Effect of protic ionic liquids (PILs) on the formation of non-ionic dodecyl poly(ethylene oxide) surfactant self-assembly structures and the effect of these surfactants on the nanostructure of PILs

The ability of a series of non-ionic dodecyl poly(ethylene oxide) surfactants to form micelles in a variety of protic ionic liquids (PILs) was investigated using small and wide angle X-ray scattering (SAXS/WAXS). The C(12)E(n) surfactants with n = 3-8 were examined in PILs which contained either an ethyl, diethyl, triethyl, butyl, pentyl, ethanol or pentanol-ammonium cation in conjunction with either a nitrate or formate anion. The ability of the PILs to support micelles of these surfactants was highly dependent on their liquid nanostructure. The PILs containing hydroxyl groups on the cations were not nanostructured and had very low surfactant solubility (<1 wt%). The highly nanostructured PILs with butylammonium or pentylammonium cations contain large non-polar domains, and had excellent surfactant solubility, but due to the greater hydrocarbon solubility they had insufficient drive from the "solvophobic effect" to enable micelle formation. The PILs of ethylammonium nitrate (EAN), propylammonium nitrate (PAN), diethylammonium formate (DEAF) and triethylammonium formate (TEAF) had smaller non-polar domains, and all supported micelle formation below 20 wt% surfactant. The critical micelle concentration (CMC) of surfactants in EAN were two orders of magnitude greater than in water. The minimum molecular areas of the poly(ethylene oxide) head groups at the air/ionic liquid interface, A(min), were significantly larger in EAN than in water. The SAXS patterns from the micelles present in EAN fitted well to ellipsoids, whereas the micelles present in PAN fitted well to spheres. The nanostructure of select PILs was also influenced by the presence of surfactants.     

Solvent/gelator interactions and supramolecular structure of gel fibers in cyclic bis-urea/primary alcohol organogels

An organogel system consisting of trans-(1S,2S)-bis(ureidododecyl)cyclohexane (SS-BUC) and a series of primary alcohols was explored with optical polarizing microscopy (OPM), electron microscopy, circular dichroism (CD), wide-angle X-ray scattering (WAXS), and synchrotron small-angle X-ray scattering (SAXS). OPM, SAXS, and especially WAXS showed that the gel fiber of SS-BUC/methanol gels essentially consists of SS-BUC crystal itself. SAXS showed that the SS-BUC crystal in the gel takes a lamella with a domain spacing of 5.2 nm. When we left the gel at room temperature, the spacing decreased to 3.1 nm after several months. This distance change may correspond to the structural transition from a double-layer structure to an intercalated-layer structure, which was proposed by Feringa et al. (Chem.-Eur. J. 1999, 5, 937-950) as a possible arrangement of the molecular packing. When the gels in ethanol, propanol, butanol, or octanol were examined, they never showed crystalline peaks in WAXS and SAXS, indicating the amorphous nature of the gels. With increasing the alkyl chain length from ethanol to octanol, dramatic changes were observed in the CD spectrum in the 200-500-nm range. Because these CD changes are correlated to the absorbance of urea, those can be considered as the evidence that the solvents strongly relate to the spatial arrangement between the adjacent urea groups. For the amorphous gels, the cross-sectional correlation function [gammaCu] was directly obtained by the inverse Hankel transform of the SAXS data. The value of gammaCu for the gels is decreased with increasing u (distance between the two scattering bodies, see eq 5). Furthermore, it more rapidly decreases than that of the rigid cylinder model. This feature can be explained by the speculation that many solvent molecules permeate into the SS-BUC fiber. There was a clear difference between ethanol and the other gels, indicating that the solvents with a longer alkyl chain give the more permeated and diffused fiber. This permeated fiber (i.e., wet fiber) can rationalize the dramatic CD change, by presuming that the permeated solvent molecules alter the molecular stacking form.     

