Ionic liquid-based green processes for energy production

The impact of wingtip N-substitution on the bioactivity of azolium salts

Studies have shown that the physicochemical properties of five-membered heterocyclic azolium compounds directly affect their biological activity as therapeutic drugs (spectrum of activity and potency) and the associated pharmacokinetic, pharmacologic, and toxicological profiles of the compounds. Hence, this review focused on the influence of N-functionalisation at the wingtip of such compounds, mainly the diazolium and the triazolium-based salts. The contribution of the N-donor groups to the overall biological efficacy of the azolium compounds and the ensuing structure-activity mechanisms in their pharmacological applications are comprehensively discussed.

Isolating and Purification Technologies for Glycyrrhizic Acid

Glycyrrhizic acid (GA) is the primary active component of the traditional Chinese medicinal herb licorice. It possesses antimicrobial, anti-inflammatory, and antitumor activities. In addition, due to its unique sweetness, it can also be used as a food additive. Traditional Chinese medicines are typically used directly as drugs. However, the chemical composition of Chinese medicinal materials such as licorice is complex, containing not only effective components but also ineffective and even toxic substances. To efficiently exert their medicinal value and minimize the side effects of harmful substances, the extraction and separation of the active components is an important means to achieve the modernization of traditional Chinese medicine utilization. This article focuses on the extraction of GA, summarizes the current technologies related to the extraction and separation of GA, reveals the underlying chemical principles, and evaluates the advantages and disadvantages of the corresponding technologies. On this basis, it proposes challenges faced in the separation of GA and provides corresponding solutions. The author believes that with the continuous introduction of precise chemical synthesis and other methods in separation, the extraction and separation of the active substance will become greener and more efficient. It will also provide a reference for the extraction of other effective components of traditional Chinese medicine.

Electrochemical CO2 Conversion Commercialization Pathways: A Concise Review on Experimental Frontiers and Technoeconomic Analysis

Technoeconomic analysis (TEA) studies are vital for formulating guidelines that drive the commercialization of electrochemical CO2 reduction (eCO2R) technologies. In this review, we first discuss the progress in the field of eCO2R processes by providing current state-of-the-art metrices (e.g., faradic efficiency, current density) based on the recent heterogeneous catalysts' discovery, electrolytes, electrolyzers configuration, and electrolysis process designs. Next, we assessed the TEA studies for a wide range of eCO2R final products, different modes of eCO2R systems/processes, and discussed their relative competitiveness with relevant commercial products. Finally, we discuss challenges and future directions essential for eCO2R commercialization by linking suggestions from TEA studies. We believe that this review will catalyze innovation in formulating advanced eCO2R strategies to meet the TEA benchmarks for the conversion of CO2 into valuable chemicals at the industrial scale.

Molecular Insights of 5-Hydroxymethylfurfural in a Mixture of Ionic Liquids and Alkylated Phenolic Solvents

This paper presents all-atom molecular dynamics to understand the separation behavior of 5-hydroxymethylfurfural (5-HMF) from 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM]+[BF4]- using alkylated phenols as extractants. We have utilized four solvents such as 4-methyl phenol (4-MP), 4-ethyl phenol (4-EP), 4-propyl phenol (4-PP), and 4-butyl phenol (4-BP). We perform structural, dynamic, and rigorous thermodynamic analyses of 5-HMF in the mixture of ILs and solvents. The [BMIM]+[BF4]- show a strong interaction with phenols. The self-diffusion coefficient of 5-HMF shows a 3-fold increase with a decrease in the methyl group on the phenol. The solvation-free energy (ΔGsolvation) of 5-HMF shows favorably in phenols. On the other hand, the transfer free energy (ΔGtransfer) of 5-HMF presents favorable from ILs to phenols. The partition coefficient (log P) values show favorability for separation of 5-HMF using phenols. Overall, the molecular level analysis provides the role of the alkyl group effect on the phenols for extracting 5-HMF from the ILs.

