<Emphasis Type="Italic">Schizosaccharomyces pombe</Emphasis> as an Efficient Yeast to Convert Sugarcane Bagasse Pretreated with Ionic Liquids in Ethanol

Pretreatment of lignocellulosic biomass with ionic liquids (ILs) has been extensively studied, being regarded as one of the most promising methods for obtaining fermentable sugars. In this research, it was investigated the production of ethanol from sugars released from sugarcane bagasse pretreated with the ionic liquids [C₄mim][OAc] and [C₂mim][OAc], hydrolysed with Penicillium echinulatum enzymes and using Saccharomyces cerevisiae and Schizosaccharomyces pombe. Yields of about 43 and 56% of ethanol were observed for S. cerevisiae and biomass pretreated with [C₂mim][OAc] and [C₄mim][OAc], respectively. S. pombe yielded 52 and 78% ethanol for [C₂mim][OAc] and [C₄mim][OAc], respectively. These results indicate that S. pombe showed best performance for alcoholic fermentation from sugars released from pretreated biomass by ILs.     

High‐Tc Enantiomeric Ferroelectrics Based on Homochiral Dabco‐derivatives (Dabco=1,4‐Diazabicyclo[2.2.2]octane)

1,4‐Diazabicyclo[2.2.2]octane (dabco) and its derivatives have been extensively utilized as building units of excellent molecular ferroelectrics for decades. However, the homochiral dabco‐based ferroelectric remains a blank. Herein, by adding a methyl (Me) group accompanied by the introduction of homochirality to the [H₂dabco]²⁺ in the non‐ferroelectric [H₂dabco][TFSA]₂ (TFSA=bis(trifluoromethylsulfonyl)ammonium), we successfully designed enantiomeric ferroelectrics [R and S‐2‐Me‐H₂dabco][TFSA]₂. The two enantiomers show two sequential phase transitions with transition temperature (T_c) as high as 405.8 K and 415.8 K, which is outstanding in both dabco‐based ferroelectrics and homochiral ferroelectrics. To our knowledge, [R and S‐2‐Me‐H₂dabco][TFSA]₂ are the first examples of dabco‐based homochiral ferroelectrics. This finding opens an avenue to construct dabco‐based homochiral ferroelectrics and will inspire the exploration of more eminent enantiomeric molecular ferroelectrics.     

High-Tc Enantiomeric Ferroelectrics Based on Homochiral Dabco-derivatives (Dabco=1,4-Diazabicyclo[2.2.2]octane)

1,4-Diazabicyclo[2.2.2]octane (dabco) and its derivatives have been extensively utilized as building units of excellent molecular ferroelectrics for decades. However, the homochiral dabco-based ferroelectric remains a blank. Herein, by adding a methyl (Me) group accompanied by the introduction of homochirality to the [H₂dabco]²⁺ in the non-ferroelectric [H₂dabco][TFSA]₂ (TFSA=bis(trifluoromethylsulfonyl)ammonium), we successfully designed enantiomeric ferroelectrics [R and S-2-Me-H₂dabco][TFSA]₂. The two enantiomers show two sequential phase transitions with transition temperature (T_c) as high as 405.8 K and 415.8 K, which is outstanding in both dabco-based ferroelectrics and homochiral ferroelectrics. To our knowledge, [R and S-2-Me-H₂dabco][TFSA]₂ are the first examples of dabco-based homochiral ferroelectrics. This finding opens an avenue to construct dabco-based homochiral ferroelectrics and will inspire the exploration of more eminent enantiomeric molecular ferroelectrics.     

Structural,Thermal, and Storage Stability of Rapana Thomasiana Hemocyanin in the Presence of Cholinium-Amino Acid-Based Ionic Liquids

Novel biocompatible compounds that stabilize proteins in solution are in demand for biomedical and/or biotechnological applications. Here, we evaluated the effect of six ionic liquids, containing mono- or dicholinium [Chol]_1or2 cation and anions of charged amino acids such as lysine [Lys], arginine [Arg], aspartic acid [Asp], or glutamic acid [Glu], on the structure, thermal, and storage stability of the Rapana thomasiana hemocyanin (RtH). RtH is a protein with huge biomedicinal potential due to its therapeutic, drug carrier, and adjuvant properties. Overall, the ionic liquids (ILs) induce changes in the secondary structure of RtH. However, the structure near the Cu-active site seems unaltered and the oxygen-binding capacity of the protein is preserved. The ILs showed weak antibacterial activity when tested against three Gram-negative and three Gram-positive bacterial strains. On the contrary, [Chol][Arg] and [Chol][Lys] exhibited high anti-biofilm activity against E. coli 25213 and S. aureus 29213 strains. In addition, the two ILs were able to protect RtH from chemical and microbiological degradation. Maintained or enhanced thermal stability of RtH was observed in the presence of all ILs tested, except for RtH-[Chol]₂[Glu].     

