Bioinspired Herbicides-Ionic Liquids or Liquid Cocrystals?

This research provides information about combinations of several amino acids, including l-proline (Pro), l-arginine (Arg), and l-histidine (His), with phenoxyacetic acid herbicides (MCPA and 2,4-D). Five amino acid ionic liquids (AAILs), one amino acid higher-melting salt (AAHMS), and two amino acid liquid cocrystals (AALCs) were obtained in high yields (>90%). The ionization of the six new structures was confirmed by NMR, IR, and molecular modeling. X-ray crystallography was used to definitively confirm the binding location of the mobile hydrogen. Furthermore, we propose a computational method for estimating the energy of specific hydrogen bond(s) in AAIL crystals based on the NBO and QTAIM hydrogen bond parameters obtained by model calculations. An in-depth analysis of the structures allowed to answer the question posed in the title, ionic liquids or liquid cocrystals? AAILs based on arginine and histidine were obtained. In contrast, combining proline with MCPA and 2,4-D led to AALCs. Finally, the compounds were analyzed to measure their herbicidal activity. These studies proved that the novel form of MCPA or 2,4-D improved its ability to control weeds compared to commercial formulations containing the same active ingredients.

Ionic Liquids: New Forms of Active Pharmaceutical Ingredients with Unique, Tunable Properties

This Review aims to summarize advances over the last 15 years in the development of active pharmaceutical ingredient ionic liquids (API-ILs), which make up a prospective game-changing strategy to overcome multiple problems with conventional solid-state drugs, for example, polymorphism. A critical part of the present Review is the collection of API-ILs and deep eutectic solvents (DESs) prepared to date. The Review covers rules for rational design of API-ILs and tools for API-IL formation, syntheses, and characterization. Nomenclature and ionic speciation, and the confusion that these may cause, are highlighted, particularly for speciation in both ILs and DESs of intermediate ionicity. We also highlight in vivo and in vitro pharmaceutical activity studies, with differences in pharmacokinetic/pharmacodynamic depending on ionicity of API-ILs. A brief overview is provided for the ILs used to deliver drugs, and the Review concludes with key prospects and roadblocks in translating API-ILs into pharmaceutical manufacturing.

Social and economic costs of gambling problems and related harm among UK military veterans

INTRODUCTION

Military veterans are at heightened risk of problem gambling. Little is known about the costs of problem gambling and related harm among United Kingdom (UK) Armed Forces (AF) veterans. We investigated the social and economic costs of gambling among a large sample of veterans through differences in healthcare and social service resource use compared with age-matched and gender-matched non-veterans from the UK AF Veterans' Health and Gambling Study.

METHODS

An online survey measured sociodemographic characteristics, gambling experience and problem severity, mental health and healthcare resource utilisation. Healthcare provider, personal social service and societal costs were estimated as total adjusted mean costs and utility, with cost-consequence analysis of a single timepoint.

RESULTS

Veterans in our sample had higher healthcare, social service and societal costs and lower utility. Veterans had greater contacts with the criminal justice system, received more social service benefits, had more lost work hours and greater accrued debt. A cost difference of £590 (95% CI -£1016 to -£163) was evident between veterans with scores indicating problem gambling and those reporting no problems. Costs varied by problem gambling status.

CONCLUSIONS

Our sample of UK AF veterans has higher healthcare, social service and societal costs than non-veterans. Veterans experiencing problem gambling are more costly but have no reduction in quality of life.

Commercialization of Ionic Liquids in Pursuit of Green Chemistry: Must we Each Become an Entrepreneur?

There will be common challenges to scaling-up any ionic liquids separations technologies which require very large volumes of ionic liquid. Some of these challenges are illustrated in this personal account which chronicles the extraction of chitin from shrimp shell from discovery to current commercialization efforts. The road being taken from discovery in an academic laboratory, through attempts to navigate the scaling-up to commercial scale using the vehicle of a faculty startup company is rewarding, but fraught with roadblocks, detours, and unexpected challenges. The differences in 'technically feasible' and 'commercially viable' are not always evident from the beginning of the journey, however, one wonders what achievements we miss as a Society because it was assumed to not be commercially viable.

