Increasing Alkyl Chain Length Research Articles

Synthesis and characterization of analogues of glycine-betaine ionic liquids and their use in the formation of aqueous biphasic systems

A series of novel analogues of glycine-betaine ionic liquids (AGB-ILs), viz. 1-(4-ethoxy-4-oxobutyl)-1-methylpyrrolidin-1-ium, N,N,N-tri(n-butyl)(4-ethoxy-4-oxobutyl)-1-phosphonium and N,N,N-trialkyl(4-ethoxy-4-oxobutyl)-1-aminium cations with ethyl, n-propyl and n-butyl alkyl chains, combined with the bromide anion, have been synthesized and characterized. Their synthesis and characterization by spectroscopic methods and elemental analysis is here reported. These ILs were further characterized in what concerns their thermal properties and ecotoxicity against Allvibrio fischeri, and compared with the commercial tetra(n-butyl)ammonium and tetra(n-butyl)phosphonium bromide. The novel AGB-ILs described in this work have low melting points, below 100 °C, display high degradation temperatures (180–310 °C), and low toxicity as shown by being harmless or practically harmless towards the marine bacteria Allvibrio fischeri. Finally, the ability of the synthesized AGB-ILs to form aqueous biphasic systems with potassium citrate/citric acid (at pH 7) was evaluated, and the respective ternary phase diagrams were determined. It is shown that the increase of the cation alkyl chain length facilitates the creation of ABS, and that phosphonium-based ILs present a slightly better separation performance in presence of aqueous solutions of the citrate-based salt.

Influence of in Vitro Assay Setup on the Apparent Cytotoxic Potency of Benzalkonium Chlorides.

The nominal concentration is generally used to express concentration–effect relationships in in vitro toxicity assays. However, the nominal concentration does not necessarily represent the exposure concentration responsible for the observed effect. Surfactants accumulate at interphases and likely sorb to in vitro system components such as serum protein and well plate plastic. The extent of sorption and the consequences of this sorption on in vitro readouts is largely unknown for these chemicals. The aim of this study was to demonstrate the effect of sorption to in vitro components on the observed cytotoxic potency of benzalkonium chlorides (BAC) varying in alkyl chain length (6–18 carbon atoms, C6–18) in a basal cytotoxicity assay with the rainbow trout gill cell line (RTgill-W1). Cells were exposed for 48 h in 96-well plates to increasing concentration of BACs in exposure medium containing 0, 60 μM bovine serum albumin (BSA) or 10% fetal bovine serum (FBS). Before and after exposure, BAC concentrations in exposure medium were analytically determined. Based on freely dissolved concentrations at the end of the exposure, median effect concentrations (EC50) decreased with increasing alkyl chain length up to 14 carbons. For BAC with alkyl chains of 12 or more carbons, EC50’s based on measured concentrations after exposure in supplement-free medium were up to 25-times lower than EC50’s calculated using nominal concentrations. When BSA or FBS was added to the medium, a decrease in cytotoxic potency of up to 22 times was observed for BAC with alkyl chains of eight or more carbons. The results of this study emphasize the importance of expressing the in vitro readouts as a function of a dose metric that is least influenced by assay setup to compare assay sensitivities and chemical potencies.

Effects of phosphonium-based ionic liquids on the lipase activity evaluated by experimental results and molecular docking.

