Thermal Properties of Macrocyclic Polyethers: Implications for the Design of Crown Ether-Based Ionic Liquids

Pawlak, Alan J.; Dietz, Mark L.

doi:10.1080/01496395.2014.946146

Cited by 10 publications

(9 citation statements)

References 46 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…25 -is a strong Lewis base, the ion-ion interaction must be strong, giving the phase separation. Such phase separation has not been reported in other crownether-K + salt mixtures when larger anions or weaker Lewis bases are used, [25][26][27][28] indicating that the K + -O 2 -and the K + -18C6 interaction is comparable.…”

Section: Resultsmentioning

confidence: 87%

See 1 more Smart Citation

An Ionic Liquid State Composed of Superoxide Radical Anions and Crownether-Coordinated Potassium Cations

Kitada

Ishikawa

Fukami

et al. 2017

J. Electrochem. Soc.

View full text Add to dashboard Cite

We report an "ionic liquid state" substance composed of superoxide radical anions (O 2 -) and crownether-coordinated potassium cations. A binary mixture of 18-crown-6-ether (18C6) and potassium superoxide (KO 2 ) becomes liquid above ca. 38 • C. The coordination of 18C6 to K + and the presence of O 2 -were confirmed in the liquid state by Raman spectroscopy measurements. Below 38 • C, however, the 18C6-KO 2 mixture does not form a complex but undergoes phase separation to parent phases of solid 18C6 and KO 2 , because the ion-dipole interaction between K + and 18C6 is overwhelmed by the ion-ion interaction between K + and O 2 -. In other words, the pair of O 2 -and 18C6-coordinated K + only appears above the melting point of pure 18C6, to form an "ionic liquid state". Among radical-containing ionic liquids, the liquid 18C6-KO 2 mixture has high fluidity and comparable conductivity. , aprotic solvents were used to dissolve KO 2 . For example, a highly polar aprotic solvent, dimethylsulfoxide (DMSO), was used with a cyclic ionophore dicyclohexyl-18-crown-6-ether (D18C6) to prepare KO 2 solution. 5The highest concentration of O 2 -in organic solution, however, is only 0.15 mol dm -3 in D18C6-containing DMSO solution, i.e. KO 2 :D18C6:DMSO = 1:2:100 by mole.5 O 2 -solutions can also be obtained chemically or electrochemically in aprotic solvents including ionic liquids, but the concentrations are small. 6-10 Therefore, drastic increase in superoxide radical concentration is of interest; for this purpose, designing novel superoxide radical compounds in liquid state is necessary.Examples of known superoxides are alkaline and alkaline-earth metal superoxides, of which magnetism have attracted attention. 11-15These counter cations have small ionic radii and high charge densities, i.e. they were "hard acids" to give strong cation-anion interactions and melting points much higher than RT. From this viewpoint, larger counter cations need to be designed. There are several superoxides using large cations such as quaternary ammonium cations, but their liquid properties are missing due to rapid decomposition. 16,17 An alternative approach for novel "superoxide liquids" may be coordination of metal cations by ethers. This is because ethers were judged to be more stable to O 2 -attack than organic carbonates, 18 which attracted attention as metal-air battery electrolytes. [19][20][21][22][23] It is also because ethers have been used to prepare so-called "solvate ionic liquids", where ether-coordinated metal cations are component cations. 24-28Our preliminary results showed that an equimolar mixture of 18-crown-6-ether (18C6) and potassium superoxide (KO 2 ) becomes liquid above 41• C, without sizable decomposition of O 2 -, while equimolar mixtures of KO 2 and other ethers such as glymes and D18C6 rapidly decomposed. 29 In this work, we study the detailed physico- * Electrochemical Society Member. z E-mail: kitada.atsushi.3r@kyoto-u.ac.jp chemical properties of 18C6-KO 2 mixture: in addition to our earlier work, 29 we performed ...

show abstract

Section: Resultsmentioning

confidence: 87%

“…[19][20][21][22][23] It is also because ethers have been used to prepare so-called "solvate ionic liquids", where ether-coordinated metal cations are component cations. [24][25][26][27][28] Our preliminary results showed that an equimolar mixture of 18-crown-6-ether (18C6) and potassium superoxide (KO 2 ) becomes liquid above 41…”

Section: Superoxide Anion Omentioning

confidence: 99%

An Ionic Liquid State Composed of Superoxide Radical Anions and Crownether-Coordinated Potassium Cations

Kitada

Ishikawa

Fukami

et al. 2017

J. Electrochem. Soc.

View full text Add to dashboard Cite

show abstract

“…The solvate ILs reported so far are binary mixtures of alkali-metal salts and polyethers. [7][8][9][10][11][12][13] In contrast, the hydronium solvate IL, the first example of a nonmetal-cation-solvate IL, is a ternary mixture of water, crown ether, and fluorinated imide superacid. Surveying the analogous compounds would give hydronium solvate ILs that have wide temperature windows of usage.…”

