Adsorption Features of Flavonoids on Macroporous Adsorption Resins Functionalized with Ionic Liquids

A series of macroporous adsorption resins (MARs) with novel structures is synthesized via Friedel–Crafts catalyzed reaction. The adsorption kinetics of the synthetic resins with respect to the purification effect is systematically investigated by means of the response surface methodology (RSM). The kinetic data cannot be fitted to the classical model because it does not take multicompartments and desorption rates into consideration. A new multicompartment louver‐tide theory is thus developed considering that adsorption is an indefinite dynamic equilibrium process, which can be divided into innumerable ingredients with different desorption rates. This theory produces much better fits to the experimental data and provides a quantitative explanation with multicompartments and adsorption/desorption rates.     

Ionic‐Liquid‐Assisted Formation of Silver Nanowires

Down to the wire : A simple and effective method to synthesize silver nanowires through an ionic‐liquid‐assisted polyol process is developed (see scheme; scale bar=5 nm). The ionic liquids are tuned to provide the anisotropic growth of silver nanoparticles into nanowires.

     

Ionic‐Liquid‐Based Polymer Electrolytes for Battery Applications

The advent of solid‐state polymer electrolytes for application in lithium batteries took place more than four decades ago when the ability of polyethylene oxide (PEO) to dissolve suitable lithium salts was demonstrated. Since then, many modifications of this basic system have been proposed and tested, involving the addition of conventional, carbonate‐based electrolytes, low molecular weight polymers, ceramic fillers, and others. This Review focuses on ternary polymer electrolytes, that is, ion‐conducting systems consisting of a polymer incorporating two salts, one bearing the lithium cation and the other introducing additional anions capable of plasticizing the polymer chains. Assessing the state of the research field of solid‐state, ternary polymer electrolytes, while giving background on the whole field of polymer electrolytes, this Review is expected to stimulate new thoughts and ideas on the challenges and opportunities of lithium‐metal batteries.     

Microenvironment Effects in Electrocatalysis: Ionic‐Liquid‐Like Coating on Carbon Nanotubes Enhances the Pd‐Electrocatalytic Alcohol Oxidation

A new catalyst consisting of ionic liquid (IL)‐functionalized carbon nanotubes (CNTs) obtained through 1,3‐dipolar cycloaddition support‐enhanced electrocatalytic Pd nanoparticles (Pd@IL(Cl^?)‐CNTs) was successfully fabricated and applied in direct ethanol alkaline fuel cells. The morphology, structure, component and stability of Pd@IL(Cl^?)‐CNTs were systematic characterized by transmission electron microscopy (TEM), high‐resolution transmission electron microscopy (HRTEM), Raman spectra, thermogravimetric analysis (TGA) and X‐ray diffraction (XRD). The new catalyst exhibited higher electrocatalytic activity, better tolerance and electrochemical stability than the Pd nanoparticles (NPs) immobilized on CNTs (Pd@CNTs), which was ascribed to the effects of the IL, larger electrochemically active surface area (ECSA), and greater processing performance. Cyclic voltammograms (CVs) at various scan rates illustrated that the oxidation behaviors of ethanol at all electrodes were controlled by diffusion processes. The investigation of the different counteranions demonstrated that the performance of the IL‐CNTs hybrid material was profoundly influenced by the subtly varied structures of the IL moiety. All the results indicated that the Pd@IL(Cl^?)‐CNTs catalyst is an efficient anode catalyst, which has potential applications in direct ethanol fuel cells and the strategy of IL functionalization of CNTs could be available to prepare other carbonaceous carrier supports to enhance the dispersivity, stability, and catalytic performance of metal NPs as well.     

Triphilic Ionic‐Liquid Mixtures: Fluorinated and Non‐fluorinated Aprotic Ionic‐Liquid Mixtures

We present here the possibility of forming triphilic mixtures from alkyl‐ and fluoroalkylimidazolium ionic liquids, thus, macroscopically homogeneous mixtures for which instead of the often observed two domains—polar and nonpolar—three stable microphases are present: polar, lipophilic, and fluorous ones. The fluorinated side chains of the cations indeed self‐associate and form domains that are segregated from those of the polar and alkyl domains. To enable miscibility, despite the generally preferred macroscopic separation between fluorous and alkyl moieties, the importance of strong hydrogen bonding is shown. As the long‐range structure in the alkyl and fluoroalkyl domains is dependent on the composition of the liquid, we propose that the heterogeneous, triphilic structure can be easily tuned by the molar ratio of the components. We believe that further development may allow the design of switchable, smart liquids that change their properties in a predictable way according to their composition or even their environment.     

