has been used to classify the ionic liquids depending on the relationship between conductivity and fluidity. (C) 2009 Elsevier Ltd. All rights reserved.