Stable dispersion of carbon nanotubes in a molten salt of KNO3-NaNO3-NaNO2-LiNO3-LiOH

Carbon nanotubes (CNTs) have excellent mechanical and electrical properties; however, they suffer from dispersion problems in various applications. Traditional dispersing strategies of CNTs mostly use oxidation with strong acids or mechanical milling with high energy, which causes serious damage to the intrinsic structures and properties of CNTs. Therefore, it is important to develop new methods for dispersing CNTs without destroying their structures. This paper proposes to disperse CNTs in low-temperature molten salts composed of KNO3-NaNO3-NaNO2-LiNO3-LiOH. By adjusting the composition ratio of molten salts and alkaline, the interaction between charged ions and CNT electrons in the molten salt is studied. The alkaline molten salts can stably disperse CNTs and do not destroy their lengths, thereby offering better electric conductivity. This work will provide a new yet effective method for dispersing CNTs with high aspect ratios, which are important for the application of CNTs and other nanocarbons.

Biomimetic Ion Channel Regulation for Temperature-Pressure Decoupled Tactile Perception

The perception of temperature and pressure of skin plays a vital role in joint movement, hand grasp, emotional expression, and self-protection of human. Among many biomimetic materials, ionic gels are uniquely suited to simulate the function of skin due to its ionic transport mechanism. However, both the temperature and pressure sensing are heavily dependent on the changes in ionic conductivity, making it impossible to decouple the temperature and pressure signals. Here, a pressure-insensitive and temperature-modulated ion channel is designed by synergistic strategies for gel skeleton's compact packing and ultra-thin structure, mimicking the function of the temperature ion channel in human skin. This ion-confined gel can completely suppress the pressure response of the temperature sensing layer. Furthermore, a temperature-pressure decoupled ionic sensor is fabricated and it is demonstrated that the ionic sensor can sense complex signals of temperature and pressure. This novel and effective approach has great potential to overcome one of the current barriers in developing ionic skin and extending its applications.

Regulating the electrical double layer to prevent water electrolysis for wet ionic liquids with cheap salts

Hydrophobic ionic liquids (ILs), broadly utilized as electrolytes, face limitations in practical applications due to their hygroscopicity, which narrows their electrochemical windows via water electrolysis. Herein, we scrutinized the impact of incorporating cheap salts on the electrochemical stability of wet hydrophobic ILs. We observed that alkali ions effectively manipulate the solvation structure of water and regulate the electrical double layer (EDL) structure by subtly adjusting the free energy distribution of water in wet ILs. Specifically, alkali ions significantly disrupted the hydrogen bond network, reducing free water, strengthening the O-H bond, and lowering water activity in bulk electrolytes. This effect was particularly pronounced in EDL regions, where most water molecules were repelled from both the cathode and anode with the disappearance of the H-bond network connectivity along the EDL. The residual interfacial water underwent reorientation, inhibiting water electrolysis and thus enhancing the electrochemical window of wet hydrophobic ILs. This theoretical proposition was confirmed by cyclic voltammetry measurements, demonstrating a 45% enhancement in the electrochemical windows for salt-in-wet ILs, approximating the dry one. This work offers feasible strategies for tuning the EDL and managing interfacial water activity, expanding the comprehension of interface engineering for advanced electrochemical systems.

Diamide-linked imidazolyl Poly(dicationic ionic liquid)s for the conversion of CO2 to cyclic carbonates under ambient pressure

The ionic active centers and hydrogen-bond donors (HBDs) in heterogeneous catalytic materials are highly beneficial for enhancing the interaction between solid-liquid-gas three-phase interfaces and promoting effective fixation of carbon dioxide (CO2). Diamide-linked imidazolyl poly(dicationic ionic liquid)s catalysts PIMDILs (PMAIL-x and PBAIL-2) were synthesized through the copolymerization of diamide-linked imidazolyl dicationic ionic liquids (IMDILs) with divinylbenzene (DVB), which successfully enable the simultaneous construction of high-density and uniformly distributed ionic active centers (2.014-4.883 mmol g-1) and hydrogen-bond donors (HBDs). The as-synthesized PIMDILs present excellent catalytic activity in promoting the cycloaddition of CO2 with epoxides. PMAIL-2 could convert epichlorohydrin (ECH) with a quantitative conversion of 99.8 % (selectivity > 99 %) under ambient pressure. Furthermore, only a decrease in activity of 5 % was observed even after six cycles of recycling. The excellent conversions (>97.3 %) were achieved for various terminal substituted epoxides. The experimental and characterization results reveal that the high-density ionic active centers and amide HBDs can effectively activate the reaction substrates, their synergistic effect plays a crucial role at the catalyst interface. This work is expected to provide some useful insights for the rational construction of heterogeneous catalysts for CO2 conversion.

