1-Alkyl-3-methylimidazolium Bis(perfluoroalkylsulfonyl)imide Water-Immiscible Ionic Liquids

Abstract

This study presents the electrochemical properties of room-temperature ionic liquids ͑RTILs͒ at a variety of liquid-liquid interfaces. The RTILs used here consist of 1-alkyl-3-methylimidazolium ͑C n mim, n = 6, 8, 10, 12͒ cations with bis͑perfluoromethyl-sulfonyl͒imide ͑BMSI͒ and bis͑perfluoroethylsulfonyl͒imide ͑BETI͒ anions. Ion transfer across the polarizable 1,2-dichloroethane/ water and the neat RTIL/water interfaces were examined. The ion-transfer experiments suggested that the RTILs made with C n mim and BMSI or BETI are moderately hydrophobic with polarizable potential windows as large as 274 mV for C 12 mimBETI in 1,2-dichloroethane and 137 mV for the neat C 12 mimBETI/water interface. In addition, the effect of the junction potential at the aqueous Ag/AgCl reference electrode/RTIL interface was studied using the oxidation/reduction of ferrocene and decamethylferrocene. The junction potential at the reference electrode was found to decrease as a function of the cation chain length for both anions studied. The ⌬ o w G tr of transfer found for all the systems studied was ϳ3 kJ/mol per CH 2 group of the cation.

Highly deformable liquid-state heterojunction sensors

“…The sensitivity is often attributed to enhanced ion conductivity and/or concentration 32,33 . On the other hand, hydrophobic ionic liquids show minimal sensitivity to humidity, with the response decreasing with increasing hydrophobicity 34,35 . We observe the same trend in the conductance and capacitance of our liquid-state heterojunction devices (Fig.…”

Investigation of the Effect of Functional Group Substitutions on the Gas-Phase Electron Affinities and Ionization Energies of Room-Temperature Ionic Liquids Ions using Density Functional Theory

“…This is consistent with the fact that alkyl groups are electron-donating in nature and hence would tend to stabilize a cation against reduction. Fitchett et al [12] • The initial effect of alkylation on the EA is greater than subsequent alkylation. This may be explained by the fact that the initial alkylation typically takes place at hydrogens connected to the aromatic ring structure (in the case of imidazolium or pyridinium based ions) or the atom of formal positive charge (e.g.…”

“…In the case of ILs, this is further compounded by their sensitivity to water, air and other impurities. [12,13,14] For example, Randstrom et al [13] have recently shown that while the innate cathodic stability of pure and dry ILs are generally set by the reduction potential of the cation, anion reduction [15] may occur at a higher potential than cation reduction in the presence of water and oxygen.…”

Investigating the Long-Term Stability and Kinetics of Superoxide Ion in Dimethyl Sulfoxide Containing Ionic Liquids and the Application of Thiophene Destruction

“…The main impurities in ILs are water and halide ions. Electrochemically speaking, water impurities have been shown to decrease the viscosity (Widegren et al, 2005;Zhang et al, 2006), increase the conductivity (Fitchett et al, 2005) and shrink the electrochemical window significantly (Schröder et al, 2000;Fitchett et al, 2005). Although water is by far the major impurity affecting the ILs, O2 from air is also easily dissolved in the ILs and often accompanies water; since this molecule is electroactive, its removal is required before any electrochemical measurement (Ohno, 2005).…”