Protic ionic liquids with fluorous anions: physicochemical properties and self-assembly nanostructure

A series of 11 new protic ionic liquids with fluorous anions (FPILs) have been identified and their self-assembled nanostructure, thermal phase transitions and physicochemical properties were investigated. To the best of our knowledge this is the first time that fluorocarbon domains have been reported in PILs. The FPILs were prepared from a range of hydrocarbon alkyl and heterocyclic amine cations in combination with the perfluorinated anions heptafluorobutyrate and pentadecafluorooctanoate. The nanostructure of the FPILs was established by using small- and wide-angle X-ray scattering (SAXS and WAXS). In the liquid state many of the FPILs showed an intermediate range order, or self-assembled nanostructure, resulting from segregation of the polar and nonpolar hydrocarbon and fluorocarbon domains of the ionic liquid. In addition, the physicochemical properties of the FPILs were determined including the melting point (T(m)), glass transition (T(g)), devitrification temperature (T(c)), thermal stability and the density ρ, viscosity η, air/liquid surface tension γ(LV), refractive index n(D), and ionic conductivity κ. The FPILs were mostly solids at room temperature, however two examples 2-pyrrolidinonium heptafluorobutyrate (PyrroBF) and pyrrolidinium heptafluorobutyrate (PyrrBF) were liquids at room temperature and all of the FPILs melted below 80 °C. Four of the FPILs exhibited a glass transition. The two liquids at room temperature, PyrroBF and PyrrBF, had a similar density, surface tension and refractive index but their viscosity and ionic conductivity were very different due to dissimilar self-assembled nanostructure.     

Properties of ionic liquids containing silver(I) or protic alkylethylenediamine cations with a bis(trifluoromethanesulfonyl)amide anion

Ionic liquids of an N-alkylethylenediamine-silver(I) complex cation (alkyl=hexyl, 2-ethylhexyl, and octyl) or a protic N-alkylethylenediaminium cation (alkyl=butyl, hexyl, 2-ethylhexyl, octyl, decyl, and dodecyl) with a bis(trifluoromethanesulfonyl)amide counter anion (Ag-ILs and PILs, respectively) were prepared and their physicochemical properties were investigated. The trend of solidification decreased in the order octyl?hexyl>2-ethylhexyl for the Ag-ILs, and butyl>dodecyl>decyl>octyl>hexyl?2-ethylhexyl for the PILs. The diffusion coefficients of the cations indicated stronger intermolecular interactions in PILs than in the Ag-ILs because of hydrogen-bonding networks, and it has been revealed that the intermolecular interactions increase in the order, hexyl相似文献   

The Use of A 25 Factorial Design to Study the Effect of Various Alcohols on the Paper Chromatographic Separation of Selected Amino Acids

Abstract

A 2⁵ factorial design was used to evaluate the effect of methanol, ethanol, propanol, butanol and pentanol on the paper chromatographic separation of Arginine, Threonine, Leucine, Histidine, and Tryptophan. The most significant effects occur for the alcohols themselves with an increasing effect with an increase in carbon chain length. The major interaction terms involve the combinations of butanol and pentanol with the other alcohols or with themselves.     

Charge ordering and intermediate range order in ammonium ionic liquids

Molecular dynamics simulations were performed for ionic liquids based on the bis(trifluoromethylsulfonyl)imide anion, [NTf(2)], and ammonium cations with increasing length of the alkyl chain and ether functionalized chain. The signature of charge ordering is a sharp peak in the charge-charge structure factor, S(qq)(k), whose intensity is barely affected for longer carbon chain in tetraalkylammonium systems, but decreases in ether functionalized ionic liquids. The first sharp diffraction peak (FSDP) and the corresponding intermediate range order (IRO) are observed in the total S(k) of ionic liquids containing ammonium cations with relatively long chains. The intensity of the FSDP is lower in the total S(k) of the ether derivative in comparison with the tetraalkylammonium counterpart of the same chain length. It is shown that the nature of the IRO is structural heterogeneity of polar and non-polar domains, even though domains defined by chain interactions in the ether derivatives become more polar. Charge correlation in the ether derivative is modified because cations can be coordinated by oxygen atoms of the ether functionalized chain of neighboring cations.     

