Molecules

2021

Jump to: 2019, 2018, 2012, 2010, 2009

18 pages, 5068 KiB

Open AccessArticle

Salicylic Acid as Ionic Liquid Formulation May Have Enhanced Potency to Treat Some Chronic Skin Diseases

by Joanna Klebeko, Paula Ossowicz-Rupniewska, Ewelina Świątek, Joanna Szachnowska, Ewa Janus, Stefka G. Taneva, Elena Krachmarova and Maya Guncheva

Molecules 2022, 27(1), 216; https://doi.org/10.3390/molecules27010216 - 30 Dec 2021

Cited by 12 | Viewed by 3649

Abstract

In recent years, numerous studies have shown that conversion of conventional drugs in ionic liquid (IL) formulation could be a successful strategy to improve their physicochemical properties or suggest a new route of administration. We report the synthesis and detailed characterization of eight [...] Read more.

In recent years, numerous studies have shown that conversion of conventional drugs in ionic liquid (IL) formulation could be a successful strategy to improve their physicochemical properties or suggest a new route of administration. We report the synthesis and detailed characterization of eight salicylic acid-based ILs (SA-ILs) containing cation non-polar or aromatic amino acid esters. Using in vitro assays, we preliminary evaluated the therapeutic potency of the novel SA-ILs. We observed that conversion of the SA into ionic liquids led to a decrease in its cytotoxicity toward NIH/3T3 murine embryo fibroblasts and human HaCaT keratinocytes. It should be mentioned is that all amino acid alkyl ester salicylates [AAOR][SA] inhibit the production of the proinflammatory cytokine IL-6 in LPS-stimulated keratinocytes. Moreover, keratinocytes, pretreated with [PheOMe][SA] and [PheOPr][SA] seem to be protected from LPS-induced inflammation. Finally, the novel compounds exhibit a similar binding affinity to bovine serum albumin (BSA) as the parent SA, suggesting a similar pharmacokinetic profile. These preliminary results indicate that SA-ILs, especially those with [PheOMe], [PheOPr], and [ValOiPr] cation, have the potential to be further investigated as novel topical agents for chronic skin diseases such as psoriasis and acne vulgaris. Full article

► Show Figures

Figure 1

2019

Jump to: 2021, 2018, 2012, 2010, 2009

11 pages, 1510 KiB

Open AccessArticle

Effect of Ionic Composition on Physicochemical Properties of Mono-Ether Functional Ionic Liquids

by Hancheng Zhou, Lifei Chen, Zhuo Wei, Yongjuan Lu, Cheng Peng, Bin Zhang, Xiaojuan Zhao, Lan Wu and Yanbin Wang

Molecules 2019, 24(17), 3112; https://doi.org/10.3390/molecules24173112 - 27 Aug 2019

Cited by 14 | Viewed by 3558

Abstract

Tunable properties prompt the development of different “tailor-made” functional ionic liquids (FILs) for specific tasks. FILs with an ether group are good solvents for many organic compounds and enzymatic reactions. However, ionic composition influences the solubility by affecting the physiochemical properties of these [...] Read more.

Tunable properties prompt the development of different “tailor-made” functional ionic liquids (FILs) for specific tasks. FILs with an ether group are good solvents for many organic compounds and enzymatic reactions. However, ionic composition influences the solubility by affecting the physiochemical properties of these FILs. To address the structure effect, a series of novel FILs with a mono-ether group (ME) based on imidazole were prepared through cationic functionalization and anionic exchange reactions, and characterized by NMR, mass spectroscopy, and Thermogravimetric analysis (TGA). The effect of ionic composition (cationic structure and anions) on density, viscosity, ionic conductivity, electrochemical window, and thermal properties of these ME-FILs were systematically investigated. In general, the viscosity and heat capacity increases with the bigger cationic volume of ME-FILs; in particular, the 2-alkyl substitution of imidazolium enhances the viscosity remarkably, whereas the density and conductivity decrease on the condition of the same [NTf₂]⁻ anion; For these ME-FILs with the same cations, the density follows the order of [NTf₂]⁻ > [PF₆]⁻ > [BF₄]⁻. The viscosity follows the order of [PF₆]⁻ > [BF₄]⁻ > [NTf₂]⁻. Ion conductivity follows the order of [NTf₂]⁻ ≈ [BF₄]⁻ > [PF₆]⁻. It is noted that the dynamic density has a good linear relationship with the temperature, and the slopes are the same for all ME-FILs. Furthermore, these ME-FILs have broad electrochemical windows and glass transition temperatures in addition to a cold crystallization and a melt temperature for ME-FIL7. Therefore, the cationic structure and counter anion affect the physicochemical properties of these ME-FILs together. Full article

► Show Figures

Figure 1

2018

Jump to: 2021, 2019, 2012, 2010, 2009

12 pages, 1463 KiB

Open AccessArticle

A Kinetic Approach of DPPH Free Radical Assay of Ferulate-Based Protic Ionic Liquids (PILs)

by Nur Afiqah Ahmad, Khairulazhar Jumbri, Anita Ramli, Noraini Abd Ghani, Haslina Ahmad and Jun Wei Lim

Molecules 2018, 23(12), 3201; https://doi.org/10.3390/molecules23123201 - 5 Dec 2018

Cited by 14 | Viewed by 5799

Abstract

The antiradical efficiency (AE) and kinetic behavior of a new ferulate-based protic ionic liquids (PILs) were described using 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical assay. The reduction of the DPPH free radical (DPPH•) was investigated by measuring the decrease in absorbance at 517 nm. The [...] Read more.

