Ionic Liquids in Analytical Chemistry

Abstract

oom-temperature ionic liquids (RTILs), also known as liquid organic, molten, or fused salts, are a class of nonmolecular ionic solvents with low melting points. The accepted definition of an RTIL is any salt that has a melting point lower than ambient temperature (1). However, "ionic liquid" (IL) is often applied to any compound that has a melting point <100°C. Most common RTILs are composed of unsymmetrically substituted nitrogen-containing cations (e.g., imidazole, pyrrolidine, pyridine) with inorganic anions (e.g., Cl -, PF 6 -, BF 4 -). ILs are also interesting because of their other useful and intriguing physicochemical properties. Wilkes et al. first reported ambient-temperature ILs based on the 1-alkyl-3-methylimidazolium cation in 1982 (2). Since then, many ILs containing a variety of cations and anions of different sizes have been synthesized to provide specific characteristics.Over the past few years, research and applications of ILs have expanded tremendously. The initial impetuses for this expansion were organic synthesis and the growth of green chemistry. In this article, we will give an overview of the structure and properties of ILs and describe their expanding use in various applications in separations and chromatography, MS, spectroscopy, and electrochemistry. Description and propertiesILs have negligible vapor pressures at room temperature, possess a wide range of viscosities, can be custom-synthesized to be miscible or immiscible, often have high stability, and are capable of un-

Dynamic Solvation in Phosphonium Ionic Liquids: Comparison of Bulk and Micellar Systems and Considerations for the Construction of the Solvation Correlation Function, C(t)

“…The results obtained from both bands were identical. The mean aggregation number of the [(C 4 ) 3 Preparation of Solutions for Stern-Volmer Quenching Experiments. We initially attempted to perform quenching experiments with iodide anion, as we did in our previous work.…”

“…[1][2][3][4] The importance of ionic liquids has consequently stimulated considerable interest in their dynamic solvation properties. A special issue of The Journal of Physical Chemistry has recently been devoted to ionic liquids.…”

Tunable Wavelength Soft Photoionization of Ionic Liquid Vapors

“…8,9 Furthermore, ILs are also used in ionic propulsion, 10,11 for hypergolic fuels 12 and various chemical extraction applications. 13 The vast number of possible anion-cation combinations 14 makes it valuable to rationally predict IL properties based on their constituents, 15 and considerable experimental and theoretical work has been performed to predict and measure ionic liquid properties. 16 Ab initio calculations, used to predict the structure and interactions of ILs, are typically performed on isolated "gas phase" systems.…”

Assessing the Roles of the Constituents of Ionic Liquids in Dynamic Solvation: Comparison of an Ionic Liquid in Micellar and Bulk Form

“…[1][2][3][4] The importance of ionic liquids has consequently stimulated considerable interest in their dynamic solvation properties, both in the experimental and the theoretical arenas. [26][27][28][29][30][31][32] An intriguing aspect of certain ionic liquids, which has only recently become appreciated, is their ability to promote micelle formation or to form micelles themselves.…”