Nucleic acid bases in 1-alkyl-3-methylimidazolium acetate ionic liquids: A thermophysical and ionic conductivity analysis

The use of ionic liquids as a media for dissolving DNA holds great promise for the development of new base materials in electrochemistry. This paper reports the systematic study of the effect of two nucleic acid bases, uracil and adenine, on the ionicity of 1-alkyl-3-methylimidazolium acetates achieved by monitoring several thermodynamic and transport properties. Density, dynamic viscosity, speed of sound, refractive index and ionic conductivity of 1-ethyl-3-methylimidazolium acetate and 1-butyl-3-methylimidazolium acetate were studied as a function of temperature at atmospheric pressure. The thermal expansion coefficients and molar volumes of these ionic liquids were calculated from the experimental density values. The various properties of the binary mixtures 1-ethyl-3-methylimidazolium acetate with uracil or adenine, namely, their ionic conductivity, density and viscosity in the temperature range 298 K-343 K were determined as a function of the nucleobase content. Walden plots were determined and used to clarify the role of the nucleobases in the ionic liquids ionicity. (C) 2012 Elsevier Ltd. All rights reserved.