The antiradical efficiency (AE) and kinetic behavior of a new ferulate-based protic ionic liquids (PILs) were described using 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical assay. The reduction of the DPPH free radical (DPPH•) was investigated by measuring the decrease in absorbance at 517 nm. The time to reach steady state for the reaction of parent acid (ferulic acid) and synthesized PILs with DPPH• was continuously recorded for 1 h. Results revealed that the AE of 2-butylaminoethanol ferulate (2BAEF), 3-dimethylaminopropanol ferulate (3DMAPF) and 3-diethylaminopropanol ferulate (3DEAPF) PILs have improved compared to ferulic acid (FA) as the reaction class changes from low to medium. This attributed to the strong hydrogen abstraction occurred in the PILs. Furthermore, these PILs were found to have a good kinetic behavior compared to FA due to the high rate constant (k₂) (164.17, 242.84 and 244.73 M⁻¹ s⁻¹, respectively). The alkyl chain length and more alkyl substituents on the nitrogen atom of cation were believed to reduce the cation-anion interaction and speed up the hydrogen atom transfer (HAT) and electron transfer (ET) mechanisms; hence, increased rate constant was observed leading to a strong antioxidant activity of the synthesized PILs. Full article

► Show Figures

Graphical abstract

15 pages, 3332 KiB

Open AccessFeature PaperArticle

Novel Alkylimidazolium Ionic Liquids as an Antibacterial Alternative to Pathogens of the Skin and Soft Tissue Infections

by Oscar Forero Doria, Ricardo Castro, Margarita Gutierrez, Diego Gonzalez Valenzuela, Leonardo Santos, David Ramirez and Luis Guzman

Molecules 2018, 23(9), 2354; https://doi.org/10.3390/molecules23092354 - 14 Sep 2018

Cited by 49 | Viewed by 5355

Abstract

Keeping in mind the concept of green chemistry, this research aims to synthesize and characterize new ionic liquids (ILs) derived from N-cinnamyl imidazole with different sizes of alkyl chains (1, 6, 8, and 10 carbon atoms), and evaluate their antibacterial activity against [...] Read more.

Keeping in mind the concept of green chemistry, this research aims to synthesize and characterize new ionic liquids (ILs) derived from N-cinnamyl imidazole with different sizes of alkyl chains (1, 6, 8, and 10 carbon atoms), and evaluate their antibacterial activity against Skin and soft tissue infections (SSTIs) causative bacteria. The antibacterial screening was carried out by agar well diffusion and the Minimum Inhibitory Concentration (MIC) and Half Maximum Inhibitory Concentration (IC₅₀) of the different ILs were determined by microdilution in broth, also Molecular dynamics simulations were performed to study the interaction mechanism between ILs and membranes. The MIC value in Gram-positive bacteria showed that as the hydrocarbon chain increases, the MIC value decreases with a dose-dependent effect. Furthermore, Gram-negative bacteria showed high MIC values, which were also evidenced in the antibacterial screening. The molecular dynamics showed an incorporation of the ILs with the longer chain (10 C), corresponding to a passive diffusion towards the membrane surface, for its part, the ILs with the shorter chain due to its lack of hydrophobicity was not incorporated into the bilayer. Finally, the new ILs synthesized could be an alternative for the treatment of Gram-positive bacteria causative of SSTIs. Full article

► Show Figures

Graphical abstract

2012

Jump to: 2021, 2019, 2018, 2010, 2009

1022 KiB

Open AccessArticle

Effect of Ionic Liquid on the Determination of Aromatic Amines as Contaminants in Hair Dyes by Liquid Chromatography Coupled to Electrochemical Detection

by Thiago Mescoloto Lizier and Maria Valnice Boldrin Zanoni

Molecules 2012, 17(7), 7961-7979; https://doi.org/10.3390/molecules17077961 - 2 Jul 2012

Cited by 27 | Viewed by 6970

Abstract

The room temperature ionic liquid (IL) 1-butyl-3-methylimidazolium bis-(trifluorometanesulfonyl)imide BMIm[NTf₂] was used as a novel medium for improvement of separation and quantization of 16 aromatic amines typically present as contaminants in consumer products and detected by HPLC coupled to an electrochemical detector. [...] Read more.

The room temperature ionic liquid (IL) 1-butyl-3-methylimidazolium bis-(trifluorometanesulfonyl)imide BMIm[NTf₂] was used as a novel medium for improvement of separation and quantization of 16 aromatic amines typically present as contaminants in consumer products and detected by HPLC coupled to an electrochemical detector. The aromatic amines, namely 4,4'-diaminodiphenylmethane, 4-chloroaniline, 2-methoxy-5-methyl-aniline, 3,3'-dimethylbenzidine, 2,4-diaminotoluidine, 2-chloro-4-nitroaniline, 4,4'-oxydianiline, aniline, 3,3'-dichlorobenzidine, benzidine, 4-aminobiphenyl, o-dianisidine, o-anisidine, o-toluidine, 4,4'-methylene-bis-2-chloroaniline and 2-naphthyl-amine are oxidized in methanol/BMIm[NTf₂] at a potential around +0.68V to +0.93V vs. Ag/AgCl at a glassy carbon electrode, which is the base for their determination by HPLC/ED. Using the optimized conditions of methanol/BMIm[NTf₂] 70:30 (v/v) as mobile phase, flow-rate of 0.8 mL·min⁻¹, column CLC-ODS, E_ap = +1.0 V and T = 40 °C analytical curves were constructed for each of the tested amines. Good linearity was obtained in the concentration range of 1.09 mg·L⁻¹ to 217 mg·L⁻¹, with excellent correlation coefficients. The limits of detection reached 0.021 mg·L⁻¹ to 0.246 mg·L⁻¹ and good relative standard deviations (RSD, n = 3) were obtained from the measurements. Satisfactory recovery for each aromatic amine was achieved, ranging from 95 to 103%. The developed method was successfully applied to determine six aromatic amines present as contaminants in commercial hair dye samples. Full article

► Show Figures

Figure 1

638 KiB

Open AccessArticle

In Situ Electrochemical SFG/DFG Study of CN⁻ and Nitrile Adsorption at Au from 1-Butyl-1-methyl-pyrrolidinium Bis(trifluoromethylsulfonyl) Amide Ionic Liquid ([BMP][TFSA]) Containing 4-{2-[1-(2-Cyanoethyl)-1,2,3,4-tetrahydroquinolin-6-yl]diazenyl} Benzonitrile (CTDB) and K[Au(CN)₂]

by Benedetto Bozzini, Bertrand Busson, Audrey Gayral, Christophe Humbert, Claudio Mele, Catherine Six and Abderrahmane Tadjeddine