Evaporation of ionic liquids at atmospheric pressure: study by ion mobility spectrometry

A conventional ion mobility spectrometry (IMS) was used to study atmospheric pressure evaporation of seven pure imidazolium and pyrrolidinium ionic liquids (ILs) with [Tf₂N], [PF₆], [BF₄] and [fap] anions. The positive drift time spectra of the as-received samples measured at 220 °C exhibited close similarity; the peak at reduced mobility K₀ = 1.99 cm² V⁻¹ s⁻¹ was a dominant spectral pattern of imidazolium-based ILs. With an assumption that ILs vapor consists mainly of neutral ion pairs, which generate the parent cations in the reactant section of the detector, and using the reference data on the electrical mobility of ILs cations and clusters, this peak was attributed to the parent cation [emim]. Despite visible change in color of the majority of ILs after the heating at 220 °C for 5 h, essential distinctions between spectra of the as-received and heated samples were not observed. In negative mode, pronounced peaks were registered only for ILs with [fap] anion.     

Property Comparison of Cellulose Acetate Prepared Homogenously in Different Ionic Liquids

Cellulose acetates were synthesized homogeneously in four types of ionic liquids without any catalyst using cotton linter as the raw material and acetic anhydride as the esterification agent. FTIR, XRD and DSC were used to characterize the obtained products. It was shown that the homogeneously prepared cellulose acetates became completely amorphous. Degree of substitution of cellulose acetate synthesized in [C₄C₁Im][OAc] was found the highest; whereas T_g of this ester was the lowest. It was also found that the film made of cellulose acetate prepared in [C₄C₁Im][OAc] had lower toughness.     

Phase Behavior of Aqueous Biphasic Systems with Choline Alkanoate Ionic Liquids and Phosphate Solutions: The Influence of pH

Aqueous biphasic systems (ABS) composed of the choline alkanoate ionic liquids (ILs) choline acetate [Cho][OAc], choline propanoate [Cho][Pro], choline butyrate [Cho][But], and choline hexanoate [Cho][Hex], mixed with K₃PO₄ solutions at pH 7.2 and 14.5, were prepared and their phase diagrams were compared. The ability to form ABS with alkaline K₃PO₄ solutions decreased in the order [Cho][OAc] ≈ [Cho][Pro] > [Cho][But] > [Cho][Hex], while with neutral K₃PO₄ solutions, [Cho][OAc] could not form an ABS, and the other three ILs performed similarly. All of the biphasic regions of the ABS decreased with the increase in pH. ¹H-NMR data indicated anion exchange between phases in ABS at neutral pH. The ABS at neutral pH were evaluated to extract the triazine herbicides simazine, cyanazine, and atrazine, and the ABS formed by [Cho][Pro] and the pH 7.2 K₃PO₄ solution has shown extraction recoveries higher than 90%.     

Rapid analysis of Fructus forsythiae essential oil by ionic liquids-assisted microwave distillation coupled with headspace single-drop microextraction followed by gas chromatography–mass spectrometry

A rapid, green and effective miniaturized sample preparation and analytical technique, i.e. ionic liquids-assisted microwave distillation coupled with headspace single-drop microextraction (ILAMD-HS-SDME) followed by gas chromatography–mass spectrometry (GC–MS) was developed for the analysis of essential oil (EO) in Fructus forsythiae. In this work, ionic liquids (ILs) were not only used as the absorption medium of microwave irradiation but also as the destruction agent of plant cell walls. 1-Ethyl-3-methylimidazolium acetate ([C₂mim]OAc) was chosen as the optimal ILs. Moreover, n-heptadecane (2.0 μL) was selected as the appropriate suspended solvent for the extraction and concentration of EO. Extraction conditions of the proposed method were optimized using the relative peak area of EO constituents as the index, and the optimal operational parameters were obtained as follows: irradiation power (300 W), sample mass (0.7 g), mass ratio of ILs to sample (2.4), temperature (78 °C) and time (3.4 min). In comparison to previous reports, the proposed method was faster and required smaller sample amount but could equally monitor all EO constituents with no significant differences.     

