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[Display omitted] • Four imidazolium ([1MeimPS]+) based protic ionic liquids (PILs) are developed with potential amine-based structural functionalities. • All the reported PILs have shown excellent antioxidant potential depicting antiaging properties. • Glutamine based-IL ([1MeimPS][Gln]) showed selectively promising antioxidant activity. • Least IC 50 values are observed for Glutamine based-PIL ([1MeimPS][Gln]) indicating maximum antioxidant activity. • Maximum IC 50 values are observed for Proline based-PIL ([1MeimPS][Pro]) indicating least antioxidant activity. • Increased primary amine moieties enhanced the antioxidant activity by providing more radical scavenging sites. Sulfonyl hydroxide functionalized imidazolium based protic ionic liquids (PILs) have been evaluated as a new form of antioxidants. The antioxidant activity was performed using free radical quenching using UV–visible spectroscopy and cyclic voltammetry. The studies confirmed that the investigated ILs with variable anions exhibited substantial radical scavenging activity. In UV–Visible study, Glutamine based-IL ([1MeimPS][Gln]) showed least IC 50 value of 95 µM indicating maximum radical quenching activity as an oxidant, while proline based-IL ([1MeimPS]Pro]) exhibited highest IC 50 value of 675 µM, demonstrating least anti-oxidant activity. Moreover, cyclic voltammetry results complemented well the UV–visible findings with least IC 50 value of 90 µM for [1MeimPS][Gln], showing maximum antioxidant activity, and highest IC 50 value of 593 µM for [1MeimPS]Pro], exhibiting the least antioxidant activity. The presence of two primary amines moieties in glutaminate anion may be responsible for enhanced antioxidant activity by providing more active sites for radical quenching. Contrarily, lack of primary amine functionality in prolinate anion may contribute to reduced antioxidant activity of respective IL. The Density Functional Theory (DFT) calculations predicted that the trend of radical scavenging potential was comparable with the experimentally obtained IC 50 values. Molecular Electrostatic Potential (MESP) Maps illustrated that [1MeimPS][Pro] has the maximum red zones indicating a poor potential against electron scavenging capacity among all the studied ILs, while blue region in [1MeimPS][Gln], corresponding to low electron density, suggested strong attraction for the incoming electrons. Also, the high electronic distribution of HOMO orbital, appreciable stability, and significant chemical potential to attack on radical species provided by [1MeimPS][Gln] with the maximum radical scavenging potential. Furthermore, the associated LUMO energy for [1MeimPS][Pro] (−1.297 eV) is quite higher than that of [1MeimPS][Gln] (−1.422 eV) which reduced the ability of [1MeimPS][Pro] to attack free radicals of 2,2-diphenyl-1-picrylhydrazyl (DPPH) and thus have higher associated IC 50 values. This is also supported by the results of chemical hardness (η) and chemical potential (μ) descriptors values indicating [1MeimPS][Pro] is least stable and reactive than [1MeimPS][Gln]. These findings further explain the least IC 50 values observed experimentally and consequent enhanced antioxidant potential of [1MeimPS][Gln]. [ABSTRACT FROM AUTHOR]

• Imidazolium and pyridinium based ILs having bromide and dioctylsuccinamic acid anions were synthesized and characterized. • Antibacterial potential of ILs was evaluated against pathogens, gram-positive Staphylococcus aureus , gram-negative Escherichia coli , and Pseudomonas aeruginosa. • Imidazolium based ILs proved better candidates against Staphylococcus aureus , while bromide based ILs against Escherichia coli , and Pseudomonas aeruginosa. • [C 88 im][Br] and [C 88 im][DOSA], exhibited the least MIC values of 0.244 mM and 0.488 mM. • The mechanism behind antibacterial activity investigated by density functional theory calculations. A substantial public health risk is bacterial infections, but the effectiveness of antibiotics has declined due to their overuse. In the quest for effective antimicrobial agents, Ionic liquids (ILs) have emerged as promising candidates. We have described the synthesis and comparison of pyridinium- and imidazolium-based ILs using bromide and dioctyl succinamate (DOSA) anions. These synthesized ILs were tested for their antibacterial efficacy against gram-positive Staphylococcus aureus , gram-negative Escherichia coli , and Pseudomonas aeruginosa using the agar disc diffusion method. The ILs based on Imidazolium cation showed better antibacterial activities against Staphylococcus aureus. The least MIC values of 0.244 mM and 0.488 mM are shown by [C 88 im] [Br] and [C 88 im] [DOSA] respectively, showing the key effect of a counter ion with Imidazolium ILs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Entropy Scaling Theory with SAFT Equations of State to correlate and predict the Viscosity of Ionic Liquids through Two Approaches. • Molecular-Based Approach uses PC-SAFT to calculate reduce entropy considering the ionic liquid (cation & anion) as a single species. • Ion-Based Approach uses ePC-SAFT considering the ionic liquid is a binary mixture of its cation & anion. • Scaling Coefficients correlate with molecular weight within cations allowing interpolation and extrapolation beyond ILs in training set. • Viscosity of mixtures of different Ionic Liquids well-predicted. Entropy scaling is a promising method for the development of engineering models for transport properties of ionic liquids (ILs). Here we present two entropy scaling models for the viscosity of ionic liquids and their mixtures at various temperatures and pressures: 1) a molecular-based approach treating each IL as one pure species and using the PC-SAFT equation of state (EoS); and 2) treating each ion as a separate species and using the ePC-SAFT EoS. Both approaches were correlated to viscosity data of 12 ionic liquids from the imidazolium cation class and three different anions comprising 4233 data points with overall average absolute deviations (%AARDs) of less than 8 % over a wide range of temperature and pressures. The ion-based approach was better able to correlate IL viscosity at low temperatures and/or high pressure (to 4011 bar) than the molecular approach. The functional entropy-scaling coefficients for both models were regressed as linear functions of molecular weight, which allowed good prediction of another nine ionic liquids not in the training set. Interestingly, both approaches well predict the viscosity of binary mixtures of imidazolium ionic liquids. In addition, the effect of various reference viscosities and comparison with the Peng-Robinson EoS was performed. [ABSTRACT FROM AUTHOR]

• Ionogels are formed by assembly of DNA in imidazolium-based Ionic Liquids. • In situ and operando UV Resonance Raman is used to investigate DNA ionogels. • Molecular insights on structural organization of the gel network are obtained. • Imidazolium-mediated stacking interactions mainly involve the guanine bases. • Length of the alkyl chain of imidazolium cation modulates the gelation of DNA. Double-stranded DNA dissolved in aqueous solutions of imidazolium-based Ionic Liquids (ILs) exhibits a characteristic gel transition, leading to the formation of DNA ionogels. In this study, we utilize state-of-the-art operando UV Resonance Raman (UVRR) spectroscopy, along with UV and Circular Dichroism (CD) absorption experiments, to monitor the self-assembly of a class of DNA ionogels derived from low-concentration aqueous solutions of DNA in imidazolium-based ILs. Our experimental approach offers insights at the molecular level into the structural organization and interactions that stabilize the gel network. Furthermore, operando UVRR spectroscopy allows efficient monitoring of the different stages of the thermal pathway leading to the self-assembly of DNA/ILs solutions into ionogels. A key achievement of our study is demonstrating that the sol–gel transition in DNA ionogels in the presence of imidazolium-based ILs can be modulated by the length of the alkyl chain of the imidazolium cation to achieve desired premelting, melting, and gelation temperatures. [ABSTRACT FROM AUTHOR]