Current trends and prospects in catalytic upgrading of lignocellulosic biomass feedstock into ultrapure biofuels

Eco-friendly renewable energy sources have recommended as fossil fuel alternatives in recent years to reduce environmental pollution and meet future energy demands in various sectors. As the largest source of renewable energy in the world, lignocellulosic biomass has received considerable interest from the scientific community to advance the fabrication of biofuels and ultrafine value-added chemicals. For example, biomass obtained from agricultural wastes could catalytically convert into furan derivatives. Among furan derivatives, 5-hydroxymethylfurfural (HMF) and 2, 5-dimethylfuran (DMF) are considered the most useful molecules that can be transformed into desirable products such as fuels and fine chemicals. Because of its exceptional properties, e.g., water insolubility and high boiling point, DMF has studied as the ideal fuel in recent decades. Interestingly, HMF, a feedstock upgraded from biomass sources can easily hydrogenate to produce DMF. In the present review, the current state of the art and studies on the transformation of HMF into DMF using noble metals, non-noble metals, bimetallic catalysts, and their composites have discussed elaborately. In addition, comprehensive insights into the operating reaction conditions and the influence of employed support over the hydrogenation process have demonstrated.

Electrocatalyst Microenvironment Engineering for Enhanced Product Selectivity in Carbon Dioxide and Nitrogen Reduction Reactions

Carbon and nitrogen fixation strategies are regarded as alternative routes to produce valuable chemicals used as energy carriers and fertilizers that are traditionally obtained from unsustainable and energy-intensive coal gasification (CO and CH₄), Fischer-Tropsch (C₂H₄), and Haber-Bosch (NH₃) processes. Recently, the electrocatalytic CO₂ reduction reaction (CO₂RR) and N₂ reduction reaction (NRR) have received tremendous attention, with the merits of being both efficient strategies to store renewable electricity while providing alternative preparation routes to fossil-fuel-driven reactions. To date, the development of the CO₂RR and NRR processes is primarily hindered by the competitive hydrogen evolution reaction (HER); however, the corresponding strategies for inhibiting this undesired side reaction are still quite limited. Considering such complex reactions involve three gas-liquid-solid phases and successive proton-coupled electron transfers, it appears meaningful to review the current strategies for improving product selectivity in light of their respective reaction mechanisms, kinetics, and thermodynamics. By examining the developments and understanding in catalyst design, electrolyte engineering, and three-phase interface modulation, we discuss three key strategies for improving product selectivity for the CO₂RR and NRR: (i) targeting molecularly defined active sites, (ii) increasing the local reactant concentration at the active sites, and (iii) stabilizing and confining product intermediates.

The antibacterial activity and mechanism of imidazole chloride ionic liquids on Staphylococcus aureus

Ionic liquids (ILs) have garnered increasing attention in the biomedical field due to their unique properties. Although significant research has been conducted in recent years, there is still a lack of understanding of the potential applications of ILs in the biomedical field and the underlying principles. To identify the antibacterial activity and mechanism of ILs on bacteria, we evaluated the antimicrobial potency of imidazole chloride ILs (C_nMIMCl) on Staphylococcus aureus (S. aureus). The toxicity of ILs was positively correlated to the length of the imidazolidinyl side chain. We selected C₁₂MIMCl to study the mechanism of S. aureus. Through the simultaneous change in the internal and external parts of S. aureus, C₁₂MIMCl caused the death of the bacteria. The production of large amounts of reactive oxygen species (ROS) within the internal parts stimulated oxidative stress, inhibited bacterial metabolism, and led to bacterial death. The external cell membrane could be destroyed, causing the cytoplasm to flow out and the whole cell to be fragmented. The antibacterial effect of C₁₂MIMCl on skin abscesses was further verified in vivo in mice.

The development of novel ionic liquid-based solid catalysts and the conversion of 5-hydroxymethylfurfural from lignocellulosic biomass

Ionic liquids have attracted attention due to their excellent properties and potential for use as co-solvents, solvents, co-catalysts, catalysts, and as other chemical reagents. This mini-review focuses on the properties and structures of ionic liquids, the pretreatment of lignocellulosic biomass, and the development of novel ionic liquid-based solid catalysts for cellulose and hemicellulose derived HMF production.