Ionic liquids enhanced oil recovery from oily sludge-experiment and mechanism

The oily sludge would cause environment pollution, and would cause the heavy oil waste. Therefore, it was vital for us to find novel methods to obtain heavy oil from the oily sludges. In this study, the [C₁₂mim][PF₆] and [C₁₂mim][Br] ionic liquids(ILs) were used to enhance the oil recovery. The toluene could obtain the highest oil recovery, and both the two ILs could increase the oil recovery. Toluene could obtain the highest oil recovery (89.4 wt%), and n-octane could obtain the lowest oil recovery (76.8 wt%). [C₁₂mim] [PF₆] could efficiently increase the heavy oil recovery to 91.2 wt%(by toluene). The [C₁₂mim][Br] could increase the heavy oil recovery further. Both the [C₁₂mim] [PF₆] and the [C₁₂mim][Br] ionic liquids could increase the heavy ois C/H ratio, decrease heavy oil viscosity and increase the sands hydrophilicity. The [C₁₂mim][Br] ionic liquids showed better effect. In addition, the ionic liquids could increase the solvents recovery, and the ionic liquids recovery were high. Therefore, the ionic liquids enhanced oil recovery could be recycled to ten times. The two ionic liquids could effectively decrease the heavy oil interaction force, and when the ionic liquids increased to 200 ppm, the force remained stable. In the end, the ionic liquids enhancing solvent extraction mechanism was put forward.     

Survey on ionic liquids effect based on metal anions over the thermal stability of heavy oil

A survey on the effect of ionic liquids (ILs) over the thermal stability of a heavy Mexican oil was performed. ILs used were based on [C_nim]⁺ and [C_npyr]⁺ organic cations with FeCl₄⁻ metal anion. Mixtures of heavy crude oil (HCO) with ILs show three oxidation zones: low temperature oxidation (LTO), full deposition (FD) and high temperature oxidation (HTO). Thermal stability and mass loss decrease in the LTO zone but increase in the FD and HTO zones for every ILs used. The activation energy of the oxidation is influenced by the ILs in the HTO zone. It decreases when increasing the size of the organic radical substitute in the cation of the ILs while it increases with the presence of hydroxyl groups. The influence of electronic structure and reactivity indexes are rationalized to understand the variations of activation energy obtained of the reaction systems. Among all cations used, cation-3 (IL-3) shows the greater value of HOMO-LUMO gap as well as the lower activation energy.     

New ionic liquids with the bis[bis(pentafluoroethyl)phosphinyl]imide anion, [(C2F5)2P(O)]2N—Synthesis and characterization

A new series of low melting and hydrophobic ionic liquids (ILs) containing the bis[bis(pentafluoroethyl)phosphinyl]imide anion, [(C₂F₅)₂P(O)]₂N⁻ (FPI), and ammonium, phosphonium, imidazolium, pyridinium or pyrrolidinium cations were prepared and characterized. Their density, viscosity, melting point, glass transition temperature, decomposition temperature and conductivity are discussed. Many of these ionic liquids are liquids at room temperature with melting points below 15 °C, viscosities below 110 mm² s⁻¹ and thermal stabilities above 300 °C.     

Effects of Cationic Structure on Cellulose Dissolution in Ionic Liquids: A Molecular Dynamics Study

In recent years, great progress has been made in the dissolution of cellulose with ionic liquids (ILs). However, the mechanism of cellulose dissolution, especially the role the IL cation played in the dissolution process, has not been clearly understood. Herein, the mixtures of cellulose with a series of imidazolium‐based chloride ionic liquids and 1‐butyl‐3‐methyl pyridinium chloride ([C₄mpy]Cl) were simulated to study the effect that varying the heterocyclic structure and alkyl chain length of the IL cation has on the dissolution of cellulose. It was shown that the dissolution of cellulose in [C₄mpy]Cl is better than that in [C₄mim]Cl. For imidazolium‐based ILs, the shorter the alkyl chain is, the higher the solubility will be. In addition, an all‐atom force field for 1‐allyl‐3‐methyl imidazolium cation ([Amim]⁺) was developed, for the first time, to investigate the effect the electron‐withdrawing group within the alkyl chain of the IL cation has on the dissolution of cellulose. It was found that the interaction energy between [Amim]⁺ and cellulose was greater than that between [C₃mim]⁺ and cellulose, indicating that the presence of electron‐withdrawing group in alkyl chain of the cation enhanced the interaction between the cation and cellulose due to the increase of electronegativity of the cations. These findings are used to assess the cationic effect on the dissolution of cellulose in ILs. They are also expected to be important for rational design of novel ILs for efficient dissolution of cellulose.     