Highly-ordered layered organo-mineral materials prepared via reactions of n-alkylphosphonic acids with apatite

This work describes a novel class of layered organo-mineral materials manufactured via a single-step solution-phase reaction of n-alkylphosphonic acids (CnH(2n+1)P(O)(OH)2) with calcium hydroxyapatite mineral (CaHAP). TEM, SAXS, WAXS, FTIR, and Vapor Phase Adsorption data suggest that these alkyl-CaHAP materials present a surface-modified CaHAP matrix coated with ordered layers of calcium alkylphosphonates that are strongly adhered to the surface. Interlayer spacing increases from 1.47 (C3-CaHAP) to 4.77 nm (C18-CaHAP). According to FTIR, ordering of alkyl chains improves with the alkyl chain length. The organic loads in these alkyl-CaHAP can be controlled over a wide range (up to approximately 60%) by varying alkyl chain and the concentration of alkylphosphonic acids in the solution.     

Protic ionic liquids: physicochemical properties and behavior as amphiphile self-assembly solvents

The physicochemical properties of 22 protic ionic liquids (PILs) and 6 protic molten salts, and the self-assembly behavior of 3 amphiphiles in the PILs, are reported. Structure-property relationships have been explored for the PILs, including the effect of increasing the substitution of ammonium cations and the presence of methoxy and hydroxyl moieties in the cation. Anion choices included the formate, pivalate, trifluoroacetate, nitrate, and hydrogen sulfate anions. This series of PILs had a diverse range of physicochemical properties, with ionic conductivities up to 51.10 mS/cm, viscosities down to 5.4 mPa.s, surface tensions between 38.3 and 82.1 mN/m, and densities between 0.990 and 1.558 g/cm3. PILs were designed with various levels of solvent cohesiveness, as quantified by the Gordon parameter. Fourteen PILs were found to promote the self-assembly of amphiphiles. High-throughput polarized optical microscopy was used to identify lamellar, hexagonal, and bicontinuous cubic amphiphile self-assembly phases. The presence and extent of amphiphile self-assembly have been discussed in terms of the Gordon parameter.     

Photocatalytic decomposition of an alkylammonium cation in a Langmuir-Blodgett film of a titania nanosheet

The formation of inorganic-organic hybrid films of a titania nanosheet and an amphiphilic alkylammonium cation has been investigated, and the photocatalytic decomposition of the alkylammonium cation in the film has been pursued. When a solution of the amphiphilic alkylammonium salt (octadecylammonium chloride: ODAH+ Cl-) was spread on an interface between the air and a titania nanosheet suspension, the negatively charged nanosheets were adsorbed onto the floating monolayer of ODAH+ to form a hybrid monolayer. The hybridization was confirmed by pi-A isotherm measurements, atomic force microscopy, and X-ray photoelectron spectroscopy. Multilayered films were fabricated in a layer-by-layer way by transferring the hybrid monolayers onto glass plates. Areas per ODAH+ cation in the films were estimated from the infrared (IR) spectra of the films, but these areas were smaller than those estimated from the pi-A isotherm curves. The orientation of the alkyl chain of ODAH+ in the hybrid film was determined by means of polarized IR spectroscopy. The alkyl chains were tilted 41 +/- 1 degrees and 47 +/- 1 degrees from the surface normal for the films prepared from the 8 and 20 ppm (ppm = mg dm(-3)) suspensions, respectively. Together with X-ray diffraction data of the films, the structure of the hybrid film was discussed. When the films were illuminated with a UV light, the absorption intensities due to the alkyl chain of ODAH+ decreased exponentially, indicating the photocatalytic decomposition of ODAH+ by the titania nanosheets in the films. Deviation from the exponential trend in the decomposition rate was observed in the initial period for the hybrid films prepared from the suspensions at low concentrations. Interestingly, the layered structure of the hybrid film was disturbed significantly after the ODAH+ cations were decomposed.     

