Acid-functionalized Ionic Liquid Research Articles

Sulfonic Acid Functionalized Ionic Liquids for Defect Passivation via Molecular Interactions for High-Quality Perovskite Films and Stable Solar Cells.

The high photoelectric conversion efficiency and low cost of perovskite solar cells (PSCs) have further inspired people's determination to push this technology toward industrialization. The high-quality perovskite films and high-efficiency and stable PSCs are the crucial factors. Ionic liquids have been proven to be an effective strategy for regulating high-quality perovskite films and high-performance PSCs. However, the regulation mechanism between ionic liquids and perovskites still needs further clarification. In this study, a novel sulfonic acid-functionalized ionic liquid, 1-butyl-3-methylimidazolium trifluoromethanesulfonate (BSO3HMImOTf), was used as an effective additive to regulate high-quality perovskite films and high-performance devices. Microscopic mechanism studies revealed strong interactions between BSO3HMImOTf and Pb2+ ions as well as halogens in the perovskite. The perovskite film is effectively passivated with the controlled crystal growth, suppressed ion migration, facilitating to the greatly improved photovoltaic performance, and superior long-term stability. This article reveals the regulatory mechanism of sulfonic acid type ionic liquids through testing characterization and mechanism analysis, providing a new approach for the preparation of high-quality perovskite devices.

Incorporation of Amino Acid-Functionalized Ionic Liquids into Highly Porous MOF-177 to Improve the Post-Combustion CO2 Capture Capacity.

This study presents the encapsulation of two amino acid-based ionic liquids (AAILs), 1-ethyl-3-methylimidazolium glycine [Emim][Gly] and 1-ethyl-3-methylimidazolium alanine [Emim][Ala], in a highly porous metal-organic framework (MOF-177) to generate state-of-the-art composites for post-combustion CO2 capture. Thermogravimetric analysis (TGA) demonstrated a successful encapsulation of the AAILs, with a dramatic reduction in the composites' surface areas and pore volumes. Both [Emim][Gly]@MOF-177 and [Emim][Ala]@MOF-177 had close to three times the CO2 uptake of MOF-177 at 20 wt.% loading, 0.2 bar, and 303 K. Additionally, 20-[Emim][Gly]@MOF-177 and 20-[Emim] [Ala]@MOF-177 enhanced their CO2/N2 selectivity from 5 (pristine MOF-177) to 13 and 11, respectively.

Amino-anchored sulfonic acid-functionalized heteropolyacid ionic liquid: A highly selective and recyclable catalyst for the Baeyer-Villiger oxidation of cyclohexanone

A novel amino-anchored sulfonic acid functional heteropolyacid ionic liquid ([NHSO]3PW12O40) was designed, synthesized and used as a catalyst in the Baeyer-Villiger (BV) oxidation of cyclohexanone to synthetic ε-caprolactone (ε-CL). The catalyst was well characterized by FT-IR, XRD, 1H NMR, XPS, TG-DTA and SEM analysis methods, which showed that the tungsten phosphate anion (PW12O403−) was successfully modified from the sulphonate-functionalised IL precursor NHSO and formed a new hydrogen bond between the introduced –NH2 group and PW12O403−. The combined effect of ionic bonds and hydrogen bonds contributed to the good stability of the catalyst. Catalyst activity evaluation experiments confirmed that [NHSO]3PW12O40 exhibited superior performances such as a cyclohexanone conversion of 86% and ε-CL yield and selectivity of 82% and 95%, respectively. Furthermore, [NHSO]3PW12O40 could be recovered by simple treatment and the activity of the catalyst did not decrease significantly after five replicae experiments. In addition, the reaction kinetics and mechanism of the catalyst were investigated and a simple validation was given in conjunction with the bond energy changes of the catalyst during the reaction. The innovative of the green, stable and high-performance functionalised heteropolyacid IL catalyst provides a new solution for the efficient production of ε-CL.