Investigation of the role of hydrogen bonding in ionic liquid-like salts with both N- and S-soft donors

Ionic liquid or not: hydrogen bonds such as the relatively rare N–H⋯S hydrogen bond lead in ionic liquid forming ion combinations to higher melting temperatures and lower decomposition points.

Metal–organic frameworks as hypergolic additives for hybrid rockets

Hybrid rocket propulsion can contribute to reduce launch costs by simplifying engine design and operation. Hypergolic propellants, i.e. igniting spontaneously and immediately upon contact between fuel and oxidizer, further simplify system integration by removing the need for an ignition system. Such hybrid engines could also replace currently popular hypergolic propulsion approaches based on extremely toxic and carcinogenic hydrazines. Here we present the first demonstration for the use of hypergolic metal–organic frameworks (HMOFs) as additives to trigger hypergolic ignition in conventional paraffin-based hybrid engine fuels. HMOFS are a recently introduced class of stable and safe hypergolic materials, used here as a platform to bring readily tunable ignition and combustion properties to hydrocarbon fuels. We present an experimental investigation of the ignition delay (ID, the time from first contact with an oxidizer to ignition) of blends of HMOFs with paraffin, using White Fuming Nitric Acid (WFNA) as the oxidizer. The majority of measured IDs are under 10 ms, significantly below the upper limit of 50 ms required for functional hypergolic propellant, and within the ultrafast ignition range. A theoretical analysis of the performance of HMOFs-containing fuels in a hybrid launcher engine scenario also reveals the effect of the HMOF mass fraction on the specific impulse (I_sp) and density impulse (ρI_sp). The use of HMOFs to produce paraffin-based hypergolic fuels results in a slight decrease of the I_sp and ρI_sp compared to that of pure paraffin, similar to the effect observed with Ammonia Borane (AB), a popular hypergolic additive. HMOFs however have a much higher thermal stability, allowing for convenient mixing with hot liquid paraffin, making the manufacturing processes simpler and safer compared to other hypergolic additives such as AB.

Hypergolic hybrid rocket propulsion, achieved through the addition of metal–organic frameworks, can contribute to reduce launch costs by simplifying engine design and operation.

CO2 capture from ambient air via crystallization with tetraalkylammonium hydroxides

Aqueous solutions of tetra(n-alkyl)ammonium hydroxides, [Nnnnn][OH] with n = 2: n-ethyl, 3: n-propyl, 4: n-butyl are effective in direct air carbon capture (DAC) with high CO2/[Nnnnn][OH] ratio.

Shape Preserving Single Crystal to Amorphous to Single Crystal Polymorphic Transformation Is Possible

Many crystalline materials form polymorphs and undergo solid–solid transitions between different forms as a function of temperature or pressure. However, there is still a poor understanding of the mechanism of transformation. Conclusions about the transformation process are typically drawn by comparing the crystal structures before and after the conversion, but gaining detailed mechanistic knowledge is strongly impeded by the generally fast rate of these transitions. When the crystal morphology does not change, it is assumed that crystallinity is maintained throughout the process. Here we report transformation between polymorphs of ZnCl₂(1,3-diethylimidazole-2-thione)₂ which are sufficiently slow to allow unambiguous assignment of single crystal to single crystal transformation with shape preservation proceeding through an amorphous intermediate phase. This result fundamentally challenges the commonly accepted views of polymorphic phase transition mechanisms.

Ready Access to Anhydrous Anionic Lanthanide Acetates by Using Imidazolium Acetate Ionic Liquids as the Reaction Medium

Access to lanthanide acetate coordination compounds is challenged by the tendency of lanthanides to coordinate water and the plethora of acetate coordination modes. A straightforward, reproducible synthetic procedure by treating lanthanide chloride hydrates with defined ratios of the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate ([C2 mim][OAc]) has been developed. This reaction pathway leads to two isostructural crystalline anhydrous coordination complexes, the polymeric [C2 mim]n [{Ln2 (OAc)7 }n ] and the dimeric [C2 mim]2 [Ln2 (OAc)8 ], based on the ion size and the ratio of IL used. A reaction with an IL : Ln-salt ratio of 5 : 1, where Ln=Nd, Sm, and Gd, led exclusively to the polymer, whilst for the heaviest lanthanides (Dy-Lu) the dimer was observed. Reaction with Eu and Tb resulted in a mixture of both polymeric and dimeric forms. When the amount of IL and/or the size of the cation was increased, the reaction led to only the dimeric compound for all the lanthanide series. Crystallographic analyses of the resulting salts revealed three different types of metal-acetate coordination modes where η2 μκ2 is the most represented in both structure types.