Molecules 2012, 17(7), 7722-7736; https://doi.org/10.3390/molecules17077722 - 25 Jun 2012

Cited by 10 | Viewed by 6042

Abstract

In this paper we report an in situ electrochemical Sum-/Difference Frequency Generation (SFG/DFG) spectroscopy investigation of the adsorption of nitrile and CN⁻ from the ionic liquid 1-butyl-1-methyl-pyrrolidinium bis(trifluoromethylsulfonyl) amide ([BMP][TFSA]) containing 4-{2-[1-(2-cyanoethyl)-1,2,3,4-tetrahydroquinolin-6-yl]- diazenyl}benzonitrile (CTDB) at Au electrodes in the absence and in [...] Read more.

In this paper we report an in situ electrochemical Sum-/Difference Frequency Generation (SFG/DFG) spectroscopy investigation of the adsorption of nitrile and CN⁻ from the ionic liquid 1-butyl-1-methyl-pyrrolidinium bis(trifluoromethylsulfonyl) amide ([BMP][TFSA]) containing 4-{2-[1-(2-cyanoethyl)-1,2,3,4-tetrahydroquinolin-6-yl]- diazenyl}benzonitrile (CTDB) at Au electrodes in the absence and in the presence of the Au-electrodeposition process from K[Au(CN)₂]. The adsorption of nitrile and its coadsorption with CN⁻ resulting either from the cathodic decomposition of the dye or from ligand release from the Au(I) cyanocomplex yield potential-dependent single or double SFG bands in the range 2,125–2,140 cm⁻¹, exhibiting Stark tuning values of ca. 3 and 1 cm⁻¹ V⁻¹ in the absence and presence of electrodeposition, respectively. The low Stark tuning found during electrodeposition correlates with the cathodic inhibiting effect of CTDB, giving rise to its levelling properties. The essential insensitivity of the other DFG parameters to the electrodeposition process is due to the growth of smooth Au. Full article

► Show Figures

Figure 1

1121 KiB

Open AccessReview

Ionic Liquids — Promising but Challenging Solvents for Homogeneous Derivatization of Cellulose

by Martin Gericke, Pedro Fardim and Thomas Heinze

Molecules 2012, 17(6), 7458-7502; https://doi.org/10.3390/molecules17067458 - 15 Jun 2012

Cited by 299 | Viewed by 15880

Abstract

In the past decade, ionic liquids (ILs) have received enormous interest as solvents for cellulose. They have been studied intensively for fractionation and biorefining of lignocellulosic biomass, for dissolution of the polysaccharide, for preparation of cellulosic fibers, and in particular as reaction media [...] Read more.

In the past decade, ionic liquids (ILs) have received enormous interest as solvents for cellulose. They have been studied intensively for fractionation and biorefining of lignocellulosic biomass, for dissolution of the polysaccharide, for preparation of cellulosic fibers, and in particular as reaction media for the homogeneous preparation of highly engineered polysaccharide derivatives. ILs show great potential for application on a commercial scale regarding recyclability, high dissolution power, and their broad structural diversity. However, a critical analysis reveals that these promising features are combined with serious drawbacks that need to be addressed in order to utilize ILs for the efficient synthesis of cellulose derivatives. This review presents a comprehensive overview about chemical modification of cellulose in ILs. Difficulties encountered thereby are discussed critically and current as well as future developments in this field of polysaccharide research are outlined. Full article

► Show Figures

Graphical abstract

355 KiB

Open AccessArticle

A Convenient Synthesis of Triflate Anion Ionic Liquids and Their Properties

by Nikolai V. Ignat’ev, Peter Barthen, Andryi Kucheryna, Helge Willner and Peter Sartori

Molecules 2012, 17(5), 5319-5338; https://doi.org/10.3390/molecules17055319 - 7 May 2012

Cited by 61 | Viewed by 13062

Abstract

A solvent- and halogen-free synthesis of high purity triflate ionic liquids via direct alkylation of organic bases (amines, phosphines or heterocyclic compounds) with methyl and ethyl trifluoromethanesulfonate (methyl and ethyl triflate) has been developed. Cheap and non-toxic dimethyl and diethyl carbonate serve as [...] Read more.

A solvent- and halogen-free synthesis of high purity triflate ionic liquids via direct alkylation of organic bases (amines, phosphines or heterocyclic compounds) with methyl and ethyl trifluoromethanesulfonate (methyl and ethyl triflate) has been developed. Cheap and non-toxic dimethyl and diethyl carbonate serve as source for the methyl and ethyl groups in the preparation of methyl and ethyl triflate by this invented process. The properties of ionic liquids containing the triflate anion are determined and discussed. Full article

► Show Figures

Figure 1

212 KiB

Open AccessArticle

Preparation of S_RN1-Type Coupling Adducts from Aliphatic gem-Dinitro Compounds in Ionic Liquids

by Akio Kamimura and Seiichi Toyoshima

Molecules 2012, 17(5), 4782-4790; https://doi.org/10.3390/molecules17054782 - 25 Apr 2012

Viewed by 4938

Abstract

S_RN1-type coupling adducts are readily prepared by the reaction between a-sulfonylesters or a-cyanosulfones and gem-dinitro compounds in ionic liquids. The reactions progress smoothly and recovered ionic liquids can be used for several iterations, as long as they are washed with [...] Read more.