• The properties of the solvents are defined by its constituents. • Water can alter the thermophysical properties of the solutions. • Molar ratio is an important factor in defining the properties of DESs. • Thermophysical properties of ILs is depending on its alkyl chain length. • The effects of temperature can be trivial or significant depends on properties types. In respond to the queries of deep eutectic solvent (DES) as a better analogue over ionic liquid (IL), this research aims in contributing a comparative study on the thermophysical properties of choline chloride-based DESs and imidazolium-based ILs to provide a general understanding on the similarities and differences of their properties. The thermal conductivity, viscosity and ionic conductivity of choline chloride-based DESs with glycerol (Gly) and ethylene glycol (EG) as hydrogen bond donors (HBDs) are characterized and compared with those of 1-ethyl-3-methylimidazolium chloride (EmimCl) and 1-hexyl-3-methylimidazolium chloride (HmimCl). It is observed that the thermal conductivity of DESs increases with salt: HBD molar ratio while that of ILs increases with alkyl chain length. Meanwhile, the viscosity of DESs is depending on the nature of HBD. DESs with glycerol as HBD show an incremental trend in viscosity with increasing molar ratio, while DESs with ethylene glycol as HBD depict an opposite trend. For ILs, longer alkyl chain length results in greater viscosity. The ionic conductivity of both DESs and ILs increase as their viscosity decrease. The effect of temperature is insignificant on the thermal conductivity of DESs and ILs. The viscosity of both DESs and ILs is reduced while their ionic conductivity is enhanced with increase of temperatures. When aqueous form of DESs and ILs is considered, water has greatly enhanced the thermal conductivity and ionic conductivity of DESs and ILs. However, the viscosity of DESs and ILs is drastically reduced with the presence of water content. In general, the thermophysical properties of both DESs and ILs are comparable, including in their aqueous forms. A prefeasibility study is conducted to further evaluate the potential and practicality of DESs and ILs in comparison with the conventional lubricant and battery electrolyte. [ABSTRACT FROM AUTHOR]

• Aqueous solutions of [MIM]-based PILs in the water-rich domain were investigated. • Hydration water and ionic aggregation features were obtained by UV Raman spectroscopy. • Ionic aggregates form at increasing PIL concentration starting from x PIL ∼ 0.05. • The water-anion H-bonding energy decreases following the order: [Cl] ∼ [HSO 4 ] > [NO 3 ] > [TfO]. • The [MIM][Cl] shows the larger aggregation propensity. Water molecules, present as additive or as contaminant of Protic Ionic Liquids (PILs), can compete for the hydrogen bond sites leading to important modifications of the local order of these liquids and to the modulation of their physical–chemical properties. In this work, aqueous solutions of a set of N-methylimidazolium-based PILs [MIM][X] (X = NO 3 −, TfO−, HSO 4 −, and Cl−) were investigated by deep UV Resonance Raman (UVRR) spectroscopy in the water-rich domain where ionic aggregates and bulk-like water coexist. A differential method was used to analyze the OH stretching profile to extract the so-called solute-correlated (SC) spectrum, which is particular informative of the hydration features of the PILs. Moreover, specific bands of the cation, sensitive to the hydrogen bonding, were comparatively investigated. The progressive evolution from solvent-separated ion pairs (SIP) and/or solvent-shared ion pairs (SSIP) to contact ion pairs (CIP) and/or larger ionic aggregates can be monitored as a function of the hydration level, in the water-rich domain. Our approach showed that, in the high-diluted regime, the hydration environment around the [MIM] cation does not depend on the type of anion. Moreover, [MIM][NO 3 ] and [MIM][TfO] showed cation-water (ionic) H-bonds at the NH site stronger than the cation–anion (double-ionic) ones. The analysis of SC Raman spectra points out the formation of cation–anion H-bonds (through the CH ring groups), stronger than cation-water ones, upon PILs concentration increase, especially evident in the case of [MIM][Cl]. The H-bond strength between the anion and hydration water is found to decrease following the order: [Cl] ∼ [HSO 4 ] > [NO 3 ] > [TfO]. Chloride ions tend to perturb a larger number of water molecules than the other anions. The number of perturbed water molecules decreases at increasing PIL concentration, showing a larger dependence for [MIM][Cl], consistently with its larger propensity to form ionic aggregates. The unique response of [MIM][Cl] to hydration found by analyzing SC-UVRR data is related to the synergy of different factors such as the anion reduced size (higher charge density), spherical symmetry, and high H-bond basicity. [ABSTRACT FROM AUTHOR]

Abstract The rheological behavior of a fluid is an important property that has a distinct impact on its flow conduct, which influence viscosity dependent phenomena and applications such as pumping, mass transfer rates, and hydrodynamics. As a result, the necessity of studying the different rheograms and the viscoelastic properties of fluids is essential. In this review, a vast number of novel imidazolium-based combinations of ionic liquids (IL) and natural deep eutectic solvents (NADES) in terms of different hydrogen bond donors (HBD) and hydrogen bond acceptors (HBA) having different molar ratios of HBA:HBD were classified. The rheological behaviors of these combinations at ambient temperature conditions and higher temperatures are critically evaluated. The influence of different parameters such as the effect of adding different polymers, metal oxides, and water on the rheological behaviors and eventually on the flow assurance of these solvents are investigated. Moreover, an intensive overview of all the key research papers, mainly highlighting the initial apparent viscosity and steady-state viscosity for both IL & NADES solvents with different scenarios was conducted by collecting the different trends in rheograms using different measuring devices from several experimental efforts. Also, the relatively few studies on the oscillatory measurement was also highlighted, as it has shown to be a useful analysis method to determine the elastic properties. In addition, oscillatory mode measurements were best to describe and enhance studies on IL and NADES with high viscosities, which can aid their potential uses in challenging applications such as in pumping of liquid material in many industrial processes, through the study of their elasticity behaviors under the effect of several field operation conditions. Furthermore, eight different rheological regression models from different polynomial degrees were used to describe and physically interpret the viscous and viscoelastic behaviors of the studied solvents. Highlights • Different rheograms and the viscoelastic behaviors of IL and NADES are highlighted. • IL and NADES structures have clear effect on the overall flow behavior. • Rheology of IL and NADES are important in many applications such as pumping, mass transfer rates, and hydrodynamics. [ABSTRACT FROM AUTHOR]