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%.

Herbicidal Ionic Liquids: A Promising Future for Old Herbicides? Review on Synthesis, Toxicity, Biodegradation, and Efficacy Studies

The transformation of agrochemicals into herbicidal ionic liquids (HILs) has been suggested as a solution to problems associated with commercial forms of herbicides. The aim of this review was to summarize the latest progress in the field of HILs, including their synthesis as well as physicochemical and biological properties, and to address the areas that require further research in order to ensure their safe commercialization (e.g., data regarding biodegradability, toxicity, and environmental fate). The first part of the review provides an in-depth summary of the current state of knowledge regarding HILs, particularly the anions and cations used for their synthesis. The second part highlights the employed synthesis methods and elucidates their respective advantages and limitations. The third section is focused on the characterization of HILs with emphasis on the methods and factors that are significant in terms of their practical application. Subsequently, the issues associated with the biodegradation and toxic effects of HILs are discussed based on the relevant literature reports. All sections include comprehensively tabulated data in order to enable rapid comparison of utilized approaches. Finally, all the findings are critically analyzed in terms of crucial disadvantages (especially the lack of standardization), which allowed us to establish future recommendations and basic guidelines that are presented in the last section.

Are Myths and Preconceptions Preventing us from Applying Ionic Liquid Forms of Antiviral Medicines to the Current Health Crisis?

At the moment, there are no U.S. Food and Drug Administration (U.S. FDA)-approved drugs for the treatment of COVID-19, although several antiviral drugs are available for repurposing. Many of these drugs suffer from polymorphic transformations with changes in the drug's safety and efficacy; many are poorly soluble, poorly bioavailable drugs. Current tools to reformulate antiviral APIs into safer and more bioavailable forms include pharmaceutical salts and cocrystals, even though it is difficult to classify solid forms into these regulatory-wise mutually exclusive categories. Pure liquid salt forms of APIs, ionic liquids that incorporate APIs into their structures (API-ILs) present all the advantages that salt forms provide from a pharmaceutical standpoint, without being subject to solid-state matter problems. In this perspective article, the myths and the most voiced concerns holding back implementation of API-ILs are examined, and two case studies of API-ILs antivirals (the amphoteric acyclovir and GSK2838232) are presented in detail, with a focus on drug property improvement. We advocate that the industry should consider the advantages of API-ILs which could be the genesis of disruptive innovation and believe that in order for the industry to grow and develop, the industry should be comfortable with a certain element of risk because progress often only comes from trying something different.

Are ionic liquids and liquid coordination complexes really different? - Synthesis, characterization, and catalytic activity of AlCl3/base catalysts

Lewis acid/base catalysts of AlCl3/N-methyl-2-pyrrolidone (O-NMP) and AlCl3/1-methylimidazole (N-Mim) were prepared and found to have higher catalytic activity in the Friedel-Crafts alkylation of benzene than the known super acidic ionic liquid chloroaluminate [HN222][Al2Cl7] ([HN222]+ = triethylammonium). Crystals structures were obtained for AlCl3(N-Mim), [AlCl2(O-NMP)2][AlCl4], and [Al(O-NMP)6][AlCl4]3·(C6H6)3 supporting the assignments of neutral and charged catalytic species.