Ionic Complexes of Polyacids and Cationic Surfactants

Comb-like ionic complexes were prepared from polyuronic acids (pectinic and alginic acids) and alkyltrimethylammonium surfactants bearing linear alkyl chains with 18, 20 and 22 carbon atoms. In the condensed state, these complexes were able to self-assemble in ordered structures which were thermally stable up to ∼200 °C. The complexes were analysed by DSC and WAXS/SAXS and compared to their analogous made from poly(γ-glutamic acid). They all adopt a biphasic layered structure in which the main chain and the alkyl side chain alternate with a nanometric periodicity. Alkyl side chains were partially crystallized in these complexes and they show reversible melting at temperatures within the 60-80 °C range depending on the length of the polymethylene segment.     

Structure Effects on the Ionicity of Protic Ionic Liquids

We report on the characterisation of 16 protic ionic liquids (PILs) prepared by neutralisation of primary or tertiary amines with a range of simple carboxylic acids, or salicylic acid. The extent of proton transfer was greater for simple primary amine ILs compared to tertiary amines. For the latter case, proton transfer was increased by providing a better solvation environment for the ions through the addition of a hydroxyl group, either on the tertiary amine, or by formation of PIL/molecular solvent mixtures. The library of PILs was characterised by differential scanning calorimetry and a range of transport properties (i. e. viscosity, conductivity and diffusivity) were measured. Using the (fractional) Walden rule, the conductivity and viscosity results were analysed with respect to their deviation from ideal behaviour. The validity of the Walden plot for PILs containing ions of varying sizes was also verified for a number of samples by directly measuring self-diffusion coefficients using pulsed-field gradient spin-echo (PGSE) NMR. Ionicity was found to decrease as the alkyl chain length and degree of branching of both the cations and anions was increased. These results aim to develop a better understanding of the relationship between PIL properties and structure, to help design ILs with optimal properties for applications.     

Thermogravimetric study of <Emphasis Type="Italic">n</Emphasis>-alkylammonium-intercalated montmorillonites of different cation exchange capacity

Three n-alkylammonium salts of varying alkyl chain length were ion exchanged with montmorillonites (MMT) of different cation exchange capacity (CEC). The intercalated MMTs were characterized by thermogravimetry (TG), XRD, FTIR to acquire an insight into the intergallery structural arrangement of the organic alkylammonium cations (AAC). The increment in the intergallery spacing from XRD pattern was correlated with chain length and interlayer arrangement of AAC. Multiple organic mass-loss stages in thermogravimetric analysis indicate two types of anchorage of AAC in intercalated clay. CEC of MMT was found to influence the intergallery confinement and excess adsorption of AAC.     

联苯类对映体在直链淀粉类手性固定相上的高效液相色谱法直接拆分

 涂敷直链淀粉 三 (3,5 二甲基苯基氨基甲酸酯 )于自制的球形氨丙基硅胶上 ,制备了手性固定相。用该固定相直接拆分了一系列外消旋联苯类保肝药物 ,考察了一系列伯醇 (乙醇、正丙醇、正丁醇 )和异丙醇等流动相改性剂对保留和立体选择性的影响 ,讨论了固定相对样品的作用机理。     

Dynamical Regime of the Phloroglucinol‐Based Chemical Oscillator in the Presence of Alcohols: Rebirth of Oscillations after an Inhibition Time

This study pertains to the dynamic evolution of the Belousov–Zhabotinsky (BZ) chemical oscillator upon the addition of different aliphatic alcohols (methanol, ethanol, n‐propanol, iso‐propanol, n‐butanol, sec‐butanol, iso‐butanol, and tert‐butanol) at 30°C in a stirred batch reactor. The oscillations are monitored potentiometrically. The experimental findings reveal that the course of the BZ reaction is significantly altered depending on the concentration of the alcohol and the type of the carbon chain present. The mechanism of the alcohol perturbation has been interpreted on account of the experimental results. Besides the qualitative study, a new approach for monitoring the analytical concentration of these alcohols using the BZ oscillatory regime has been explored and it has been found that the alcohol perturbation is directly related to the concentration of the alcohol added, which in turn depends on the inhibition time for the rebirth of oscillatory regime.     