Regulating the Acidity of SO3 H-Functionalized Ionic Liquids: Hydrogen Bonding or Electrostatic Potential?

The SO₃ H-functionalized ionic liquids (ILs) with high acidity are important catalysts for acid-catalyzed reactions. However, the acidity of these ILs have been found to decrease due to intramolecular hydrogen bonds (H-bonds). In this work, a series of anionic SO₃ H-functionalized ILs were designed and the factors resulting in weak acidity were investigated, including H-bonds strength and electrostatic potential on the leaving proton (ESPLP). Using catalytic experiment, atoms in molecules topology analysis and electrostatic potential calculation, it was found that the acidity of ILs was correlated with the value of ESPLP rather than the H-bond strength. Meanwhile, there were several ways to increase the acidity of anionic SO₃ H-functionalized ILs, such as enhancing the electron-withdrawing ability of cation, introducing H-bond acceptor sites on cation or separating the intramolecular H-bonds through substitution position. These strategies made the conversion of TBA in Friedel-Crafts alkylation increase from 19 % to 84 %.

CO2 Electroreduction in Organic Aprotic Solvents: A Mini Review

An annual increase of CO2 concentrations in the atmosphere causes global environmental problems, addressed by systematic research to develop effective technologies for capturing and utilizing carbon dioxide. Electrochemical catalytic reduction is one of the effective directions of CO2 conversion into valuable chemicals and fuels. The electrochemical conversion of CO2 at catalytically active electrodes in aqueous solutions is the most studied. However, the problems of low selectivity for target products and hydrogen evolution are unresolved. Literature sources on CO2 reduction at catalytically active cathodes in nonaqueous mediums, particularly in organic aprotic solvents, are analyzed in this article. Two directions of cathodic reduction of CO2 are considered—nonaqueous organic aprotic solvents and organic aprotic solvents containing water. The current interpretation of the cathodic conversion mechanism of carbon (IV) oxide into CO and organic products and the main factors influencing the rate of CO2 reduction, Faradaic efficiency of conversion products, and the ratio of direct cathodic reduction of CO2 are given. The influence of the nature of organic aprotic solvent is analyzed, including the topography of the catalytically active cathode, values of cathode potential, and temperature. Emphasis is placed on the role of water impurities in reducing CO2 electroreduction overpotentials and the formation of new CO2 conversion products, including formate and H2.

Ionic liquid-based electrolytes for CO2 electroreduction and CO2 electroorganic transformation

CO₂ is an abundant and renewable C1 feedstock. Electrochemical transformation of CO₂ can integrate CO₂ fixation with renewable electricity storage, providing an avenue to close the anthropogenic carbon cycle. As a new type of green and chemically tailorable solvent, ionic liquids (ILs) have been proposed as highly promising alternatives for conventional electrolytes in electrochemical CO₂ conversion. This review summarizes major advances in the electrochemical transformation of CO₂ into value-added carbonic fuels and chemicals in IL-based media in the past several years. Both the direct CO₂ electroreduction (CO₂ER) and CO₂-involved electroorganic transformation (CO₂EOT) are discussed, focusing on the effect of electrocatalysts, IL components, reactor configurations and operating conditions on catalytic activity, selectivity and reusability. The reasons for the enhanced CO₂ conversion performance by ILs are also discussed, providing guidance for the rational design of novel IL-based electrochemical processes for CO₂ conversion. Finally, the critical challenges remaining in this research area and promising directions for future research are proposed.

Efficient synthesis of cyclic carbonates from CO2 under ambient conditions over Zn(betaine)2Br2: experimental and theoretical studies

It is very interesting to synthesize high value-added chemicals from CO₂ under mild conditions with low energy consumption. Here, we report that a novel catalyst, Zn(betaine)₂Br₂, can efficiently promote the cycloaddition of CO₂ with epoxides to synthesize cyclic carbonates under ambient conditions (30 °C, 1 atm). DFT calculations provide important insights into the mechanism, particularly the unusual synergistic catalytic action of Zn²⁺, Br^- and NR⁴⁺, which is the critical factor for the outstanding performance of Zn(betaine)₂Br₂. The unique features of the catalyst are that it is cheap, green and very easy to prepare.

