Ionic liquid induced changes in the properties of aqueous zwitterionic surfactant solution

Modifying properties of aqueous surfactant solutions by addition of external additives is an important area of research. Unusual properties of ionic liquids (ILs) make them ideal candidates for this purpose. Changes in important physicochemical properties of aqueous zwitterionic N-dodecyl- N, N-dimethyl-3-ammonio-1-propanesulfonate (SB-12) surfactant solution upon addition of hydrophilic IL 1-butyl-3-methylimidazolium tetrafluoroborate, [bmim][BF 4], are reported. Dynamic light scattering results indicate a dramatic reduction in the average micellar size in the presence of [bmim][BF 4]; micellar (or micelle-like) aggregation in the presence of as high as 30 wt % [bmim][BF 4] is confirmed. Responses from fluorescence probes are used to obtain critical micelle concentration (cmc), aggregation number ( N agg), and dipolarity and microfluidity of the micellar pseudophase of aqueous SB-12 in the presence of [bmim][BF 4]. In general, increasing the amount of [bmim][BF 4] to 30 wt % results in decrease in N agg and increase in cmc. Increase in the dipolarity and the microfluidity of the probe cybotactic region within the micellar pseudophase is observed on increasing [bmim][BF 4] concentration in the solution. It is attributed to increased water penetration into the micellar pseudophase as [bmim][BF 4] is added to aqueous SB-12. It is proposed that IL [bmim][BF 4] behaves similar to an electrolyte and/or a cosurfactant when present at low concentrations and as a polar cosolvent when present at high concentrations. Electrostatic attraction between cation of IL and anion of zwitterion, and anion of IL and cation of zwitterion at low concentrations of [bmim][BF 4] is evoked to explain the observed changes. Presence of IL as cosolvent appears to reduce the efficiency of micellization process by reducing the hydrophobic effect.     

离子液体[bmim][BF4]对联苯甲酰光化学反应影响的瞬态吸收光谱

利用纳秒级激光光解瞬态吸收光谱研究了联苯甲酰(BZ)在离子液体1-丁基-3-甲基咪唑四氟硼酸盐([bmim][BF₄])与乙腈(MeCN)混合体系中的光化学反应行为. 考察了探针分子BZ存在下[bmim][BF₄]/MeCN比例对体系中化学反应动力学的影响. 实验发现: 在N₂饱和条件下, BZ溶液经激光辐照后产生的激发三线态³BZ^*遵循一级反应动力学规律衰减. 离子液体(IL)相对比例增加对³BZ^*瞬态吸收峰的位置和强度没有产生明显影响. 但离子液体体积分数V_IL的变化对[bmim][BF₄]/MeCN混合溶剂中光诱导电子转移的影响却非常显著, 总体上电子转移产生的自由基的表观生成速率常数k_gr随[bmim][BF₄]的V_IL增大而减小. 在[bmim]BF₄]比例足够大的情况下, ³BZ^*与三乙胺或四甲基对苯二胺之间的电子转移被抑制.     

Concentration-dependent dual behavior of hydrophilic ionic liquid in changing properties of aqueous sodium dodecyl sulfate

Modifying physicochemical properties of aqueous surfactant solutions in favorable fashion by addition of environmentally benign room-temperature ionic liquids (ILs) has enormous future potential. Due to its unusual properties, an IL may demonstrate a unique role in altering the properties of aqueous surfactant solutions. Changes in the properties of aqueous sodium dodecyl sulfate (SDS), an anionic surfactant, upon addition of a common and popular "hydrophilic" ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate [bmim][BF4] are presented. Addition of low concentrations of [bmim][BF4] (i.e., 相似文献   

Heteronuclear NOE spectroscopy of ionic liquids

(19)F,(1)H HOESY experiments with three ionic liquids ([bmim]BF(4), [bmim]PF(6) and [emim]BF(4)) were run in two different solvents and neat. The results give preferred probabilities of presence and enable us to systematically study interactions between the cations and the anions in the ionic liquid phase by NMR spectroscopy. The influence of different solvents and of the presence or absence of air (i.e. oxygen) is discussed. This enabled us to substantially speed up the NMR experiments and to develop a more precise method for the investigation of liquid-phase structures in ionic liquids.     