Section: Synthesis Of [H 3 Omentioning

confidence: 99%

“…The appearance of the Raman peak centered at 873 cm -1 , the so-called breathing mode, means a change in the COC stretching and CH 2 rocking modes of 18C6 due to the complex formation, as in the case of alkali metal ether complexes. [7][8][9][10][11][12][13] In the IR spectra, the COC stretching absorption for pure 18C6 is seen as a broad Figure 2. Raman spectra between 700 cm -1 and 900 cm -1 of pure 18C6 (50 • C) 13 Fig.…”

Section: Synthesis Of [H 3 Omentioning

confidence: 99%

See 1 more Smart Citation

A Hydronium Solvate Ionic Liquid: Facile Synthesis of Air-Stable Ionic Liquid with Strong Brønsted Acidity

Kitada

Takeoka

Kintsu

et al. 2018

J. Electrochem. Soc.

View full text Add to dashboard Cite

A new kind of ionic liquid (IL) with strong Brønsted acidity, i.e., a hydronium (H 3 O + ) solvate ionic liquid, is reported. The IL can be described as [H 3 When two or more kinds of substances are mixed, the properties of the mixture can differ from those of the pure substances. Depending on the interactions between the components, some components undergo ionization, e.g. dissociation, protonation, solvation and complexation, due to the neutralization of Brønsted or Lewis acids and bases. Sometimes, the acid-base mixtures can be categorized as ionic liquids (ILs) with melting points below 100• C, which consist only of cations and anions. ILs are regarded as "the third liquid" and some ILs have fascinating physicochemical properties, such as low volatility, low flammability, high chemical, and thermal stability. Furthermore, ILs have received growing interest due to their various uses as media in chemical, biochemical, and/or electrochemical systems. [1][2][3][4][5][6] Common anions of ILs such as BF 4 -, PF 6 -, and AlCl 4 -are produced by neutralization, i.e. the adducts of a Lewis acid (BF 3 , PF 5 , or AlCl 3 ) and a Lewis base (F -or Cl -). Examples of ILs prepared through neutralization include solvate ILs.7-13 Solvate ILs often consist of equimolar molten mixtures of polyethers (linear or cyclic ones, i.e. glymes or crown ethers) and certain metal salts, where the Lewis acidic metal cations are solvated by equimolar amounts of Lewis basic glymes to give complex cations. Besides, neutralization of Brønsted acids and bases produces so-called protic ILs, which are preferred as acid-catalyzed reaction media due to the presence of an acidic proton.3-6 Since proton transfer is a common chemical transformation, Brønsted acidic ILs receive research attention especially for acid catalysts, fuel cells, biomass processing, polymerization, CO 2 fixation, etc.6,14-19 The design of stronger Brønsted acidic ILs and evaluation of the acidity in ILs are important for exploring their possible applications as media for acid-base reactions.Although 21-24 However, there is an exception. In solid, anhydrous HTf 2 N, the proton is bonded to the anion nitrogen and two oxygens of a neighboring HTf 2 N molecule. 25 Likewise, in the case of monohydrate, the imide superacid HTf 2 N remains associated and does not protonate water, as suggested experimentally and theoretically. In the infrared measurements for an H 2 O and HTf 2 N mixture in CCl 4 , strong Fermi resonance for N-H vibrations serves as evidence that HTf 2 N remains * Electrochemical Society Member.z E-mail: kitada.atsushi.3r@kyoto-u.ac.jp intact, and from the ab initio calculations, spontaneous proton dissociation was not observed for the Fig. 1a

show abstract

Two-stage thermal decomposition of 18-crown-6 and dicyclohexano-18-crown-6 complexes with alkaline earth metal halides as evidence for non-equivalence of macrocycle symmetry

Zakurdaeva,

Kuchkina,

Kurkin

et al. 2023

J Therm Anal Calorim

View full text Add to dashboard Cite

Thermal Properties of Macrocyclic Polyethers: Implications for the Design of Crown Ether-Based Ionic Liquids

Cited by 10 publications

References 46 publications

An Ionic Liquid State Composed of Superoxide Radical Anions and Crownether-Coordinated Potassium Cations

An Ionic Liquid State Composed of Superoxide Radical Anions and Crownether-Coordinated Potassium Cations

A Hydronium Solvate Ionic Liquid: Facile Synthesis of Air-Stable Ionic Liquid with Strong Brønsted Acidity

Two-stage thermal decomposition of 18-crown-6 and dicyclohexano-18-crown-6 complexes with alkaline earth metal halides as evidence for non-equivalence of macrocycle symmetry

Contact Info

Product

Resources

About