Synthesis, measurement, and correlation study of physico-chemical properties of diethanolamine glycinate ionic liquid as a solvent for CO2 capture units

Amino acid-functionalized ionic liquids (ILs), known as environmentally green non-molecular solvents, have been particular interested in the CO2 capture processes due to their unique physico-chemical properties. Proper development of CO2 capture processes utilizing amino-functionalized ILs, requires the exact determination of the ILs’ physico-chemical properties. In this paper, a novel amino acid-functionalized IL, namely diethanolamine glycinate ([DEA][GLY]), was synthesized and then characterized via Nuclear Magnetic Resonance (H NMR) and Fourier Transform Infrared (FT-IR) spectroscopy analysis. The density, dynamic viscosity, and surface tension were experimentally measured over the temperature range of 303.15–323.15 K and a wide verity of IL concentrations from 5 to 25 wt% of IL aqueous solution under atmospheric pressure. Furthermore, simple but reliable correlations with minimum input variables were implemented to model the density, dynamic viscosity, and surface tension data of the binary mixtures of [DEA][GLY] + H2O in terms of temperature and composition. Regarding the statistical criteria, it was indicated that the two-descriptor-based models could well describe the effect of temperature in different concentrations of the glycine amino acid-functionalized IL compared with those single temperature-dependent correlations.

Preparation of sulfonic acid-functionalized polymeric ionic liquid-based magnetic adsorbent and its applications to diquat extraction

有效萃取复杂食品样品中的极性污染物是实现其准确测定的瓶颈,也是食品安全分析的难点。针对污染物的结构特点,设计和发展能与之产生特定作用的新型材料是高效萃取的关键。敌草快是一种广谱性除草剂,为碱性的阳离子有机化合物。该文以1-乙烯基咪唑和1,3-丙磺酸内酯为原料合成了磺酸功能化的离子液体,通过自由基聚合反应,将其固载至磁性纳米颗粒表面,得到磺酸功能化的聚(1-乙烯基-3-丙基磺酸基咪唑氯盐)修饰的磁性纳米颗粒(Poly([VPImi-SO3H][Cl])-MP)。采用红外光谱、扫描电镜、振动样品磁强计和热重分析等对其结构、形貌和磁性进行了表征。将其作为磁性固相萃取的吸附剂,萃取青菜中的敌草快。磺酸基的功能化使Poly([VPImi-SO3H][Cl])-MP的表面在一定pH下带有丰富的负电荷,与敌草快之间产生强的静电吸引作用,可实现对敌草快的有效萃取。对影响萃取效率的各种参数如溶液pH、吸附剂质量、吸附时间、解吸剂种类和体积等进行了优化。在优化条件下,结合磁性固相萃取和高效液相色谱技术,对方法的性能及适用性进行了考察。敌草快在0.2~20 μg/g内具有良好的线性(r=0.9981),检出限(S/N=3)和定量限(S/N=10)分别为0.09 μg/g和0.2 μg/g; 3个水平(0.5、1.0和2.5 μg/g)下的加标回收率为82.7%~97.5%,相对标准偏差为2.8%~5.0%(n=3)。结果表明,磺酸功能化的Poly([VPImi-SO3H][Cl])-MP能快速、有效地萃取敌草快,建立的方法能用于青菜中敌草快的准确测定。

Metal-Free, Adjustable, and Recyclable Catalytic Systems for the Construction of C–C Bonds by Activating Propargylic Alcohols

Pyrano[3,2-c]coumarin derivatives and C3-substituted 4-hydroxycoumarins as important skeletal structures of active natural products and pharmaceutically relevant molecules have received increasing attention. However, developing an adjustable system for selectively synthesizing them is still a challenging task. Herein, sulfonic acid-functionalized ionic liquid was successfully used as the catalyst for the alkylation of 4-hydroxycoumarin derivatives with secondary aromatic propargylic alcohols using dimethyl carbonate as the green solvent, giving up to 98% yield. On the other hand, protonated imidazole-based ionic liquid-catalyzed cyclization was also selectively achieved with a nearly quantitative yield. Developed metal-free catalytic systems exhibited well adjustable and recyclable properties, avoiding the contamination of metal and halogen, reducing the neutralization after the reaction, and benefiting the separation between the catalyst and the product. New strategies were applied for performing the gram-scale reaction smoothly. The adjustable systems might occur through two different mechanisms involving propargylic or allenic carbocation and hydrogen bonding effects between the catalysts and the substrates.