Forcing Dicyanamide Coordination to f-Elements by Dissolution in Dicyanamide-Based Ionic Liquids

A robust general route to lanthanide dicyanamide (DCA^–) complexes has been developed where f-element salts are dissolved in DCA^–-based ionic liquids (ILs) directly or formed in situ, forcing coordination of these normally weakly coordinating soft N-donor anions, even in an ambient, non-moisture-excluding environment. A series of lanthanide complexes [C₂mim][Ln(DCA)₄(H₂O)₄] (C₂mim = 1-ethyl-3-methylimidazolium; Ln = La, Nd, Eu, Tb, Dy, and Yb) and [C₂mim]_3n[La(OH₂)₄(μ²-DCA)₄]_n[La(OH₂)₂(μ³-DCA)₃(μ²-DCA)₄]_2n(Cl)_4n were crystallized under a variety of conditions using this methodology and structurally characterized using single crystal X-ray diffraction. Although not all examples were isostructural, the dominant feature across the series was the presence of [Ln(DCA)₄(H₂O)₄]⁻ anionic nodes with all terminal DCA^– ligands accepting hydrogen bonds from the coordinated water molecules forming a 3D metal organic framework. To determine if any structural clues might aid in the further development of the synthetic methodology, the metal-free IL [C₁mim][DCA] (C₁mim = 1,3-dimethylimidazolium), a room-temperature solid, crystalline analogue of the reaction IL, which is liquid at room temperature, was also prepared and structurally characterized. The ready isolation of these compounds allowed us to begin an investigation of the physical properties such as the luminescence at room and low temperatures for the Eu, Tb, and Dy representatives.

Direct dissolution of lanthanide chloride hydrates in the DCA⁻ ionic liquids leads to coordination of DCA⁻ anions to Ln³⁺ under full displacement of chloride and partial displacement of water ligands leading to the formation of metal organic frameworks under ambient conditions. X-ray analyses reveal a significant influence of the hydrogen bonding and lanthanides’ size on crystallographic disorder in their crystal structures.

Benchtop access to anhydrous actinide N-donor coordination complexes using ionic liquids

By dehydrating actinide salts with an ionic liquid containing a common anion and subsequent reaction with N-heterocyclic ligands, we challenge the concept that actinides prefer O- over N-donors; rather the acidic hydrogen atoms of protic solvents hinder the formation of more elusive f-element N-donor coordination complexes.

Dehydration of UO2Cl2·3H2O and Nd(NO3)3·6H2O with a Soft Donor Ligand and Comparison of Their Interactions through X-ray Diffraction and Theoretical Investigation

We investigated whether the relatively Lewis basic imidazole-2-thiones could be used to substitute water ligands bound to f-element cations and generate f-element soft donor complexes. Reactions of 1,3-diethylimidazole-2-thione (C₂C₂ImT) with Nd(NO₃)₃·6H₂O and UO₂Cl₂·3H₂O led to the isolation of the anhydrous thione complexes Nd(NO₃)₃(C₂C₂ImT)₃ and UO₂Cl₂(C₂C₂ImT)₂, characterized by single crystal X-ray diffraction. Differences in the strength of metal-thione interactions have been examined by means of the crystal structure analysis and density functional theory (DFT) calculations. The C₂C₂ImT ligands were found to be affected by both coordination and noncovalent interactions, making it impossible to deconvolute the effects of one from the other. Calculated partial atomic charges indicated greater ligand-to-metal charge transfer in the [UO₂]²⁺ complex, indicative of a stronger interaction. The reactivity of C₂C₂ImT demonstrates its usefulness in the preparation of f-element soft donor complexes from readily available hydrates that could be useful intermediates for promoting the coordination and studying the effects of soft donor anions.

Insights into Ionic Liquid/Aromatic Systems from NMR Spectroscopy: How Water Affects Solubility and Intermolecular Interactions

Hydrocarbon solubility and chemical interactions in ten imidazolium- and pyridinium-based ionic liquids (ILs) with four different anions (thiocyanate [SCN]^- , dicyanamide [DCA]^- , tricyanomethanide [TCM]^- , and bis(trifuoromethylsulfonyl)imide [NTf₂ ]^- ) have been studied by ¹ H and ¹³ C NMR spectroscopy. The anion structure has the main influence on the anion-aromatic chemical interaction strength; it is directly correlated to the NMR chemical shift deviations but not to the hydrocarbon solubility. The [TCM]^- anion shows the largest chemical shift deviations, but the [NTf₂ ]^- anion has the highest hydrocarbon solubility due to steric effects. Higher water contents decrease the hydrocarbon solubility in ILs. Ion-water solvation mainly occurs until 1 mol_water /mol_IL with the saturation limit at 10 mol_water /mol_IL . Toluene-ion interactions are stronger than water-ion interactions in [DCA]^- and [TCM]^- -based ILs, but they have a similar or even lower strength in [SCN]^- -based ILs.

