| Abstract
| - Room-temperature ionic liquids (ILs) have been proposed as alternative solvents for organic synthesis,separations, and electrochemical applications. Here, we report studies that probe the electrochemical andsolvation properties of a tetraalkylammonium (methyltributylammonium bis(trifluoromethylsulfon)imide,M3BNIm) and an imidazolium (1-butyl-3-methylimidazolium hexafluorophosphate, BMIPF6) based ionicliquid. It is demonstrated that despite impurities, the cathodic limit at a Pt electrode is enhanced for thetetraalkylammonium-based IL. Electrogenerated chemiluminescence of tris(2,2‘-bipyrindinyl)ruthenium(Ru(bpy)32+) was observed in both ionic liquids, and differences in the response were interpreted in termsof the solvent reactivity and polarity. As ILs have been proposed as alternatives to organic solvents inextraction processes, an understanding of the relative lipophilicity of the IL ions and the equilibriumpotential difference established across the IL/water interface is of fundamental relevance. Here,electrochemical measurements at a conventionally polarized liquid−liquid interface (water/1,2-dichloroethane) were used to determine the relative lipophilicity of the IL constituent ions. From formal iontransfer potential values () obtained, the standard ionic partition coefficients could be estimated. Thepolarizability of the neat ionic liquid/water interface was investigated. From these studies, it can be seenthat BMIPF6 is hydrophilic while M3BNIm is moderately hydrophobic. The significance of the potentialdifference established across the IL/water interface is discussed.
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