Effect of Protic Ionic Liquid and Surfactant Structure on Partitioning of Polyoxyethylene Non‐ionic Surfactants

The partitioning constants and Gibbs free energies of transfer of poly(oxyethylene) n‐alkyl ethers between dodecane and the protic ionic liquids (ILs) ethylammonium nitrate (EAN) and propylammonium nitrate (PAN) are determined. EAN and PAN have a sponge‐like nanostructure that consists of interpenetrating charged and apolar domains. This study reveals that the ILs solvate the hydrophobic and hydrophilic parts of the amphiphiles differently. The ethoxy groups are dissolved in the polar region of both ILs by means of hydrogen bonds. The environment is remarkably water‐like and, as in water, the solubility of the ethoxy groups in EAN decreases on warming, which underscores the critical role of the IL hydrogen‐bond network for solubility. In contrast, amphiphile alkyl chains are not preferentially solvated by the charged or uncharged regions of the ILs. Rather, they experience an average IL composition and, as a result, partitioning from dodecane into the IL increases as the cation alkyl chain is lengthened from ethyl to propyl, because the IL apolar volume fraction increases. Together, these results show that surfactant dissolution in ILs is related to structural compatibility between the head or tail group and the IL nanostructure. Thus, these partitioning studies reveal parameters for the effective molecular design of surfactants in ILs.     

Enantiomer Separation of α—Dimethyl Dicarboxylate Biphenyl and Related Biphenyl Compounds by Normal Phase HPLC on Polysaccharide Based Chiral Stationary Phases

Cellulose tris(4-methylphenylcarbamate),amylose tris(3,5-dimethylphenylcarbamate) and amylose tris (phenylcarbamate) were prepared by the method reported by Okamoto and were coated onto an aminopropylated mesoporous spherical silica gel.These final products were used as chiral stationary phases of high performance liquid chromatography for the eighteen structurally related biphenyl compounds.The resolution was made using normal-phase methodology with a mobile phase consisting of n-hexane-alcohol(ethanol,1-propanol,2-propanol or 1-butanol).The effects of various aliphatic alcohols in the mobile phase were studied.The structural features of the solutes that influence their k′ were discussed.A dominant effects of trifluoroacetic acid on chiral separation of acidic solutes was noted.     

Transport properties of protic ionic liquids,pure and in aqueous solutions: Effects of the anion and cation structure

Ionic conductivities of twelve protic ionic liquids (PILs) and their mixtures with water over the whole composition range are reported at 298.15 K and atmospheric pressure. The selected PILs are the pyrrolidinium-based PILs containing nitrate, acetate or formate anions; the formate-based PILs containing diisopropylethylammonium, amilaminium, quinolinium, lutidinium or collidinium cations; and the pyrrolidinium alkylcarboxylates, [Pyrr][C_nH_2n+1COO] with n = 5–8. This study was performed in order to investigate the influence of molecular structures of the ions on the ionic conductivities in aqueous solutions. The ionic conductivities of the aqueous solutions are 2–30 times higher than the conductivities of pure PILs. The maximum in conductivity varies from ww=0.41 ??to ??0.74$w_w=0.41\text{\hspace{0.17em}??}\text{to}\text{\hspace{0.17em}??}0.74$ and is related to the nature of cations and anions. The molar conductance and the molar conductance at infinite dilution for (PIL + water) solutions are then determined. Self-diffusion coefficients of the twelve protic ionic liquids in water at infinite dilution and at 298.15 K are calculated by using the Nernst–Haskell, the original and the modified Wilke–Chang equations. These calculations show that similar values are obtained using the modified Wilke–Chang and the Nernst–Haskell equations. Finally, the effective hydrodynamic (or Stokes) radius of the PILs was determined by using the Stokes–Einstein equation. A linear relationship was established in order to predict this radius as a function of the anion alkyl chain length in the case of the pyrrolidinium alkylcarboxylates PILs.     