S_RN1-type coupling adducts are readily prepared by the reaction between a-sulfonylesters or a-cyanosulfones and gem-dinitro compounds in ionic liquids. The reactions progress smoothly and recovered ionic liquids can be used for several iterations, as long as they are washed with water to remove alkali metallic salts. The reaction rate is slower than the corresponding S_RN1 reaction in DMSO, but no acceleration on irradiation or no inhibition in the presence of m-DNB are observed. Full article

► Show Figures

Figure 1

571 KiB

Open AccessReview

Ionic Liquid Applications in Peptide Chemistry: Synthesis, Purification and Analytical Characterization Processes

by Alesia A. Tietze, Pascal Heimer, Annegret Stark and Diana Imhof

Molecules 2012, 17(4), 4158-4185; https://doi.org/10.3390/molecules17044158 - 5 Apr 2012

Cited by 52 | Viewed by 12050

Abstract

This review aims to provide a comprehensive overview of the recent advances made in the field of ionic liquids in peptide chemistry and peptide analytics. Full article

► Show Figures

Figure 1

472 KiB

Open AccessArticle

A Simple Halide-to-Anion Exchange Method for Heteroaromatic Salts and Ionic Liquids

by Ermitas Alcalde, Immaculada Dinarès, Anna Ibáñez and Neus Mesquida

Molecules 2012, 17(4), 4007-4027; https://doi.org/10.3390/molecules17044007 - 2 Apr 2012

Cited by 60 | Viewed by 17849

Abstract

A broad and simple method permitted halide ions in quaternary heteroaromatic and ammonium salts to be exchanged for a variety of anions using an anion exchange resin (A⁻ form) in non-aqueous media. The anion loading of the AER (OH⁻ form) was [...] Read more.

A broad and simple method permitted halide ions in quaternary heteroaromatic and ammonium salts to be exchanged for a variety of anions using an anion exchange resin (A⁻ form) in non-aqueous media. The anion loading of the AER (OH⁻ form) was examined using two different anion sources, acids or ammonium salts, and changing the polarity of the solvents. The AER (A⁻ form) method in organic solvents was then applied to several quaternary heteroaromatic salts and ILs, and the anion exchange proceeded in excellent to quantitative yields, concomitantly removing halide impurities. Relying on the hydrophobicity of the targeted ion pair for the counteranion swap, organic solvents with variable polarity were used, such as CH₃OH, CH₃CN and the dipolar nonhydroxylic solvent mixture CH₃CN:CH₂Cl₂ (3:7) and the anion exchange was equally successful with both lipophilic cations and anions. Full article

► Show Figures

Graphical abstract

746 KiB

Open AccessArticle

Coupling of Nanoporous Chromium, Aluminium-Containing Silicates with an Ionic Liquid for the Transformation of Glucose into 5-(Hydroxymethyl)-2-furaldehyde

by Margarida M. Antunes, Sérgio Lima, Martyn Pillinger and Anabela A. Valente

Molecules 2012, 17(4), 3690-3707; https://doi.org/10.3390/molecules17043690 - 26 Mar 2012

Cited by 6 | Viewed by 8285

Abstract

Micro/mesoporous chromium, aluminium-containing silicates of the type TUD-1 (Al-TUD-1, Cr-TUD-1, CrAl-TUD-1) and zeolite BEA, Cr-BEA, and related composites BEA/TUD-1 and Cr-BEA/TUD-1, were prepared, characterised, and tested as solid acids coupled with the ionic liquid (IL) 1-butyl-3-methylimidazolium chloride ([bmim]Cl) as solvent, in the transformation [...] Read more.

Micro/mesoporous chromium, aluminium-containing silicates of the type TUD-1 (Al-TUD-1, Cr-TUD-1, CrAl-TUD-1) and zeolite BEA, Cr-BEA, and related composites BEA/TUD-1 and Cr-BEA/TUD-1, were prepared, characterised, and tested as solid acids coupled with the ionic liquid (IL) 1-butyl-3-methylimidazolium chloride ([bmim]Cl) as solvent, in the transformation of d-glucose into 5-(hydroxymethyl)-2-furaldehyde (Hmf), at 120 °C. The chromium-containing catalytic systems lead to considerably higher Hmf yields in comparison to the related systems without chromium. The IL is a favourable solvent for this target reaction (in terms of Hmf yields reached) compared to water or dimethylsulfoxide. A detailed study on the stabilities of the nanoporous solid acids in the IL medium is presented. Full article

► Show Figures

Graphical abstract

2010

Jump to: 2021, 2019, 2018, 2012, 2009

345 KiB

Open AccessReview

Recent Applications of Ionic Liquids in Separation Technology

by Dandan Han and Kyung Ho Row

Molecules 2010, 15(4), 2405-2426; https://doi.org/10.3390/molecules15042405 - 5 Apr 2010

Cited by 485 | Viewed by 20949

Abstract

Ionic liquids (ILs) have been applied in different areas of separation, such as ionic liquid supported membranes, as mobile phase additives and surface-bonded stationary phases in chromatography separations and as the extraction solvent in sample preparations, because they can be composed from various [...] Read more.

Ionic liquids (ILs) have been applied in different areas of separation, such as ionic liquid supported membranes, as mobile phase additives and surface-bonded stationary phases in chromatography separations and as the extraction solvent in sample preparations, because they can be composed from various cations and anions that change the properties and phase behavior of liquids. Although the applications of ILs in separations are still in their early stages, the academic interest in ILs is increasing. An overview of the principle applications of ILs in separation technology is present in this work. Furthermore, the prospects of the ILs in separation techniques are discussed. Full article

206 KiB

Open AccessCommunication

The Solubility of Hen Lysozyme in Ethylammonium Nitrate/H₂O Mixtures and a Novel Approach to Protein Crystallization

by Nolene Byrne and C. Austen Angell

Molecules 2010, 15(2), 793-803; https://doi.org/10.3390/molecules15020793 - 4 Feb 2010

Cited by 35 | Viewed by 8563

Abstract

We report on the solubility of hen lysozyme (HEWL) in aqueous ethylammonium nitrate (EAN) as a function of water content. We find the solubility behavior to be complex, exhibiting both a maximum (400 mg/mL) at very high EAN content) and a minimum at [...] Read more.

