Branched and cyclic alkyl groups in imidazolium-based ionic liquids: Molecular organization and physico-chemical properties

Andresová, Adéla; Storch, Jan; Traı̈kia, Mounir; Wagner, Z.; Bendová, Magdalena; Husson, Pascale

doi:10.1016/j.fluid.2014.03.004

Cited by 34 publications

(20 citation statements)

References 22 publications

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“…4 shows the viscosities plotted as functions of temperature. This tendency is consistent with previous reports that the viscosity of ionic liquids with branched substituents are generally greater than for ionic liquids with linear substituents, 7,8 owing to the more stable packing between cations and anions. (1107 mPa s).…”

Section: Viscositiessupporting

confidence: 93%

“…1 Ionic liquids, which are salts with melting points below 100 1C, exhibit various characteristic properties such as nonvolatility, zero flammability, and high ionic conductivity. [4][5][6][7][8][9][10][11] Although most ionic liquids contain organic cations such as imidazolium cations, various metal-containing ionic liquids that exhibit intriguing functionalities have recently been developed. Therefore, the effects of molecular structure, such as the length of alkyl substituents, on the physical properties of ionic liquids have been extensively investigated.…”

Section: Introductionmentioning

confidence: 99%

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Effects of substituent branching and chirality on the physical properties of ionic liquids based on cationic ruthenium sandwich complexes

Higashi

Ueda

Mochida

2016

Phys. Chem. Chem. Phys.

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An appropriate understanding of how substituents affect the physical properties of ionic liquids is important for the molecular design of ionic liquids. Toward this end, we investigated how the branching and chirality of substituents affect the physical properties of organometallic ionic liquids. We synthesized a series of ionic liquids bearing a branched or linear alkoxy group with the same number of carbons: [Ru(C5H5)(η(6)-C6H5OR)]X (rac-[1]X: R = -CH(C2H5)(C6H13), [2]X: R = -CH(C4H9)2, [3]X: R = -C9H19), where X = PF6(-), (SO2F)2N(-), and (SO2CF3)2N(-). rac-[1]X are racemic salts. Salts with less symmetrical substituents tend to maintain the liquid state due to suppression of crystallization; crystallization is completely suppressed in most of the rac-[1]X salts and in some of the [2]X salts, whereas not in [3]X salts. The glass-transition temperatures and viscosities of the salts with branched substituents are greater than those with linear substituents. Chiral resolution of rac-[1][PF6] was performed by chiral chromatography. The melting point of rac-[1][PF6] is much lower than that of the enantiopure salt (chiral-[1][PF6]), which we ascribe to the formation of a conglomerate in the solid state. X-ray structure analysis revealed that the solid salts form layered structures.

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Section: Viscositiessupporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Effects of substituent branching and chirality on the physical properties of ionic liquids based on cationic ruthenium sandwich complexes

Higashi

Ueda

Mochida

2016

Phys. Chem. Chem. Phys.

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“…The ionic liquid mbmim [Br] (1-(3-methylbutyl) -3methylimidazolium bromide) was synthesized as described by Andresova et al 36 . Using this IL as starting material, anion exchange was carried out with lithium salt (LiTf 2 N) addition 36 , resulting in mbmim[Tf 2 N] (1-(3-methylbutyl) -3-methylimidazolium bis-(trifluoromethanesulfonylimide). ILs syntheses were confirmed by proton nuclear magnetic resonance ( 1 H-NMR) 36…”