Synthesis of Anhydrous Acetates for the Components of Nuclear Fuel Recycling in Dialkylimidazolium Acetate Ionic Liquids

A series of anhydrous acetate salts with uranium {[C₂C₁im][UO₂(OAc)₃] (1), [C₂C₂im][UO₂(OAc)₃] (2), and [C₄C₁im][UO₂(OAc)₃] (3)}, lanthanides {[C₂C₂im]₂[La(OAc)₅] (4) and [C₂C₁im]₂[Nd(OAc)₅] (5)}, and strontium {[C₂C₁im]_n[Sr(OAc)₃]_n (6)} (where C₂C₁im = 1-ethyl-3-methylimidazolium, C₂C₂im = 1,3-diethylimidazolium, C₄C₁im = 1-butyl-3-methylimidazolium, and OAc = acetate) have been prepared and structurally characterized. Both lanthanides and strontium are common components of the nuclear fuel waste, and their separation from uranium is an important but still challenging task. A new synthetic approach with dialkylimidazolium acetate ionic liquids (ILs) as the solvent has been developed for the direct synthesis of homoleptic acetates from the corresponding hydrates and, unexpectedly, hardly soluble f-element oxides. Although the group of characterized compounds shows perfect structural variability, all actinide and lanthanide metal ions form monomeric complex anions where the metal cation coordinates to five ligands including two oxygen atoms in the case of uranium, as is commonly observed for uranyl compounds. Crystallographic analyses revealed that the complex [UO₂(OAc)₃]^- anions possess rather standard D_3h symmetry featuring a hexagonal-bipyramidal coordination environment, while the lanthanide anions [Ln(OAc)₅]^2- are fully asymmetric and the Ln³⁺ cations are 10-coordinated in the form of a distorted bicapped tetragonal antiprism. This is the first report of lanthanide ions coordinated in this fashion. For Sr²⁺, 9-fold coordination through oxygen atoms in the form of a strongly distorted tricapped trigonal prism is observed. The crystallization of anhydrous, homoleptic, anionic acetate complexes from such a large variety of different metal salts appears to be due to the properties of dialkylimidazolium acetate ILs themselves, including enhanced basicity from the high concentration of free anions and their greater affinity for hydrogen-bonding solutes relative to metal cations.

A fivefold UO 2 2 + node is a path to dodecagonal quasicrystal approximants in coordination polymers

Aperiodic formations continue to focus interest in areas ranging from advanced scientific theories to practical everyday applications. Starting from diverse and tightly bonded intermetallic compounds, this world showed an important breakthrough toward the so-called soft systems of meso/macroscale: liquid crystals, thin films, polymers, proteins, etc. This work opens a route for making bulk quasicrystals (QC) in an unprecedented but very common area, with molecular ligands. Since these systems are, to a large extent, transparent, they extend the possible areas of QC application to previously unreachable corners, e.g., photonics. We combined efficient bridging ligands with uranyl pentagonal bonding centers and, unexpectedly, brought the unique attributes of f-element coordination chemistry to an interdisciplinary area of aperiodic formations. Taking advantage of the planar coordination of uranyl ions, we were able to direct the structure expansion solely in two directions with a characteristic snub square tiling, a predicted but previously unobtainable dodecagonal approximant.

Hypergolic Triggers as Co-crystal Formers: Co-crystallization for Creating New Hypergolic Materials with Tunable Energy Content

We demonstrate a co-crystal-based strategy to create new solid hypergols, that is, materials exhibiting spontaneous ignition when in contact with an oxidant, from typically non-hypergolic fuel molecules. In these materials, the energy content and density can be changed without affecting the ignition delay. The use of an imidazole-substituted decaborane as a hypergolic "trigger" component in combination with energy-rich but non-hypergolic nitrobenzene or pyrazine yielded hypergolic co-crystals that combine improved combustion properties with ultrashort ignition delays as low as 1 ms.

