New dimensions in salt-solvent mixtures: a 4th evolution of ionic liquids

Effects of Ionic Liquids on the Nucleofugality of Dimethyl Sulfide

The nucleofugality of dimethyl sulfide was measured in solvent mixtures containing ionic liquids. The first-order rate constants of the solvolysis of sulfonium salts were determined in mixtures containing different proportions of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide in ethanol, representing the first report on the solvolysis of a charged species in an ionic liquid. Temperature-dependent kinetic studies allowed determination of activation parameters and rationalization of observed solvent effects in different ionic liquid mixtures. From the solvolysis data, the nucleofugality of dimethyl sulfide in different proportions of this ionic liquid in ethanol was determined. Further, the nucleofugality of dimethyl sulfide was determined in mixtures containing high proportions of each of seven other ionic liquids in ethanol. These data allowed quantification of the effects of varying both the amount of ionic liquid present and on changing the components of the ionic liquid on the nucleofugality of dimethyl sulfide. The ionic liquid mixtures were shown to affect the nucleofugality of this nucleofuge in a different manner to the previously studied monatomic charged nucleofuges, owing to different microscopic interactions in solution. This work highlighted the necessity of considering electrofuges with an appropriate range of electrofugality values along with the importance of the nucleofuge-specific sensitivity parameter.

Scattering approaches to unravel protein solution behaviors in ionic liquids and deep eutectic solvents: From basic principles to recent developments

Proteins in ionic liquids (ILs) and deep eutectic solvents (DESs) have gained significant attention due to their potential applications in various fields, including biocatalysis, bioseparation, biomolecular delivery, and structural biology. Scattering approaches including dynamic light scattering (DLS) and small-angle X-ray and neutron scattering (SAXS and SANS) have been used to understand the solution behavior of proteins at the nanoscale and microscale. This review provides a thorough exploration of the application of these scattering techniques to elucidate protein properties in ILs and DESs. Specifically, the review begins with the theoretical foundations of the relevant scattering approaches and describes the essential solvent properties of ILs and DESs linked to scattering such as refractive index, scattering length density, ion-pairs, liquid nanostructure, solvent aggregation, and specific ion effects. Next, a detailed introduction is provided on protein properties such as type, concentration, size, flexibility and structure as observed through scattering methodologies. This is followed by a review of the literature on the use of scattering for proteins in ILs and DESs. It is highlighted that enhanced data analysis and modeling tools are necessary for assessing protein flexibility and structure, and for understanding protein hydration, aggregation and specific ion effects. It is also noted that complementary approaches are recommended for comprehensively understanding the behavior of proteins in solution due to the complex interplay of factors, including ion-binding, dynamic hydration, intermolecular interactions, and specific ion effects. Finally, the challenges and potential research directions for this field are proposed, including experimental design, data analysis approaches, and supporting methods to obtain fundamental understandings of complex protein behavior and protein systems in solution. We envisage that this review will support further studies of protein interface science, and in particular studies on solvent and ion effects on proteins.

Enhancing the Cycle Life of Zinc-Iodine Batteries in Ionic Liquid-Based Electrolytes

Aqueous zinc-iodine (Zn-I2) batteries are gaining significant attention due to their low-cost, high safety and high theoretical capacity. Nevertheless, their long cycle and durability have been hampered due to the use of aqueous media that, over time, lead to Zn dendrite formation, hydrogen evolution reaction, and polyiodide dissolution. Xiao et al. recently reported the addition of an imidazolium-based ionic liquid (IL) to an aqueous electrolyte and found that the IL plays a key role in modifying the solvation of Zn2+ ions in the bulk electrolyte and the inner Helmholtz plane, repelling H2O molecules away from the Zn anode surface. UV/Vis and NMR spectroscopy also indicates a strong interaction between imidazolium cation [EMIM]+ and I3 -, thereby reducing polyiodide shuttling and enhancing the cycle life of the battery. Overall, a capacity decay rate of only 0.01 % per cycle after over 18,000 cycles at 4 A g-1, is observed, making the use of IL additives in aqueous electrolytes highly promising candidates for Zn-I2 batteries.