Above Room Temperature Organic Dielectric Switchable Material: Diprotonated 1,4‐Diazabicyclo[2.2.2]octane Shifts between Two Pyruvic Acids

A pure organic single crystal, [H₂dabco] · [PA]₂ ([H₂dabco]²⁺ = diprotonated 1,4‐diazabicyclo‐[2.2.2]octane, PA = pyruvic acid), was synthesized and its dielectric property was studied. [H₂dabco] · [PA]₂ owns a distinctive architecture composed of discrete hydrogen‐bonded trimeric units, of which one [H₂dabco]²⁺ cation bridged by two PA^– anions through N–H ··· O hydrogen bonding. The switchable property around 348 K was revealed by crystal structure studies between low and high dielectric states. In the high temperature phase, the [H₂dabco]²⁺ cation presents itself in a rotationally disordered state and lies at the symmetric center of the trimer. In the room temperature phase, it is frozen in an ordered state and shifts toward a PA^– anion at one end along the hydrogen bond.     

Halide-Free Synthesis of New Difluoro(oxalato)borate [DFOB]−-Based Ionic Liquids and Organic Ionic Plastic Crystals

The implementation of next-generation batteries requires the development of safe, compatible electrolytes that are stable and do not cause safety problems. The difluoro(oxalato)borate ([DFOB]⁻) anion has been used as an electrolyte additive to aid with stability, but such an approach has most commonly been carried out using flammable solvent electrolytes. As an alternative approach, utilisation of the [DFOB]⁻ anion to make ionic liquids (ILs) or Organic Ionic Plastic Crystals (OIPCs) allows the advantageous properties of ILs or OIPCs, such as higher thermal stability and non-volatility, combined with the benefits of the [DFOB]⁻ anion. Here, we report the synthesis of new [DFOB]⁻-based ILs paired with triethylmethylphosphonium [P₁₂₂₂]⁺, and diethylisobutylmethylphosphonium [P_122i4]⁺. We also report the first OIPCs containing the [DFOB]⁻ anion, formed by combination with the 1-ethyl-1-methylpyrrolidinium [C₂mpyr]⁺ cation, and the triethylmethylammonium [N₁₂₂₂]⁺ cation. The traditional synthetic route using halide starting materials has been successfully replaced by a halide-free tosylate-based synthetic route that is advantageous for a purer, halide free product. The synthesised [DFOB]⁻-based salts exhibit good thermal stability, while the ILs display relatively high ionic conductivity. Thus, the new [DFOB]⁻-based electrolytes show promise for further investigation as battery electrolytes both in liquid and solid-state form.     

Temperature-Dependent Surface-Enrichment Effects of Imidazolium-Based Ionic Liquids

We present the first systematic study of the influence of temperature on the degree of surface enrichment of 1-alkyl-3-methylimidazolium-based ionic liquids (ILs). Using angle-resolved X-ray photoelectron spectroscopy, we demonstrate that the degree of surface enrichment strongly decreases with increasing temperature for all the studied ILs. For ILs with the same cation, but different anions, [C₈C₁Im]Br, [C₈C₁Im][TfO] and [C₈C₁Im][Tf₂N], no significant differences of the temperature-induced partial loss of surface enrichment are found. Measurements for [C₄C₁Im][TfO], [C₈C₁Im][TfO] and [C₁₈C₁Im][TfO] indicate a small effect of the chain length. For [C₁₈C₁Im][TfO], a continuous decrease of alkyl surface enrichment is found with increasing temperature, with no abrupt changes at the phase-transition temperature from the smectic A to the isotropic phase, indicating that the surface enrichment is not affected by this phase transition.     

Ionic Fluids Containing Both Strongly and Weakly Interacting Ions of the Same Charge Have Unique Ionic and Chemical Environments as a Function of Ion Concentration

Liquid multi‐ion systems made by combining two or more salts can exhibit charge ordering and interactions not found in the parent salts, leading to new sets of properties. This is investigated herein by examining a liquid comprised of a single cation, 1‐ethyl‐3‐methylimidazolium ([C₂mim]⁺), and two anions with different properties, acetate ([OAc]^?) and bis(trifluoromethylsulfonyl)imide ([NTf₂]^?). NMR and IR spectroscopy indicate that the electrostatic interactions are quite different from those in either [C₂mim][OAc] or [C₂mim][NTf₂]. This is attributed to the ability of [OAc]^? to form complexes with the [C₂mim]⁺ ions at greater than 1:1 stoichiometries by drawing [C₂mim]⁺ ions away from the less basic [NTf₂]^? ions. Solubility studies with molecular solvents (ethyl acetate, water) and pharmaceuticals (ibuprofen, diphenhydramine) show nonlinear trends as a function of ion content, which suggests that solubility can be tuned through changes in the ionic compositions.     