In this work, the effect of several phosphonium-based ionic liquids (ILs) on the activity of lipase from Burkholderia cepacia (BCL) was evaluated by experimental assays and molecular docking. ILs comprising different cations ([P4444 ]+ , [P444(14) ]+ , [P666(14) ]+ ) and anions (Cl- , Br- , [Deca]- , [Phosp]- , [NTf2 ]- ) were investigated to appraise the individual roles of IL ions on the BCL activity. From the activity assays, it was found that an increase in the cation alkyl chain length leads to a decrease on the BCL enzymatic activity. ILs with the anions [Phosp]- and [NTf2 ]- increase the BCL activity, while the remaining [P666(14) ]-based ILs with the Cl- , Br- , and [Deca]- anions display a negative effect on the BCL activity. The highest activity of BCL was identified with the IL [P666(14) ][NTf2 ] (increase in the enzymatic activity of BCL by 61% at 0.055 mol·L-1 ). According to the interactions determined by molecular docking, IL cations preferentially interact with the Leu17 residue (amino acid present in the BCL oxyanion hole). The anion [Deca]- has a higher binding affinity compared to Cl- and Br- , and mainly interacts by hydrogen-bonding with Ser87, an amino acid residue which constitutes the catalytic triad of BCL. The anions [Phosp]- and [NTf2 ]- have high binding energies (-6.2 and -5.6 kcal·mol-1 , respectively) with BCL, and preferentially interact with the side chain amino acids of the enzyme and not with residues of the active site. Furthermore, FTIR analysis of the protein secondary structure show that ILs that lead to a decrease on the α-helix content result in a higher BCL activity, which may be derived from an easier access of the substrate to the BCL active site.

Protic Ionic Liquids Based on the Alkyl-Imidazolium Cation: Effect of the Alkyl Chain Length on Structure and Dynamics.

Protic ionic liquids are known to form extended hydrogen-bonded networks that can lead to properties different from those encountered in the aprotic analogous liquids, in particular with respect to the structure and transport behavior. In this context, the present paper focuses on a wide series of 1-alkyl-imidazolium bis(trifluoromethylsulfonyl)imide ionic liquids, [HC nIm][TFSI], with the alkyl chain length ( n) on the imidazolium cation varying from ethyl ( n = 2) to dodecyl ( n = 12). A combination of several methods, such as vibrational spectroscopy, wide-angle X-ray scattering (WAXS), broadband dielectric spectroscopy, and 1H NMR spectroscopy, is used to understand the correlation between local cation-anion coordination, nature of nanosegregation, and transport properties. The results indicate the propensity of the -NH site on the cation to form stronger H-bonds with the anion as the alkyl chain length increases. In addition, the position and width of the scattering peak q1 (or the pre-peak), resolved by WAXS and due to the nanosegregation of the polar from the nonpolar domains, are clearly dependent on the alkyl chain length. However, we find no evidence from pulsed-field gradient NMR of a proton motion decoupled from molecular diffusion, hypothesized to be facilitated by the longer N-H bonds localized in the segregated ionic domains. Finally, for all protic ionic liquids investigated, the ionic conductivity displays a Vogel-Fulcher-Tammann dependence on inverse temperature, with an activation energy Ea that also depends on the alkyl chain length, although not strictly linearly.

Functionalization of Cerium Oxide Nanoparticles to Influence Hydrophobic Properties.

Electroless functionalization of cerium oxide nanoparticles (NPs) based on the grafting of aryl groups from the reduction of diazonium salts is presented as a useful and facile method for enhancing the properties of the NPs. For this study, 4-methyl-, 4-ethyl-, and 4- n-butyl-benzene diazonium salts were used as model molecules to demonstrate the ability to change the hydrophobic properties of the cerium oxide (CeO2) NPs. The grafting reaction was investigated under two reducing environments: the addition of a chemical reducing agent and the use of cerium oxide's native reducing property. Spectroscopic evidence for the successful attachment of aryl groups to the CeO2 NPs was given by infrared and 13C SS-NMR, which clearly detect characteristic aryl C-C peaks and the alkyl chains. X-ray diffraction results confirmed that the NPs underlying the crystal structure was unaffected by the grafting process. Thermal gravimetric analysis of the NPs suggested that this method enables the formation of multilayers at the surface, as well as an increase in the hydrophobic character. Hydrophobic properties of the resultant NPs further examined with a water contact angle test on pressed pellets revealed increase in hydrophobicity with increasing alkyl chain length. This research opens up new possibilities for controlling the surface chemical composition of CeO2 NPs as well as other NPs using procedures operated in aqueous environments at room temperature.