Structure, aggregation dynamics and crystallization of superfolder green fluorescent protein: Effect of long alkyl chain imidazolium ionic liquids

Green fluorescent protein (GFP) and its variants are widely used in medical and biological research, especially acting as indicators of protein structural integrity, protein-protein interactions and as biosensors. This study employs superfolder GFP (sfGFP) to investigate the impact of varying alkyl chain length of 1-Cn-3-methylimidazolium chloride ionic liquid (IL) series ([Cnmim]Cl, n = 2, 4, 6, 8, 10, 12) on the protein fluorescence, structure, hydration, aggregation dynamics and crystallization behaviour. The results revealed a concentration-dependent decrease in the sfGFP chromophore fluorescence, particularly in long alkyl chain ILs ([C10mim]Cl and [C12mim]Cl). Tryptophan (Trp) fluorescence showed the quenching rate increased with longer alkyl chains indicating a nonpolar interaction between Trp57 and the alkyl chain. Secondary structural changes were observed at the high IL concentration of 1.5 M in [C10mim]Cl and [C12mim]Cl. Small-angle X-ray scattering (SAXS) indicated relatively stable protein sizes, but with IL aggregates present in [C10mim]Cl and [C12mim]Cl solutions. Dynamic light scattering (DLS) data showed increased protein size and aggregation with longer alkyl chain ILs. Notably, ILs and salts, excluding [C2mim]Cl, promoted sfGFP crystallization. This study emphasizes the influence of the cation alkyl chain length and concentration on protein stability and aggregation, providing insights into utilizing IL solvents for protein stabilization and crystallization purposes.

Ionic-Liquid-Based Nanofluids and Their Heat-Transfer Applications: A Comprehensive Review

Due to the improved thermophysical characteristics of ionic liquids (ILs), such as their strong ionic conductivity, negligible vapor pressure, and thermal stability at high temperatures, they are being looked at viable contender for future heat transfer fluids. Additionally, the dispersing nanoparticles can further improve the thermophysical characteristics and thermal performance of ionic liquids, which is one of the emerging research interests to increase the heat transfer rates of the thermal devices. The latest investigations about the utilization of ionic liquid nanofluids as a heat transfer fluid is summarized in this work. These summaries are broken down into three types: (a) the thermophysical parameters including thermal conductivity, viscosity, density, and specific heat of ionic liquids (base fluids), (b) the thermophysical properties like thermal conductivity, viscosity, density, and viscosity of ionic liquids based nanofluids (IL nanofluids), and (iii) utilization of IL nanofluids as a heat transfer fluid in the thermal devices. The techniques for measuring the thermophysical characteristics and the synthesis of IL nanofluids are also covered. The suggestions for potential future research directions for IL nanofluids are summarized.

Probing ion-binding at a protein interface: Modulation of protein properties by ionic liquids

Ions are important to modulate protein properties, including solubility and stability, through specific ion effects. Ionic liquids (ILs) are designer salts with versatile ion combinations with great potential to control protein properties. Although protein-ion binding of common metals is well-known, the IL effect on proteins is not well understood. Here, we employ the model protein lysozyme in dilute and concentrated IL solutions to determine the specific ion binding effect on protein phase behaviour, activity, size and conformational change, aggregation and intermolecular interactions. A combination of spectroscopic techniques, activity assays, small-angle X-ray scattering, and crystallography highlights that ILs, particularly their anions, bind to specific sites in the protein hydration layer via polar contacts on charged, polar and aromatic residues. The specific ion binding can induce more flexible loop regions in lysozyme, while the ion binding in the bulk phase can be more dynamic in solution. Overall, the protein behaviour in ILs depends on the net effect of nonspecific interactions and specific ion binding. Compared to formate, the nitrate anion induced high protein solubility, low activity, elongated shape and aggregation, which is largely owing to its higher propensity for ion binding. These findings provide new insights into protein-IL binding interactions and using ILs to modulate protein properties.

Trace Water Changes Metal Ion Speciation in Deep Eutectic Solvents: Ce3+ Solvation and Nanoscale Water Clustering in Choline Chloride-Urea-Water Mixtures

Eutectic mixtures of choline chloride, urea, and water in deep eutectic solvent (DES)/water molar hydration ratios (w) of 2, 5, and 10, with dissolved cerium salt, were measured using neutron diffraction with isotopic substitution. Structures were modeled using empirical potential structure refinement (EPSR). Ce3+ was found to form highly charged complexes with a mean coordination number between 7 and 8, with the shell containing mostly chloride, followed by water. The shell composition is strongly affected by the molar ratio of dilution, as opposed to the mass or volume fraction, due to the high affinity of Cl- and H2O ligands that displace less favorable interactions with ligands such as urea and choline. The presence of Ce3+ salt disrupted the bulk DES structure slightly, making it more electrolyte-like. The measured coordination shell of choline showed significant discrepancies from the statistical noninteracting distribution, highlighting the nonideality of the blend. Cluster analysis revealed the trace presence of percolating water clusters (25 ≥ n ≥ 2) in solvent compositions of 5 and 10w for the first time.

