It is important to study the interaction of ionic liquids (ILs) with protein for the applications of ILs in biochemical process, and help the researchers to choose and design the better ILs to serve as a solvent. In this work, the interaction between 1-alkyl-3-methylimidazolium bromide [Cnmim]Br (n=4, 6, 8, 10) and bovine serum albumin (BSA) was systematically investigated for the first time by multi-spectroscopic approach (fluorescence, UV–vis and FT-IR spectroscopy) and density functional theory (DFT). [Cnmim]Br (n=4, 6, 8, 10) can bind to BSA by H-bond interaction between their cationic headgroups and Asp/Glu amino acid residue at the surface of BSA, and hydrophobic interaction between their hydrocarbon chains and the hydrophobic amino acid residues in the interior of BSA. On the basis of thermodynamic parameters and the similar structure of [Cnmim]Br (n=4, 6, 8, 10), it can be inferred that the hydrophobic interaction plays a major role in the interaction of [C10mim]Br with BSA, while the hydrogen bond and van der Waals force play a major role in the interaction of [Cnmim]Br (n=4, 6, 8) with BSA. Synchronous fluorescence and FT-IR spectra indicate that [C10mim]Br could markedly change the secondary structure of BSA, while [Cnmim]Br (n=4, 6, 8) could slightly change the secondary structure of BSA. The results allowed us to understand (i) the effect of the alkyl chain length of the cation on the mechanism of ILs–protein interaction and (ii) the effect of the alkyl chain length of the cation on the protein secondary structure. 相似文献
Structures of ionic liquids (ILs) 1-decyl-3-methylimidazolium bis(trifluoromethanesulfonyl)azanide ([C10mim][TFSA]) and 1-decyl-dimethylimidazolium bis(trifluoromethanesulfonyl)azanide ([C10(mim)2](TFSA)2) in different-sized mica slits have been investigated using molecular dynamics simulations. Ion density and angular distributions for monocationic IL [C10mim][TFSA] were analysed to elucidate the IL structures under different surface charges and especially their changes in the direction perpendicular to the surfaces. [C10mim][TFSA] formes in bilayers, compatible with existing models of ILs with long alkyl chains. For dicationic IL [C10(mim)2](TFSA)2, cations adjacent to the mica surface tend to stay parallel to the surface with both positively charged rings absorbed. While near the centre of the slit, dications show the weak tendency of orientation distribution, more random than [C10mim]+ ions. Structures of [C10(mim)2](TFSA)2 cannot be described by bilayer models. Additionally, the in-plane arrangement of [C10mim][TFSA] is more ordered when K+ ions completely neutralise the negative charge of the mica surface, and [C10mim]+ ions tend to be located in hexagonal mica lattices with two aluminium atoms in replacement of silicon atoms. [TFSA]? ions are constrained by the neighbouring K+ ions absorbed onto mica lattices. 相似文献
The interaction of an amino-functionalized ionic liquid, 1-(2-aminoethyl)-3-butylimidazolium bromide ([NH2C2C4im]Br), with cytochrome c (cyt c) at pH 7.4 was investigated using fluorescence and UV-Vis absorption spectroscopic techniques. From the experimental results, it is found that cyt c has a strong ability to quench the intrinsic fluorescence of [NH2C2C4im]Br and the quenching mechanism is considered as a static quenching process. The binding constants and the number of binding sites (n) were calculated at different temperatures. The thermodynamic parameters such as free energy change (ΔG), enthalpy change (ΔH), and entropy change (ΔS) were calculated by thermodynamic equations. According to the results, the values of ΔG, ΔH, and ΔS are all negative, suggesting that interaction between [NH2C2C4im]Br and cyt c is spontaneous and mainly driven by hydrogen bonding and van der Waals forces. 相似文献
Ionic liquids, ILs, based on fluorinated pyrrolidinium and piperidinium ammonium cations and imide anion were prepared and characterized. The physicochemical and electrochemical properties of these ILs including melting point, glass transition and degradation temperatures, viscosity, ionic conductivity, and electrochemical stability were determined and compared to alkyl pyrrolidinium and piperidinium ILs. The incorporation of a CF3 group instead of a CH3 induces an increase of the IL viscosity, thus a conductivity decrease. However, good ionic conductivity is obtained with fluorinated pyrrolidinium IL. Cyclic amine ILs with propyl alkyl chain or fluorinated ammonium exhibit very high electrochemical stability toward oxidation. The effect of the addition of LiTFSI on the IL properties was studied with the same methodology. 相似文献