Physicochemical, traction and tribofilm formation properties of three octanoate-, laurate- and palmitate-anion based ionic liquids

Three new ionic liquids with different anions and the same cation were synthesized from fatty acids through a metathesis reaction. All the ionic liquids were identified via NMR and FTIR and several properties (density, viscosity, thermal, and environmental) were measured. Traction tests were performed under different entrainment speeds (10–2000 mm/s), at slide-roll ratio (SRR) of 50% and 30 N-load, and at different temperatures (40, 60, 80 and 100 °C) using a mini-traction machine (MTM). Tribofilm formation tests were also made in the MTM at 50 N-load, 150 mm/s of entrainment speed, at SRR of 50% and temperature of 100 °C, for 60 min. This work showed that the alkyl chain length in the anion affects properties such as viscosity, toxicity, biodegradability and lubrication. Viscosity decreased with increasing alkyl chain length but only below 60 °C, at higher temperatures the viscosity values of the ionic liquids converge. The toxicity increases with the alkyl chain length; whereas, biodegradability shows the opposite behavior. These novel ionic liquids are much better from both toxicity and biodegradability points of view than the [N8881][TFSI] ionic liquid, which contains the same cation and anion not coming from fatty acids. The ionic liquids at low temperature (40 °C) performed under elastohydrodynamic lubrication and changed to mixed lubrication at higher temperatures and decreasing speeds, according to the alkyl chain length of each anion. All ionic liquids adsorbed on the steel surfaces, and the tribofilm thickness and the kinetics of formation were different.

Solution Properties of Alkyl β‐D‐Maltosides

AbstractAlkyl β‐D‐maltosides are an important class of sugar‐based nonionic surfactants and have been widely studied. Nevertheless, it is still necessary to investigate further their amphiphilic structure‐surface property relationships. In this article, we reported a series of properties of synthetic alkyl β‐D‐maltosides (6a–6i, n = 6–18) including their hydrophilic–lipophilic balance (HLB) number, water solubility, hygroscopicity, moisture‐retention capacity, foaming ability, surface tension, thermotropic phase behavior, and skin irritation. Their HLB number and water solubility decreased with increasing alkyl chain length. Hexyl β‐D‐maltoside exhibited the strongest hygroscopicity and moisture‐retention capacity. Decyl β‐D‐maltoside and dodecyl β‐D‐maltoside possessed excellent foaming power and foaming stability. Furthermore, the critical micelle concentration (CMC) of alkyl β‐D‐maltoside (6a–6g, n = 6–14) and their surface tension at CMC decreased with increasing alkyl chain length. At last, alkyl β‐D‐maltosides (6a–6g) should be considered as safe surfactants by the skin irritation assessment.

Synthesis of novel colorants for DSSC to study effect of alkyl chain length alteration of auxiliary donor on light to current conversion efficiency

Five (MA1-MA5) hemicyanine based sensitizer having N, N-diethyl aniline as a primary donor and hydroxy or alkoxy as an auxiliary donor have been synthesized to establish a correlation between amphiphilic nature of the sensitizer and charge recombination. A strong electron withdrawing 3-(carboxymethyl)-2-methylbenzo[d]thiazol-3-ium bromide has been explored as an acceptor. All the dyes were characterized by 1H-NMR, 13C-NMR and CHN analysis. The photophysical properties of these dyes were recorded in seven different solvents which do not show any significant impact on absorption and emission maxima while molar absorptivity coefficient decreases with increase in alkyl chain length. These dyes show very poor emission in all the solvents. Nano-crystalline mesoporous TiO2 based dye-sensitized solar cells were fabricated using MA1 to MA5 sensitizers to evaluate their photovoltaic performance. MA5 having six carbon alkyl chain shows maximum efficiency of 4.97% while MA1 without any alkyl chain shows the lowest efficiency of 3.40%. As the length of alkyl chain increase efficiency increase due to increment in short circuit current (Jsc) and retardation in the recombination process. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) were explored to obtain vertical excitation, HOMO-LUMO energy and electron density distribution.