Ionic‐Liquid‐Based Acidic Aqueous Biphasic Systems for Simultaneous Leaching and Extraction of Metallic Ions

The first instance of an acidic aqueous biphasic system (AcABS) based on tributyltetradecyl phosphonium chloride ([P₄₄₄₁₄][Cl]) and an acid is here reported. This AcABS exhibits pronounced thermomorphic behavior and is shown to be applicable to the extraction of metal ions from concentrated acidic solutions. Metal ions such as cobalt(II), iron(III), platinum(IV) and nickel(II) are found to partition preferentially to one of the phases of the acidic aqueous biphasic system and it is here shown that it successfully allows the difficult separation of Co^II from Ni^II, here studied at 24 and 50 °C.     

Ionic‐Liquid–Nanoparticle Hybrid Electrolytes: Applications in Lithium Metal Batteries

Development of rechargeable lithium metal battery (LMB) remains a challenge because of uneven lithium deposition during repeated cycles of charge and discharge. Ionic liquids have received intensive scientific interest as electrolytes because of their exceptional thermal and electrochemical stabilities. Ionic liquid and ionic‐liquid–nanoparticle hybrid electrolytes based on 1‐methy‐3‐propylimidazolium (IM) and 1‐methy‐3‐propylpiperidinium (PP) have been synthesized and their ionic conductivity, electrochemical stability, mechanical properties, and ability to promote stable Li electrodeposition investigated. PP‐based electrolytes were found to be more conductive and substantially more efficient in suppressing dendrite formation on cycled lithium anodes; as little as 11 wt % PP‐IL in a PC‐LiTFSI host produces more than a ten‐fold increase in cell lifetime. Both PP‐ and IM‐based nanoparticle hybrid electrolytes provide up to 10 000‐fold improvements in cell lifetime than anticipated based on their mechanical modulus alone. Galvanostatic cycling measurements in Li/Li₄Ti₅O₁₂ half cells using IL–nanoparticle hybrid electrolytes reveal more than 500 cycles of trouble‐free operation and enhanced rate capability.     

The Microwave‐Assisted Ionic‐Liquid Method: A Promising Methodology in Nanomaterials

In recent years, the microwave‐assisted ionic‐liquid method has been accepted as a promising methodology for the preparation of nanomaterials and cellulose‐based nanocomposites. Applications of this method in the preparation of cellulose‐based nanocomposites comply with the major principles of green chemistry, that is, they use an environmentally friendly method in environmentally preferable solvents to make use of renewable materials. This minireview focuses on the recent development of the synthesis of nanomaterials and cellulose‐based nanocomposites by means of the microwave‐assisted ionic‐liquid method. We first discuss the preparation of nanomaterials including noble metals, metal oxides, complex metal oxides, metal sulfides, and other nanomaterials by means of this method. Then we provide an overview of the synthesis of cellulose‐based nanocomposites by using this method. The emphasis is on the synthesis, microstructure, and properties of nanostructured materials obtained through this methodology. Our recent research on nanomaterials and cellulose‐based nanocomposites by this rapid method is summarized. In addition, the formation mechanisms involved in the microwave‐assisted ionic‐liquid synthesis of nanostructured materials are discussed briefly. Finally, the future perspectives of this methodology in the synthesis of nanostructured materials are proposed.     

Ionic‐Liquid‐Mediated Active‐Site Control of MoS2 for the Electrocatalytic Hydrogen Evolution Reaction

The layered crystal MoS₂ has been proposed as an alternative to noble metals as the electrocatalyst for the hydrogen evolution reaction (HER). However, the activity of this catalyst is limited by the number of available edge sites. It was previously shown that, by using an imidazolium ionic liquid as synthesis medium, nanometre‐size crystal layers of MoS₂ can be prepared which exhibit a very high number of active edge sites as well as a de‐layered morphology, both of which contribute to HER electrocatalytic activity. Herein, it is examined how to control these features synthetically by using a range of ionic liquids as synthesis media. Non‐coordinating ILs with a planar heterocyclic cation produced MoS₂ with the de‐layered morphology, which was subsequently shown to be highly advantageous for HER electrocatalytic activity. The results furthermore suggest that the crystallinity, and in turn the catalytic activity, of the MoS₂ layers can be improved by employing an IL with specific solvation properties. These results provide the basis for a synthetic strategy for increasing the HER electrocatalytic activity of MoS₂ by tuning its crystal properties, and thus improving its potential for use in hydrogen production technologies.     