Sustainable and Reusable Sulfonic Acid-Functionalized Task-Specific Ionic Liquid Catalysts for Multicomponent Reactions. A Review

Improvements in Sustainable Organic Synthesis are usually related to the investigation of less hazardous, non-corrosive and renewable materials, as well as waste prevention, energy efficiency, solvent-free reactions, and the development of efficient reusable catalysts. In this context, multicomponent reactions emerged as important strategies for the rapid and more sustainable synthesis of organic molecules. In addition, the use of task-specific ionic liquids as non-conventional solvents and/or catalysts in multicomponent reactions has recently received great attention, contributing to the development of greener synthetic methodologies. This review describes the studies on the use of structurally diverse homogeneous and heterogeneous sulfonic acid-functionalized task-specific ionic liquids as acidic catalysts for multicomponent reactions applied to the synthesis of nitrogen- and oxygen-based heterocycles, as well as related compounds. The combination of the green credentials of multicomponent reactions and acidic ionic liquids are able to improve process sustainability and green metrics, contributing to sustainable chemical development and, ultimately, to economic growth and cleaner industrial production.

Significant effects of the anion on the catalytic behaviour of sulfonic acid-functionalized ionic liquids in transesterification reactions – A combined electrochemical/catalytic study

• The counterion in sulfonated task-specific ionic liquids affects proton availability. • Protons at ionic liquid bases are more available in chlorides respect to bisulphates. • Chlorides of sulfonated imidazolic bases are intrinsically good acid catalysts. • Transesterification proceeds efficiently using chlorides of protic imidazolic bases. This work studies the strong influence of the counterion on the performance of ionic liquids (ILs) with sulfonic acid-functionalized butyl-imidazolic bases as homogeneous acid catalysts. Through a voltammetric analysis, it was shown that the availability of protons from the sulfonic acid groups in ILs with chloride and bisulphate anions is quite different, thus affecting their intrinsic activity as acid catalysts. The study was focused on the chlorides and bisulphates of 1-(4-sulfonic acid)-butyl-3-methylimidazolium ([bsmim]) and 1-(4-sulfonic acid)-butyl-imidazolium ([bsHim]), and the test reaction to evaluate these ILs as catalysts was the transesterification of p-nitrophenyl acetate with methanol. In ILs with counterion bisulphate, protons at the sulfonic acid groups are deeply involved in building the IL´s H-bonded network, so the acceptable catalytic activity for the tested reaction that was verified on these ILs was mostly sustained by the free sulphuric acid that was always present with the ionic pairs. On the contrary, ILs with chloride counterion conform more loosen networks where protons from the sulfonic acid groups are readily available and allow to efficiently catalyse the reaction, independently of the amounts of free hydrochloric acid that may be along with the ionic pair. Remarkably, the same contrast was verified in the catalytic performances of bisulphate and chloride of the non-sulfonated base 1-butyl-imidazolium ([bHim]), where the imidazolic hydrogen acted as an efficient acid catalyst only in [bHim]Cl.

Application of 2-methylfuran and 5-methylfurfural for the synthesis of C16 fuel precursor over fibrous silica-supported heteropoly acid-functionalized ionic liquid

Application of 2-methylfuran and 5-methylfurfural for the synthesis of C16 fuel precursor over fibrous silica-supported heteropoly acid-functionalized ionic liquid

Bifunctional acidic ionic liquid-catalyzed decarboxylative cascade synthesis of quinoxalines in water under ambient conditions

An acid-functionalized ionic liquid (IL)-catalyzed cascade decarboxylative cyclization of 2-arylanilines with α-oxocarboxylic acids was developed.

Insights on the catalytic behaviour of sulfonic acid-functionalized ionic liquids (ILs) in transesterification reactions - voltammetric characterization of sulfonic task-specific ILs with bisulfate anions.