The dilational rheology and splashing behavior of ionic liquid-type imidazolium Gemini surfactant solutions: Impact of alkyl chain length

A new series of ionic liquid-type imidazolium Gemini surfactants, 1,10-(Propane-1,3-diyl-2-ol)bis(3-alkyl-1H-imidazol-3-ium) chloride, were synthesized and investigated for their dilational rheology at the air/water interface using the oscillating drop method. The surface properties and splashing behavior of these ionic liquid-type imidazolium Gemini surfactants were studied at different hydrophobic chain lengths, surfactant concentrations and dilational frequencies. With increasing concentration, increasing intermolecular interaction had a positive effect on the dilational modulus, and the increasing surfactant molecular diffusion exchange had a negative effect on the dilational modulus; thus, the surface dilational modulus demonstrated a maximum value. Furthermore, the surface dilational modulus for 1,10-(Propane-1,3-diyl-2-ol) bis (3-tetradecyl-1H-imidazol-3-ium) chloride is higher than that for the other two short-chain ionic liquid-type imidazolium Gemini surfactants, which is due to an increase in the hydrophobic interaction. The results reveal that the bouncing heights of ionic liquid-type imidazolium Gemini surfactants on a paraffin liquid surface decrease with increasing alkyl chain length. The splashing behavior of ionic liquid-type imidazolium Gemini surfactants observed on liquid surfaces and the spreading behavior observed on a paraffin surface are closely related to the dilational loss modulus. These findings not only reveal the relationship between dilational rheology and splashing behavior but also provide insights for the potential application of ionic liquid-type imidazolium Gemini surfactants in more fields.

Alkyl chain length effects of hydroxyl-functionalized imidazolium ionic liquids in the ionothermal synthesis of LiFePO4

LiFePO4 is one of the most promising cathode materials for lithium ion batteries. To investigate the role of the cation in the ionothermal synthesis of LiFePO4, three imidazolium-based ionic liquids, containing hydroxyl-terminated alkyl chains of various lengths, were synthesized using microwave-assisted methods: 1-(3-hydroxypropyl)-3-methyl imidazolium bis(trifluoromethylsulfonyl)amide, 1-(6-hydroxyhexyl)-3-methyl imidazolium bis(trifluoromethylsulfonyl)amide, and 1-(9-hydroxynonyl)-3-methyl imidazolium bis(trifluoromethylsulfonyl)amide. An ionothermal synthesis was attempted with each ionic liquid, using various precursors. The resulting solid products were investigated using powder X-ray diffraction and solid state nuclear magnetic resonance spectroscopy. The yield of LiFePO4 increased with an increase in the hydroxyl-terminated alkyl chain length on the imidazolium.

Preparation and Evaluation of Antimicrobial Hyperbranched Emulsifiers for Waterborne Coatings.

Nosocomial infections are a major problem in medical health care. To solve this problem, a series of antimicrobial waterborne paints were prepared by using antimicrobial hyperbranched (HB) emulsifiers. The HB-emulsifiers were prepared by polymerizing AB2 monomers obtained in a one-step reaction of bis(hexamethylene)triamine and carbonyl biscaprolactam. The blocked isocyanate end groups (B groups) of the HB-polymer were utilized to introduce tertiary amino groups through the reaction with compounds comprising either a hydroxyl or a primary amino group and a tertiary amino group. Quaternization of the tertiary amines with 6 different alkyl bromides resulted in 12 amphiphilic cationic species. The 12 emulsifiers showed the successful inhibition and killing of 8 bacterial and 2 fungal strains. The killing efficacy increased with increasing alkyl chain length. The octyl-functionalized compound was chosen for suspension polymerizations because of the good compromise between killing and emulsifying properties. With this emulsifier, aqueous poly(methacrylate) suspensions were prepared, which were stable and had excellent killing properties.