Adsorption and Desorption Characteristics of Total Flavonoids from Acanthopanax senticosus on Macroporous Adsorption Resins

We examined the application of six different resins with the aim of selecting a macroporous resin suitable for purifying Acanthopanax senticosus total flavonoids (ASTFs) from Acanthopanax senticosus crude extract (EAS) by comparing their adsorption/desorption capacities, which led to the selection of HPD-600. Research on the adsorption mechanism showed that the adsorption process had pseudo-second-order kinetics and fit the Freundlich adsorption model. Moreover, the analysis of thermodynamic parameters indicated that the adsorption process is spontaneous and endothermic. The optimal conditions for purification of ASTFs were determined as sample pH of 3, 60% ethanol concentration, and 3 BV·h⁻¹ flow rate, for both adsorption and desorption, using volumes of 2.5 and 4 BV, respectively. The application of macroporous resin HPD-600 to enrich ASTFs resulted in an increase in the purity of total flavonoids, from 28.79% to 50.57%. Additionally, the antioxidant capacity of ASTFs was higher than that of EAS, but both were lower than that of L-ascorbic acid. The changes in ASTFs compositions were determined using ultra-performance liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS), with the results illustrating that the levels of seven major flavonoids of ASTFs were increased compared to that in the crude extract.     

Impedance Analysis of Inherently Redox‐Active Ionic‐Liquid‐Based Photoelectrochemical Cells: Charge‐Transfer Mechanism in the Presence of an Additional Redox Couple

An intensive electrochemical impedance study was carried out to understand the charge‐transfer processes in photoelectrochemical (PEC) cells based on ionic liquid (IL) electrolytes. Three different electrolytes were utilized to understand the role of redox species as well as the medium on the charge‐transfer mechanism. The negligible diffusion resistance, despite the presence of two different redox species in the case of Fe(CN)₆^?4/?3 in IL, was explained on the basis of charge transfer between species of two different redox couples. Accordingly, the redox species are not required to travel through the bulk of the electrolyte for the removal of accumulated charges, as short‐range charge transfer between the IL and the Fe(CN)₆^?4/?3 species facilitates the removal of accumulated charges. It is also shown that PEC cells utilizing dual redox couples are highly stable with larger photoelectrochmeical windows, >3 V.     

Proton‐Transfer Reactions of Acridine in Water‐Containing Ionic‐Liquid‐Rich Mixtures

To assess the potential of ionic liquids (ILs) as a solubilizing media that facilitates proton‐transfer reactions, acridine prototropism is investigated using UV/Vis molecular absorbance as well as steady‐state and time‐resolved fluorescence with different ILs in the presence of a small amount of dilute acid or base. It is found that protonation and deprotonation of acridine, when dissolved in different ILs, can be triggered by the addition of a small amount of dilute aqueous HCl and NaOH, respectively, in both the ground and excited states, irrespective of the identity of the IL. However, the amount of dilute acid/base needed to protonate/deprotonate acridine dissolved in different ILs is found to vary from one IL to another. Steady‐state fluorescence measurements also imply the presence of interactions between the acidic proton(s) of IL cation and excited acridine. The interconversion of neutral and protonated acridine, as well as the presence of a weakly fluorescent complex between excited acridine and the acidic proton(s) of the IL cation, is further corroborated by the parameters recovered from the fitting of the excited‐state intensity‐decay data. It is established that ILs as solubilizing media readily support facile proton transfer in both ground and excited states.     

Ionic‐Liquid‐Grafted Rigid Poly(p‐Phenylene) Microspheres: Efficient Heterogeneous Media for Metal Scavenging and Catalysis

Novel guanidinium ionic liquid‐grafted rigid poly(p‐phenylene) (PPPIL) microspheres have been developed for metal scavenging and catalysis. The noble‐metal nanoparticles supported on the microspheres surface can be used as efficient heterogeneous catalysts. The combination of nanoparticles and ionic liquid fragments on the microsphere surfaces enhance the activity and durability of the catalyst. The PPPIL ? Pd⁰ catalyst has been tested in the Suzuki cross‐coupling reaction, and exhibits much higher catalytic activity than Pd catalysts supported on porous polymer matrices. The PPPIL ? Pd⁰ catalyst can be recycled at least for nine runs without any significant loss of activity. The present approach may, therefore, have potential applications in transition‐metal‐nanocatalyzed reactions.     

大孔吸附树脂对款冬花总黄酮的吸附分离特性

选择6种大孔吸附树脂,比较其对款冬花总黄酮的吸附量,解吸率及吸附动力学特性,筛选出较优的款冬花黄酮吸附树脂.结果表明：在静态吸附和动态吸附实验中均以SP825具有较优的吸附和解吸效果.     