Solubility Studies of Cyclosporine Using Ionic Liquids

Six ionic liquids (ILs) were selected based on their chemical and physical properties to study the solubility of cyclosporine A. Of these, cyclosporine exhibited higher room temperature solubility in 1-ethyl-3-methylimidazolium acetate ([C₂mim][OAc]) than in acetone, an effective molecular solvent used to solubilize and purify cyclosporine. The solubility of cyclosporine in the ILs dramatically increased at higher temperatures, a critical factor that cannot be varied in a wide range with low boiling molecular solvents. The differences in solubility were explored for cyclosporine purification. Cyclosporine was purified up to ∼93% with n-butylammonium acetate ([C₄NH₃][OAc]) and could be further purified to 95% using an IL/organic solvent biphasic system. After purification, cyclosporine was recovered as an amorphous solid using the ILs.

Azolate Anions in Ionic Liquids: Promising and Under-Utilized Components of the Ionic Liquid Toolbox

Owing to their ease of synthesis, diffuse positive charge, and chemical stability, 1-alkyl-3-methylimidazolium cations (i.e., [C_n mim]⁺ ) are one of the most routinely utilized and historically important components in ionic liquid (IL) chemistry. However, while this is a routinely encountered member of the IL family as cations, relatively few workers have explored the versatile chemistry of azoles to allow their use as an anionic component in ILs, as azolates. Azolate anions possess many of the desired properties for IL formation, including a diffuse ionic charge, tailorable asymmetry, and synthetic flexibility, with the added advantages of not relying on halogen atoms for electron-withdrawing effects, as is commonly encountered with IL anions such as hexafluorophosphate. This review explores the 122 azolate-containing ILs known in the literature (prepared from only 39 disparate azolate anions), with a view to highlighting not only their demonstrated utility as an IL component, but the ways in which the larger scientific community may utilize their advantageous properties for new tailored materials.

Crystallographic Insights into the Behavior of Highly Acidic Metal Cations in Ionic Liquids from Reactions of Titanium Tetrachloride with [1-Butyl-3-Methylimidazolium][X] Ionic Liquids (X = Chloride, Bromide, Tetrafluoroborate)

Highly charged metal ions are difficult to investigate in weakly coordinating ionic liquids (ILs) because of the insolubility of their solid forms, but the molecular liquid TiCl₄ offers a way to react tetravalent metal ions in an IL. Reactions of TiCl₄ with 1-butyl-3-methylimidazolium ([C₄mim]⁺)-based ILs containing chloride or bromide lead to mixtures of highly metastable amorphous solids and small amounts of crystalline chlorotitanate salts including [C₄mim]₂[TiCl₆] and two polymorphs of [C₄mim]₂[Ti₂Cl₁₀] in a manner not well correlated with stoichiometry or anion identity. The reaction of TiCl₄ with [C₄mim][BF₄] yields crystals of the mixed fluoro-chloro complex [C₄mim]₂[Ti₄F₆Cl₁₂], indicating spontaneous reaction of the IL ions to generate HF in situ. These unusual behaviors are explained in terms of the exceptionally high acidity of Ti⁴⁺ and the unusual behavior of TiCl₄ among metal halides as a nonpolar molecular compound.

New Reactions for Old Ions: Cage Rearrangements, Hydrolysis, and Two-Electron Reduction of nido-Decaborane in Neat 1-Ethyl-3-Methylimidazolium Acetate

The access to free, unsolvated ions at high concentrations and ambient temperatures enabled by ionic liquids results in previously unobserved reactivity for even well-studied ions, demonstrated here by acetate ([OAc]-) acting as a reducing agent for B10H14 but only when used as a neat liquid in [C2mim][OAc] at ambient temperature. More typical reaction products are obtained when B10H14 is reacted with [C2mim][OAc] at an elevated temperature or in the presence of strong bases.