We report on the solubility of hen lysozyme (HEWL) in aqueous ethylammonium nitrate (EAN) as a function of water content. We find the solubility behavior to be complex, exhibiting both a maximum (400 mg/mL) at very high EAN content) and a minimum at intermediate EAN content. We exploit this solubility profile in a novel approach to generating crystals of hydrophilic proteins, based on rehydration of a high concentration protein solution. We describe the production of crystals of X-ray diffraction quality. Two related ionic liquid solvent systems, with the same solubility profiles but different effective pH characteristics, are identified for future evaluation. Full article

► Show Figures

Figure 1

2009

Jump to: 2021, 2019, 2018, 2012, 2010

278 KiB

Open AccessArticle

18-Crown-6 and Dibenzo-18-crown-6 Assisted Extraction of Cesium from Water into Room Temperature Ionic Liquids and Its Correlation with Stability Constants for Cesium Complexes

by Andrey Grigoryevich Vendilo, Dmitry Ivanovich Djigailo, Svetlana Valeryevna Smirnova, Irina Ivanovna Torocheshnikova, Konstantin Ivanovich Popov, Vladimir Georgyevich Krasovsky and Igor Vladimirovich Pletnev

Molecules 2009, 14(12), 5001-5016; https://doi.org/10.3390/molecules14125001 - 2 Dec 2009

Cited by 31 | Viewed by 13713

Abstract

The pH-profiles of the extraction of Cs⁺ into four conventional (1-butyl-3-methylimidazolium hexafluorophosphate and bis[trifluoromethyl)sulphonyl]imides of 1-butyl-3-methylimidazolium, 1-hexyl-3-methylimidazolium, and 1-(2-ethylhexyl)-3- methylimidazolium) and two novel (trioctylmethylammonium salicylate and tetrahexylammonium dihexylsulfosuccinate) room temperature ionic liquids have been determined both in the absence and in the [...] Read more.

The pH-profiles of the extraction of Cs⁺ into four conventional (1-butyl-3-methylimidazolium hexafluorophosphate and bis[trifluoromethyl)sulphonyl]imides of 1-butyl-3-methylimidazolium, 1-hexyl-3-methylimidazolium, and 1-(2-ethylhexyl)-3- methylimidazolium) and two novel (trioctylmethylammonium salicylate and tetrahexylammonium dihexylsulfosuccinate) room temperature ionic liquids have been determined both in the absence and in the presence of crown ether (18-crown-6 or dibenzo-18-crown-6). The pH-profiles of distribution ratio of crown ethers have been established in the same conditions. The relationship of cesium extraction efficiency both with the stability of its complexes with crown ethers and crown ethers’ distribution ratio has been clarified. Full article

► Show Figures

Graphical abstract

764 KiB

Open AccessArticle

Cellulose/Gold Nanocrystal Hybrids via an Ionic Liquid/Aqueous Precipitation Route

by Zhonghao Li and Andreas Taubert

Molecules 2009, 14(11), 4682-4688; https://doi.org/10.3390/molecules14114682 - 18 Nov 2009

Cited by 20 | Viewed by 9896

Abstract

Injection of a mixture of HAuCl₄ and cellulose dissolved in the ionic liquid (IL) 1-butyl-3-methylimidazolium chloride [Bmim]Cl into aqueous NaBH4 leads to colloidal gold nanoparticle/cellulose hybrid precipitates. This process is a model example for a very simple and generic approach towards (noble) [...] Read more.

Injection of a mixture of HAuCl₄ and cellulose dissolved in the ionic liquid (IL) 1-butyl-3-methylimidazolium chloride [Bmim]Cl into aqueous NaBH4 leads to colloidal gold nanoparticle/cellulose hybrid precipitates. This process is a model example for a very simple and generic approach towards (noble) metal/cellulose hybrids, which could find applications in sensing, sterile filtration, or as biomaterials. Full article

► Show Figures

Figure 1

158 KiB

Open AccessArticle

1-Methyl-3-octylimidazolium Chloride—Sorption and Primary Biodegradation Analysis in Activated Sewage Sludge

by Marta Markiewicz, Christian Jungnickel, Aleksandra Markowska, Urszula Szczepaniak, Monika Paszkiewicz and Jan Hupka

Molecules 2009, 14(11), 4396-4405; https://doi.org/10.3390/molecules14114396 - 2 Nov 2009

Cited by 29 | Viewed by 10474

Abstract

Ionic liquids (ILs) are known to be non-volatile and thus to have low potential for atmospheric contamination or intoxication of humans by inhalation. However ILs have the potential to contaminate soil and water as they might be water soluble and can be sorbed [...] Read more.

Ionic liquids (ILs) are known to be non-volatile and thus to have low potential for atmospheric contamination or intoxication of humans by inhalation. However ILs have the potential to contaminate soil and water as they might be water soluble and can be sorbed onto solids. The investigation of possible natural ways of reducing the concentration of ILs in the environment is of high importane, especially because the requirement for biodegradable chemicals increases, together with pressure for reduction of incineration and landfill waste. It was found that the upper concentration threshold for primary biodegradation of 1-methyl-3-octylimidazolium chloride is 0.2 mM. At higher concentrations the dehydrogenase activity of the cells dropped markedly, indicating that the IL inhibits cell activity. This concentration is in good agreement with the minimal inhibitory concentration of the same compound found for a series of bacteria and fungi by this research group. The sorption of 1-methyl-3-octylimidazolium chloride was found to be significant, and the sorption coefficient was determined to be 98.2 L kg^-1. Full article

► Show Figures

Graphical abstract

93 KiB

Open AccessArticle

Oxidative Desulfurization of Fuel Oil by Pyridinium-Based Ionic Liquids

by Dishun Zhao, Yanan Wang and Erhong Duan

Molecules 2009, 14(11), 4351-4357; https://doi.org/10.3390/molecules14114351 - 28 Oct 2009

Cited by 61 | Viewed by 11906

Abstract

In this work, an N-butyl-pyridinium-based ionic liquid [BPy]BF₄ was prepared. The effect of extraction desulfurization on model oil with thiophene and dibenzothiophene (DBT) was investigated. Ionic liquids and hydrogen peroxide (30%) were tested in extraction-oxidation desulfurization of model oil. The results [...] Read more.