Surface structures of equimolar mixtures of imidazolium-based ionic liquids (ILs) having a common cation (1-butyl-3-methylimidazolium ([C4MIM]) or 1-hexyl-3-methylimidazolium ([C6MIM])) and different anions (bis(trifluoromethanesulfonyl)imide ([TFSI]), hexafluorophosphate ([PF6]) or chlorine) are studied using high-resolution Rutherford backscattering spectroscopy (HRBS). Both cations and anions have the same preferential orientations at the surface as in the pure ILs. In the mixture, the larger anion is located shallower than the smaller anion. The [TFSI] anion is slightly enriched at the surface relative to [PF6] with coverage of ~ 60% for the equimolar mixtures of [C4(6)MIM] [TFSI] and [C4(6)MIM] [PF6]. No surface segregation is observed for [C6MIM] [TFSI]0.5[Cl]0.5 and [C6MIM] [PF6]0.5[Cl]0.5. These results are different from the recent TOF-SIMS measurement where very strong surface segregation of [TFSI] was concluded for the mixture of [C4MIM] [TFSI] and [C4MIM] [PF6]. 相似文献
A comparative study of the immobilized Candida antarctica lipase B (Novozym 435)-catalyzed acylation of cordycepin with vinyl acetate in ionic liquids (ILs) under ultrasonic irradiation and shaking was conducted. The application of ultrasonic irradiation instead of shaking during acylation resulted in an enhanced reaction rate and a higher level of substrate conversion. Among the various ILs examined, 1-butyl-3-methylimidazolium tetrafluorobrate ([C4MIm][BF4]) was the best medium for the reaction because it produced the highest substrate conversion. In [C4MIm][BF4], the optimal ultrasonic power, water activity, and reaction temperature were 120 W, 0.33, and 50 °C, respectively. The acylation of cordycepin in [C4MIm][BF4] proved to be regioselective under both conditions: the C5′-OH was acylated. Novozym 435 exhibited a much higher operational stability in [C4MIm][BF4], and 58.0% of its original activity was maintained after ten reuse cycles under ultrasonic irradiation. Compared with the cordycepin, the rate of adenosine deaminase-catalyzed deamination was greatly reduced when the 5′-OH was substituted by acetyl group. These results demonstrated that the combined application of ultrasonic irradiation and IL as a medium was an efficient approach for the enzymatic modification of cordycepin. 相似文献
Nanostructured ZnO has been synthesized by a hydrothermal route, using different ionic liquids (ILs) as the morphology templates.
The morphology of ZnO changes from rod-like to star-like and flower-like in different ILs. A 3D nano/micro structure ZnO with
unique flower-like morphology has been synthesized via the assembly of dicationic IL and [Zn(OH)4]2−. The flower-like pattern was obtained in the presence of IL 1. The flower-like ZnO structure has a hexagonal prism, with a hexagonal pyramid on the tip, and diameter of ~444 nm. While
the ZnO prepared in IL 2, shows uniform rod-like shape with a diameter of 91 nm, star-like morphology consisting of nanorods with diameter of ~109 nm
was formed in IL 3. The XRD, SEM, and PL spectra have been employed for characterization of the synthesized ZnO nano structures. 相似文献
Surface interactions of alkylimidazolium ionic liquids (ILs) with aluminium alloy Al 2011 have been studied by immersion tests in seven neat ILs [1-n-alkyl-3-methylimidazolium X− (X = BF4; n = 2 (IL1), 6 (IL2), 8 (IL3). X = CF3SO3; n = 2 (IL4). X = (4-CH3C6H4SO3); n = 2 (IL5). X = PF6; n = 6 (IL6)] and 1-butyl-3-methylpyridinium bis(trifluoromethylsulfonyl)imide (IL7)]. Immersion tests for Al 2011 have also been carried out in 1 wt.% and 5 wt.% solutions of 1-ethyl,3-methylimidazolium tetrafluoroborate (IL1) in water. No corrosion of Al 2011 by neat ILs is observed. The highest corrosion rate for Al 2011 in water is observed in the presence of a 5 wt.% IL1 due to hydrolysis of the anion with hydrogen evolution and formation of aluminium fluoride. Erosion-corrosion processes have been studied for three aluminium alloys (Al 2011, Al 6061 and Al 7075) in a 90 wt.% IL1 solution in water in the presence of α-alumina particles. The erosion-corrosion rates are around 0.2 mm/year or lower, and increase with increasing copper content to give a corrosion resistance order of Al 6061 > Al 7075 > Al 2011. Results are discussed on the basis of scanning electron microscopy (SEM) observations, energy dispersive spectroscopy (EDS) analysis, X-ray diffraction (XRD) patterns and X-ray photoelectron spectroscopy (XPS) determinations. 相似文献
