Physicochemical Properties and Electrochemical Behavior of Systematically Functionalized Aryltrifluoroborate-Based Room-Temperature Ionic Liquids

The physicochemical properties and electrochemical behavior of 1-butyl-3-methylimidazolium aryltrifluoroborate ([C₄mim]­[ArBF₃]) with various substituents, e.g., methoxy, fluoro, trifluoromethyl, and cyano groups, introduced on the phenyl moiety on the anion are examined. Several position isomers of the [ArBF₃]⁻ anion are also prepared to provide further insight into the effect of the position. The equivalent conductivity and the electrochemical stability for some [C₄mim]­[ArBF₃] room-temperature ionic liquids (RTILs) is qualitatively discussed from the results of quantum chemical calculations of the cation–anion interaction and the HOMO energy level of the anion. Interestingly, [C₄mim]­[ArBF₃] RTILs with an electron-withdrawing group on the phenyl moiety electrochemically form an ion-selective membrane on a Pt electrode, and only neutral and cationic species can pass through the membrane

Alkali Metal Salts with Designable Aryltrifluoroborate Anions

Aryltrifluoroborate ([ArBF₃]⁻) has a designable basic anion structure. Various [ArBF₃]⁻-based anions were synthesized to create novel alkali metal salts using a simple and safe process. Nearly 40 novel alkali metal salts were successfully obtained, and their physicochemical characteristics, particularly their thermal properties, were elucidated. These salts have lower melting points than those of simple inorganic alkali halide salts, such as KCl and LiCl, because of the weaker interactions between the alkali metal cations and the [ArBF₃]⁻ anions and the anions’ larger entropy. Moreover, interestingly, potassium cations were electrochemically reduced in the potassium (<i>meta</i>-ethoxyphenyl)­trifluoroborate (K­[<i>m</i>-OEtC₆H₄BF₃]) molten salt at 433 K. These findings contribute substantially to furthering molten salt chemistry, ionic liquid chemistry, and electrochemistry

Schematic illustration of water absorption process of a SAP particle.

<p>Schematic illustration of water absorption process of a SAP particle.</p

Digital optical microscope images of (a) original dry and (b) hydrous SAP particles.

<p>The images were taken under atmospheric condition.</p

A schematic drawing of the pretreatment protocol for SEM observation of SAP specimens used in this investigation.

<p>A schematic drawing of the pretreatment protocol for SEM observation of SAP specimens used in this investigation.</p

Chemical structures and abbreviation forms of the cations and anions making up the RTILs used in this article.

<p>Chemical structures and abbreviation forms of the cations and anions making up the RTILs used in this article.</p

SEM images of hydrous SAP particles pretreated with different neat RTILs.

<p>(a) [C₂mim][BF₄]; (b) [C₂mim][AcO]; (c) [C₂mim][Lac]; (d) [C₄mim][BF₄]; (e) [Ch][Lac]; (f) [P_{4, 4, 4, 1}][DMP].</p

SEM images of original dry SAP particles pretreated with different neat RTILs.

<p>(a) [C₂mim][BF₄]; (b) [C₂mim][AcO]; (c) [C₂mim][Lac]; (d) [C₄mim][BF₄]; (e) [Ch][Lac]; (f) [P_{4, 4, 4, 1}][DMP].</p