Ionic Liquids—An Overview

Forsyth, Stewart A.; Pringle, Jennifer M.; MacFarlane, Douglas R.

doi:10.1071/ch03231

Cited by 588 publications

(369 citation statements)

References 2 publications

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“…16 ILs are organic salts composed of anions and cations that are in the liquid state at ambient conditions and many show negligible volatility and non-flammability. 17 Hence, they are being actively investigated as alternative solvent media in synthesis, 18 catalysis, 19 polymerization, [20][21][22] separation, 23 electrochemistry 24,25 and electrochemical devices. 26,27 However, the basic science involved with fully characterizing these ILs is still in its infancy, and this may be holding back the complete and most efficient utilization of these potentially, and only in some cases, 28 41 dried under vacuum at 40 1C for 48 h, and stored under argon at 20 1C before analysis.…”

Section: Introductionmentioning

confidence: 99%

Photo- and solvatochromic properties of nitrobenzospiropyran in ionic liquids containing the [NTf2]− anion

Byrne

Fraser

Izgorodina

et al. 2008

Phys. Chem. Chem. Phys.

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The photo-, thermo-and solvatochromic properties of 2,3-dihydro-1 0 ,3 0 ,3 0 -trimethyl-6-nitrospiro-[1-benzopyran-2,2 0 -1H-indole] (BSP-NO 2 ) were studied in ILs containing the anion [NTf 2 ] À by UV-Vis absorption spectroscopy, ab initio molecular orbital theory and density functional theory (DFT) calculations. It was found that the kinetics and thermodynamics of the BSP-NO 2 2 MC (merocyanine) Q4 equilibrium was sensitive to the nature of the cation. It was also observed that the imidazolium cation can form a through-space orbital interaction with the MC isomer, rather than a simple electrostatic interaction, thus preventing the MC conversion back to the BSP-NO 2 isomer. The BSP-NO 2 2 MC equilibrium thus serves as a model system for studying modes of interaction of the cations in ionic liquids.

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Section: Introductionmentioning

confidence: 99%

Photo- and solvatochromic properties of nitrobenzospiropyran in ionic liquids containing the [NTf2]− anion

Byrne

Fraser

Izgorodina

et al. 2008

Phys. Chem. Chem. Phys.

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“…Past reviews have provided detailed insight into the synthesis and properties of ILs and have promoted their implementation as common laboratory solvents. 8 non-polar functional groups to encourage specific location within the liquid domains. 9 It was found that the interactions with the ions allowed for the spiropyran moiety to be located in distinctly different regions and report on them through thermodynamic and kinetic parameters.…”

Section: Introductionmentioning

confidence: 99%

Photochromic imidazolium based ionic liquids based on spiropyran

Coleman

Byrne

Alhashimy

et al. 2010

Phys. Chem. Chem. Phys.

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We investigate the photo, solvate and thermochromic properties of a novel photoswitchable spiropyran derivative; SP Im in imidazolium based ionic liquids (ILs). SP Im was prepared by alkylation of the photoswitchable compound to an imidazolium cation and is added to imidazolium based ILs with increasing chain length to examine the stability of funtionalised cations its merocyanine (MC) and spiropyran (SP) forms and compared to standard spiropyran; BSP. The rate of thermal relaxation of the new derivative is found to be about ten times faster than that of BSP as reflected in rates of 13.9 x10 -3 s -1 and 1.0 x10 -3 s -1 for SP Im and BSP respectively in [C 6 mIm][NTf 2 ]. Since ILs are believed to form nano-structured domains it is proposed that the covalent attachment of the imidazolium side group of SP Im fully integrates the photoswitchable moiety into the non-polar region through side-chain association. In contrast, unbound BSP is relatively free to migrate between both polar and non-polar regions and the MC form is more readily stablised by the IL charge via through space interactions and spontaneous movement to charged nano-domains leading to enhancement of the MC lifetime. At higher concentrations, rheological and transport properties were investigated to determine the impact of covalent attachment of the BSP fragment to an imidazolium cation had upon the ionic liquid structure. Ionic Conductivity was found to decrease by up to 23% for SP Im with effects increasing with cation side-chain length. Unlike BSP, the photoswitching of the SP Im did not affect conductivity or viscosity values. This may indicate that the mobility of the photoswitchable compound and the resulting disruption of such movement may be critical to the evolution of this physical property.2

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“…Several reviews have provided detailed insight into ILs and have promoted their implementation was common laboratory solvents. 6 However, the lack of exact knowledge of the physical properties has resulted in their widespread application not being completely realised. Recent studies have proposed that imidazolium based ILs may form ordered systems resembling psuedo-crystalline systems based on stacking of mutual charges (aggregation) or ordered association of cation to surrounding anions and vice versa.…”

Section: Introductionmentioning

confidence: 99%

Investigating Nanostructuring within Imidazolium Ionic Liquids: A Thermodynamic Study Using Photochromic Molecular Probes

et al. 2009

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Following previous studies involving the thermal relaxation of spirocyclic compounds we extended our studies to investigate the formation of nano-structured domains in ionic liquids (ILs). Two compounds, spiropyran (BSP) and spirooxazine (SO) were added to imidazolium cation based ionic liquids with increasing chain lenghts (C 2 -C 12 ). Increasing side-chain length was found to have only minor effects on the rate of thermal relaxation of BSP and SO. BSP was found to be a suitable probe molecule as linear correlations in parameters were observed for this compound. This is believed to be due to the fact that BSP-IL interactions were based on hydrogen bonding between MC BSP and the cation compared to MC SO The resulting reorganisation of the system produced positive entropies of activation, 13.79 J.K -1 .mol -1 for C 4 mIm to 46.15 J.K -1 .mol -1 for C 12 mIm, following an increase in disorder due to probe dye closure from MC to BSP and migration of dye to regions of preferential solvation. The ability for spirocyclic compounds to form both polar and non-polar isomers resulted in the ability to analyse both solvent regions using a single probe dye. Ground state equilibrium, K e , examined non-polar regions of the IL while equilibrium of activation, K ‡ , examined the polar regions. A linear response to side chain length to equilibrium of activation was believed to be due to the fact that polar regions were possibly expanding due to increasing influence of non-polar side chain interactions upon the over solvent structure. The result of such reordering and dispersion of polar regions reduces solvent-solute interactions which increases rate of MC-BSP relaxation.

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Ionic Liquids—An Overview

Cited by 588 publications

References 2 publications

Photo- and solvatochromic properties of nitrobenzospiropyran in ionic liquids containing the [NTf2]− anion

Photo- and solvatochromic properties of nitrobenzospiropyran in ionic liquids containing the [NTf2]− anion

Photochromic imidazolium based ionic liquids based on spiropyran

Investigating Nanostructuring within Imidazolium Ionic Liquids: A Thermodynamic Study Using Photochromic Molecular Probes

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