Abstract Formulations based on proteins and surfactants are in demand in pharmaceutics, cosmetics and several biotechnological applications. One of the key problems in this area is the driving forces of components binding, about what at the moment disjointed and contradicting each other data are collected. Herein, using various physico-chemical methods (tensiometry, spectrophotometry, fluorescence spectroscopy, dynamic and electrophoretic light scattering, transmission electron microscopy) binding capacity of amphiphiles bearing imidazolium head group and hydrophobic tail of various length (C n H 2n+1 Im+Br−, where n = 12, 14, 16, 18) toward bovine serum albumin (BSA) has been investigated. It has been exhibited, that BSA addition to surfactant solutions resulted in synergetic 45-fold decrease of aggregation thresholds. The size of surfactant/BSA complexes remains constant throughout the whole amphiphile concentration range and is determined by the size of polypeptide. Using fluorescence spectroscopy technique, it has been established, that the binding site of BSA macromolecule and surfactant is tryptophane amino acid residue. More significant solubilizing capacity of amphiphile/BSA complexes toward hydrophobic dye in comparison with individual micelles of imidazole-containing amphiphiles has been revealed. Improvement of the penetration ability of the drug metronidazole through lipid membranes in the presence of the surfactant and BSA has been exhibited. Capability of lipid formulations (liposomes) based on imidazolium-containing amphiphile to 4-fold prolongation of metronidazole release has been demonstrated. Graphical abstract Unlabelled Image Highlights • Imidazolium-containing amphiphiles form complexes with bovine serum albumin (BSA). • Tryptophan amino acid residue is the favorable binding site between components. • Solubilizing power of amphiphiles increases in the presence of BSA. • Drug membranotropic properties could be improved by amphiphile and BSA addition. [ABSTRACT FROM AUTHOR]

Abstract In this work the synthesis of five new Brönsted acidic ionic liquids (BAILs) bearing same anion (camphorsulfonate) but different cations; 3-(3-sulfopropyl)-imidazolium, 1-methyl-3-(3-sulfopropyl)-imidazolium, 1-methyl-3-(4-sulfobutyl)-imidazolium, 1-ethyl-3-(3-sulfopropyl)-imidazolium, 1-butyl-3-(3-sulfopropyl)-imidazolium) were synthesized and characterized. The characterization of BAILs was carried out using NMR, FTIR and elemental analysis (CHNS). The thermophysical properties of these ILs such as density, refractive index, viscosity and thermal stability were analyzed in wide temperature window. Furthermore, the effect of alkyl chain length of cations on thermophysical properties was well studied. The experimental values of density were further used to calculate other significant properties such as molar volume, standard molar entropy, lattice energy and thermal expansion coefficients. The Brönsted acidities of investigated ILs were determined using Hammett method. Furthermore, COSMO-RS study was performed to determine δ-surface, and δ-profile of the studied ILs. Graphical abstract Unlabelled Image Highlights • Five camphorsulfonate-based ILs with imidazolium and substituted imidazolium-based cations were synthesized and characterized. • Effect of cation and temperature on physicochemical properties was determined. • The Brönsted acidities of investigated ILs were evaluated using Hammett equation. • COSMO-RS model was used to determine δ-surface, δ-potential and δ-profile of the studied ILs. [ABSTRACT FROM AUTHOR]

Abstract In this study, four new protic ionic liquids (PILs), possessing camphorsulfonate anion with four different cations, 2-methyl-3-(3-sulfopropyl)-imidazolium (7,7-dimethyl-2-oxobicyclo[2.2.1]heptan-1-yl)methanesulfonate [2MeimPS][CS], 2-ethyl-3-(3-sulfopropyl)-imidazolium (7,7-dimethyl-2-oxobicyclo[2.2.1]heptan-1-yl)methanesulfonate [2EteimPS][CS], 2-phenyl-3-(3-sulfopropyl)-imidazolium (7,7-dimethyl-2-oxobicyclo[2.2.1]heptan-1-yl)methanesulfonate [2PhimPS][CS] and 3-(3-sulfopropyl)-benzimidazolium (7,7-dimethyl-2-oxobicyclo[2.2.1]heptan-1-yl)methanesulfonate [BnzimPS][CS] were synthesized and characterized. The effect of alkyl and aromatic substitution on the imidazolium cation was investigated in terms of fluctuations in density, viscosity and thermal degradation of ILs. The density and viscosity were determined within a broad temperature range and measured values of density were used to calculate molar volume, standard molar entropy, lattice energy and thermal expansion coefficients. The refractive indices were measured with an ATAGO refractrometer (RX-5000a) within the temperature range of 288.15–333.15 K. The studied ILs exhibited strong Brönsted acidities as determined by Hammett method. Three human pathogenic bacteria i.e. Escherichia coli E149 (EC), Staphlylococcus aureus S244 (SA) and Aeromonas hydrophilla A97 (AH), were deployed to investigate the toxicity behaviour of studied ILs and their 50% effective concentrations (EC 50) were found in comparison with the least toxic imidazolium-based ILs. COSMO-RS was used to determine δ-surface, δ-potential and δ-profile of the investigated ILs. Graphical abstract Unlabelled Image Highlights • Four camphorsulfonate-based ILs with substituted imidazolium-based cations were synthesized and characterized. • Effect of cationic chain length and temperature on physicochemical properties were determined. • The Brönsted acidities of prepared ILs were calculated using Hammett equation. • Ecotoxicity was evaluated for the synthesized ILs. • COSMO-RS model was used to determine δ-surface, δ-potential and δ-profile of the investigated ILs. [ABSTRACT FROM AUTHOR]

Abstract Functionalized multi-walled carbon nanotubes (MWCNTs) were synthesized by simple chemical method, and dispersed using imidazolium and pyridinium-based ionic liquids (ILs). The as-synthesized ILs-MWCNT composites were studied using FTIR spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), thermogravimetric analysis (TGA), and solubility in different polar and non-polar solvents. Spectroscopic and microscopy analyses confirmed the formation of the ILs-MWCNT composites with new functionalities. Spectra studies showed graphitic and carboxylic groups in the pure MWCNTs. MWCNT SEM images showed entangled bundles, while ILs-MWCNTs showed debundled composites with increased diameter and unaltered MWCNTs morphology. TGA indicates that the MWCNTs are thermally stable which could be ascribed to van der Waals and non-covalent interactions within the composites matrices. Solubility studies indicate the ILs-MWCNT composites are hydrophobic, insoluble in water and other polar solvents. Graphical abstract Unlabelled Image Highlights • Ionic liquids disperse carbon nanotubes without morphological alteration. • Ionic liquid-carbon nanotubes composites are more thermal stable than individual components. • Ionic liquid-functionalized carbon nanotubes composites are hydrophobic. • Non-covalent and van der Waals interactions facilitate the ionic liquids/carbon nanotubes bonding. [ABSTRACT FROM AUTHOR]

A series of paramagnetic ionic liquids (PILs) based on N , N ′-bis(alkyl)imidazolium bromotrichloroferrate(III), [(C n ) 2 Im][FeCl 3 Br] (Im = imidazole; C n  = ethyl, butyl, hexyl, octyl, decyl, dodecyl), was prepared and compared against the more traditional [C n C 1 Im][FeCl 3 Br] (C 1  = methyl) analogs. Both series were extensively characterized by physical, chemical, and computational methods including differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), spectroscopy (FTIR and UV‐vis-NIR), magnetic susceptibility, surface tensiometry, density, and viscosity. The X-ray crystal structure of [(C 12 ) 2 Im][FeCl 3 Br] was also obtained. Notably, all ionic liquids prepared in this study show short-term thermal stabilities exceeding 300 °C in air and have melting points equal to or lower than 25 °C, which is surprisingly low for ionic liquids containing symmetrical cations. In addition, all presented ionic liquids have relatively low viscosities allowing for easier transitioning into applications. Physical property trends are discussed. [ABSTRACT FROM AUTHOR]