The effects of ionic liquids on the ethanolysis of a chloroacenaphthene. Evaluation of the effectiveness of nucleofugality data to predict reaction outcome

The reaction of a chlorobenzene in mixtures containing ethanol and eight different ionic liquids was investigated in order to understand the effects of varying proportions and constituent ions of an ionic liquid on the rate constant of the process. The results were found to be generally consistent with previously studied reactions of the same type, with small proportions of an ionic liquid resulting in a rate constant increase compared to ethanol and large proportions causing a rate constant decrease. Temperature dependent kinetic studies were used to interpret the changes in reaction outcome, particularly noting an entropic cost on moving to high proportions of ionic liquid, consistent with organisation of solvent around the transition state. While attempts to use empirical solvent parameters to correlate outcome with the ionic liquid used were unsuccessful, use of recently acquired nucleofugality data for chloride and estimations for the electrofuge allowed for excellent prediction of the effects of ionic liquids, with rate constants quantitatively predicted in systems containing both different proportions of ionic liquid (mean absolute error (MAE) log(k₁) = 0.11) and different ionic liquids (MAE log(k₁) = 0.33). Importantly, this demonstrates the ready application of these quantitative reactivity parameters.

The structure of protic ionic liquids based on sulfuric acid, doped with excess of sulfuric acid or with water

Neutron scattering with isotopic substitution was used to study the structure of concentrated sulfuric acid, and two protic ionic liquids (PILs): a Brønsted-acidic PIL, synthesised using pyridine and excess of sulfuric acid, [Hpy][HSO₄]·H₂SO₄, and a hydrated PIL, in which an equimolar mixture of sulfuric acid and pyridine has been doped with water, [Hpy][HSO₄]·2H₂O. Brønsted acidic PILs are excellent solvents/catalysts for esterifications, driving reaction to completion by phase-separating water and ester products. Water-doped PILs are efficient solvents/antisolvents in biomass fractionation. This study was carried out to provide an insight into the relationship between the performance of PILs in the two respective processes and their liquid structure. It was found that a persistent sulfate/sulfuric acid/water network structure was retained through the transition from sulfuric acid to PILs, even in the presence of 2 moles (∼17 wt%) of water. Hydrogen sulfate PILs have the propensity to incorporate water into hydrogen-bonded anionic chains, with strong and directional hydrogen bonds, which essentially form a new water-in-salt solvent system, with its own distinct structure and physico-chemical properties. It is the properties of this hydrated PIL that can be credited both for the good performance in esterification and beneficial solvent/antisolvent behaviour in biomass fractionation.

Understanding specific ion effects and the Hofmeister series

Specific ion effects (SIE), encompassing the Hofmeister Series, have been known for more than 130 years since Hofmeister and Lewith's foundational work. SIEs are ubiquitous and are observed across the medical, biological, chemical and industrial sciences. Nevertheless, no general predictive theory has yet been able to explain ion specificity across these fields; it remains impossible to predict when, how, and to what magnitude, a SIE will be observed. In part, this is due to the complexity of real systems in which ions, counterions, solvents and cosolutes all play varying roles, which give rise to anomalies and reversals in anticipated SIEs. Herein we review the historical explanations for SIE in water and the key ion properties that have been attributed to them. Systems where the Hofmeister series is perturbed or reversed are explored, as is the behaviour of ions at the liquid-vapour interface. We discuss SIEs in mixed electrolytes, nonaqueous solvents, and in highly concentrated electrolyte solutions - exciting frontiers in this field with particular relevance to biological and electrochemical applications. We conclude the perspective by summarising the challenges and opportunities facing this SIE research that highlight potential pathways towards a general predictive theory of SIE.

Protein aggregation and crystallization with ionic liquids: Insights into the influence of solvent properties

Ionic liquids (ILs) have been used in solvents for proteins in many applications, including biotechnology, pharmaceutics, and medicine due to their tunable physicochemical and biological properties. Protein aggregation is often undesirable, and predominantly occurs during bioprocesses, while the aggregation process can be reversible or irreversible and the aggregates formed can be native/non-native and soluble/insoluble. Recent studies have clearly identified key properties of ILs and IL-water mixtures related to protein performance, suggesting the use of the tailorable properties of ILs to inhibit protein aggregation, to promote protein crystallization, and to control protein aggregation pathways. This review discusses the critical properties of IL and IL-water mixtures and presents the latest understanding of the protein aggregation pathways and the development of IL systems that affect or control the protein aggregation process. Through this feature article, we hope to inspire further advances in understanding and new approaches to controlling protein behavior to optimize bioprocesses.