Elucidating Interactions between DMSO and Chelate‐Based Ionic Liquids

The C?D bond stretching vibrations of deuterated dimethyl sulfoxide ([D₆]DMSO) and the C₂?H bond stretching vibrations of 1,1,1,5,5,5‐hexafluoropentane‐2,4‐dione (hfac) ligand in anion are chosen as probes to elucidate the solvent–solute interaction between chelate‐based ionic liquids (ILs) and DMSO by vibrational spectroscopic studies. The indirect effect from the interaction of the adjacent S=O functional group of DMSO with the cation [C₁₀mim]⁺ and anion [Mn(hfac)₃]^? of the ILs leads to the blue‐shift of the C?D stretching vibrations of DMSO. The C₂?H bond stretching vibrations in hfac ligand is closely related to the ionic hydrogen bond strength between the cation and anion of chelate‐based ILs. EPR studies reveal that the crystal field of the central metal is kept when the chelate‐based ILs are in different microstructure environment in the solution.     

Synthesis of 1,3- and 1,4-bis-methoxy- and ethoxy-4-(m-carborane-C-methanoyloxy)phenylmethylene- and phenylmethyl]phenylenediamines

1,3- and 1,4-bis[3-methoxy and ethoxy-4-(m-carborane-C-methanoyloxy)phenylmethylene]phenylenediamines were synthesized from the vanillin and vanillal m-carborane-C-carboxylates by the reaction with 1,3- and 1,4-phenylenediamines in anhydrous methanol. Reduction of the title compounds with Na[BH(OAc)₃] in benzene yielded 1,3- and 1,4-bis[3-methoxy- and ethoxy-4-(m-carborane-C-methanoyloxy)phenylmethyl] phenylenediamines.     

Using the solvation parameter model to characterize functionalized ionic liquids containing the tris(pentafluoroethyl)trifluorophosphate (FAP) anion

Ionic liquids (ILs) containing the tris(pentafluoroethyl)trifluorophosphate anion [FAP]⁻ have attracted increased attention due to their unique properties including ultrahigh hydrophobicity, hydrolytic stability, and wide electrochemical window. In this study, the solvation parameter model is used via gas chromatography to characterize the solvation interactions of seven ILs containing amino, ester, and hydroxyl functional groups appended to the cation and paired with [FAP]⁻, as well as three ILs containing the bis[(trifluoromethyl)sulfonyl]imide anion [NTf₂]⁻. The role of the functional groups, nature of the counter anion, and cation type on the system constants were evaluated. ILs containing [FAP]⁻ possessed lower hydrogen bond basicity than NTf₂-based ILs having the same cationic component; in the case of hydroxyl-functionalized cations, the presence of [FAP]⁻ led to an enhancement of the hydrogen bond acidity, relative to the NTf₂-analogs. The system constants support the argument that [FAP]⁻ weakly coordinates the cation and any appended functional groups, promoting properties of the cation which might be masked by stronger interactions with other anion systems. The chromatographic performance of the IL stationary phases was evaluated by examining the retention behavior and separation selectivity for chosen analytes. The results from this work can be used as a guide for choosing FAP-based ILs capable of exhibiting desired solvation properties while retaining important physical properties including high thermal stability and high hydrophobicity. Figure In this study, the solvation parameter model is used via gas chromatography to characterize the solvation interactions of seven ILs containing amino, ester, and hydroxyl functional groups appended to the cation and paired with tris(pentafluoroethyl)trifluorophosphate [FAP]⁻, as well as three ILs containing the bis[(trifluoromethyl)sulfonyl]imide anion [NTf₂]⁻. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Aggregation behavior of alkyl triphenyl phosphonium bromides in aprotic and protic ionic liquids

The aggregation behavior of alkyltriphenylphonium bromides, C _n TPB (n?=?12 and 14), has been investigated in two different room-temperature ionic liquids (ILs), the aprotic 1-butyl-3-metyllimidazolium tetrafluoroborate ([bmim][BF₄]), and the protic ethylammonium nitrate (EAN). The critical micelle concentration was determined by the surface tension measurements. The calculated thermodynamic parameters based on surface tension measurements at various temperatures indicate that the micellization for C _n TPB in both aprotic [bmim][BF₄] and protic EAN is enthalpy-driven. But stronger solvophobic interactions presented between C _n TPB and protic EAN than aprotic [bmim][BF₄]. ¹H NMR spectra were further conducted to reveal that ethylammonium cation can insert into the micelle while imidazole cation only locates among the head groups of C _n TPB.