1-butyl-3-ethylimidazolium bromide ionic liquid, [beim]Br, was studied experimentally and theoretically as a potential inhibitor of copper corrosion in acidic media (pH = 3) by dc polarization, quartz crystal microbalance (QCM), scanning electron microscopy (SEM) and density functional theory (DFT). This ionic liquid is selected to study an effect of the alkyl chain length at the position N-3, since so far only ionic liquids with different alkyl substituents at the position N-1 are investigated. Improved inhibitory properties of the investigated ionic liquid against corrosion of copper in acidic solution at the given conditions are confirmed comparing to corresponding 1-butyl-3-methylimidazolium bromide ionic liquid. It is found that [beim]Br acts as a cathodic corrosion inhibitor, whereby its effectiveness depends on the applied concentration. The inhibitory effect of the studied ionic liquid (IL) was achieved through quick and spontaneous adsorption on the copper surface following the Langmuir's adsorption isotherm. Results obtained by SEM showed that copper protection is achieved through the less damaged copper surface in the presence of inhibitor. Applying DFT calculations, it is found that interactions with the metal surface occur by donating electron from the Br − anion to the copper. Based on the obtained Fukui functions influence of the inductive effect of ethyl/methyl group on the inhibitory activity is also discussed. [ABSTRACT FROM AUTHOR]

The characteristics of intermolecular forces in 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide + ethanol mixtures were studied in the full composition range using a combined experimental and theoretical approach. Molecular clusters were used to model the short-range interactions between the ionic liquid and the primary alcohol, studied using density functional theory calculations, inferring preferred interaction sites, strength of interactions and topological characteristics of intermolecular forces. Dynamic viscosity and refraction index were measured as a function of mixture composition and temperature and analysed in terms of evolution of intermolecular forces. Raman IR studies were carried out and the analysis of selected spectral regions allowed to characterize hydrogen bonding evolution for all the possible interacting sites. [ABSTRACT FROM AUTHOR]

The preparation of a series of novel low viscosity 1-allyl-3-methylimidazolium ionic liquids (ILs) is performed following dedicated synthetic routes. The physico-chemical properties of resulting molecular solvent-free ILs (true ILs) are investigated and discussed systematically toward the anion constituents. Herein, six electrolytes are studied including one planar structured anion (DCA − ) and five anions presenting non-planar structures (PF 6 − , TFSI − , BF 4 − , TFA − and OTf − ). The as-prepared ILs are employed as green electrolytes for symmetric electrochemical double layer capacitors (EDLCs) based on graphene nanosheets (GNS) electrodes. The EDLC devices deliver specific capacitances ranging from 135 to 228 F·g − 1 , and suitable energy densities, ranging from 41 to 115 Wh·kg − 1 . An electrochemical stability of 94% is reached upon 1000 charge/discharge cycles over a large cell voltage window (3–4 V) with a quasi-ideal capacitive behaviour. Among the studied ILs, 1-allyl-3-methylimidazolium dicyanmide (AMIM-DCA) exhibit the highest specific capacitance and the maximum energy density. Such a performance is attributed to the compatibility between the channel-based 2-D graphene network and the planar structure of AMIM-DCA. The resulting AMIM-DCA/GNS interface facilitates the reversible adsorption/desorption process of electrolyte ions during the charge storage. Accordingly, the studied EDLC cells are promising candidates for high-capacity and high-reliability energy-storage applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Formation of NHC generated on the headgroup of imidazolium sulfonate zwitterionic surfactants was investigated. • The reaction is accelerated above the cmc because the micelles weakly attract hydroxide from solution. • The rate of NHC formation is dependent on the type of anion present in solution. • The generated NHCs can selectively catalyze the oxidation of 4-nitrobenzaldehyde to 4-nitrobenzoic acid. N-heterocyclic carbenes (NHCs) are important compounds that are often prepared and used in water free environment. Herein we investigate transient formation of a NHC in the headgroup of zwitterionic imidazolium sulfonate surfactants of the type 3-(1-alkyl-1 H -imidazol-3-ium-3-yl)propane-1-sulfonate (ImS3- n) in water. As demonstrated by a series of 1H NMR experiments, the formation of the NHC reactive species is accelerated above the critical micelle concentration of these surfactants due to an increased local concentration of the hydroxide or deuteroxide ions (OH−/OD−) responsible for deprotonation of C(2)-H. The rate of NHC formation can be modulated by the nature and concentration of the anions of added salts, reflecting the selectivity of anion binding to the zwitterionic micelle surface. Analogous anion binding affects are observe in the NMR chemical shifts of the C(2)-H signal of the imidazolium headgroup of the surfactants. The NHCs generated at the surface of ImS3- n micelles promote the selective oxidation of 4-nitrobenzaldehyde to 4-nitrobenzoic acid, a reaction known to be catalyzed by nucleophilic carbenes. Below the cmc or in the presence of a short-chain non-micelle-forming analogue, 3-(1-methyl-1 H -imidazol-3-ium-3-yl)propane-1-sulfonate (ImS3-1), no selective oxidation of 4-nitrobenzaldehyde takes place. The results demonstrate the importance of the micellar microenvironment for controlling the reactivity and selectivity of chemical reactions involving NHC species in aqueous media and can ultimately lead to greener catalytic systems. [ABSTRACT FROM AUTHOR]

The heat capacity and thermal behavior trend along the 1-alkyl-3-methylimidazolium hexafluorophosphate [C n C 1 im][PF 6 ] (with n = 2–10, 12) ionic liquids series, is used to explore the effect of the alkyl chain length in the nanostructuration. The heat capacities of the studied ILs were measured with an uncertainty better than ± 0.15% and are in excellent agreement with the available data in the literature. An odd-even effect for the specific and volumic heat capacities of the [C n C 1 im][PF 6 ] series was found. The observed odd-even effect in the liquid heat capacity was rationalized considering the preferential orientation of the terminal CH 3 group. The higher specific/volumic heat capacities shown for the [C 6 C 1 im][PF 6 ] and [C 8 C 1 im][PF 6 ] are an indication of an additional conformational disorder increase in the liquid phase that could be related with a weaker alkyl chain interdigitation capability of the even number chain ILs. The melting temperatures and consequent ∆ s l H m o and ∆ s l S m o trend along the alkyl series present a V-shape profile that is explained based on the analysis of the balance between the initial decrease of the electrostatic interaction potential and the increase of the van der Waals interactions with the increasing size of the alkyl side chain of the cation. The inhibition of crystallization for intermediate alkyl chain size (from [C 5 C 1 im][PF 6 ] to [C 8 C 1 im][PF 6 ]) seems to arise from the overlapping of the hypothetical cold crystallization temperature by the melting temperature. Above the critical alkyl size, CAS, a regular increase in the entropy and enthalpy profiles presents a similar shape than the observed in other alkane series and is a strong support of the intensification of the ILs nanostructuration. [ABSTRACT FROM AUTHOR]