Protic Ionic Liquid Cation Alkyl Chain Length Effect on Lysozyme Structure

Solvents that stabilize protein structures can improve and expand their biochemical applications, particularly with the growing interest in biocatalytic-based processes. Aiming to select novel solvents for protein stabilization, we explored the effect of alkylammonium nitrate protic ionic liquids (PILs)-water mixtures with increasing cation alkyl chain length on lysozyme conformational stability. Four PILs were studied, that is, ethylammonium nitrate (EAN), butylammonium nitrate (BAN), hexylammonium nitrate (HAN), and octylammonium nitrate (OAN). The surface tension, viscosity, and density of PIL-water mixtures at low to high concentrations were firstly determined, which showed that an increasing cation alkyl chain length caused a decrease in the surface tension and density as well as an increase in viscosity for all PIL solutions. Small-angle X-ray scattering (SAXS) was used to investigate the liquid nanostructure of the PIL solutions, as well as the overall size, conformational flexibility and changes to lysozyme structure. The concentrated PILs with longer alkyl chain lengths, i.e., over 10 mol% butyl-, 5 mol% hexyl- and 1 mol% octylammonium cations, possessed liquid nanostructures. This detrimentally interfered with solvent subtraction, and the more structured PIL solutions prevented quantitative SAXS analysis of lysozyme structure. The radius of gyration (R_g) of lysozyme in the less structured aqueous PIL solutions showed little change with up to 10 mol% of PIL. Kratky plots, SREFLEX models, and FTIR data showed that the protein conformation was maintained at a low PIL concentration of 1 mol% and lower when compared with the buffer solution. However, 50 mol% EAN and 5 mol% HAN significantly increased the R_g of lysozyme, indicating unfolding and aggregation of lysozyme. The hydrophobic interaction and liquid nanostructure resulting from the increased cation alkyl chain length in HAN likely becomes critical. The impact of HAN and OAN, particularly at high concentrations, on lysozyme structure was further revealed by FTIR. This work highlights the negative effect of a long alkyl chain length and high concentration of PILs on lysozyme structural stability.

Mixed Oxime-Functionalized IL/16-s-16 Gemini Surfactants System: Physicochemical Study and Structural Transitions in the Presence of Promethazine as a Potential Chiral Pollutant

The increasing concern about chiral pharmaceutical pollutants is connected to environmental contamination causing both chronic and acute harmful effects on living organisms. The design and application of sustainable surfactants in the remediation of polluted sites require knowledge of partitioning between surfactants and potential pollutants. The interfacial and thermodynamic properties of two gemini surfactants, namely, alkanediyi-α,ω-bis(dimethylhexadecyl ammonium bromide) (16-s-16, where s = 10, 12), were studied in the presence of the inherently biodegradable oxime-functionalized ionic liquid (IL) 4-((hydroxyimino)methyl)-1-(2-(octylamino)-2-oxoethyl)pyridin-1-ium bromide (4-PyC8) in an aqueous solution using surface tension, conductivity, fluorescence, FTIR and 1H NMR spectroscopic techniques. The conductivity, surface tension and fluorescence measurements indicated that the presence of the IL 4-PyC8 resulted in decreasing CMC and facilitated the aggregation process. The various thermodynamic parameters, interfacial properties, aggregation number and Stern–Volmer constant were also evaluated. The IL 4-PyC8-gemini interactions were studied using DLS, FTIR and NMR spectroscopic techniques. The hydrodynamic diameter of the gemini aggregates in the presence of promethazine (PMZ) as a potential chiral pollutant and the IL 4-PyC8 underwent a transition when the drug was added, from large aggregates (270 nm) to small micelles, which supported the gemini:IL 4-PyC8:promethazine interaction. The structural transitions in the presence of promethazine may be used for designing systems that are responsive to changes in size and shape of the aggregates as an analytical signal for selective detection and binding pollutants.

Mixed Oxime-Functionalized IL/16-s-16 Gemini Surfactants System: Physicochemical Study and Structural Transitions in the Presence of Promethazine as a Potential Chiral Pollutant