From Polymerizable Ionic Liquids to Poly(ionic liquid)s: Structure-Dependent Thermal, Crystalline, Conductivity, and Solution Thermoresponsive Behaviors

This contribution describes the synthesis of 3-alkyl-1-vinylimidazolium bromide ionic liquid monomers (ILMs), ion exchange with bis(trifluoromethane)sulfonimide anion (NTf2–), and their radical polymerization to a homologous series of poly(ionic liquid)s (PILs) containing an imidazolium ion substituted with alkyl chains of different lengths (C2(n=7–11)). Owing to the presence of a long alkyl chain, all the ILMs show crystalline phases whose melting point and melting enthalpy increase sharply with increasing alkyl chain length, and those parameters decrease upon replacing Br– with a NTf2– anion. In addition to the solid crystalline phase, the ILMs with a Br– ion only show liquid crystalline mesophases above the melting of solid crystals. The corresponding PILs are semicrystalline in nature due to crystallizable alkyl side chain showing similar chain length and counteranion-dependent melting behaviors with poor crystallinity compared to those of ILMs. The formation of strong birefringent crystals of various...

Comparative study of effect of alkyl chain length on thermophysical characteristics of five N-alkylpyridinium bis(trifluoromethylsulfonyl)imides with selected imidazolium-based ionic liquids

The series of N-alkylpyridinium bis(trifluoromethylsulfonyl)imide, [Cnpy][NTf2], where n = 2, 3, 4, 6, and 8 have been synthesized and the effect of alkyl chain length in cation on their thermophysical properties have been studied and compared with those observed in analogous imidazolium-based ILs. To drive this comparison, the speed of sound, density, isobaric heat capacity, electric conductivity, TGA for all [Cnpy][NTf2], as well as, refractive index of [Cnpy][NTf2] (n = 3, 6) and surface tension of [Cnpy][NTf2] (n = 2, 4, 6, 8) were determined as a function of temperature at atmospheric pressure. From these experimental data, the isentropic compressibility, isobaric thermal expansion, isothermal compressibility, isochoric heat capacity, internal pressure, as well as, the surface entropy and surface enthalpy were calculated. The electric conductivity together with the literature viscosity data are used to obtain the Walden plot for the investigated ionic liquids. The minimum of the speed of sound dependence on the alkyl chain length in the cation is observed for [C6py][NTf2]. The isentropic compressibility and the isothermal compressibility of [Cnpy][NTf2] increase with increasing alkyl chain length in the cation and the slope of this dependence is changed around n = 6. These effects were more pronounced than that for imidazolium-based ionic liquids with [NTf2]− anion. Finally, COSMOthermX software was used to further evaluate its predictive capability by comparing calculated density and isobaric heat capacity as a function of the IL structure and temperature with experimental data for the [Cnpy][NTf2] (n = 2, 3, 4, 6, 8) series. This analysis shows a very good agreement in the case of the Cp with an average absolute relative deviation close to 1.4% while a deviation close to 0.72% is observed in the case of the density of the [Cnpy][NTf2].

Organic ammonium salt surface treatment stabilizing all-inorganic CsPbI<sub>2</sub>Br perovskite

All-inorganic perovskite cesium lead halides with superior stability, suitable bandgap and high absorption efficient have become a promising candidate for photovoltaic application. In all-inorganic cesium lead halide perovskites, CsPb<i>X</i><sub>3</sub> (<i>X</i> = Br, I) exhibits excellent photoelectric properties, which are similar to those of organic-inorganic hybrid perovskites. The CsPbI<sub>3</sub> faces a challenge of unideal tolerant factor for perovskite phase while CsPbI<sub>3–<i>x</i></sub>Br<i><sub>x</sub></i> has better tolerant factor. Among them, CsPbI<sub>2</sub>Br is one of most popular candidates because of its good thermal stability. Nevertheless, CsPbI<sub>2</sub>Br shows instability due to the phase transition caused by moisture and lower efficiency because of defects. For all inorganic perovskite devices, the alkyl chain length of surface treatment agent should be taken into account when using organic cationic passivation method. In this paper, CsPbI<sub>2</sub>Br perovskite is treated with different organic ammonium salts to enhance its phase stability. The experimental results show that <i>α</i>-phase CsPbI<sub>2</sub>Br is more stable with the increase of the alkyl chain length. Butylamine iodine (BAI) among three kinds of surface treating agents is proved to have the best defect passivation and phase stabilization effect. With the increase of alkyl chain length, the hydrophobicity of the organic molecular layer increases, which plays a crucial role in protecting optically active CsPbI<sub>2</sub>Br. Meanwhile, it is found that the stability of perovskite is enhanced with the concentration of the BAI solution increasing. This should be related to the organic cation termination formed on the surface of CsPbI<sub>2</sub>Br film. Solar cell devices based on the CsPbI<sub>2</sub>Br thin films treated with different concentrations of BAI are assembled and then the effect of organic ion surface treatment on the photoelectric performance of batteries is further explored. The experimental results show that when the concentration of BAI is relatively high (4 mg/mL and 8 mg/mL), the device’s photovoltaic performance decreases especially the photocurrent obviously decreases, while the post-treatment process using 2 mg/mL BAI will enhance not only the phase stability but also the photovoltaic parameters after defect passivation. Considering both humidity resistance and device efficiency, this work demonstrates that the CsPbI<sub>2</sub>Br thin film with suitable BAI treatment can improve the wet stability of perovskite, and enhance the photovoltaic performance.