Sixteen imidazolium based chiral ionic liquids (CILs) containing Br − and BF 4 − anions, derived from both enantiomers of phenylethylamine, were synthesized. The imidazole ring was constructed through a condensation reaction of formaldehyde, glyoxal and ammonium hydroxide in aqueous media resulting in a simple, versatile and environmentally friendly protocol. The CILs were synthesized with propyl, butyl, pentyl or hexyl alkyl substituents, which provoke a change of the physicochemical properties that were evaluated (glass transition temperature, thermal stability, optical rotation, ionic conductivity, electrochemical window and toxicity). The 1-alkyl-3-(1-phenylethyl) imidazolium tetrafluoroborate ([C n peim]BF 4 ) family showed good thermal stability, large electrochemical window, low toxicity at moderate concentrations, and adequate viscosity. Therefore, these CILs are a good candidates to be used in asymmetric reactions and may be a viable alternative to organic solvents. [ABSTRACT FROM AUTHOR]

Novel C2-functionalized 1,3-dialkylimidazolium-based ionic liquids (ILs) are prepared, in which the acidic hydrogen at the 2-position of 1,3-dialkylimidazolium is replaced with the oxygen-containing methoxymethyl (CH 3 OCH 2 -, MOM) and (2-methoxyethoxy)methyl (CH 3 OCH 2 CH 2 OCH 2 -, MEM) groups to increase their hydrogen bonding interactions with cellulose. While the chloride salts of these C2-functionalized imidazolium cations are unable to dissolve cellulose, the formate and acetate salts exhibit moderate to excellent solvation of high molecular weight cellulose with a degree of polymerization (DP) of 850. Cellulose undergo a decrease in molecular weight with temperature during dissolution in the 1,2,3-trisubstituted imidazolium acetates devoid of the acidic C2 hydrogen, which is similar to that in 1,3-dialkylimidazolium acetates. Deuterium exchange studies suggest that the cellulose degradation is caused by the increased acidity of the hydrogens at C4 and C5 as well as at C2 methylene of the imidazolium cation. The addition of N -methylimidazole as an organic base suppresses the degradation of cellulose. [ABSTRACT FROM AUTHOR]

[Display omitted] • Evaporation and decomposition are competing processes during heating of BMImBF 4 ionic liquid. • Vapor composition of the ionic liquid is complex and depends significantly on evaporation conditions. • Evaporation of decomposition products is kinetically hindered. Thermodynamic properties of evaporation of 1‐butyl‐3‐methylimidazolium tetrafluoroborate (BMImBF 4) ionic liquid (IL) were determined by Knudsen effusion mass spectrometry. Heating of this compound is accompanied by competing evaporation and decomposition. Interpretation of mass spectrum was carried out by the analysis of data obtained for different evaporation conditions: i) Knudsen cell with a small effusion orifice, ii) open Knudsen cell, and iii) open surface of IL. It was revealed that at non-equilibrium Langmuir conditions BMImBF 4 IL evaporates congruently practically only in the form of neutral ion pairs (NIPs). In equilibrium conditions, decomposition products prevail in vapor with only about 7 % vapor fraction of NIPs. The main route of IL decomposition is the formation of substituted imidazole‐2‐ylidene (C 8 N 2 H 14 BF 3) and hydrofluoric acid (HF). The mass spectrum of C 8 N 2 H 14 BF 3 was obtained by the analysis of a distillate collected during evaporation in the Knudsen cell. The decomposition products, due to their high volatility, do not accumulate practically in the liquid phase and hence the activity of IL may be considered to be 1. This circumstance makes it possible to perform the thermodynamic calculations for the IL evaporation reaction. The temperature dependence of the NIPs' vapor pressure, ln(p /Pa) = (–13.806 ± 0.252)∙103/ T + (23.443 ± 0.519), was used to obtain the vaporization enthalpy, Δ v H °(298.15 K) = 138 ± 5 kJ·mol−1, by the methods of the second and third laws. The formation enthalpy of BMImBF 4 NIPs, Δ f H °(298.15 K) = −1084 ± 15 kJ·mol−1, was found from combination of the vaporization enthalpy and the formation enthalpy of IL. The vapor composition over BMImBF 4 under equilibrium conditions was computed. It was demonstrated that decomposition of IL is kinetically hindered so the studied system is characterized by a partial equilibrium. [ABSTRACT FROM AUTHOR]

The seemingly outdated gas-phase HF/6-31G* level has been verified to be good enough for ionic-liquids parameterization. [Display omitted] • Atomistic simulations are performed to obtain the mass density, solvation and transfer free energies in ionic liquids. • The considered ionic solvents are formed by voluminous perfluorinated anions and imidazolium cations. • Despite structural differences, the general guidelines summarized in our previous works are still applicable to the current cases. Ionic liquids as promising green solvents are widely applied in laboratory and industrial applications. Despite the massive experimental efforts on various applications, accurate computational modelling of such complex solution remains challenging. Our previous extensive numerical experiences on bulk properties, solvation and partition of external drug-like molecules between water and ionic-liquids phases lead to the recommended modelling regime of 0.8-scaled RESP charges and the GAFF2 parameter set. Such protocol has been found to be effective in reproducing the experimental thermodynamic properties that require balanced descriptions of solute–solvent and solvent–solvent interactions. A deficiency in the previous benchmark set is the lack of voluminous and highly halogen-substituted anions. Therefore, in this work, we explore the calculation of ionic liquids involving large voluminous perfluorinated anionic species. Also, the analysis of electrostatic potential (ESP) confirms the similarity of molecular ESP produced by the traditional gas-phase HF/6-31G*-targeted atomic charges and the higher-level gas-phase/implicit-solvent calculations. The quality of the HF/6-31G*-targeted charges is further validated by a face-to-face comparison of the bulk density estimated from molecular simulation under different charge sets, where satisfactory agreements are observed. Therefore, the 'cheap' HF/6-31G* option is already good enough for charge generation in ionic-liquids modelling. [ABSTRACT FROM AUTHOR]

The ionic liquids (ILs) are green solvents with numerous applications in technology and science. Among the physical properties of the ILs which have a great effect on their application, thermal stability is an important issue which has been discussed in this paper. Kinetics aspect of thermal decomposition of the ILs is considered as a scale of thermal stability. The ILs which have been studied here are composed of 1-hexyl-3-methylimidazolium cation with halide anion [Hmim][X], (X = F, Cl, Br). Three probable paths for thermal decomposition of ILs have been proposed. The first and second paths are the SN2 mechanism in which there are two possible sites on the imidazolium ring position, methyl and hexyl chain. Third path is E2 mechanism which is initiated from hexyl chain. In the case of [Hmim][X] (X = Cl, Br), since the first path has a lower activation energy, it occurs faster than the second path, while in the case of [Hmim][F], path B has a lower barrier than path A and occurs faster. Energy analysis for three studied ILs, showed that [Hmim][Br] with E a = 137.5 kJ mol − 1 is decomposed faster than other ILs. [ABSTRACT FROM AUTHOR]