In our previous paper, we extended the Tao and Mason equation of state (TM EOS) to refrigerant fluids, using the speed of sound data. Here, we predict the equation of state for ionic liquids (ILs). The considered ILs are [Bmim][PF6], [C2mim][NtF2], [C3mim][NtF2], [C6mim][NtF2], [C7mim][NtF2], [C2mim][EtOSO3], [Bmim][MeSO4], [Bmim][OcSO4], and [C4mim][dca]. The equation of state consists of three temperature-dependent parameters: the second virial coefficient, a constant for scaling the softness of repulsive force, and an effective hard-sphere diameter equivalent to the van der Waals co-volume. The second virial coefficients of ILs are scare and there is no accurate potential energy function to allow their theoretical calculation. In this work, the second virial coefficient have been calculated using corresponding states correlation based on temperature and density at normal boiling point. The other two parameters of the equation of state can be calculated using a scaling rule. Analysis of our predicted results shows that the Tao?CMason equation of state is capable of accurately predicting the density of ILs at any temperature and pressure. The overall average absolute deviation densities for 1,633 data points are 2.05%. Also, the density of ILs obtained from the TM EOS has been compared with those calculated from vdW?CCS?C?? and Peng?CRobinson (PR) equation of state. Our results are in favor of the preference of the TM EOS over the two other equations of state. The overall average absolute deviation for 1,633 data points calculated by vdW?CCS?C?? and PR equation of state are 6.63% and 12.19%, respectively. 相似文献
ABSTRACT The hydrogen-bonded bromocyclohexane–ammonia complex has been isolated and characterized for the first time in argon matrices at 16 K. Coordination of the proton adjacent to the Br substituent on the cyclohexane ring to the amino nitrogen was evidenced by distinct blue shifts of bending modes involving the H-C1–Br unit. In particular, C–C1–Br, H–C1–Br, and C–C1–H bending modes produced blue shifts ranging from 2.8 to 12.2 cm?1. Density Functional Theory (DFT) calculations at the B3LYP/6–31 + G(d, p) level yield an essentially linear Br–C1–H–NH3 hydrogen bond with a C-H–N distance of 2.412 Å and a hydrogen bond energy of 2.95 kcal/mol. 相似文献
The microwave spectrum of gaseous bromomethyl cyclopropane is reported in the range 12 to 36 GHz. Lines of the 79Br and 81Br species of cis and gauche forms are assigned and partial r0-structures derived. The rotational constants in MHz are: gauche C3H5CH279Br, A = 11 469.285, B = 1 374.777, C = 1 295.394; gauche C3H5CH281Br, A = 11 400.100, B = 1 364.088, C = 1 283.952; cis C3H5CH279Br, A = 8 759.918, B = 1 597.413, C = 1 522.141; cis C3H5CH281Br, A = 8 716.552, B = 1 583.761, C = 1 509.017. 相似文献
Molecular dynamics simulations were carried to investigate the structure and dynamics of [BMIM][PF6] ionic liquid (IL) confined inside a slit-like Au metal nanopore with a pore size of 5.0 nm. The calculations show that the mass and number densities of the confined ILs are oscillatory; the solid-like high density layers are formed in the vicinity of the metal surface. The orientational investigation shows that the imidazolium ring of [BMIM] cations prefers to form a small tilt angle with the pore walls. Furthermore, the mean squared displacement (MSD) calculation indicates that the dynamics of confined ILs are remarkably slower than those observed in bulk systems. Our results suggest that the confinement of the Au nanopore can strongly affect the structural and dynamical properties of the confined ILs. 相似文献
ABSTRACTThe present study investigates the dissolution behaviour of cellulose and hemicellulose in potential ionic liquids (ILs) using both the quantum chemical and experimental validation. For converging upon the recommended IL, 1428 ILs consisting of 42 cations and 34 anions were studied with the conductor like screening model for real solvents (COSMO-RS) model. Based on the infinite dilution activity coefficient of the components in IL, the selected anions and cations were visualised by observing their interactions with cellulose and hemicellulose using interaction energies, natural bonding orbital analysis and molecular dynamics simulations. The dissolution order of cellulose and hemicellulose in ILs was primarily determined by the evaluation of hydrogen bonds between the oxygen atom of anion and hydroxyl proton of cellulose/hemicellulose. From this discernible fact, the anion of the IL was observed to play a leading role in the solvation process as compared to the cation. Eventually, acetate [OAc]– anion and 1-ethyl-3-methylimidazolium [EMIM]+ cation were found to be good candidates for the dissolution of cellulose and hemicellulose. This was further confirmed by the measurement of solid-liquid equilibria with cellulose and hemicellulose. The regenerated cellulose powder was then characterised by Fourier transform spectroscopy(FTIR), X-ray diffraction (XRD) and Thermal gravimetric analysis (TGA). 相似文献