The increasing concern about chiral pharmaceutical pollutants is connected to environmental contamination causing both chronic and acute harmful effects on living organisms. The design and application of sustainable surfactants in the remediation of polluted sites require knowledge of partitioning between surfactants and potential pollutants. The interfacial and thermodynamic properties of two gemini surfactants, namely, alkanediyi-α,ω-bis(dimethylhexadecyl ammonium bromide) (16-s-16, where s = 10, 12), were studied in the presence of the inherently biodegradable oxime-functionalized ionic liquid (IL) 4-((hydroxyimino)methyl)-1-(2-(octylamino)-2-oxoethyl)pyridin-1-ium bromide (4-PyC8) in an aqueous solution using surface tension, conductivity, fluorescence, FTIR and 1H NMR spectroscopic techniques. The conductivity, surface tension and fluorescence measurements indicated that the presence of the IL 4-PyC8 resulted in decreasing CMC and facilitated the aggregation process. The various thermodynamic parameters, interfacial properties, aggregation number and Stern–Volmer constant were also evaluated. The IL 4-PyC8-gemini interactions were studied using DLS, FTIR and NMR spectroscopic techniques. The hydrodynamic diameter of the gemini aggregates in the presence of promethazine (PMZ) as a potential chiral pollutant and the IL 4-PyC8 underwent a transition when the drug was added, from large aggregates (270 nm) to small micelles, which supported the gemini:IL 4-PyC8:promethazine interaction. The structural transitions in the presence of promethazine may be used for designing systems that are responsive to changes in size and shape of the aggregates as an analytical signal for selective detection and binding pollutants.

Site-specific DNA functionalization through the tetrazene-forming reaction in ionic liquids

Site-specific chemical modification of unprotected DNAs through a phosphine-mediated amine–azide coupling reaction in ionic liquid.

Phosphine-mediated three-component bioconjugation of amino- and azidosaccharides in ionic liquids

Bioconjugation of carbohydrates has been a challenging task because of their chemical, functional, and structural diversities, and no single chemical modification tool can be universally applicable to all the target substrates in different environments.

Electrochemical Synthesis of Unique Nanomaterials in Ionic Liquids

The review considers the features of the processes of the electrochemical synthesis of nanostructures in ionic liquids (ILs), including the production of carbon nanomaterials, silicon and germanium nanoparticles, metallic nanoparticles, nanomaterials and surface nanostructures based on oxides. In addition, the analysis of works on the synthesis of nanoscale polymer films of conductive polymers prepared using ionic liquids by electrochemical methods is given. The purpose of the review is to dwell upon an aspect of the applicability of ILs that is usually not fully reflected in modern literature, the synthesis of nanostructures (including unique ones that cannot be obtained in other electrolytes). The current underestimation of ILs as an electrochemical medium for the synthesis of nanomaterials may limit our understanding and the scope of their potential application. Another purpose of our review is to expand their possible application and to show the relative simplicity of the experimental part of the work.

Solvation Effects in Organic Chemistry: A Short Historical Overview

This short overview describes the historical development of the physics and chemistry of organic solvents and solutions from the alchemist era until the present time based on some carefully selected examples that can be considered landmarks in the history of solution chemistry.

Tuning the solvation of indigo in aqueous deep eutectics

The solubility of synthetic indigo dye was measured at room temperature in three deep eutectic solvents (DESs)-1:3 choline chloride:1,4-butanediol, 1:3 tetrabutylammonium bromide:1,4-butanediol, and 1:2 choline chloride:p-cresol-to test the hypothesis that the structure of DESs can be systematically altered, to induce specific DES-solute interactions, and, thus, tune solubility. DESs were designed starting from the well-known cholinium chloride salt mixed with the partially amphiphilic 1,4-butanediol hydrogen bond donor (HBD), and then, the effect of increasing salt hydrophobicity (tetrabutylammonium bromide) and HBD hydrophobicity (p-cresol) was explored. Measurements were made between 2.5 and 25 wt. % H₂O, as a reasonable range representing atmospherically absorbed water, and molecular dynamics simulations were used for structural analysis. The choline chloride:1,4-butanediol DES had the lowest indigo solubility, with only the hydrophobic character of the alcohol alkyl spacers. Solubility was highest for indigo in the tetrabutylammonium bromide:1,4-butanediol DES with 2.5 wt. % H₂O due to interactions of indigo with the hydrophobic cation, but further addition of water caused this to reduce in line with the added water mole fraction, as water solvated the cation and reduced the extent of the hydrophobic region. The ChCl:p-cresol DES did not have the highest solubility at 2.5 wt. % H₂O, but did at 25 wt. % H₂O. Radial distribution functions, coordination numbers, and spatial distribution functions demonstrate that this is due to strong indigo-HBD interactions, which allow this system to resist the higher mole fraction of water molecules and retain its solubility. The DES is, therefore, a host to local-composition effects in solvation, where its hydrophobic moieties concentrate around the hydrophobic solute, illustrating the versatility of DES as solvents.

