Imidazolium functional feature

Although the first ionic liquid expressly categorized as being task-spedfic featured the incorporation of function within the cation core, subsequent research has focused on the incorporation of functionality into a branch appended to the cation [11]. In this fashion, a great number of the task-specific ionic liquids have been prepared that have been built-up from 1-methyl and 1-butylimidazole. By far the most of these ionic liquids have been prepared by quaternization of the aforementioned imidazoles with a functionalized alkyl halide to afford the corresponding functionalized imidazolium halides in usually good yield (Scheme 2.3-1). 

Unlike polarity, the solubility of ionic liquids depends strongly on the structure of the associated anion. In fact, the miscibiUty of ionic liquids with traditional solvents is one of their most interesting features and is clearly observed during the anion metathesis of imidazolium derivatives. The starting chlorine salt, for example [bmim][Cl], is completely soluble in water. After exchange of the anion, [bmim][PF6] or [bmim][NTf2] salts are obtained as hydrophobic products and therefore form a separate layer. Table 2.7 summarizes the solubility of l-butyl-3-methylimidazolium salts as function of the anion. ... 

The pH dependence of zeta potential for six selected proteins is shown in Figs. 27, 28 and 29 as function of IL concentration. The observed strong quenching of zeta potential with increase in IL concentration can be attributed to the fact that IL molecules present in the hydration shell located close to the protein molecular surface selectively interact with imidazolium cation and chloride anion through electrostatic forces. A typical zeta potential-pH profile of a protein has three distinctive features (i) at pH < pi, the protein molecule is highly protonated and has the highest zeta potential (Cmax at a specific pH), (ii) every protein has a... 

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