Section: Ionic Liquids Synthesismentioning

confidence: 99%

Imidazolium-based Ionic Liquids Impregnated in Silica and Alumina Supports for CO2 Capture

et al. 2019

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Ionic liquids (ILs) physical immobilization in solid materials is a key strategy for developing efficient and low cost CO 2 capture processes. In this work, two porous commercial substrates with different characteristics (silica and alumina) were impregnated with ILs by physical wet method. Imidazolium based IL combined with [Br]and [Tf 2 N]anions were used in impregnation process. CO 2 sorption capacity and selectivity (CO 2 /N 2) of these materials were investigated. The best results regarding CO 2 /N 2 selectivity and CO 2 sorption were obtained with [Tf 2 N]anion. In relation to solid support, commercial alumina exhibited enhanced CO 2 uptake and higher selective capacity (CO 2 /N 2) (6.1 (± 0.1)). Combination of commercial alumina as support and 20 wt% of mbmim [Tf 2 N] resulted in higher CO 2 /N 2 selectivity of 9.5 ± 1.0. In addition, this material also showed fast sorption kinetics when compared to pure IL besides reuse capacity.

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“…Previous studies suggested that the branching of the alkyl side chain not affect their density significantly, but when some cycle group (aromatic and non-aromatic) is present in the alkyl chain, the densities increase. [20,23,26] Regarding transport properties, such as viscosity, a small variation of the aliphatic side group may lead to substantial changes in their properties; [23,25]as the nanostructuration of ILs becomes highly affected a significant impact occurs in the shear stress of ILs. Aromatic ILs with branched and cyclic alkyl side chains were shown to have higher viscosities than their n -alkyl homologous.…”

Section: Introductionmentioning

confidence: 99%

“…Aromatic ILs with branched and cyclic alkyl side chains were shown to have higher viscosities than their n -alkyl homologous. [20,23] For different cyclic groups in the alkyl chain or the cation core, the viscosity is expected to be dependent on the size and structure of the cyclic group and in the magnitude of dispersive intermolecular interactions (van der Waals). The relatively high viscosity for these ILs compared with their n -alkyl homologous depends heavily on the reorientation motion on ILs.…”

Section: Introductionmentioning

confidence: 99%

The effect of n vs. iso isomerization on the thermophysical properties of aromatic and non-aromatic ionic liquids

Rodrigues

Almeida

Freire

et al. 2016

Fluid Phase Equilibria

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This work explores the n vs. iso isomerization effects on the physicochemical properties of different families of ionic liquids (ILs) with variable aromaticity and ring size. This study comprises the experimental measurements, in a wide temperature range, of the ILs' thermal behavior, heat capacities, densities, refractive indices, surface tensions, and viscosities. The results here reported show that the presence of the iso-alkyl group leads to an increase of the temperature of the glass transition, T g . The iso-pyrrolidinium (5 atoms ring cation core) and iso-piperidinium (6 atoms ring cation core) ILs present a strong differentiation in the enthalpy and entropy of melting. Non-aromatic ILs have higher molar heat capacities due to the increase of the atomic contribution, whereas it was not found any significant differentiation between the n and iso-alkyl isomers. A small increase of the surface tension was observed for the non-aromatic ILs, which could be related to their higher cohesive energy of the bulk, while the lower surface entropy observed for the iso isomers indicates a structural resemblance between the IL bulk and surface. The significant differentiation between ILs with a 5 and 6 atoms ring cation in the n-alkyl series (where 5 atoms ring cations have higher surface entropy) is an indication of a more efficient arrangement of the non-polar region at the surface in ILs with smaller cation cores. The ILs constituted by non-aromatic piperidinium cation, and iso-alkyl isomers were found to be the most viscous among the studied ILs due to their higher energy barriers for shear stress.

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Branched and cyclic alkyl groups in imidazolium-based ionic liquids: Molecular organization and physico-chemical properties

Cited by 34 publications

References 22 publications

Effects of substituent branching and chirality on the physical properties of ionic liquids based on cationic ruthenium sandwich complexes

Effects of substituent branching and chirality on the physical properties of ionic liquids based on cationic ruthenium sandwich complexes

Imidazolium-based Ionic Liquids Impregnated in Silica and Alumina Supports for CO2 Capture

The effect of n vs. iso isomerization on the thermophysical properties of aromatic and non-aromatic ionic liquids

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