Ionic‐Liquid‐Assisted Synthesis of Uniform Fluorinated B/C‐Codoped TiO2 Nanocrystals and Their Enhanced Visible‐Light Photocatalytic Activity

Exploiting advanced photocatalysts under visible light is of primary significance for the development of environmentally relevant photocatalytic decontamination processes. In this study, the ionic liquid (IL), 1‐butyl‐3‐methylimidazolium tetrafluoroborate, was employed for the first time as both a structure‐directing agent and a dopant for the synthesis of novel fluorinated B/C‐codoped anatase TiO₂ nanocrystals (T_IL) through hydrothermal hydrolysis of tetrabutyl titanate. These T_IL nanocrystals feature uniform crystallite and pore sizes and are stable with respect to phase transitions, crystal ripening, and pore collapse upon calcination treatment. More significantly, these nanocrystals possess abundant localized states and strong visible‐light absorption in a wide range of wavelengths. Because of synergic interactions between titania and codopants, the calcined T_IL samples exhibited high visible‐light photocatalytic activity in the presence of oxidizing Rhodamine B (RhB). In particular, 300 °C‐calcined T_IL was most photocatalytically active; its activity was much higher than that of TiO_1.98N_0.02 and reference samples (T_W) obtained under identical conditions in the absence of ionic liquid. Furthermore, the possible photocatalytic oxidation mechanism and the active species involved in the RhB degradation photocatalyzed by the T_IL samples were primarily investigated experimentally by using different scavengers. It was found that both holes and electrons, as well as their derived active species, such as ^.OH, contributed to the RhB degradation occurring on the fluorinated B/C‐codoped TiO₂ photocatalyst, in terms of both the photocatalytic reaction dynamics and the reaction pathway. The synthesis of the aforementioned novel photocatalyst and the identification of specific active species involved in the photodegradation of dyes could shed new light on the design and synthesis of semiconductor materials with enhanced photocatalytic activity towards organic pollutants.     

Controlling the Formation of Ionic‐Liquid‐based Aqueous Biphasic Systems by Changing the Hydrogen‐Bonding Ability of Polyethylene Glycol End Groups

The formation of aqueous biphasic systems (ABS) when mixing aqueous solutions of polyethylene glycol (PEG) and an ionic liquid (IL) can be controlled by modifying the hydrogen‐bond‐donating/‐accepting ability of the polymer end groups. It is shown that the miscibility/immiscibility in these systems stems from both the solvation of the ether groups in the oxygen chain and the ability of the PEG terminal groups to preferably hydrogen bond with water or the anion of the salt. The removal of even one hydrogen bond in PEG can noticeably affect the phase behavior, especially in the region of the phase diagram in which all the ethylene oxide (EO) units of the polymeric chain are completely solvated. In this region, removing or weakening the hydrogen‐bond‐donating ability of PEG results in greater immiscibility, and thus, in a higher ability to form ABS, as a result of the much weaker interactions between the IL anion and the PEG end groups.     

Fullerene–Ionic‐Liquid Conjugates: A New Class of Hybrid Materials with Unprecedented Properties

A modular approach has been followed for the synthesis of a series of fullerene–ionic‐liquid (IL) hybrids in which the number of IL moieties (two or twelve), anion, and cation have been varied. The combination of C₆₀ and IL give rise to new unique properties in the conjugates such as solubility in water, which was higher than 800 mg mL^?1 in several cases. In addition, one of the C₆₀–IL hybrids has been employed for the immobilization of palladium nanoparticles through ion exchange followed by reduction with sodium borohydride. Surprisingly, during the reduction several carbon nanostructures were formed that comprised nano‐onions and nanocages with few‐layer graphene sidewalls, which have been characterized by means of thermogravimetric analysis (TGA), X‐ray photoelectron spectroscopy (XPS), X‐ray diffraction (XRD), scanning electron microscopy/energy‐dispersive X‐ray analysis (SEM‐EDAX), and high‐resolution transmission electron microscopy (HRTEM). Finally, the material thus obtained was successfully applied as catalyst in Suzuki and Mizoroki–Heck reactions in a concentration of just 0.2 mol %. In the former process it was recyclable for five runs with no loss in activity.     

On the Dynamic Interaction of n‐Butane with Imidazolium‐Based Ionic Liquids

The impact of a reactant from the gas phase on the surface of a liquid and its transfer through this gas/liquid interface are crucial for various concepts applying ionic liquids (ILs) in catalysis. We investigated the first step of the adsorption dynamics of n‐butane on a series of 1‐alkyl‐3‐methylimidazolium bis(trifluoromethanesulfonyl)imide ILs ([C_nC₁Im][Tf₂N]; n=1, 2, 3, 8). Using a supersonic molecular beam in ultra‐high vacuum, the trapping of n‐butane on the frozen ILs was determined as a function of surface temperature, between 90 and 125 K. On the C₈‐ and C₃‐ILs, n‐butane adsorbs at 90 K with an initial trapping probability of ≈0.89. The adsorption energy increases with increasing length of the IL alkyl chain, whereas the ionic headgroups seem to interact only weakly with n‐butane. The absence of adsorption on the C₁‐ and C₂‐ILs is attributed to a too short residence time on the IL surface to form nuclei for condensation even at 90 K.