Polyoxometalate catalysts for biomass dissolution: understanding and design

The use of polyoxometalate catalysts for selective delignification of biomass presents a possible route toward using ionic liquids (ILs) to efficiently obtain high-molecular weight biopolymers from biomass. Rapid progress in this area will depend on recognizing and using the link with already well-developed inorganic chemistry in ILs pursued outside the field of biomass processing. Here, we use crystal structures determined from single crystal X-ray diffraction to better understand the behavior of [PV2Mo10O40]5-, a polyoxometalate catalyst known for its ability to promote selective delignification of biomass in the IL 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]). The crystal structure of [C2mim]5[PV2Mo10O40]·THF shows the formation of cationic shells around the anions which are likely representative of the interactions of this catalyst with [C2mim][OAc] itself. The reaction of NH4VO3 with [C2mim][OAc] is explored to better understand the chemistry of vanadium(V), which is critical to redox catalysis of [PV2Mo10O40]5-. This reaction gives crystals of [C2mim]4[V4O12], showing that this IL forms discrete metavanadates which are obtained from aqueous solutions in a specific pH range and indicating that the basicity of [OAc]- dominates the speciation of vanadium (V) in this IL.

Porphyrinic Ionic Liquid Dyes: Synthesis and Characterization

Four porphyrinic ionic liquids and four higher melting salts (>100 °C) were synthesized as potential photosensitizers from highly symmetric porphyrins by introducing alkyl chains and exchanging anions to tune their solubility and singlet oxygen generation capability. Among the synthesized compounds was 5,10,15,20-tetra(4-dodecylpyridinum)porphyrin tetrakis-bis(trifluoromethylsulfonyl)-amide, a room-temperature ionic liquid that could be crystallized as a solvate with nitrobenzene.

Odd-even effect on the formation of aqueous biphasic systems formed by 1-alkyl-3-methylimidazolium chloride ionic liquids and salts

This work provides a comprehensive evaluation of the effect of the cation alkyl side chain length of the 1-alkyl-3-methylimidazolium chloride series ([C _n C₁im]Cl, n = 2-14) of ionic liquids (ILs) on their capability to form aqueous biphasic systems (ABSs) with salts and self-aggregation derived properties. The liquid-liquid phase behavior of ternary systems composed of [C _n C₁im]Cl, water, and K₃PO₄ or K₂CO₃ and the respective Setschenow salting-out coefficients (k_s ), a quantitative measure of the two-phase formation ability, were determined. An odd-even effect in the k_s values along the number of methylene groups of the longest IL cation alkyl side chain was identified for the ABS formed by K₂CO₃, a weaker salting-out agent where the phenomenon is clearly identified. In general, cations with even alkyl side chains, being likely to display higher molar volumes, are more easily salted-out and thus more prone to undergo phase separation. The odd-even effect in the k_s values is, however, more significant in ILs up to n = 6, where the nanostructuration/nanosegregation of ILs plays a less relevant role. Still, with the [C _n C₁im]Cl (n = 7-14) series of ILs, an odd-even effect was also identified in the ILs' ionization degree, molar conductivity, and conductivity at infinite dilution. In summary, it is shown here that the ILs' odd-even effect occurs in IL aqueous solutions and not just in neat ILs, an already well-established phenomenon occurring in a series of ILs' properties described as a result of the orientation of the terminal methyl groups to the imidazolium ring cation and consequent effect in the ILs' cohesive energy.

Nanodarts, nanoblades, and nanospikes: Mechano-bactericidal nanostructures and where to find them

Over the past ten years, a next-generation approach to combat bacterial contamination has emerged: one which employs nanostructure geometry to deliver lethal mechanical forces causing bacterial cell death. In this review, we first discuss advances in both colloidal and topographical nanostructures shown to exhibit such "mechano-bactericidal" mechanisms of action. Next, we highlight work from pioneering research groups in this area of antibacterials. Finally, we provide suggestions for unexplored research topics that would benefit the field of mechano-bactericidal nanostructures. Traditionally, antibacterial materials are loaded with antibacterial agents with the expectation that these agents will be released in a timely fashion to reach their intended bacterial metabolic target at a sufficient concentration. Such antibacterial approaches, generally categorized as chemical-based, face design drawbacks as compounds diffuse in all directions, leach into the environment, and require replenishing. In contrast, due to their mechanisms of action, mechano-bactericidal nanostructures can benefit from sustainable opportunities. Namely, mechano-bactericidal efficacy needs not replenishing since they are not consumed metabolically, nor are they designed to release or leach compounds. For this same reason, however, their action is limited to the bacterial cells that have made direct contact with mechano-bactericidal nanostructures. As suspended colloids, mechano-bactericidal nanostructures such as carbon nanotubes and graphene nanosheets can pierce or slice bacterial membranes. Alternatively, surface topography such as mechano-bactericidal nanopillars and nanospikes can inflict critical membrane damage to microorganisms perched upon them, leading to subsequent cell lysis and death. Despite the infancy of this area of research, materials constructed from these nanostructures show remarkable antibacterial potential worthy of further investigation.