Well-defined γ-Al 2 O 3 -supported Ir(CO) 2 complexes were coated with various 1,3-dialkylimidazolium ionic liquids (ILs) to elucidate the ligand effect of ILs. Variations in electron density of iridium sites when coated with ILs were probed by the infrared (IR) fingerprints of carbonyl ligands. Results presented here illustrate that IL layer strongly controls the electron density of metal sites; and there is a strong correlation between the interionic interactions in ILs and the degree of electron donation to the metal. These results create opportunities to tune the electronic structure of active metal sites by tailoring the structure of IL for optimum catalytic performance. [ABSTRACT FROM AUTHOR]

• H-D exchange in the cation of the ionic liquid-surfactant bmim-AOT when it forms reverse micelles was studied by 1H NMR. • Results were compared with those found for bmim-AOT in D2O showing an inhibition larger than 500-fold in reverse micelles. • The H-D exchange in bmim+ when it forms reverse micelles reflects the properties of the micellar interface. • The analysis of H-D exchange in bmim+ is a useful tool to explore the properties of reverse micelles formed by this cation. We report the study of the rate for hydrogen–deuterium (H-D) exchange in the cation of the ionic liquid-surfactant 1-butyl-3-methylimidazolium 1,4-bis-2-ethylhexylsulfosuccinate (bmim-AOT) when it forms reverse micelles (RMs). The results were compared with those found for bmim-AOT dissolved in D 2 O showing an inhibition larger than 500-fold on going from bulk D 2 O to the reverse micelle. Also, the effect of varying water content and surfactant concentration of the RMs on the deuterium exchange was evaluated by 1H NMR technique. The results demonstrate that the H-D exchange at the C(2) position of bmim+ when it forms RMs significantly reflects the properties of the micellar microenvironment, specifically of the micellar interface due to the localization of bmim+ in the interfacial region, intercalated between the AOT moiety. The rate of deuterium exchange is directly related to the properties of interfacial water, which, in turn, is closely related to the water-surfactant interaction. Thus, the analysis of deuterium exchange in the 2-position of bmim+ is proposed as a useful tool to explore the properties of RMs formed by this cation, with the advantage of being a non-invasive technique since the ionic liquid-surfactant itself acts as the molecular probe. [ABSTRACT FROM AUTHOR]

• Design of Imidazolium Nitrate-based Ionic Liquids (ILs) with high surface activity cation. • Better EOR potential in Nitrate-based ILs than halogen-based. • ILs with the highest alkyl-chain length exhibited better interfacial activity. • Increasing temperature and salinity improved the interfacial activity of ILs. • Nitrate-based ILs swept the oil from the micromodel with desirable flow distribution. Ionic liquids (ILs) are a growing trend in Enhanced Oil Recovery (EOR) studies as alternatives to commercial surfactants due to their environmentally friendly nature, and their resistance in harsh temperatures and salinities. ILs are customizable and come in an immense variety, and therefore, it is vital that different combinations of cation/anion be investigated for use in the industry. In this work, experiments are designed and performed to evaluate novel ILs' surface activity and performance in a lab-scale EOR set-up, compatible with Iranian oil reservoir conditions. Three imidazolium-based ionic liquids were used, namely, butyl-methylimidazolium nitrate, hexyl-methylimidazolium nitrate, and octyl-methylimidazolium nitrate. Nitrate anions have a less environmental impact than the often-used halogen anions, but their performance in EOR have not yet been investigated. Aqueous and saline solutions of these ILs were prepared, and subsequently, interfacial tension (IFT) tests and emulsion stability tests were carried out while the IL concentrations were kept to a minimum to account for the procedure's feasibility. A high reduction in IFT between the saline IL solution, [C 8 MIm][NO 3 ], and oil was observed compared to ILs with similar alkyl chain length in previous studies. Glass micromodels are exceptional in representing oil reservoirs under chemical EOR, and thus, were utilized to predict the ILs' contributions to sweep efficiency and recovery factor. Up to 80% oil recovery was obtained in the micromodel flooding tests with a strong sweep efficiency. Tests were repeated at two different temperatures (30 and 75 °C) and several salinities, and it was concluded that the ILs are resistant to harsh reservoir conditions, and can, potentially, improve the production efficiency of oil fields. [ABSTRACT FROM AUTHOR]

• Three newly ionic liquids were prepared and characterized. • Ionic liquids showed high protection efficiency for Aluminum alloys in 1M HCl. • The ionic liquids inhibition efficiency is molecular structure dependent. • DFT & XPS support protecting of Aluminum alloys against acid corrosion. Three newly ionic liquids namely, 1-bnzyl-2-methyl-3-octyl-1 H -imidazol-3-ium bromide, 1-bnzyl-3-decyl-2-methyl-1 H -imidazol-3-ium bromide, and 1-bnzyl-3-dodecyl-2-methyl-1 H -imidazol-3-ium bromide are synthesized and their chemical structures characterized via different spectra techniques (FT-IR, elemental analysis, and 1H NMR). The corrosion inhibition of newly ionic liquids was evaluated on aluminum alloy in 1 M HCl at varied exposure temperatures (298–318 K) and varied concentrations via various experimental and theoretical methods for example mass loss, electrochemical, spectral, and computational calculations. The results illustrate that these types of ionic liquids inhibit corrosion of aluminum in acid solution with maximum inhibition efficiency was reached 83.2 % at 298 K. The inhibition efficiency increases with the addition of zinc sulfate which has a synergistic impact which was reached to 92.7%. Also, the concentration of ionic liquids and the kind of cation have an impact on the obtained results. The existence of these inhibitors in the acidic solution improves the charge transfer resistance and lessens the double-layer capacitance. The Langmuir adsorption isotherm governs the adsorption of these inhibitors' molecules on the aluminum alloy surface, and they behave as mixed-type inhibitors. The outputs reveal that the computational calculations match the experimental data rather well. [ABSTRACT FROM AUTHOR]

Abstract: The empirical Kamlet–Taft solvent parameters for hydrogen bond donating (HBD) ability (α), hydrogen bond accepting (HBA) ability (β), and dipolarity/polarisability (π*) have been determined for 102 ionic liquids (ILs). α, β, and π* have been measured by means of the solvatochromic methods utilizing three specific dyes Fe(phen)2(CN)2 (Fe), 3-(4-amino-3-methyl-phenyl)-7-phenyl-benzo-[1,2-b:4,5-b′]-difuran-2,6-dione (ABF) and 4-tert-butyl-2-(dicyanomethylene)-5-[4-(diethylamino)benzylidene]-Δ3-thiazoline (Th) each solely sensitive to one of the Kamlet–Taft parameter. Different types of ILs with various cation structure such as 1,3-dialkyl imidazolim and 2- and 4-,5-methyl substituted derivatives, pyridinium, tetraalkylammonium, trialkylsulphonium, and tetraalkylphosphonium were used. In conjunction to the [C4mim] cation, more than 20 various established anions, such as halides, tetrafluoroborate, dicyanamide, were considered in this study. The frontiers of HBA ability strength of the anions are marked by the specific anions azide (N3 −) (large β) and FAP PF3(C2F5)3 − (lowest β). The linear intercorrelation between α and β is clearly evidenced, which shows that anion and cation interact with each other, for each type of IL used. Also correlation of molecular structure of the cation and the HBD ability can be recognized and supported by results from NMR spectroscopy. The interpretation of π* is still not satisfied because dipolarity and polarisability of each IL obviously contribute in different proportions to the value. [Copyright &y& Elsevier]