Green Solvents Combined with Bioactive Compounds as Delivery Systems: Present Status and Future Trends

Green solvents such as ionic liquids (ILs) unlock possibilities for developing innovative biomedical and pharmaceutical solutions. ILs are the most investigated solvents for compound extractions, as reaction media and/or catalysts, and a desired eco-friendly solvent to process biomacromolecules for biomaterial production. Investigations demonstrate that the tunable nature and physicochemical features of ILs are also beneficial for building up delivery systems through their combination with bioactive compounds. Bioactive compounds from synthetic origins, like ibuprofen, ketoprofen, and natural sources such as curcumin, flavonoids, and polyphenols are essential starting points as preventive and therapeutic agents for treating diseases. Therefore, the association of those compounds with ILs opens up windows of opportunities in this research field. This Review assesses some of the main and important recent information and the current challenges concerning delivery platforms based on ILs combined with bioactive compounds of both natural and synthetic origins. Moreover, the chemistry, bioavailability, and biological functions of the main bioactive compounds used in the ILs-based delivery platforms are described. These data are presented and are discussed, together with the main delivery routes of the systems.

Computational analysis of the effect of [Tea][Ms] and [Tea][H2PO4] ionic liquids on the structure and stability of Aβ(17-42) amyloid fibrils

Experimental studies have reported the possibility of affecting the growth/dissolution of amyloid fibres by the addition of organic salts of the room-temperature ionic-liquid family, raising the tantalizing prospect of controlling these processes under physiological conditions. The effect of [Tea][Ms] and [Tea][H₂PO₄] at various concentrations on the structure and stability of a simple model of Aβ42 fibrils has been investigated by computational means. Free energy computations show that both [Tea][Ms] and [Tea][H₂PO₄] decrease the stability of fibrils with respect to isolated peptides in solution, and the effect is significantly stronger for [Tea][Ms]. The secondary structure of fibrils is not much affected, but single peptides in solution show a marked decrease in their β-strand character and an increase in α-propensity, again especially for [Tea][Ms]. These observations, consistent with the experimental picture, can be traced to two primary effects, i.e., the difference in the ionicity of the [Tea][Ms] and [Tea][H₂PO₄] water solutions and the remarkable affinity of peptides for [Ms]^- anions, due to the multiplicity of H-bonds.

Deep eutectic solvents: alternative reaction media for organic oxidation reactions

Deep eutectic solvents (DESs) are a valid alternative to common organic solvents and ionic liquids (ILs) as solvent media for organic oxidation reactions.

DNA degradation in fish: Practical solutions and guidelines to improve DNA preservation for genomic research

The more demanding requirements of DNA preservation for genomic research can be difficult to meet when field conditions limit the methodological approaches that can be used or cause samples to be stored in suboptimal conditions. Such limitations may increase rates of DNA degradation, potentially rendering samples unusable for applications such as genome-wide sequencing. Nonetheless, little is known about the impact of suboptimal sampling conditions. We evaluated the performance of two widely used preservation solutions (1. DESS: 20% DMSO, 0.25 M EDTA, NaCl saturated solution, and 2. Ethanol >99.5%) under a range of storage conditions over a three-month period (sampling at 1 day, 1 week, 2 weeks, 1 month, and 3 months) to provide practical guidelines for DNA preservation. DNA degradation was quantified as the reduction in average DNA fragment size over time (DNA fragmentation) because the size distribution of DNA segments plays a key role in generating genomic datasets. Tissues were collected from a marine teleost species, the Australasian snapper, Chrysophrys auratus. We found that the storage solution has a strong effect on DNA preservation. In DESS, DNA was only moderately degraded after three months of storage while DNA stored in ethanol showed high levels of DNA degradation already within 24 hr, making samples unsuitable for next-generation sequencing. Here, we conclude that DESS was the most promising solution when storing samples for genomic applications. We recognize that the best preservation protocol is highly dependent on the organism, tissue type, and study design. We highly recommend performing similar experiments before beginning a study. This study highlights the importance of testing sample preservation protocols and provides both practical and economical advice to improve DNA preservation when sampling for genome-wide applications.

Insights into the Properties and Potential Applications of Renewable Carbohydrate-Based Ionic Liquids: A Review

Carbohydrate-derived ionic liquids have been explored as bio-alternatives to conventional ionic liquids for over a decade. Since their discovery, significant progress has been made regarding synthetic methods, understanding their environmental effect, and developing perspectives on their potential applications. This review discusses the relationships between the structural properties of carbohydrate ionic liquids and their thermal, toxicological, and biodegradability characteristics in terms of guiding future designs of sugar-rich systems for targeted applications. The synthetic strategies related to carbohydrate-based ionic liquids, the most recent relevant advances, and several perspectives for possible applications spanning catalysis, biomedicine, ecology, biomass, and energy conversion are presented herein.