Conductive polymer as a controlled microenvironment for the potentiometric high-throughput evaluation of ionic liquid cell toxicity

This paper presents both biological and potentiometric evaluations of the cell toxicity of a widely used ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim]BF(4)), to Chinese hamster lung fibroblast cells (V79 cell line). The innovative potentiometric study takes advantage of the unique properties of conductive polymer polypyrrole (PPY) for the potentiometric evaluation of cell toxicity of [bmim]BF(4) to the V79 cells in a real-time, noninvasive and high-throughput manner. The conductive polymer PPY provides a controlled microenvironment that allows the quantitative release of the anions of the ionic liquids into the cells being monitored in real time and noninvasively. Parallel biological assay results showed that V79 cells exposed to [bmim]BF(4) usually grew in clusters, and that many small vacuoles could be seen in the cytoplasm. At the 24th hour after the V79 cells had been exposed to the ionic liquid (IL), the half inhibition concentration (EC(50)) of [bmim]BF(4) was around 5 mM. From a cell cycle study performed using a FACScan flow cytometer, it was found that the V79 cells could be partially locked to the G(1) phase by [bmim]BF(4), which extended the doubling time for cell growth. Comparing with the EC(50) values of cadmium chloride and mercury chloride, [bmim]BF(4) is not very toxic, but it may have a long-term toxic effect on mammalian cells. Compared to traditional biological in vitro assays, the use of a conductive polymer substrate in combination with a potentiometric sensor array is much more sensitive, faster, and enables a simpler evaluation of chemical cell toxicity. Additionally, it simplifies the study of the reversibility of cell toxicity, i.e., cell recovery, because there is no need to refresh the culture medium since a finite amount of chemicals can be doped and released. We found that the cytotoxicity of [bmim]BF(4) at a concentration of less than 6 mM was reversible for the V79 cell line, because cell morphology and proliferation rate returned to normal after the removal of the IL from the culture medium. This finding suggests that the IL [bmim]BF(4) could be used as a tool to control mammalian cell proliferation rate.     

Unique role of hydrophilic ionic liquid in modifying properties of aqueous Triton X-100

Modification of important physicochemical properties of aqueous surfactant solutions can be achieved by addition of environmentally benign room temperature ionic liquids (ILs). While low aqueous solubility of "hydrophobic" ILs limits the amount of IL that may be added to achieve desired changes in the physicochemical properties, hydrophilic ILs do not have such restrictions associated to them. Alterations in the key physicochemical properties of aqueous solutions of a common nonionic surfactant Triton X-100 (TX100) on addition of up to 30 wt % hydrophilic IL 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]) are reported. The presence of micellar aggregates in as high as 30 wt % [bmim][BF4]-added aqueous TX100 solutions is established by dynamic light scattering and fluorescence probe behavior. Increasing the concentration of [bmim][BF4] results in decrease in average micellar size and aggregation number and increase in critical micelle concentration, indicating an overall unfavorable aggregation process. Increase in the dipolarity and the microfluidity of the probe cybotactic region within the palisade layer of the micellar phase upon [bmim][BF4] addition implies increased water penetration and the possibility of TX100-[bmim][BF4] interactions. While the changes in some of the physicochemical properties indicate the role of [bmim][BF4] to be similar to a cosurfactant, the IL acts like a cosolvent as far as changes in other properties are concerned. Effectiveness of IL [bmim][BF4] in modifying physicochemical properties of aqueous TX100 is demonstrated.     