The molecular imprinting technique is powerful to prepare functional materials with molecular recognition properties. In this work, a potentiometric sensor was fabricated by dispersing molecularly imprinted polymers (MIPs) into plasticized PVC matrix and used for the determination of 1-hexyl-3-methylimidazolium cation ([C6mim]+) in aqueous solution. The MIPs were synthesized by precipitation polymerization using 1-hexyl-3-methylimidazolium chloride ([C6mim]Cl) as the template molecule, methacrylic acid (MAA) and ethylene glycol dimethacrylat (EGDMA) as the functional monomers, and EGDMA also as the cross-linking agent. The as-prepared electrode exhibited a Nernstian response (58.87 ± 0.3 mV per decade) to [C6mim]+ in a concentration range from 1.0 × 10−6 to 0.1 mol kg−1 with a low detection limit of 2.8 × 10−7 mol kg−1, high selectivity, and little pH influence. The as-prepared electrode was used for the detection of the [C6mim]+ in distilled water, tap water, and river water with a good recovery. It was also successfully applied in the determination of mean activity coefficients of [C6mim]Br in fructose + water systems based on the potentiometric method at 298.15 K.
The oil in water (o/w) emulsions were prepared using aniline dissolved in toluene and LiCoO2 particles as stabilizers (Pickering emulsions). Pickering emulsions are stabilized by adsorbed solid particles instead of emulsifier molecules. The mean droplet diameter of emulsions was controlled by the mass ratio M (oil)/M (solid particles). The emulsions showed great stability during 3 days. The composite materials containing LiCoO2 and the conductive polymer polyaniline (PANI) have been prepared by means of polymerization of aniline emulsion stabilized by LiCoO2 particles. The composite materials were characterized by nanosphere and nanofiber-like structures. The nanofiber-like morphology of the powdered material was distinctly different of the morphologies of the parent materials. The electrochemical reactivity of PANI/LiCoO2 composites as positive electrode in a lithium battery was examined during lithium ion deinsertion and insertion by galvanostatic charge–discharge testing; PANI/LiCoO2 (1:4) composite materials exhibited the best electrochemical performance by increasing the reaction reversibility and capacity compared to that of the pristine LiCoO2 cathode. The first discharge capacity of PANI/LiCoO2 (1:4) was 167 mAh/g, while that of LiCoO2 was136 mAh/g. 相似文献
We report the synthesis of a new series of imidazolium-based halogen-free ionic liquids 1-alkyl-3-methylimidazolium lauryl
sulfates. By reacting 1-methylimidazole (MIM) with butyl, hexyl, octyl, and decyl bromides and exchanging bromide ion with
lauryl sulfate anion, a series of ionic liquids [RMIM][C12H25OSO3] were produced. The high purity of these ionic liquids was verified with 1H-NMR, 13C-NMR, FT-IR and mass spectrometry (MS), demonstrating the effectiveness of this synthetic approach. Solubility test of these
ionic liquids showed that they are soluble in most organic solvents except nonpolar solvents such as hexane and cyclohexane.
The optical properties of [BMIM]Br and [BMIM][C12H25OSO3], where B refers to butyl, were examined. Both ionic liquids absorbed light in the UV region, yet essentially no absorption
was recorded beyond 450 nm. Furthermore, both ionic liquids showed excitation wavelength-dependent fluorescence behavior.
As an example, with an excitation wavelength of 360 nm, [BMIM][C12H25OSO3] showed an emission band maximum at 447 nm. Increasing the excitation wavelength to 440 nm, the emission band maximum was
shifted to ∼500 nm. 相似文献
99Ru Mössbauer spectra at 5 K have been measured on samples of salts of ruthenocene with halogens, expressed as [Ru(C5H5)2X]Y (X=Cl, Br, Y=PF6, and X=1, Y=13). The values of both the isomer shift and the quadrupole splitting of these salts with halogens are larger compared to those of ruthenocene. It is concluded that ruthenocene gives salts having direct chemical bonding between Ru and Cl, Br, or I, and that the Ru atom in each salt is in a higher oxidation state than 2+ in ruthenocene. 相似文献