Self-Assembled Biomimetic Capsules for Self-Preservation

The inorganic semiconductor is an attractive material in sewage disposal and solar power generation. The main challenges associated with environment-sensitive semiconductors are structural degradation and deactivation caused by the unfavorable environment. Here, inspired by the pomegranate, a self-protection strategy based on the self-assembly of silver chloride (AgCl) particles is reported. The distributed photosensitive AgCl particles can be encapsulated by themselves through mixing aqueous silver nitrate and protic ionic liquids (PILs). A probable assembling mechanism is proposed based on the electrostatic potential investigation of PILs cations. The AgCl particles inside the shell maintain their morphology and structure well after 6 months light-treatment. Moreover, they exhibit excellent photocatalytic activity, same as newly prepared AgCl particles, for degradation of methyl orange (MO), neutral red (NR), bromocresol green (BG), rhodamine B (RhB), Congo red (CR), and crystal violet (CV).

The Nature of Carbon Dioxide in Bare Ionic Liquids

Ionic liquids (ILs) are among the most studied and promising materials for selective CO₂ capture and transformation. The high CO₂ sorption capacity associated with the possibility to activate this rather stable molecule through stabilization of ionic/radical species or covalent interactions either with the cation or anion has opened new avenues for CO₂ functionalization. However, recent reports have demonstrated that another simpler and plausible pathway is also involved in the sorption/activation of CO₂ by ILs associated with basic anions. Bare ILs or IL solutions contain almost invariable significant amounts of water and through interaction with CO₂ generate carbonates/bicarbonates rather than carbamic acids or amidates. In these cases, the IL acts as a base and not a nucleophile and yields buffer-like solutions that can be used to shift the equilibrium toward acid products in different CO₂ reutilization reactions. In this Minireview, the emergence of IL buffer-like solutions as a new reactivity paradigm in CO₂ capture and activation is described and analyzed critically, mainly through the evaluation of NMR data.

Induced Protic Behaviour in Aprotonic Ionic Liquids by Anion Basicity for Efficient Carbon Dioxide Capture

The interactions between aprotonic tetrabutylphosphonium carboxylate ionic liquids (ILs), [P_{4 4 4 4} ][C_n COO] (n=1, 2 and 7), and water were investigated. The cation-anion interactions occur via the α-¹ H on [P_{4 4 4 4} ]⁺ and the carboxylate headgroup of the anion. Upon addition, H₂ O localises around the carboxylate headgroups, inducing an electron inductive effect towards the oxygens, leading to ion-pair separation. Studies with D₂ O and [P_{4 4 4 4} ][C_n COO] revealed protic behaviour of the systems, with proton/deuterium exchange occurring at the α-¹ H of the cation, promoted by the basicity of the anion, forming an intermediate ylide. The greater influence of van der Waals forces of the [P_{4 4 4 4} ][C₇ COO] system allows for re-orientation of the ions through larger interdigitation. The protic behaviour of the neat ILs allows for CO₂ to be chemically absorbed on the ylide intermediate, forming a phosphonium-carboxylate zwitterion, signifying proton exchange occurs even in the absence of H₂ O. The absorption of CO₂ in equimolar IL-H₂ O mixtures forms a hydrogen carbonate, through a proposed reaction of the CO₂ with an intermediate hydroxide, and carboxylic acid.

Tracing Local Nanostructure of the Aqueous Solutions of the Biocompatible [Cho][Gly] Ionic Liquid: Importance of Hydrogen Bond Attraction between Like-Charged Ions

The neat and aqueous solutions of the cholinium glycinate ionic liquid (IL), [Cho][Gly], at different water mole fractions, x_ws, are studied by molecular dynamics simulations. The changes in the local nanostructure of systems with composition have been determined by calculation of various structural distribution functions. Hydrogen bond (H-bond) attractions determine the major relative orientations of the oppositely and like charged nearest neighbors. The cation-anion H-bonds mainly form between the hydrogen of the hydroxyl or methyl groups of the cation and the carboxylate oxygen of the anion. A preferred (antiparallel) arrangement between adjacent [Cho]⁺ cations is due to the effective H-bond between the hydroxyl oxygen and the methyl hydrogen sites that promotes the like-charge cluster formation. Adding water decreases the occurrence probability of the [Cho]⁺···[Gly]^-···[Cho]⁺ bridge structure in the aqueous solutions due to the formation of the [Gly]^-···HOH···[Gly]^- structure via H-bonding. Observed density trend versus x_w is interpreted based on an interstice model and investigating the water cluster size distribution. Finally, the effect of x_w on the infrared (IR) vibrational spectra were studied and blue and red shifts were observed for the stretching and bending vibrational modes of the hydroxyl group of [Cho]⁺, respectively. Current findings will improve the efficient engineering design and task-specific applications of aqueous solutions of bio-ILs consist of [Cho]⁺ and amino acid anions.