Insight into conformationally-dependent binding of 1-n-alkyl-3-methylimidazolium cations to porphyrin molecules using quantum mechanical calculations.

The first step in the biodegradation of imidazolium-based ionic liquids involves the insertion of the -OH group into the alkyl side chain, and it is believed to be triggered by cytochrome P450. However, at present, there is a lack of fundamental understanding of why the hydroxylation process is observed only for longer alkyl chain analogues. As the initial step of the hydroxylation reaction involves the ionic liquid binding to Fe-porphyrin (FeP) - the catalytic center of cytochrome P450, the orientation of ionic liquids presented to FeP is expected to play a crucial role in eventual hydroxylation of the alkyl side chain. In order to elucidate the chain-length dependent binding preferences exhibited by the homologous series of 1-n-alkyl-3-methylimidazolium (n = 2, 4, 6, 8, and 10) [Cnmim]+ cations, a quantum mechanical treatment of the cations in the presence of free base porphyrin (FBP) and FeP is carried out at the B3LYP-D2 and M06 levels. The binding energy of different complexes with FBP and FeP is investigated by considering three vastly different starting relative orientations of the cations with respect to FBP and FeP: tail down, tail up, and interplanar. Our calculations of binding energies reveal that the cation orientations initiated from the tail down conformations (alkyl chain facing the porphyrin molecules) are progressively destabilized as the alkyl chain length increases. The decomposition of the binding energies into various energetic contributions shows that the interaction energy between the cations and porphyrin molecules varies with the cation geometries presented to porphyrin molecules and is the primary determinant of the magnitude of the binding energies. We further demonstrate that the propensity of the cation-FeP complexes to acquire an electron, the next step in the hydroxylation reaction cycle upon substrate binding, is favored independent of the cations and conformations, suggesting that this step is not the reason for the low biodegradability of short alkyl chain bearing cations. Furthermore, the weaker binding of the ionic liquid to FeP is anticipated to facilitate dioxygen binding to FeP, the step following the electron transfer reaction. Overall, the results of the present calculations indicate that the destabilization of the tail down conformations relative to the other two conformations correlates with the experimental results of the chain length-dependent biodegradation of imidazolium-based ionic liquids.

Phenoxy‐Alkyl Maleates as Phase‐Selective Organogelators for Gelation of Edible Oils