L-Proline nitrate: An Efficient Amino Acid Ionic Liquid Catalyzed Synthesis of 5-aryl-[1, 2, 4]-triazolidine-3-thiones

Abstract:

An environmentally benign, simple, rapid synthesis of 1,2,4-triazolidine-3-thiones at room temperature is reported using amino acid-derived Brønsted acidic ionic liquid L-proline nitrate [Pro+NO3-] from aldehyde and thiosemicarbazide in an aqueous medium. A cost-effective and energy-efficient catalyst with the reusability of up to five cycles without significant loss in the catalytic activity makes this protocol superior. A faster reaction, easy work-up with excellent yields are the added advantages of this protocol.

Photopolymerized superhydrophobic hybrid coating enabled by dual-purpose tetrapodal ZnO for liquid/liquid separation

Low-cost and scalable superhydrophobic coating methods provide viable approaches for energy-efficient separation of immiscible liquid/liquid mixtures. A scalable photopolymerization method is developed to functionalize porous substrates with a hybrid coating of tetrapodal ZnO (T-ZnO) and polymethacrylate, which exhibits simultaneous superhydrophobicity and superoleophilicity. Here, T-ZnO serves dual purposes by (i) initiating radical photopolymerization during the fabrication process through a hole-mediated pathway and (ii) providing a hierarchical surface roughness to amplify wettability characteristics and suspend liquid droplets in the metastable Cassie-Baxter regime. Photopolymerization provides a means to finely control the conversion and spatial distribution of the formed polymer, whilst allowing for facile large-area fabrication and potential coating on heat-sensitive substrates. Coated stainless-steel meshes and filter papers with desired superhydrophobic/superoleophilic properties exhibit excellent performance in separating stratified oil/water, oil/ionic-liquid, and water/ionic-liquid mixtures as well as water-in-oil emulsions. The hybrid coating demonstrates desired mechanical robustness and chemical resistance for their long-term application in large-scale energy-efficient separation of immiscible liquid/liquid mixtures.

Ammonium ionic liquid cation promotes electrochemical CO2 reduction to ethylene over formate while inhibiting the hydrogen evolution on a copper electrode

The tetraethylammonium cation promotes the CO2RR to ethylene over formate and inhibits the HER on a copper electrode.

Ionic Liquid-Based Extraction System for In-Depth Analysis of Membrane Protein Complexes

Limited by the rare efficient extraction system in extracting hydrophobic membrane protein complexes (MPCs) without compromising the stability of protein-protein interactions (PPIs), the in-depth functional study of MPCs has lagged far behind. In this study, the first systematic screening of ionic liquids (ILs) was performed and showed that triethylammonium acetate (TEAA) IL exhibited excellent performance in stabilizing PPIs, which was further confirmed by molecular docking simulations. By combining TEAA with the conventional detergent Nonidet P-40 (NP-40), a novel IL-based extraction system, i-TAN (TEAA IL with 1% NP-40), was proposed, which demonstrated superior performance in extracting and stabilizing MPCs, attributed to its larger size, more uniform distribution, and closer-to-neutral microenvironment of micelles. Extraction of MPCs with i-TAN allowed the confident identification of more hydrophobic EGFR-interacting proteins that are easily dissociated during the extraction process. Quantitative analysis of the difference in EGFR complexes between trastuzumab-sensitive and trastuzumab-resistant breast cancer cells provided comprehensive insights to understand the drug resistance mechanism, suggesting that i-TAN has great potential in interactomics and functional analysis of MPCs. This study provides a novel strategy for MPC extraction and downstream processing.

Elucidation of the Roles of Ionic Liquid in CO2 Electrochemical Reduction to Value-Added Chemicals and Fuels

The electrochemical reduction of carbon dioxide (CO₂ER) is amongst one the most promising technologies to reduce greenhouse gas emissions since carbon dioxide (CO₂) can be converted to value-added products. Moreover, the possibility of using a renewable source of energy makes this process environmentally compelling. CO₂ER in ionic liquids (ILs) has recently attracted attention due to its unique properties in reducing overpotential and raising faradaic efficiency. The current literature on CO₂ER mainly reports on the effect of structures, physical and chemical interactions, acidity, and the electrode–electrolyte interface region on the reaction mechanism. However, in this work, new insights are presented for the CO₂ER reaction mechanism that are based on the molecular interactions of the ILs and their physicochemical properties. This new insight will open possibilities for the utilization of new types of ionic liquids. Additionally, the roles of anions, cations, and the electrodes in the CO₂ER reactions are also reviewed.