Influence of Carboxylate Anions on Phase Behavior of Choline Ionic Liquid Mixtures

Mixing ionic liquids is a suitable strategy to tailor properties, e.g., to reduce melting points. The present study aims to widen the application range of low-toxic choline-based ionic liquids by studying eight binary phase diagrams of six different choline carboxylates. Five of them show eutectic points with melting points dropping by 13 to 45 °C. The eutectic mixtures of choline acetate and choline 2-methylbutarate were found to melt at 45 °C, which represents a remarkable melting point depression compared to the pure compounds with melting points of 81 (choline acetate) and 90 °C (choline 2-methylbutarate), respectively. Besides melting points, the thermal stabilities of the choline salt mixtures were investigated to define the thermal operation range for potential practical applications of these mixtures. Typical decomposition temperatures were found between 165 and 207 °C, with choline lactate exhibiting the highest thermal stability.

Controlling the outcome of SN2 reactions in ionic liquids: from rational data set design to predictive linear regression models

Rate constants for a bimolecular nucleophilic substitution (SN2) process in a range of ionic liquids are correlated with calculated parameters associated with the charge localisation on the cation of the ionic liquid (including the molecular electrostatic potential). Simple linear regression models proved effective, though the interdependency of the descriptors needs to be taken into account when considering generality. A series of ionic liquids were then prepared and evaluated as solvents for the same process; this data set was rationally chosen to incorporate homologous series (to evaluate systematic variation) and functionalities not available in the original data set. These new data were used to evaluate and refine the original models, which were expanded to include simple artificial neural networks. Along with showing the importance of an appropriate data set and the perils of overfitting, the work demonstrates that such models can be used to reliably predict ionic liquid solvent effects on an organic process, within the limits of the data set.

Hydrogen-Bonding-Driven Ion-Pair Formation in Protic Ionic Liquid Aqueous Solution

Protic ionic liquids (PILs) in solution especially in water have attracted more and more attention due to their unique properties. The solvation of PILs in water is important to their properties and applications. To explore the solvation of bio-based PILs in water, acidity of 49 [AA]X amino acid ionic liquids (AAILs) consisting of 7 different cations and 7 different anions was studied as a favorable probe. The pK_a values for [AA]X PILs containing same cations were obtained and discussed. The acidity strength of the [AA]X PILs varies with both cation and anion which does not follow the conventional assumption that the acidity for PILs is independent of anions. The acidic discrepancy of [AA]X PILs aqueous solution is probably mediated by the formation of ion pairs according to a revised solvation model of PILs. Quantum-chemistry calculation was employed to unpuzzle anion's different effects on the acid balance of cations where cation-anion hydrogen bonds play an important role. Such difference in acidity allows us to understand the formation of solvated ion pairs. This work provides an insight into the fundamental solvation of PILs from acid perspective and their influence on acidity properties for the first time.

Tailoring intermolecular interactions to develop a low-temperature electrolyte system consisting of 1-butyl-3-methylimidazolium iodide and organic solvents

Ionic liquids (ILs) exhibit remarkable properties and great tunability, which make them an attractive class of electrolyte materials for a variety of electrochemical applications. However, despite the promising progress for operating conditions at high temperatures, the development of their low-temperature viability as electrolytes is still limited due to the constrains from thermal and ion transport issues with a drastic decrease in temperature. In this study, we present a liquid electrolyte system based on a mixture of 1-butyl-3-methylimidazolium iodide ([BMIM][I]), γ-butyrolactone (GBL), propylene carbonate (PC), and lithium iodide (LiI) and utilize its molecular interactions to tailor its properties for extremely low-temperature sensing applications. In particular, the carbonyl group on both PC and GBL can form hydrogen bonds with the imidazolium cation, as indicated by Fourier transform infrared spectroscopy (FTIR), and the extent of these interactions between ions and molecules was also characterized and quantified via proton nuclear magnetic resonance (1H NMR) spectroscopy. More importantly, at the optimal ratio, the organic solvents do not have excess content to form aggregates, which may cause undesired crystallization before the glass transition. The microscopic evolutions of the systems are correlated with their bulk behaviors, leading to improvements in their thermal and transport properties. The optimized formulation of [BMIM][I]/PC/GBL/LiI showed a low glass transition temperature (T g) of -120 °C and an effectively reduced viscosity of 0.31 Pa s at -75 °C. The electrochemical stability of the electrolyte was also validated to support the targeted iodide/triiodide redox reactions without interference.