Phase selective gelation may solve environmental problems such as water pollution and fire accidents during oil storage, a major problem for aquatic bodies. The objective of this work is to synthesize a series of phenoxy‐alkyl maleates (n‐PAM) oleogelators with homologous alkyl chain lengths for efficient phase selective gelation. The n‐PAM molecules are found to form oleogel in various edible oils among which sunflower oil shows best gelation. The gelation behavior increases with an increase in alkyl chain length of the n‐PAM gelators as observed from their low minimum gelation concentration (MGC) values. Oleogels thermal stability is examine through tube inversion method and differential scanning calorimetry (DSC). The rheological studies suggest that the oleogel of sunflower oil is mechanically stable and show typical viscoelastic properties. The field emission scanning electron microscopy (FE‐SEM) study of the gels shows sheet‐like morphology. Furthermore, the n‐PAM gelators exhibit quick phase selective gelation of edible oils at low MGC. Both the edible oil and gelator are quantitatively regained from recovered oleogel by employing the vacuum distillation. It is believed that these n‐PAMs could aid in reducing the environmental impacts of oil spills.Practical Applications: The phenoxy‐alkyl maleates gelators present in the MS show gelation ability in various edible oils at low minimum gelation concentration. These molecules also form efficient phase selective gelation with edible oils. Both oil and gelator can be recovered through vacuum distillation and gelator can be reused multiple times. Thus, all these advantages strongly point that out their bright future, in particular in edible oil spill recovery, could aid in reducing the environmental impacts from oil spills.Herein, the synthesized phenoxy alkyl maleate derivatives are reported as separators of edible oil from the oil‐water biphasic mixture. Initially, the gelator is solubilized in the biphasic mixture by heating. Later, gelation ability is observed by tube inversion method. From the phase selective gel, oil and gelator are separated through a distillation method. The recovered gelator can be reused in oil recovery process. This application may find use in oil recovery from waste plant of edible oil industries.

Rich liquid crystal phase behavior of novel alkyl-tri(ethylene glycol)-glucoside carbohydrate surfactants

Carbohydrates are appealing non-ionic surfactant head-groups as they are naturally abundant, generally biocompatible and biodegradable, and readily functionalized. Herein, we explore the phase behavior of seven novel carbohydrate-based surfactants (CBS) containing a tri-ethylene glycol (TEG) linker between a glucose head-group and alkyl tail-group, with linear saturated (C8–18) and cis-unsaturated (C18:1) alkyl chains. At high aqueous concentrations, these glycolipid-like surfactants transition into a variety of lyotropic liquid crystalline phases following an expected concentration phase sequence: hexagonal (H1) → bicontinuous cubic (V1) → lamellar (Lα). Using polarizing light microscopy (PLM), a binary (surfactant–water) phase diagram for each surfactant was constructed across a temperature range (25–80 °C) revealing thermotropic behavior and a broadening of liquid crystal phase regions with increasing alkyl chain length. There was also a significant difference between saturated and unsaturated alkyl chains, due to the cis-unsaturated ‘statistical bend’ lowering the melting point. Small-angle X-ray scattering (SAXS) measurements were performed to characterize the liquid crystal phases, identifying highly-ordered p6m,Ia3d, and Lα crystallographic space-groups with up to 7 resolved Bragg peaks, likely due to the highly anisometric nature of the TEG-linked surfactants. The phases were shown to be more numerous and exhibited greater thermal-stability compared to well-characterized alkyl glucoside surfactants lacking an oligoethylene spacer in the literature. Finally, the characteristic dimensions of each phase were determined to enable visualization of the internal microstructures, providing insight into the impact of molecular shape and the distribution of hydro-philicity/phobicity on the formation and stability of liquid crystalline mesophases.

Viscosity, Electrical Conductivity, Density and Surface Tension of Methyltriphenylphosphonium Carboxylate Ionic Liquids

Abstract In this paper, three new kinds of phosphonium-based room temperature ionic liquids (ILs) [Ph3PCH3][CH3(CH2)8COO] (MTPP-D), [Ph3PCH3][CH3(CH2)10COO] (MTPP-L), and [Ph3PCH3][CH3(CH2)12COO] (MTPP-M) were synthesized using triphenylphosphine, dimethyl carbonate and carboxylic acids as raw materials. The viscosity, electrical conductivity, density and surface tension of the synthesized ILs were measured in the temperature range from 298.15 K to 333.15 K under ambient pressure. Meanwhile, the effects of temperature and alkyl chain length on their viscosity, electrical conductivity, density and surface tension were also investigated. The molecular volume, standard entropy, lattice energy and isobaric expansivity of the three ILs were calculated at 298.15 K. Experimental results indicate that the viscosity, density and surface tension of the three ILs decrease significantly with the increase of temperature, while the electrical conductivity shows an opposite trend. The longer the alkyl chain, the higher the viscosity, the lower the electrical conductivity, density and surface tension of the ILs. The experimental dynamic viscosity can be well correlated by the Vogel-Fulcher-Tammann (VFT) equation and simple linear equation. The temperature dependence of electrical conductivity can be well fitted by Arrhenius equation and VFT equation. The molecular volume, standard entropy and isobaric expansivity increase with increasing alkyl chain length, while the lattice energy decreases.