In this work, an N-butyl-pyridinium-based ionic liquid [BPy]BF₄ was prepared. The effect of extraction desulfurization on model oil with thiophene and dibenzothiophene (DBT) was investigated. Ionic liquids and hydrogen peroxide (30%) were tested in extraction-oxidation desulfurization of model oil. The results show that the ionic liquid [BPy]BF₄ has a better desulfurization effect. The best technological conditions are: V(IL)/V(Oil) /V(H₂O₂) = 1:1:0.4, temperature 55 °C, the time 30 min. The ratio of desulfurization to thiophene and DBT reached 78.5% and 84.3% respectively, which is much higher than extraction desulfurization with simple ionic liquids. Under these conditions, the effect of desulfurization on gasoline was also investigated. The used ionic liquids can be recycled up to four times after regeneration. Full article

► Show Figures

Figure 1

192 KiB

Open AccessCommunication

Preparation of (S)-1-Halo-2-octanols Using Ionic Liquids and Biocatalysts

by Mireia Oromí-Farrús, Jordi Eras, Núria Sala, Mercè Torres and Ramon Canela

Molecules 2009, 14(10), 4275-4283; https://doi.org/10.3390/molecules14104275 - 23 Oct 2009

Cited by 7 | Viewed by 9535

Abstract

Preparation of (S)-1-chloro-2-octanol and (S)-1-bromo-2-octanol was carried out by the enzymatic hydrolysis of halohydrin palmitates using biocatalysts. Halohydrin palmitates were prepared by various methods from palmitic acid and 1,2-octanediol. A tandem hydrolysis was carried out using lipases from Candida [...] Read more.

Preparation of (S)-1-chloro-2-octanol and (S)-1-bromo-2-octanol was carried out by the enzymatic hydrolysis of halohydrin palmitates using biocatalysts. Halohydrin palmitates were prepared by various methods from palmitic acid and 1,2-octanediol. A tandem hydrolysis was carried out using lipases from Candida antarctica (Novozym^® 435), Rhizomucor miehei (Lipozyme IM), and “resting cells” from a Rhizopus oryzae strain that was not mycotoxigenic. The influence of the enzyme and the reaction medium on the selective hydrolysis of isomeric mixtures of halohydrin esters is described. Novozym^®435 allowed preparation of (S)-1-chloro-2-octanol and (S)-1-bromo-2-octanol after 1–3 h of reaction at 40 °C in [BMIM][PF₆]. Full article

365 KiB

Open AccessReview

On the Chemical Stabilities of Ionic Liquids

by Subbiah Sowmiah, Venkatesan Srinivasadesikan, Ming-Chung Tseng and Yen-Ho Chu

Molecules 2009, 14(9), 3780-3813; https://doi.org/10.3390/molecules14093780 - 25 Sep 2009

Cited by 450 | Viewed by 23270

Abstract

Ionic liquids are novel solvents of interest as greener alternatives to conventional organic solvents aimed at facilitating sustainable chemistry. As a consequence of their unusual physical properties, reusability, and eco-friendly nature, ionic liquids have attracted the attention of organic chemists. Numerous reports have [...] Read more.

Ionic liquids are novel solvents of interest as greener alternatives to conventional organic solvents aimed at facilitating sustainable chemistry. As a consequence of their unusual physical properties, reusability, and eco-friendly nature, ionic liquids have attracted the attention of organic chemists. Numerous reports have revealed that many catalysts and reagents were supported in the ionic liquid phase, resulting in enhanced reactivity and selectivity in various important reaction transformations. However, synthetic chemists cannot ignore the stability data and intermolecular interactions, or even reactions that are directly applicable to organic reactions in ionic liquids. It is becoming evident from the increasing number of reports on use of ionic liquids as solvents, catalysts, and reagents in organic synthesis that they are not totally inert under many reaction conditions. While in some cases, their unexpected reactivity has proven fortuitous and in others, it is imperative that when selecting an ionic liquid for a particular synthetic application, attention must be paid to its compatibility with the reaction conditions. Even though, more than 200 room temperature ionic liquids are known, only a few reports have commented their effects on reaction mechanisms or rate/stability. Therefore, rather than attempting to give a comprehensive overview of ionic liquid chemistry, this review focuses on the non-innocent nature of ionic liquids, with a decided emphasis to clearly illuminate the ability of ionic liquids to affect the mechanistic aspects of some organic reactions thereby affecting and promoting the yield and selectivity. Full article

► Show Figures

Figure 1

271 KiB

Open AccessArticle

Catalytic Epoxidation of a Technical Mixture of Methyl Oleate and Methyl Linoleate in Ionic Liquids Using MoO(O₂)₂•2QOH (QOH = 8-quinilinol) as Catalyst and NaHCO₃as co-Catalyst

by Shuang-Fei Cai, Li-Sheng Wang and Chuan-Lei Fan

Molecules 2009, 14(8), 2935-2946; https://doi.org/10.3390/molecules14082935 - 10 Aug 2009

Cited by 30 | Viewed by 13527

Abstract

The oxo-diperoxo molybdenum(VI) complex MoO(O₂)₂•2QOH (QOH = 8-quinilinol) was prepared and characterized by elemental analysis, IR and UV-Vis spectra. The ionic liquids (ILs) [bmim][BF₄], [hydemim][BF₄], and [bmim][PF₆] were characterized by¹H-NMR and [...] Read more.