High Performance Pd,PdNi, PdSn and PdSnNi Nanocatalysts Supported on Carbon Nanotubes for Electrooxidation of C2C4 Alcohols

Nanocatalysts Pd, Pd₈Ni₂, Pd₈Sn₂ and Pd₈Sn₁Ni₁ supported on multi‐walled carbon nanotubes (MWCNTs) were successively synthesized by the chemical reduction method in the glycol‐water mixture solvent. Transmission electron microscopy results show that the prepared Pd, Pd₈Ni₂, Pd₈Sn₂ and Pd₈Sn₁Ni₁ nanoparticles are uniformly dispersed on the surface of MWCNTs. The average particle sizes of the nanocatalysts are 3.5–3.8 nm. Electroactivity of the prepared catalysts towards oxidation of ethanol, 1‐propanol, 2‐propanol, n‐butanol, iso‐butanol and sec‐butanol (C2? C4 alcohols) in alkaline medium was studied by cyclic voltammetry and chronoamperometry. The current density obtained for the electrooxidation of C2? C4 alcohols depends on the catalysts and the various structures of the alcohols. Addition of Sn or/and Ni to Pd nanoparticles enhances the electroactivity of the Pd/MWCNT catalyst. Furthermore, the ternary Pd₈Sn₁Ni₁/MWCNT catalyst presents the highest electroactivity for the oxidation of C2? C4 alcohols among the prepared catalysts. Electrocatalytic activity order among propanol isomers and butanol isomers is as follows respectively: 1‐propanol > 2‐propanol, and n‐butanol > iso‐butanol > sec‐butanol > tert‐butanol. This is consistent with the Mulliken charge value of the carbon atom bonded with hydroxyl group in the corresponding alcohol molecule.     

Induction of ionic smectic C phases: a systematic study of alkyl-linked guanidinium-based liquid crystals

A series of ionic liquid crystals with an alkoxy biphenyl unit tethered via an alkyl spacer to a guanidinium head group were synthesised and the mesomorphic properties were studied by differential scanning calorimetry, polarising optical microscopy and X-ray diffraction (XRD; WAXS and SAXS). Whereas all symmetrical guanidinium chlorides with the same chain lengths in alkyl tail and spacer displayed enantiotropic SmA₂ phases, monotropic SmC₂ phases with 1–2 K temperature range were only formed for chain lengths ≥ C₁₀. Shifting the calamitic core more closely to the ionic head group by decreasing the tether length and simultaneously increasing the terminal alkyl chain improved the stability of both SmA and SmC phases considerably and led to enantiotropic SmC phases for the guanidinium chloride with C₁₄ alkyl tail and C₆ spacer. An even more pronounced effect was detected during anion exchange. Bromide, iodide, hexafluorophosphate, thiocyanate and triflate suppressed any SmC phase, whereas tetrafluoroborate behaved similar to chloride maintaining the SmC phase. However, acetate stabilised the SmC phase at the expense of the SmA phase. Based on temperature-dependant XRD measurements, a bilayer structure was proposed.     

Sorption of nonionic organic solutes from water to tetraalkylammonium bentonites: Mechanistic considerations and application of the Polanyi-Manes potential theory

This work describes the role of quaternary alkylammonium amendment length on sorption mechanisms of modified bentonites for four nonionic organic compounds; benzene, carbon tetrachloride, TCE, and 1,2-DCB. Tetramethyl to tetrabutyl alkyl amendments were studied and an important mechanistic shift occurred at the propyl chain length for all four solutes studied. Three- and four-carbon-chain functional groups on the ammonium cation resulted in a linear, rather than a curvilinear isotherm. The uptake on tetrapropyl and tetrabutylammonium clays was noncompetitive in binary systems and showed negligible sensitivity to temperature variations, indicating the linear isotherms describe a partitioning uptake mechanism for these organoclays. The adsorptive organoclays (tetramethyl and tetraethylammonium clays) were fit with the Dubinin-Radushkevich equation to investigate the application of the Polanyi-Manes potential theory to organoclay adsorption. It was found that TCE and carbon tetrachloride, with similar physical and chemical characteristics, behaved according to the Polanyi-Manes theory. Benzene showed an anomalously high adsorption volume limit, possibly due to dense packing in the adsorption space or chemisorption to the short chain alkyl groups.