Abstract: Ionic liquids have been intensively studied during the last decade, but many questions still remain unresolved. From the computational side there is the lack of good transferable force fields for molecular simulations that would allow accurate theoretical predictions and interpretations of the properties of ionic liquids. Within this article a method is described that allows for the derivation of partial charges for ionic liquids since they play a particular important role, particularly for a liquid that consists entirely of ions. Our partial charges are carefully determined in such a way that they incorporate in an average way the influence of polarization effects of the neighboring ions in a bulk situation thereby reducing the total ionic charge to values less than one. When combined with our recently introduced method for the optimization of the short-range interactions [1] we have a well described route to develop generic force fields for ionic liquids. In this article we describe our results for the partial charges for the three imidazolium based liquids [MMIM]+, [EMIM]+, and [BMIM]+ for three different anions. [Copyright &y& Elsevier]

• Formation of NHC-dimers mitigate the electroconversion of CO 2 to NHC-CO 2. • Steric effect of wingtip groups hinders the reactions between CO 2 and NHC. • The high ability of anion to establish hydrogen bond favors the conversion of CO 2. Imidazolium salts with various alkyl side chains and counter anions were synthesized. The conversion of CO 2 to N-heterocyclic carbene-CO 2 adducts (NHC-CO 2) were achieved by in situ electroreduction of the imidazolium salts under CO 2 atmosphere. The yield of NHC-CO 2 decreases with the increase of steric effect of alkyl side chains, which is attributed to the decrease of reactivity of NHCs in the case of strong steric effect. The hydrogen bond accepting ability of anion has a substantial effect on the conversion of CO 2. The high ability of anion to establish hydrogen bond favors the conversion of CO 2. A good correlation between hydrogen bond accepting abilities of anions and yields of NHC-CO 2 was demonstrated. [ABSTRACT FROM AUTHOR]

Abstract: Densities, viscosities and refractive index, as a function of temperature, and isobaric thermal expansion coefficient, were determined for 1-alkyl-3-methylimidazolium hexafluorophosphate, [CN−1C1im][PF6] (where N=5 to 10) series of ionic liquids. The density presents a regular decrease along the ionic liquid series, with no detectable alkyl chain length dependence of the thermal expansion coefficient. Both the refractive index and viscosity show a trend shift along the series around the [C6C1im][PF6] that could be associated to the impact of the change in the nanostructuration of the ionic liquids. The experimental results are compared with the analogous [CN−1C1im][NTf2] series and the effect of the anion is analyzed. The sphericity of the [PF6]− anion is reflected in the lower pre-exponential VTF parameter, Aη , and the higher viscosity of the [CN−1C1im][PF6], when compared with the [CN−1C1im][NTf2] series, is ruled by the higher energy barriers, which are related with stronger electrostatic interaction due to the low charge dispersion of the [PF6]−.anion. [Copyright &y& Elsevier]

Abstract: Room temperature ionic liquids having 1-butyl-3-methylimidazolium ([BMIM]) cations and three different anions ([BMIM][PF6], [BMIM][BF4], [BMIM]Br) were studied by using Optical Heterodyne Detected-Optical Kerr Effect (OHD-OKE) spectroscopy to find out the effect of the anion size on the intermolecular dynamics. Fourier transformation of the time-domain OHD-OKE signals yielded a broad band in the spectra below 150cm−1. The modes with frequencies around 15, 80 and 100cm−1 used to fit the spectra all shifted to higher frequencies with the decrease in the anion size due to changes in the intermolecular force and the reduced mass. [Copyright &y& Elsevier]

• Four ionic liquids have been investigated as corrosion inhibitors in acidic solution. • The new ionic liquids are potent mixed corrosion inhibitors. • Langmuir model accurately defined their adsorption on a steel substrate. • Ionic liquid inhibition effectiveness increases with the rising temperature. • NO 2 group has a negative effect on the adsorption of ionic liquid molecules. The inhibitory mechanism of four ionic liquids (ILs) generated from imidazolium is reported in this study. The goal of the research was to see how the cation structure of ILs affected the corrosion inhibition of carbon steel in 1 M HCl. The chemical structure of ILs was verified by elements analysis, Fourier-transform-infrared (FTIR), thermo gravimetric (TGA), nuclear magnetic resonance (1HNMR, D2O, 13C NMR) and hetero-nuclear single-quantum correlation (HSQC). The inhibitory efficiency was measured using mass loss and electrochemical tests and varied from 62.5% to 97.2%. The Langmuir model accurately defined their adsorption on a steel substrate. Adsorption of novel ILs on steel substrates is a mixed physisorption and chemisorption method. To ensure the mechanism of adsorption of current ionic liquids, FTIR and ultraviolet (UV) spectra were employed. [ABSTRACT FROM AUTHOR]

• Thermally stable and recyclable solvents for cellulose dissolution and processing. • Alkyl chain lengths of anion on imidazolium ring influences cellulose dissolution. • Only hexanoate containing zwitterions exhibited ∼13% (w/w) cellulose dissolution. • Cellulose solution in aq zwitterions are viscoelastic and in fibre spinning range. • Solvent recovery after cellulose dissolution and regeneration is >99.8%. Cellulose is most abundant biopolymer on earth and can be utilized as sustainable resources for many applications, however, their utilization at great extent is limited due to lack of benign and recyclable solvent. While N -methylmorpholine- N -oxide (NMMO), used in Lyocell process, is thermally unstable and may undergoes runaway conditions, commercialization of ionic liquid as solvent still suffers from recyclability issues. Herein, we present the synthesis of a series of zwitterions, composed of tethered alkyl imidazolium cation and carboxylate anion, and investigated their cellulose dissolution characteristics. Effect of alkyl chain length of imidazolium ring on its dissolution efficiencies was studied and amongst synthesized zwitterions, the hexanoate derivatives exhibited 13% (w/w) cellulose dissolution at 100–125 °C. Thermal stability of zwitterions and their cellulose solution was characterized by DSC-TGA and found to be more stable than the NMMO and Lyocell solution. Rheological studies indicate that cellulose solution in zwitterions are viscoelastic and in spinnable range of fibre processing. Structural and morphological characterization of regenerated cellulose using elemental analysis, FTIR, DSC-TGA, GPC, XRD and SEM showed that zwitterions have no adverse effect on its physicochemical and morphological properties. A method for recovery and purification of solvent after cellulose dissolution and regeneration is also presented. [ABSTRACT FROM AUTHOR]

