Fluorescent Probe Studies of Polarity and Solvation within Room Temperature Ionic Liquids: A Review

Abstract

Ionic liquids display an array of useful and sometimes unconventional, solvent features and have attracted considerable interest in the field of green chemistry for the potential they hold to significantly reduce environmental emissions. Some of these points have a bearing on the chemical reactivity of these systems and have also generated interest in the physical and theoretical aspects of solvation in ionic liquids. This review presents an introduction to the field of ionic liquids, followed by discussion of investigations into the solvation properties of neat ionic liquids or mixed systems including ionic liquids as a major or minor component. The ionic liquid based multicomponent systems discussed are composed of other solvents, other ionic liquids, carbon dioxide, surfactants or surfactant solutions. Although we clearly focus on fluorescence spectroscopy as a tool to illuminate ionic liquid systems, the issues discussed herein are of general relevance to discussions of polarity and solvent effects in ionic liquids. Transient solvation measurements carried out by means of time-resolved fluorescence measurements are particularly powerful for their ability to parameterize the kinetics of the solvation process in ionic liquids and are discussed as well.

Electron-Transfer Dynamics for a Donor–Bridge–Acceptor Complex in Ionic Liquids

“…18 Use of fluorescent probes has provided interesting details of the polarity and solvation environments experienced by solutes in ILs. 11,[19][20][21][22][23][24][25][26][27] The thermal and electrochemical stability of ILs combined with their intrinsic properties of negligible vapor pressures and high conductivities has sparked interest in implementation of these materials as media for energy transport, and they have been successfully featured as electrolytes in lithium-ion batteries and dye-sensitized solar cells. [28][29][30] Because of the interest in ILs as media for energy applications, a more detailed understanding of electron-transfer reactions in these solvents is desirable.…”

Activity Coefficients at Infinite Dilution for Organic Compounds Dissolved in 1-Alkyl-1-methylpyrrolidinium Bis(trifluoromethylsulfonyl)imide Ionic Liquids Having Six-, Eight-, and Ten-Carbon Alkyl Chains

“…Synthesis and characterization of the 1-alkyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)-imide ILs was performed as described earlier by Jin et al 43 with special attention paid to procedures and precautions necessary for attaining highly pure "spec-grade" material. 44,45 Apparatus and Experimental Procedure. Inverse chromatography experiments were performed using a Varian CP-3800 gas chromatograph equipped with a heated oncolumn injector and a flame ionization detector.…”

Applications of Ionic Liquids in Spectroscopy

“…[16][17][18][19][20][21][22][23][24][25] Though many of these review articles either contain a section on applications of ionic liquids in spectroscopy or mention this topic somewhere in the text, a detailed review article on ionic liquids in spectroscopy is difficult to find. [16][17][18][19][20][21][22][23][24][25] Though many of these review articles either contain a section on applications of ionic liquids in spectroscopy or mention this topic somewhere in the text, a detailed review article on ionic liquids in spectroscopy is difficult to find.…”

“…21 The review presents discussion of investigations into the solvation properties of neat ionic liquids or mixed systems including ionic liquids as a major or minor component. 21 The review presents discussion of investigations into the solvation properties of neat ionic liquids or mixed systems including ionic liquids as a major or minor component.…”