The oxo-diperoxo molybdenum(VI) complex MoO(O₂)₂•2QOH (QOH = 8-quinilinol) was prepared and characterized by elemental analysis, IR and UV-Vis spectra. The ionic liquids (ILs) [bmim][BF₄], [hydemim][BF₄], and [bmim][PF₆] were characterized by¹H-NMR and UV-Vis spectra. The epoxidation of a technical mixture of methyl oleate and methyl linoleate with H₂O₂, in [bmim][BF₄], [hydemim][BF₄] and [bmim][PF₆], catalyzed by MoO(O₂)₂•2QOH (QOH = 8-quinilinol) and with NaHCO₃ as co-catalyst has been studied for the first time. It was found that high conversions of methyl oleate and methyl linoleate to their respective oxidation products, as well as the total selectivity of their oxidation products to oxirane in [hydemim][BF₄] were obtained. Also, the IL phases containing the Mo(VI) catalyst can be readily recycled by washing with diethyl ether and drying, and the Mo(VI) catalyst can be reused at least five times. Full article

► Show Figures

Figure 1

450 KiB

Open AccessReview

Ionic Liquids as Advanced Lubricant Fluids

by María-Dolores Bermúdez, Ana-Eva Jiménez, José Sanes and Francisco-José Carrión

Molecules 2009, 14(8), 2888-2908; https://doi.org/10.3390/molecules14082888 - 4 Aug 2009

Cited by 571 | Viewed by 25153

Abstract

Ionic liquids (ILs) are finding technological applications as chemical reaction media and engineering fluids. Some emerging fields are those of lubrication, surface engineering and nanotechnology. ILs are thermally stable, non-flammable highly polar fluids with negligible volatility, these characteristics make them ideal candidates for [...] Read more.

Ionic liquids (ILs) are finding technological applications as chemical reaction media and engineering fluids. Some emerging fields are those of lubrication, surface engineering and nanotechnology. ILs are thermally stable, non-flammable highly polar fluids with negligible volatility, these characteristics make them ideal candidates for new lubricants under severe conditions, were conventional oils and greases or solid lubricants fail. Such conditions include ultra-high vacuum and extreme temperatures. Other very promising areas which depend on the interaction between IL molecules and material surfaces are the use of ILs in the lubrication of microelectromechanic and nanoelectromechanic systems (MEMS and NEMS), the friction and wear reduction of reactive light alloys and the modification of nanophases. Full article

► Show Figures

Figure 1

348 KiB

Open AccessArticle

Ionic Liquids: Just Molten Salts After All?

by Hon Man Yau, Si Jia Chan, Stephen R. D. George, James M. Hook, Anna K. Croft and Jason B. Harper

Molecules 2009, 14(7), 2521-2534; https://doi.org/10.3390/molecules14072521 - 13 Jul 2009

Cited by 51 | Viewed by 16391

Abstract

While there has been much effort in recent years to characterise ionic liquids in terms of parameters that are well described for molecular solvents, using these to explain reaction outcomes remains problematic. Herein we propose that many reaction outcomes in ionic liquids may [...] Read more.

While there has been much effort in recent years to characterise ionic liquids in terms of parameters that are well described for molecular solvents, using these to explain reaction outcomes remains problematic. Herein we propose that many reaction outcomes in ionic liquids may be explained by considering the electrostatic interactions present in the solution; that is, by recognising that ionic liquids are salts. This is supported by evidence in the literature, along with studies presented here. Full article

► Show Figures

Graphical abstract

217 KiB

Open AccessArticle

Transformations of Organic Molecules with F-TEDA-BF₄ in Ionic Liquid Media

by Jasminka Pavlinac, Marko Zupan and Stojan Stavber

Molecules 2009, 14(7), 2394-2409; https://doi.org/10.3390/molecules14072394 - 6 Jul 2009

Cited by 14 | Viewed by 16362

Abstract

The transformations of organic molecules with F-TEDA-BF₄ (1) were investigated in the hydrophilic ionic liquid (IL) 1-butyl-3-methyl-imidazolium tetrafluoroborate ([bmim][BF₄], 2) and the hydrophobic IL 1-butyl-3-methyl-imidazolium hexafluorophosphate ([bmim][PF₆], 3). The range of substrates included alkyl substituted phenols 4a-c, 9, [...] Read more.

The transformations of organic molecules with F-TEDA-BF₄ (1) were investigated in the hydrophilic ionic liquid (IL) 1-butyl-3-methyl-imidazolium tetrafluoroborate ([bmim][BF₄], 2) and the hydrophobic IL 1-butyl-3-methyl-imidazolium hexafluorophosphate ([bmim][PF₆], 3). The range of substrates included alkyl substituted phenols 4a-c, 9, 13, 1,1-diphenylethene (15), alkyl aryl ketones 19-22, aldehydes 23-25 and methoxy-substituted benzene derivatives 26-30. The evaluation of the outcome of reactions performed in IL media in comparison to those of the corresponding reactions in conventional organic solvents revealed that the transformations in IL are less efficient and selective. The effect of the presence of a nucleophile (MeOH, H₂O, MeCN) on the course of reaction was also studied. Full article

► Show Figures

Graphical abstract

605 KiB

Open AccessReview

Ionic Liquids in Tribology

by Ichiro Minami

Molecules 2009, 14(6), 2286-2305; https://doi.org/10.3390/molecules14062286 - 24 Jun 2009

Cited by 624 | Viewed by 24952

Abstract

Current research on room-temperature ionic liquids as lubricants is described. Ionic liquids possess excellent properties such as non-volatility, non-flammability, and thermo-oxidative stability. The potential use of ionic liquids as lubricants was first proposed in 2001 and approximately 70 articles pertaining to fundamental research [...] Read more.

Current research on room-temperature ionic liquids as lubricants is described. Ionic liquids possess excellent properties such as non-volatility, non-flammability, and thermo-oxidative stability. The potential use of ionic liquids as lubricants was first proposed in 2001 and approximately 70 articles pertaining to fundamental research on ionic liquids have been published through May 2009. A large majority of the cations examined in this area are derived from 1,3-dialkylimidazolium, with a higher alkyl group on the imidazolium cation being beneficial for good lubrication, while it reduces the thermo-oxidative stability. Hydrophobic anions provide both good lubricity and significant thermo-oxidative stability. The anions decompose through a tribochemical reaction to generate metal fluoride on the rubbed surface. Additive technology to improve lubricity is also explained. An introduction to tribology as an interdisciplinary field of lubrication is also provided. Full article

► Show Figures

Figure 1

206 KiB

Open AccessArticle

A Facile Route to C2-Substituted Imidazolium Ionic Liquids

by Elliot Ennis and Scott T. Handy

Molecules 2009, 14(6), 2235-2245; https://doi.org/10.3390/molecules14062235 - 19 Jun 2009

Cited by 22 | Viewed by 12562

Abstract

A convenient route for the preparation of C2-substituted imidazolium ionic liquids is reported. This method involves the alkylation of N-heterocyclic carbenes, which are readily generated from the C2-unsubstituted imidazolium ionic liquids. It works well for non-functionalized alkyl chlorides, and less well for [...] Read more.