添加中低浓度离子液体[bmim][BF4]对吐温-20临界胶束浓度和胶束结构的影响

添加离子液体会对表面活性剂在水溶液中的聚集行为产生重要影响。本文研究了吐温-20在中低浓度离子液体四氟硼酸1-丁基-3-甲基咪唑鎓([bmim][BF_4])中的胶束化行为。随着[bmim][BF_4]浓度(cIL)从0增加到0.2mol·L~(-1),吐温-20的临界胶束浓度逐渐增大。相比cIL0.05mol·L~(-1),在cIL0.05mol·L~(-1)时加入[bmim][BF_4]使吐温-20临界胶束浓度增大得更加显著。吐温-20胶束聚集数随着离子液体浓度的增加而逐渐减小,这一结果也说明加入离子液体会对吐温-20胶束的生成有抑制作用。吐温-20胶束化热力学研究表明,吐温-20在不同浓度离子液体中的胶束化是熵、焓共同驱动,并具有熵-焓补偿性。随着离子液体浓度的增加,吐温-20胶束平均粒径和胶束微粘性均表现出先增大后减小的变化,在cIL=0.05mol·L~(-1)时达到最大值。     

Ionic liquid-induced unprecedented size enhancement of aggregates within aqueous sodium dodecylbenzene sulfonate

Physicochemical properties of aqueous micellar solutions may change in the presence of ionic liquids (ILs). Micelles help to increase the aqueous solubility of ILs. The average size of the micellar aggregates within aqueous sodium dodecylbenzene sulfonate (SDBS) is observed by dynamic light scattering (DLS) and transmission electron microscopy (TEM) to increase in a sudden and drastic fashion as the IL 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF(6)]) is added. Similar addition of [bmim][PF(6)] to aqueous sodium dodecyl sulfate (SDS) results in only a slow gradual increase in average aggregate size. While addition of the IL [bmim][BF(4)] also gives rise to sudden aggregate size enhancement within aqueous SDBS, the IL 1-ethyl-3-methylimidazolium tetrafluoroborate ([emim][BF(4)]), and inorganic salts NaPF(6) and NaBF(4), only gradually increase the assembly size upon their addition. Bulk dynamic viscosity, microviscosity, dipolarity (indicated by the fluorescent reporter pyrene), zeta potential, and electrical conductance measurements were taken to gain insight into this unusual size enhancement. It is proposed that bmim(+) cations of the IL undergo Coulombic attractive interactions with anionic headgroups at the micellar surface at all [bmim][PF(6)] concentrations in aqueous SDS; in aqueous SDBS, beyond a critical IL concentration, bmim(+) becomes involved in cation-π interaction with the phenyl moiety of SDBS within micellar aggregates with the butyl group aligned along the alkyl chain of the surfactant. This relocation of bmim(+) results in an unprecedented size increase in micellar aggregates. Aromaticity of the IL cation alongside the presence of sufficiently aliphatic (butyl or longer) alkyl chains on the IL appear to be essential for this dramatic critical expansion in self-assembly dimensions within aqueous SDBS.     

Morphology of poly(ethylene oxide) dissolved in a room temperature ionic liquid: a small angle neutron scattering study

Solutions of deuterated poly(ethylene oxide) (d-PEO) in 1-butyl-3-methyl imidazolium tetrafluoroborate ([bmim][BF4]), a prototype room-temperature ionic liquid (RTIL), have been studied at room temperature over a range of polymer concentrations, using small angle neutron scattering (SANS), characterizing the conformation of PEO dissolved in RTILs. [bmim][BF4] behaves as a good solvent for d-PEO, which organizes in this solvent in non entangled random coils. These findings will help in optimizing the designing of microemulsions in these potentially environmentally friendly solvents.     

Ionic liquid media resulted in the first asymmetric aminohalogenation reaction of alkenes

[reaction: see text] The first asymmetric aminohalogenation of functionalized alkenes has been established. The ionic liquid [bmim][BF4] was found to be the only effective media for success as normal organic solvents failed to give any product for this reaction. The reaction is also very convenient to perform by simply mixing the three reactants, cinnamates, N,N-dichloro-p-toluenesulfonamide, and catalyst, together with 4 A molecular sieves at room temperature in [bmim][BF4] in any convenient vial of appropriate size without special protection from inert gases. Good chemical yields (60-72%) and diastereoselectivities (up to 75% de) have been obtained with a good scope of substrates. The resulting individual diastereomers have been cleanly separated via column chromatography. The absolute stereochemistry of the reaction was unambiguously determined by X-ray structural analysis.     