A Preliminary Assessment of the ‘Greenness’ of Halide-Free Ionic Liquids—An MCDA Based Approach

With the growing interests in non-aqueous media for diversified applications, ionic liquids (ILs) are frequently considered as green solvents. While the environmental, health, and safety assessments of the commercially developed ILs and their ‘greenness’ status are in debate, research focus is shifting towards the application of halide-free ILs for diversified applications. To clarify the situation on their greenness, and to understand if they really possess safe characteristics, we performed an initial assessment of 193 halide free ionic liquids composed of four groups of cations (imidazolium, pyridinium, pyrrodilinium, piperidinum) and 5 groups of anions (acetate, propionate, butyrate, alkanesulfonates, alkylsulfates). The ‘Technique for Order of Preference by Similarity to Ideal Solutions’ (TOPSIS), a multi-criteria decision analysis (MCDA) tool that allows ranking many alternatives is applied by carrying out the assessment against 14 criteria that includes hazard statements, precautionary statements, biodegradability, and toxicity towards different organisms. The ranking results obtained against the set of criteria considered show that the halide free ILs placed between recommended polar solvents: methanol and ethanol can be considered to be safer alternatives in terms of ‘greenness’. The study in this work provides an initial assessment of the halide-free ionic liquids evaluated against 14 criteria in terms of their safety characteristics (“green character”) using the MCDA-TOPSIS approach.

Lanthanide-Doped Luminescent Nanophosphors via Ionic Liquids

Lanthanide (Ln3+) ion(s)-doped or rare-earth ion(s)-doped nanomaterials have been considered a very important class of nanophosphors for various photonic and biophotonic applications. Unlike semiconductors and organic-based luminescent particles, the optical properties of Ln3+-doped nanophosphors are independent of the size of the nanoparticles. However, by varying the crystal phase, morphology, and lattice strain of the host materials along with making core-shell structure, the relaxation dynamics of dopant Ln3+ ions can be effectively tuned. Interestingly, a judicious choice of dopant ions leads to unparallel photophysical dynamics, such as quantum cutting, upconversion, and energy transfer. Recently, ionic liquids (ILs) have drawn tremendous attention in the field of nanomaterials synthesis due to their unique properties like negligible vapor pressure, nonflammability, and, most importantly, tunability; thus, they are often called "green" and "designer" solvents. This review article provides a critical overview of the latest developments in the ILs-assisted synthesis of rare-earth-doped nanomaterials and their subsequent photonic/biophotonic applications, such as energy-efficient lighting and solar cell applications, photodynamic therapy, and in vivo and in vitro bioimaging. This article will emphasize how luminescence dynamics of dopant rare-earth ions can be tuned by changing the basic properties of the host materials like crystal phase, morphology, and lattice strain, which can be eventually tuned by various properties of ILs such as cation/anion combination, alkyl chain length, and viscosity. Last but not least, different aspects of ILs like their ability to act as templating agents, solvents, and reaction partners and sometimes their "three-in-one" use in nanomaterials synthesis are highlighted along with various photoluminescence mechanisms of Ln3+ ion like up- and downconversion (UC and DC).

Ionic Liquids and Deep Eutectic Solvents for CO2 Conversion Technologies-A Review

Ionic liquids (ILs) have a wide range of potential uses in renewable energy, including CO2 capture and electrochemical conversion. With the goal of providing a critical overview of the progression, new challenges, and prospects of ILs for evolving green renewable energy processes, this review emphasizes the significance of ILs as electrolytes and reaction media in two primary areas of interest: CO2 electroreduction and organic molecule electrosynthesis via CO2 transformation. Herein, we briefly summarize the most recent advances in the field, as well as approaches based on the electrochemical conversion of CO2 to industrially important compounds employing ILs as an electrolyte and/or reaction media. In addition, the review also discusses the advances made possible by deep eutectic solvents (DESs) in CO2 electroreduction to CO. Finally, the critical techno-commercial issues connected with employing ILs and DESs as an electrolyte or ILs as reaction media are reviewed, along with a future perspective on the path to rapid industrialization.