Cocrystal formation by ionic liquid-assisted grinding: case study with cocrystals of caffeine

Liquid assisted grinding using imidazolium-based ionic liquids (IL-AG) was found to be effective in isolation of cocrystals and cocrystal polymorphs.

Advances in Processing Chitin as a Promising Biomaterial from Ionic Liquids

Chitin isolated through microwave-assisted dissolution using ionic liquids is a high molecular weight (MW) polymer that can be manufactured into materials of different architectures (e.g., fibers, films, microspheres, nanostructured materials) to be used as wound care dressings, drug delivery devices, scaffolds, etc. However, because of differences from traditional isolation methods and, thus, differences in polymer length and degree of deacetylation, it could exhibit bio-related properties that differ from those of traditionally 'pulped' chitin. Here we present the initial assessments of bio-related chitin properties in order to provide a useful scientific basis for clinical applications: biocompatibility, cytotoxicity (intracutaneous reactivity), wound healing efficacy, histological evaluation of the wounds treated with chitin dressing, and antibacterial activity. We also provide the studies that outline potential applications of chitin as a raw polymer for preparation of biomaterials. Graphical Abstract.

Mixed metal double salt ionic liquids comprised of [HN222]2[ZnCl4] and AlCl3 provide tunable Lewis acid catalysts related to the ionic environment

Tunable acidic mixed-metal double salt ionic liquids (DSILs), [HN₂₂₂]_2x[(1 − x)AlCl₃ + xZnCl₄], were prepared by mixing [HN₂₂₂]₂[ZnCl₄] with AlCl₃, and found to have unique and controllable catalytic activities.

Ionic liquids in cross-coupling reactions: “liquid” solutions to a “solid” precipitation problem

To alleviate the problem of solid salt precipitation when using inorganic bases in cross-coupling reactions, basic anions were combined with the trihexyl(tetradecyl)phosphonium ([P₆₆₆₁₄]⁺) cation to ensure an ionic liquid byproduct.

Exploring the role of ionic liquids to tune the polymorphic outcome of organic compounds

While molecular solvents are commonly used in the screening of polymorphs, the choices are often restricted. Ionic liquids (ILs) - also referred as designer solvents - have immense possibility in this regard because of their wide flexibility of tunability. More importantly, the interactions among the IL components are completely unique compared to those present in the molecular solvents. In this context, we have chosen tetrolic acid (TA) and isonicotinamide (INA), which showed solution-structure link in molecular solvents in the past, as probes to investigate the role of imidazolium based ionic liquids in the polymorphism of these two systems and whether the different solute-solvent interactions in ILs affect the polymorphic outcome. It is observed that the selected imidazolium-based ILs, with varying anion basicity have influenced the crystallization outcome by the interaction between ILs and model compounds. Later, we have utilized the concept of double salt ionic liquids (DSIL) for INA, a penta-morphic system, to investigate the variation in the polymorphic outcome. This approach helped to obtain the forms that were otherwise inaccessible in ILs.

A Triple Salting-Out Effect is Required for the Formation of Ionic-Liquid-Based Aqueous Multiphase Systems

Novel aqueous multiphase systems (MuPSs) formed by quaternary mixtures composed of cholinium-based ionic liquids (ILs), polymers, inorganic salts, and water are reported herein. The influence of several ILs, polymers, and salts was studied, demonstrating that a triple salting-out is a required phenomenon to prepare MuPSs. The respective phase diagrams and "tie-surfaces" were determined, followed by the evaluation of the effect of temperature. Finally, the remarkable ability of IL-based MuPSs to selectively separate mixtures of textile dyes is shown.