Easy access to esters with a benzylic quaternary carbon center from diallyl malonates by palladium-catalyzed decarboxylative allylation

Diallyl 2-alkyl-2-arylmalonates underwent palladium-catalyzed decarboxylative allylation quickly under mild conditions. In contrast, no reaction took place with diallyl 2,2-dialkylmalonates under the same conditions. Electron-donating phosphine ligands were found to be vital for this reaction. Most of the solvents used did not affect the catalytic cycle. Catalysis in [bmim][BF4], a well-known ionic liquid, was inhibited as a result of formation of a hydrogen bond between a carboxylate anion and a [bmim]+ cation; however, the reaction in [bdmim][BF4], in which the acidic proton of [bmim][BF4] was replaced with a methyl group, proceeded smoothly. The catalytic mechanism was investigated using a tetradeuterated substrate and an enzymatically synthesized enantio-enriched allyl methyl 2-methyl-2-phenylmalonate. Even the electron-deficient phosphite ligand was found to be active for catalysis of diallyl 2-methyl-2-(2- or 4-nitrophenyl)malonates.     

离子液体中β-葡萄糖苷酶生物催化合成红景天甙

比较了聚乙二醇修饰的β-葡萄糖苷酶在三种离子液体([bmim]PF6,[bmim]BF4,[bmim]Tf2N)及两种常用有机溶剂(1,4-二氧六环、正己烷)中的催化性能,确定了适宜的反应介质;考察了底物浓度、温度、体系含水量和反应时间等因素对β-葡萄糖苷酶催化合成红景天甙反应的影响.结果表明,在最佳反应介质[bmim...     

Compressed CO2-enhanced solubilization of 1-butyl-3-methylimidazolium tetrafluoroborate in reverse micelles of Triton X-100

We carried out the first study about the effect of a compressed gas on the properties of reverse micellar solutions with ionic liquid (IL) polar cores. And the properties of compressed CO2/cyclohexane/1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4])/Triton X-100 (TX-100) system were investigated at 288.2, 293.2, 298.2, 308.2 K and different pressures by using phase behavior measurement, small-angle x-ray scattering, and UV-Vis techniques. The concentration of the surfactant in the solution was 0.3 mol/l (M). It was found that compressed CO2 could enhance solubilization of the IL in the reverse micelles considerably at suitable pressures, and formation of the reverse micelles could be controlled easily by pressure. Increase of CO2 pressure resulted in decrease of the micellar sizes at fixed [bmim][BF4]-to-surfactant molar ratios (w), and the size of the reverse micelles increased with the increase of w values. The polarity of the IL cores increased continuously with increasing w value.     

1-丁基-3-甲基咪唑四氟硼酸盐的热稳定性、平衡蒸汽压和标准蒸发焓

利用非等温、等温热重分析(TG)法,研究了高纯氮气气氛下1-丁基-3-甲基咪唑四氟硼酸盐([bmim][BF4])离子液体的热稳定性、平衡蒸汽压和标准蒸发焓.非等温热重(TG)曲线表明[bmim][BF4]的初始分解温度(Tonset)和最大分解速率对应的温度(Tm)分别为697和734K.然而长期等温TGA研究表明,[bmim][BF4]的最高可使用温度约为513K.另外,利用基于TG的蒸发技术研究了[bmim][BF4]的平衡蒸汽压(pe)与温度的关系并计算了标准蒸发焓.在503-543K温度范围内,离子液体[bmim][BF4]的pe和温度的关系是:lgpe=(16±1)+(-6.85±0.25)×103/T.[bmim][BF4]的标准蒸发焓为(131±5)kJ·mol-1.     

Nucleophilicity in ionic liquids. 3. Anion effects on halide nucleophilicity in a series of 1-butyl-3-methylimidazolium ionic liquids

We have continued the study of halide nucleophilicity in ionic liquids, concentrating on the effect of changing the anion ([BF(4)](-), [PF(6)](-), [SbF(6)](-), [OTf](-), and [N(Tf)(2)](-)) when the cation is [bmim](+) (where bmim = 1-butyl-3-methylimidazolium). It was found that the nucleophilicities of all the halides were lower in all of the ionic liquids than in dichloromethane. Changing the anion affected the order of halide nucleophilicity, e.g., in [bmim][BF(4)] the order of nucleophilicity was Cl(-)>Br(-)>I(-) while in [bmim][N(Tf)(2)] the order was Cl(-)相似文献   