Triethylammonium Hydrogen Sulfate [Et3NH][HSO4]-Catalyzed Rapid and Efficient Multicomponent Synthesis of Pyrido[2,3-d]pyrimidine and Pyrazolo[3,4-b]pyridine Hybrids

An operationally simple, one-pot multicomponent reaction has been developed for the assembly of pyrido[2,3-d]pyrimidine and pyrazolo[3,4-b]pyridine derivatives (4a-4am) in excellent yields (92-94%) with high purity. The reactions were easy to perform simply by mixing of electron-rich amino heterocycles (including aminouracils and aminopyrazoles), aldehyde, and acyl acetonitrile in the presence of [Et3NH][HSO4] under solvent-free conditions. The remarkable feature of the present approach is that the ionic liquid possesses dual solvent-catalytic engineering capability. Results of this study revealed that 1 mmol of the ionic liquid catalyst under solvent-free conditions at 60 °C is the best reaction parameter for the construction of fused pyridine and pyrimidine derivatives in excellent yields. The present methodology showed good results under gram-scale conditions, thereby indicating its applicability in industrial as well as academic settings in the near future.

Oxidative Dissolution of Metals in Organic Solvents

Dissolution of metals in organic solvents is relevant to various application fields, such as metal extraction from ores or secondary resources, surface etching or polishing of metals, direct synthesis of organometallic compounds, and separation of metals from other compounds. Organic solvents for dissolution of metals can offer a solution when aqueous systems fail, such as separation of metals from metal oxides, because both the metal and metal oxide could codissolve in aqueous acidic solutions. This review critically discusses organic media (conventional molecular organic solvents, ionic liquids, deep-eutectic solvents and supercritical carbon dioxide) for oxidative dissolution of metals in different application areas. The reaction mechanisms of dissolution processes are discussed for various lixiviant systems which generally consist of oxidizing agents, chelating agents, and solvents. Different oxidizing agents for dissolution of metals are reviewed such as halogens, halogenated organics, donor-acceptor electron-transfer systems, polyhalide ionic liquids, and others. Both chemical and electrochemical processes are included. The review can guide researchers to develop more efficient, economic, and environmentally friendly processes for dissolution of metals in their elemental state.

Nanoheterogeneity of LiTFSI Solutions Transitions Close to a Surface and with Concentration

Water-in-salt (WIS) electrolytes composed of 21 m LiTFSI have recently emerged as a safe and environmentally friendly alternative to conventional organic electrolytes in Li-ion batteries. Several studies have emphasized the relation between the high conductivity of WIS electrolytes and their nanoscale structure. Combining force measurements with a surface forces apparatus and atomic force microscopy, this study describes the nanoheterogeneity of LiTFSI solutions as a function of concentration and distance from a negatively charged (mica) surface. We report various nanostructures coexisting in the WIS electrolyte, whose size increases with concentration and is influenced by the proximity of the mica surface. Two key concentration thresholds are identified, beyond which a transition of behavior is observed. The careful scrutinization on the concentration-dependent nanostructures lays groundwork for designing novel electrolytes in future energy storage devices.

Bifunctional Catalysts Containing Zn(II) and Imidazolium Salt Ionic Liquids for Chemical Fixation of Carbon Dioxide

Zn(II) can efficiently promote the catalytic performance of imidazolium salt ionic liquids (imi-ILs) for the chemical fixation of CO₂ into epoxides. To obtain sustainability, immobilized bifunctional catalysts containing both imi-ILs and Zn(II) were prepared using bimodal mesoporous silica (BMMs) as carrier, through grafting of Zn(OAc)₂ and 1-(trimethoxysilyl)propyl-3-methylimidazolium chloride (Si-imi) separately in the nanopores. The catalysts, named as BMMs-Zn&ILs, were identified as efficient catalysts for cycloaddition reaction of CO₂ into epoxides under solvent-free conditions. BMMs-Zn&ILs showed good catalytic activity, which increased with the increase of the molar ratio of Zn(II) to Si-imi. As a comparison, different catalytic systems including homogeneous imi-IL, BMMs-ILs and BMMs-Zn were studied to demonstrate different cooperation behaviors. Furthermore, the kinetics studies of homogeneous and heterogeneous bifunctional catalysts were employed to confirm the differences, as well as to support the proposed cooperative catalysis mechanism in the nanopores.