Interactions of sodium polystyrene sulfonate with 4-methylpyridinium based ionic liquids in aqueous solution: Viscometry, conductometry, UV–Vis spectroscopy and density functional theory studies

Viscosity (η) and molar conductivity (Λ) of aqueous solutions of sodium polystyrene sulfonate (NaPSS) in the presence of some 4-methylpyridinium based ionic liquids (1-Butyl-4-methylpyridinium bromide [BMPyr]Br, 1-Hexyl-4-methylpyridinium bromide [HMPyr]Br and 1-Octyl-4-methylpyridinium bromide [OMPyr]Br) were investigated at T = (288.15, 298.15 and 308.15) K. The viscosity values were correlated with the Wolf equation to obtain the intrinsic viscosity ([η]) of NaPSS. The intrinsic viscosity of NaPSS decreases by increasing the concentration of ionic liquids due to screens effects of ionic liquids and decreased with increasing alkyl chain length of ILs. The scaling theory is used for the description of electrical conductance of polyelectrolytes. The values of fractions of uncondensed counterions f have been estimated. The effects of the polyelectrolyte concentration, the relative permittivity of the medium, different alkyl chain length and the temperature on the fractions of uncondensed counterions of NaPSS aqueous solutions have been discussed. UV–Vis spectroscopy and Quantum chemical calculations studies are also used to confirm the existence of interactions between NaPSS and ILs. The UV–Vis spectra of NaPSS show that the conformation of NaPSS changes in the presence of ionic liquids; therefore the value of electric multipole moment decreases. Consequently, the absorption intensity of NaPSS was decreased with the addition of ionic liquids. Density functional theory (DFT) has been used to investigate the interactions between [PSS]− anion and [RMPyr]+ cations. The molecular electrostatic potential, natural bond orbital methodologies and atoms in molecules are used to analyses the nature of interactions of the ion-pairs [RMPyr]+[PSS]−.

Non‐Fullerene Small Molecule Acceptors Containing Barbituric Acid End Groups for Use in High‐performance OPVs

We synthesized two new bithiophene‐based small molecules, TT‐BBAR, and TT‐OBAR, having butyl‐ and octyl‐substituted barbituric acid (BAR) groups, respectively, via a well‐known synthetic method, the Knoevenagel condensation, in high yield. These small molecules displayed solubilities and thermal stabilities sufficient for the fabricating organic photovoltaic cells (OPVs) and were designed to have relatively low molecular orbital energy levels and act as non‐fullerene acceptors (NFAs) for use in OPVs upon introduction of electron‐withdrawing BAR groups at both ends. For example, the LUMO and HOMO energy levels of TT‐OBAR were −3.79 and of −5.84 eV, respectively, clearly lower than those of a polymer donor, PTB7‐Th. Importantly, the small molecules featured an energy offset with PTB7‐Th sufficient for achieving exciton dissociation. The optical and electrochemical properties of TT‐BBAR and TT‐OBAR did not depend on the alkyl chain length. Finally, OPV devices were fabricated in an inverted structure using a solvent process. The power conversion efficiency of TT‐OBAR (1.34%) was found to be slightly higher than that of TT‐BBAR (1.16%). The better performance and higher short‐circuit current value of TT‐OBAR could be explained based on a morphological AFM study, in which TT‐OBAR displayed a more homogeneous morphology with a root‐mean‐square value of 1.18 nm compared to the morphology of TT‐BBAR (11.7 nm) induced by increased alkyl chain length.