高活性离子液体-铑膦络合物体系催化1-己烯氢甲酰化反应

 The hydroformylation of 1-hexene catalyzed by rhodium-TPPTS complexes in the ionic liquid [bmim]BF4 was studied. The activity and selectivity of the rhodium-TPPTS complexes in [bmim]BF4 were much higher than those reported in other ionic liquids. The TOF of 1-hexene and selectivity for aldehyde were 1508 h-1 and 92%, respectively, under the optimum conditions. The high activity of the catalyst is ascribed to the absence of halide ions as well as the much higher solubility of hydrogen and rhodium-TPPTS complexes in [bmim]BF4 than in [bmim]PF6.     

Highly efficient extraction and oxidative desulfurization system using Na7H2LaW10O36⋅32 H2O in [bmim]BF4 at room temperature

Highly efficient, deep desulfurization of model oil containing dibenzothiophene (DBT), benzothiophene (BT), or 4,6-dimethyldibenzothiophene (4,6-DMDBT) has been achieved under mild conditions by using an extraction and catalytic oxidative desulfurization system (ECODS) in which a lanthanide-containing polyoxometalate Na(7)H(2)LnW(10)O(36)?32?H(2)O (LnW(10); Ln = Eu, La) acts as catalyst, [bmim]BF(4) (bmim = 1-butyl-3-methylimidazolium) as extractant, and H(2)O(2) as oxidant. Sulfur removal follows the order DBT>4,6-DMDBT>BT at 30?°C. DBT can be completely oxidized to the corresponding sulfone in 25?min under mild conditions, and the LaW(10)/[bmim]BF(4) system could be recycled for ten times with only slight decrease in activity. Thus, LaW(10) in [bmim]BF(4) is one of the most efficient systems for desulfurization using ionic liquids as extractant reported so far.     

Interaction between room temperature ionic liquid [bmim]BF4 and DNA investigated by electrochemical micromethod

Ionic liquids (ILs) as a kind of novel green solvent are being widely used in various researches related to the life sciences and chemistry, which demands the knowledge of interaction between ILs and biomacromolecules. However, the almost completely inert optical, electric, thermal properties of ILs make it difficult to directly obtain information about the interactions. Herein, by using a hydrophilic ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim]BF4) as a model, the electrostatic interaction between ILs and calf thymus DNA (ctDNA) was investigated by a surface electrochemical micromethod. A convenient and simple method was established to obtain the thermodynamic and kinetic information about the DNA-IL interaction only with microscale sample consumption. The quantitative thermodynamic and kinetic parameters about the interaction of [bmim]BF4 and ctDNA, such as the binding constant (K), the Gibbs energy of surface binding (DeltaGb), and the dissociation rate constant (k), were obtained for the first time.     

Palladium‐Catalyzed Enyne Cyclization of 2′‐Alkenyl 2‐Alkynoates in Imidazolium‐Type Ionic Liquids

The use of [bmim][BF₄], [bmim][PF₆], and [bmim][Cl] ILs as the solvents in Pd(II)‐catalyzed enyne cyclization of 2′‐alkenyl 2‐alkynoates in the presence of cupric chloride has been investigated. The Z/E stereoselectivity of the reaction could range from 90:10 to 4:96 by tuning the amount of LiCl in ILs. After the separation of the product, the IL–catalyst mixture could be recovered by treatment with hydrochloric acid and recycled several times without an obvious loss of catalytic activity.     

二醋酸纤维素-离子液体膜固定肌红蛋白制备过氧化氢传感器

将二醋酸纤维素(CDA)-(1-丁基-3-甲基咪唑四氟硼酸盐离子液体)([bmim]BF4)-肌红蛋白(Mb)的复合物修饰在玻碳电极(GCE)表面,制备了一种新型Mb修饰电极(CDA-[bmim]BF4-Mb/GCE).光谱分析表明:固定在CDA- [bmim]BF4-Mb膜中的肌红蛋白保持了其天然构象和生物活性.离子...