A convenient route for the preparation of C2-substituted imidazolium ionic liquids is reported. This method involves the alkylation of N-heterocyclic carbenes, which are readily generated from the C2-unsubstituted imidazolium ionic liquids. It works well for non-functionalized alkyl chlorides, and less well for alkyl bromides and iodides, likely due to competing elimination reactions. The resulting C2-substituted salts can be transformed into ionic liquids via standard anion metathesis reactions. Full article

► Show Figures

Graphical abstract

120 KiB

Open AccessArticle

Effect of Ionic Liquids as the Mobile Phase Additives on the HPLC Resolution of Four Active Compounds from Sophora flavescens Ait

by Minglei Tian, Junyu Liu and Kyung Ho Row

Molecules 2009, 14(6), 2127-2134; https://doi.org/10.3390/molecules14062127 - 11 Jun 2009

Cited by 17 | Viewed by 10304

Abstract

The retention behaviour of four active compounds from Sophora Flavescens Ait using three ionic liquids as mobile phase modifiers was examined. The effect of the pH and the amount of ionic liquid modifier on the retention of these compounds was determined in methanol/water [...] Read more.

The retention behaviour of four active compounds from Sophora Flavescens Ait using three ionic liquids as mobile phase modifiers was examined. The effect of the pH and the amount of ionic liquid modifier on the retention of these compounds was determined in methanol/water (v/v) as the mobile phase containing different ionic liquids ranging in concentration from 0.1 mmol/L to 3.0 mmol/L. The ionic liquids showed promise as additives in high-performance liquid chromatography. Full article

► Show Figures

Figure 1

177 KiB

Open AccessArticle

Synthesis and Properties of Acyclic Ammonium-based Ionic Liquids with Allyl Substituents as Electrolytes

by Taeeun Yim, Chang Young Choi, Junyoung Mun, Seung M. Oh and Young Gyu Kim

Molecules 2009, 14(5), 1840-1851; https://doi.org/10.3390/molecules14051840 - 15 May 2009

Cited by 31 | Viewed by 10411

Abstract

Several new acyclic ammonium-TFSI ionic liquids with an allyl substituent(s) were synthesized and their physicochemical and electrochemical properties were characterized. [AAMM]Am-TFSI (3) with two allyl groups showed the widest electrochemical stability window (5.9 V) among the ammonium-based ILs reported to date because of [...] Read more.

Several new acyclic ammonium-TFSI ionic liquids with an allyl substituent(s) were synthesized and their physicochemical and electrochemical properties were characterized. [AAMM]Am-TFSI (3) with two allyl groups showed the widest electrochemical stability window (5.9 V) among the ammonium-based ILs reported to date because of the increment of both the anodic and cathodic limits. The charge-discharge performance of a LiCoO₂-based half-cell containing [AAMM]Am-TFSI as an electrolyte was better in cycleability (the capacity retention ratio: 99% after 20 cycles) than that of the cell with the corresponding partially saturated analogue, [AMMP]Am-TFSI (2) (the capacity retention ratio: 92% after 20 cycles). Full article

► Show Figures

Graphical abstract

241 KiB

Open AccessArticle

Non-Equilibrium Thermodynamic Analysis of Transport Properties in the Nanofiltration of Ionic Liquid-Water Solutions

by Bo Wu, Yu M. Zhang and Hua P. Wang

Molecules 2009, 14(5), 1781-1788; https://doi.org/10.3390/molecules14051781 - 11 May 2009

Cited by 10 | Viewed by 9594

Abstract

Thenanofiltration of aqueous solutions of the ionic liquids (ILs) 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF₄), and 1-butyl-3-methylimidazolium bromide ([Bmim]Br) with a polyamide nanofiltration membrane was investigated. The practical transport coefficients, including hydrodynamic permeability (L_p), reflection (σ) and solute permeability [...] Read more.

Thenanofiltration of aqueous solutions of the ionic liquids (ILs) 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF₄), and 1-butyl-3-methylimidazolium bromide ([Bmim]Br) with a polyamide nanofiltration membrane was investigated. The practical transport coefficients, including hydrodynamic permeability (L_p), reflection (σ) and solute permeability (ω) were calculated in terms of a non-equilibrium thermodynamics approach. It was found that L_p and σ diminished as the concentration of the IL solutions increased. These characteristics are similar to those observed in inorganic electrolyte-water systems. In addition, it was shown that the rejection and volume flux for both ionic liquid solutions rose with feed pressure, while it decreased with feed concentration. The maximum rejection efficiencies for [Bmim]Br and [Bmim]BF₄ are 67 % and 60 %, respectively, on our experimental scale. All the data suggests that a highly efficient process for IL separation could be developed when the operating conditions are optimized further. Full article

► Show Figures

Figure 1

Journal Menu

Journal Browser

Ionic Liquids (Closed)

Share This Topical Collection

Editor

Topical Collection Information

Related Special Issues

Published Papers (29 papers)

2021

Jump to: 2019, 2018, 2012, 2010, 2009

2019

Jump to: 2021, 2018, 2012, 2010, 2009

2018

Jump to: 2021, 2019, 2012, 2010, 2009

2012

Jump to: 2021, 2019, 2018, 2010, 2009

2010

Jump to: 2021, 2019, 2018, 2012, 2009

2009

Jump to: 2021, 2019, 2018, 2012, 2010

Further Information

Guidelines

MDPI Initiatives

Follow MDPI