Over the past decades, imidazolium-based ionic liquids (ILs) have been studied extensively in numerous previous experimental and analysis works to produce ILs with tunable physicochemical properties. Imidazolium-based ILs is one of the most studied ionic liquid in the literature, and the number of published papers related to ILs have also been rising exponentially. It can be used in polymer synthesis due to its intrinsically low viscosity, low melting points, simplicity of preparation, and high stability toward oxidative and reductive conditions. However, very limited information on characterisation of imidazolium-based ILs was available in the literature. Thus, this paper provides a comprehensive review of the characterisation analysis of imidazolium-based ILs. The characterisation of imidazolium-based ILs via spectrochemical methods (FTIR, 1H and 13C NMR, and UV-Vis), CHNSO elemental analysis, thermal stability analysis (TGA and DSC) and crystallinity analysis using XRD were thoroughly discussed herein. Moreover, this review also presents the cutting-edge-knowledge of different synthesis method of imidazolium-based ILs and its potential applications in polymer preparation. • Synthesis protocols for imidazolium-based ILs are discussed. • Their spectroscopic, elemental, thermal, and crystallinity analysis are elaborated. • The effect of alkyl substituents and anion on the structure are addressed. • Recent development imidazolium-based ILs in polymer preparation are covered. [ABSTRACT FROM AUTHOR]

New geminal dicationic ionic liquids, ILs, containing both imidazolium and pyridinium cations were synthesized to apply as effective demulsifiers for stable sea water-in-heavy petroleum crude oil emulsions. In this respect, vinyl imidazolium and 4- amino-4-pyridyl diethoxylate (APE) or 4-pyridyl tetradecanamide were quaternized either with 1,4-dibromobutane or 1,12-dibromododecane to produce ILs monomers. Their vinyl group was polymerized via solution radical polymerization to produce geminal poly (ionic liquids), PILs, and their chemical structures were identified by nuclear magnetic resonance. The thermal stability and thermal characteristics of the prepared geminal dicationic imidazolium and pyridinium cations indicate that all prepared compounds behave as ILs and PILs having lower melting temperature below 100 °C and lower glass transition temperatures below 0 °C. The surface activity, micellization or aggregation, and adsorption at air/seawater or seawater/petroleum crude oil interfaces were investigated from surface and interfacial tension measurements. The interactions of the prepared ILs and PILs with asphaltenes were evaluated from particle sizes and zeta potentials. The demulsification of stable W/O emulsions at temperature of 60 °C using different concentrations of the prepared ILs and PILs confirm that the demulsification was carried out at lower injection dose (from 100 to 250 ppm) and shorter demulsification time (from 40 to 240 min). Unlabelled Image • New geminal ionic liquids (ILs) combined both imidazolium and pyridinium cations. • Highly surface active ILs and PILs reduces surface and interfacial tensions. • Higher demulsification at lower concentrations of geminal ILs and PILs used to demulsify stable water-in-oil emulsions. • PILs exhibited higher demulsification efficiency 100% at low concentration 100 ppm for several demulsification cycles. [ABSTRACT FROM AUTHOR]

Complexation ability of homologous series of amphiphiles bearing imidazolium and urethane moieties (IAC-n, n = 14, 16, 18) toward bovine serum albumin (BSA) has been investigated by various physico-chemical methods (tensiometry, fluorescence spectroscopy, spectrophotometry, dynamic and electrophoretic light scattering, circular dichroism, and transmission electron microscopy). It has been revealed, that aggregation thresholds of systems based on IAC-n could be 5–8-fold reduced by BSA addition. Fluorescent analysis allows to estimate that binding of components is favorably mediated by tryptophan amino acid residues and is driven by different forces depending on the length of amphiphile hydrophobic tail. In particular, dominate contribution of Van der Waals interactions to the complexation has been shown in the case of IAC-14 and IAC-16, while hydrophobic interactions prevailed for IAC-18. It has been demonstrated that amphiphile addition causes reversible unfolding of protein macromolecules in all cases. Spectrophotometry assay exhibits that amphiphile/BSA complexes have more significant solubilization capacity toward hydrophobic guest in comparison with individual IAC-n systems. Unlabelled Image • Amphiphiles contained imidazolium and urethane fragments. • Binding of bovine serum albumin (BSA) and new cationic amphiphiles has been studied. • Amphiphiles addition lead to insignificant and reversible structure changes of BSA. • The length of amphiphile tail affects the balance of driving forces of binding. • BSA addition could improve solubilization properties of the system. [ABSTRACT FROM AUTHOR]

In the framework of this report the bottom-up strategy has been used for the development of novel soft nanocontainers through self-assembly of homologous series of newly synthesized amphiphilic compounds of N-(2-ethylaminocarbonyloxyethyl)-N-alkylimidazolium bromides. Their aggregation properties, solubilization capacity, antimicrobial activity, membranotropic properties and capability to form lipoplexes have been investigated. Using various physico-chemical techniques it has been demonstrated that introduction of urethane moiety into amphiphile structure results in the 2-3-fold decrease of critical micelle concentration in comparison with their unsubstituted counterparts. It has been suggested, that interaction of amphiphiles with DNA decamer is predominantly driven by cooperative electrostatic interactions. Membranotropic properties of novel amphiphiles could be regulated by the change of the length of hydrophobic tail; with these properties being the more markedly expressed in the case of the lower homologue. Estimation of antimicrobial activity against several strains of microorganisms has revealed, that these amphiphiles were by several-fold more active toward Staphylococcus aureus , Bacillus cereus bacteria and Candida albicans fungi in comparison with reference compounds – norfloxacin and ketoconazole. Hemolytic activity of these amphiphiles has not exceeded 0.9% under bactericide and bacteriostatic concentrations. The combination of advanced characteristics allows us to recommend these amphiphiles for fabrication of soft materials with the wide spectrum of practically useful properties like effective nanocontainers for drug and gene delivery, capable of crossing the cell membrane, and harmless for human agents against pathogenic microorganisms. • Novel amphiphiles bearing imidazolium and urethane moieties have been synthesized. • All compounds have a high capability to interact with decanucleotide. • Novel amphiphiles exhibited high antimicrobial properties and low hemolytic activity. • Membranotropic properties strongly depend on the length of alkyl tail of surfactants studied. [ABSTRACT FROM AUTHOR]

A series of substituted cyclophosphazene derivatives containing imidazolium ionic liquids having variable alkyl groups were successfully synthesized and characterized by different spectroscopic techniques. The synthesized ionic liquids with butyl, pentyl, hexyl, heptyl, octyl and decyl groups were designated as IL1, IL2, IL3, IL4, IL5, and IL6 respectively. Physicochemical studies in terms of viscosity, density, thermal stability and conductivity were carried out as a function of temperature and molecular weight to see the lengthening effect of the alkyl group. The viscosity and density of the ionic liquids tend to decrease linearly with temperature. Further, experimental values of viscosity and density calculated the viscosity index, thermal expansion coefficient and molar volume. Similarly, all other physicochemical properties were evaluated to study structure-property correlation. Unlabelled Image • Novel series of cyclophosphazene derivatives containing imidazolium ionic liquids • Effect of variable alkyl chain on the physicochemical properties of the ILs • Effect of temperature on the viscosity and density of the synthesized ILs • Detailed structural characterization of the synthesized ILs • Thermal stability of the synthesized ILs [ABSTRACT FROM AUTHOR]