This work shows for the first time the link between the amount of free sulfuric acid (as detected by cyclic voltammetry) and the activity of sulfonic-acid-functionalized ionic liquids (ILs) as acid catalysts for a transesterification reaction, and demonstrates that sulfonic acid groups, while are not directly involved in the catalysis, release the free acid during the reaction. Two imidazolic ILs with bisulfate as the counterion and their corresponding task-specific ILs (TSILs) that resulted from the addition of a sulfonic acid group inside the imidazolic-base structure were studied. The outstanding catalytic activity at room temperature of the TSILs 1-(4-sulfonic acid)-butyl-3-methylimidazolium bisulfate ([bsmim]HSO4) and 1-(4-sulfonic acid)-butyl-imidazolium bisulfate ([bsHim]HSO4) for the transesterification of p-nitrophenyl acetate with methanol was associated to the significant amounts of free sulfuric acid in equilibria with the ionic pairs. It was concluded that these TSILs function as reservoirs for releasing the free acid, which is the actual acid catalyst. In contrast, the corresponding non-sulfonic ILs supply very little amounts of free acid and consequently present low catalytic activities at room temperature, which in fact can be improved by increasing the reaction temperature up to 100 °C.

Hydroxy acid-functionalized ionic liquids as green alternatives for the efficient catalytic conversion of epoxides to cyclic carbonates under solvent and co-catalyst-free conditions

Environmentally friendly synthesis route of carbonates from CO2 and epoxides catalysed by novel hydroxy acid ionic liquids under metal/halogen/cocatalyst/solvent-free conditions.

Kinetics of phenol alkylation with tert-butyl alcohol using supported ionic liquid catalyst

Sulphonic acid functional ionic liquid was prepared by covalently bonded with mesoporous silica material (SBA-15). The physical structure, composition and functional groups were characterised. The prepared catalyst activity was investicated in tert-butylation of phenol with tert-butyl alcohol (TBA) was using a batch autoclave reactor. The different parameters like reaction time, reaction temperature, catalyst amount and reactant mole ratio on the conversion of phenol and selectivity towards 2‑tert-butyl phenol (4-TBP), 4‑tert‑butyl phenol (2-TBP) and 2,4-di‑tert‑butyl phenol (2,4-DTBP) was studied. Maximum phenol conversion of 72% was obtained at Lower tert‑butanol to phenol mole ratios and lower catalyst loading. The activation energy was found to be 4.2 kcal/mol with second order rate equation from the experimental data.

Synthesis of a series of novel dihydro-[1,2,4]triazolo [1,5-a]pyrimidine scaffolds: Dual solvent-catalyst activity of a low viscous and acid-functionalized ionic liquid

The viscosity of neat ionic liquids is very important for their application in organic synthesis as a solvent because most of the neat ionic liquids are very viscous, which would result in the less efficient mass transfer of reactants. In the present study, a series of novel dihydro-[1,2,4]triazolo[1,5-a]pyrimidines were prepared using a low viscous and acid-functionalized ionic liquid. Our results showed that new ionic liquid can act as a green solvent and acid catalyst due to low viscosity and acid functionality. The products were simply extracted and the ionic liquid was retrieved several times without reducing its catalytic efficiency. The current application of TMDPS in the one-pot multicomponent reactions as dual solvent-catalyst highlights the importance of low viscous acid-functionalized ionic liquids in organic synthesis, and we hope that further research will be conducted in the future to finding other applications of TMDPS with promising results.

Multi-spectroscopic monitoring of molecular interactions between an amino acid-functionalized ionic liquid and potential anti-Alzheimer's drugs.

Inhibiting the formation of amyloid fibrils is a crucial step in the prevention of the human neurological disorder, Alzheimer's disease (AD). Ionic liquid (IL) mediated interactions are an expedient approach that exhibits inhibition effects on amyloid fibrils. In view of the beneficial role of ILs, in this work we have explored complexation of anti-Alzheimer's drugs (i.e., tacrine and PC-37) and an amino acid-functionalized IL [AIL (4-PyC8)]. Maintaining standard physiological conditions, the binding mechanism, thermo-dynamical properties and binding parameters were studied by employing UV-vis, fluorescence, FTIR, 1H NMR, COSY and NOESY spectroscopy. The present investigation uncovers the fact that the interaction of anti-Alzheimer's drugs with 4-PyC8 is mediated through H-bonding and van der Waals forces. The Benesi–Hildebrand relation was used to evaluate the binding affinity and PC-37 showed the highest binding when complexed with 4-PyC8. FTIR spectra showed absorption bands at 3527.98 cm−1 and 3527.09 cm−1 for the PC-37 + 4-PyC8 system which is quite promising compared to tacrine. 1H-NMR experiments recorded deshielding for tacrine at relatively higher concentrations than PC-37. COSY investigations suggest that anti-Alzheimer's drugs after complexation with 4-PyC8 show a 1 : 1 ratio. The cross-peaks of the NOESY spectra involve correlations between anti-Alzheimer's drugs and AIL protons, indicating complexation between them. The observed results indicate that these complexes are expected to have a possible therapeutic role in reducing/inhibiting amyloid fibrils when incorporated into drug formulations.

Porous polymer microsphere functionalized with benzimidazolium based ionic liquids as effective solid catalysts for esterification

Abstract To prepare polymer supported ionic liquids (PSILs) as effective catalysts for esterification, the free radical suspension copolymerization of vinylbenzyl chloride (VBC, monomer), styrene (St, monomer) and divinylbenzene (DVB, crosslinker) with the addition of n-heptane (porogen) was carried out for the fabrication of the porous polymer (PVD) microsphere as support, followed by the immobilization of sulfonic acid-functionalized ionic liquids by the successive treatment of benzimidazole (BIm), 1,3-propane sultone and sulfuric acid (H2SO4) or trifluoromethanesulfonic acid (CF3SO3H). The effects of the compositions of DVB and n-heptane on the internal structure of the polymer supports were investigated, and it was found that the support with 40 wt% DVB and 60 wt% n-heptane (with relative to the monomer) could endow the final PSILs with the relatively optimal catalytic performance. The preliminary experiment in the batch reactor indicated that PSILs herein exhibited higher catalytic activities than commercial Amberlyst 46 resin for the esterification of propanoic acid (PROAc) with n-propanol (PROOH). Consequently, the optimal PSILs catalyst, PVD-[Bim-SO3H]HSO4, was selected for further study in the batch reactive distillation column because of low cost and its ease of preparation. The yield of propyl ropionate (PROPRO) could reach up to 97.78% at the optimized conditions of PROOH/PROAc molar ratio (2:1) and catalyst dosage (2.0 wt%). The investigation of the reaction kinetic manifested that the calculated results of second order pseudo-homogeneous kinetic model were in good agreement with experimental values. The pre-exponential factor and activation energy were 4.12 × 107 L·mol−1·min−1 and 60.57 kJ·mol−1, respectively. It is worth noting that the PSILs catalyst could be simply recovered and reused with relatively satisfactory decrease in the catalytic activity, which made it an environmental friendly and promising catalyst in the industrial application.

1,1′-Butylenebis(3-sulfo-3H-imidazol-1-ium) hydrogensulfate: a versatile task-specific ionic liquid catalyst for the synthesis of 4H-pyran scaffolds through non-conventional process

In the present study, the catalytic efficiency of 1,1′-butylenebis(3-sulfo-3H-imidazol-1-ium) hydrogensulfate (BBSI-HSO4) as a versatile sulfonic acid-functionalized ionic liquid was demonstrated for the one-pot mechanosynthesis of pyrano[4,3-b]-pyrans using planetary ball mill at room temperature under solvent-free conditions. This efficient mechanosynthesis approach to the 4H-pyran scaffolds displays a combination of the structure–activity relationship of ionic liquids with ecological benefits of a mechanocatalytic procedure. The ionic liquid was easily recycled and reused several times with no significant loss of its catalytic activity.

Theoretical Elucidation of β-O-4 Bond Cleavage of Lignin Model Compound Promoted by Sulfonic Acid-Functionalized Ionic Liquid.

While the depolymerization of lignin to chemicals catalyzed by ionic liquids has attracted significant attention, the relevant molecular mechanism, especially the cleavage of specific bonds related to efficient depolymerization, still needs to be deeply understood for the complexity of this natural aromatic polymer. This work presents a detailed understanding of the cleavage of the most abundant β-O-4 bond in the model system, guaiacylglycerol β-guaiacyl ether, by a Brønsted acidic IL (1-methyl-3-(propyl-3-sulfonate) imidazolium bisulfate ([C3SO3Hmim][HSO4]) using density functional theory calculation and molecular dynamics simulation. It has been found that [C3SO3Hmim][HSO4] generates zwitterion/H2SO4 via proton transfer with an energy barrier of 0.38 kcal/mol, which plays a dominant role in the lignin depolymerization process. Subsequently, the reaction can be carried out via three potential pathways, including (1) the dehydration of α-C-OH, (2) dehydration of γ-C-OH, and (3) the protonation of β-O. The electrophilic attack of H2SO4 and the hydrogen-bonding interaction between GG and zwitterion are the two most important factors to promote the depolymerization reaction. In all steps, the dehydration of α-C-OH route is computed to be favored for the experiment. The relatively higher energy barrier for β-O-4 bond dissociation among these reaction steps is attributed to the hindrance of the self-assembled clusters of GG in the mixed system. Further, the dense distribution of H13([C3SO3Hmim]) surrounding O21(GG), indicated by sharp peaks in RDFs, reveals that -SO3H in cations plays a substantial role in solvating lignin. Hopefully, this work will demonstrate new insights into lignin depolymerization by functionalized ILs in biomass conversion chemistry.

Synthesis of new low-viscous sulfonic acid-functionalized ionic liquid and its application as a Brönsted liquid acid catalyst for the one-pot mechanosynthesis of 4H-pyrans through the ball milling process

In the present study, a new low-viscous sulfonic acid-functionalized ionic liquid (SAIL) viz. 4,4′-trimethylene-N,N′-sulfonic acid-dipiperidinium chloride was synthesized and characterized by FTIR, 1D and 2D NMR, and Mass spectra. Then, some properties of new SAIL were determined including pH, viscosity, density, and solubility in some common solvents. The catalytic activity of new SAIL was demonstrated for the one-pot mechanosynthesis of pyrano[4,3-b]pyrans, dihydropyrano[3,2-c]chromene and tetrahydrobenzo[b]pyrans using planetary ball mill under solvent-free conditions. This current mechanosynthesis methodology for the synthesis of 4H-pyran-annulated heterocyclic scaffolds displays a combination of the synthetic virtues of conventional multi-component reaction with ecological benefits and convenience of a simple mechanocatalytic procedure. New SAIL was easily recycled and reused several times with no significant loss of activity.

Direct synthesis of 2,5-diformylfuran from carbohydrates via carbonizing polyoxometalate based mesoporous poly(ionic liquid)

A promising atom-effective heterogeneous catalyst derived from the partial carbonization of polyoxometalate based mesoporous poly(ionic liquid) was constructed for the direct (one-pot and one-step) conversion of carbohydrates into 2,5-diformylfuran (DFF). The carbon precursor was synthesized through the free radical copolymerization of carboxylic acid functional ionic liquid and divinyl benzene, followed by the ion-exchange with heteropolyacid H5PMo10V2O40 to introduce heteropolyanions. Partial carbonization dramatically enhanced the acid and oxidation properties, rendering the greatly strengthened activity in both the degradation of fructose into 5-hydroxymethylfurfural (HMF) and oxidation of HMF into DFF. As a result, the catalyst exhibited remarkable performance in the direct synthesis of DFF from fructose in a one-pot and one-step reaction, offering a high yield of 87.3% and a maximum turnover number (TON) of 77.7. The catalyst was facilely recovered and reused without apparent deactivation. The one-pot and one-step conversion of glucose into DFF reached the highest yield of 51.2% so far. Other carbohydrates such as inulin and sucrose were also effectively transformed into DFF, displaying good substrate compatibility.