Search Results (174)

Two crystals of N,N′-bis(phosphonomethyl)-1,4,5,8-naphthalenediimide were grown in the presence of neutral (water) and charged (imidazolium cation) species, yielding [(H₂O₃P)CH₂-(C₁₄H₄N₂O₄)-CH₂(PO₃H₂)]∙H₂O (1) and [C₃H₅N₂][(H_1.5O₃P)CH₂-(C₁₄H₄N₂O₄)-CH₂(PO₃H_1.5)] (2), respectively. The ligand N,N′-bis(phosphonomethyl)-1,4,5,8-naphthalenediimide was synthesized via the condensation of naphthalene-1,4,5,8-tetracarboxylic dianhydride with (aminomethyl)phosphonic acid in N,N′-dimethylformamide or imidazole. The flexible N-methyl phosphonic acid groups adopt a cis configuration in compound 1 and a trans configuration in compound 2. In compound 1, the phosphonate groups engage in extensive hydrogen bonding, as well as with water molecules and π–π stacking, resulting in a three-dimensional closely packed structure. Compound 2 forms a densely packed three-dimensional network stabilized by charge-assisted hydrogen bonding (anion-cation), anion–π interactions, and π–π stacking interactions. Hirshfeld surface analysis was conducted and the associated two-dimensional fingerprint plots were generated to further elucidate the nature and contributions of these noncovalent interactions. Direct bandgap measurements estimated from Tauc plots yielded values of 2.92 eV and 2.85 eV for compounds 1 and 2, respectively, highlighting their potential as promising n-type organic semiconductors. Thermal analysis reveals that compound 2 exhibits greater thermal stability than compound 1. Full article

1-Butyl-3-methylimidazolium (bmim) ionic liquids (ILs) are widely used for lignocellulose fractionation, yet their role extends beyond mere solvents. This study revealed that bmim-based ILs act as active chemical reagents, modifying the lignin structure in an anion-dependent manner. Thermal treatment (80–150 °C) of spruce dioxane lignin with [bmim]OAc, [bmim]Cl, and [bmim]MeSO₄ resulted in two distinct transformation pathways. In [bmim]MeSO₄, acidic catalysis dominates, leading to lignin condensation (increase in weight-average molecular weight, M_w, to 15.2 kDa at 150 °C) and intense sulfur incorporation (up to 9.9%) via anion-derived methylation/sulfation. Conversely, [bmim]OAc promotes depolymerization (decrease in M_w to 3.6 kDa) and efficient covalent bonding of the bmim cation to lignin (up to 10.8 cations per 100 aromatic units and a 6.5% nitrogen content at 150 °C), preventing condensation. Two-dimensional NMR and HPLC-HRMS analyses revealed the formation of a C–C bond between the C₂ atom of the imidazole ring and the α-carbon of the phenylpropane lignin fragments and allowed for the identification of a number of individual nitrogen-containing lignin oligomers in the [bmim]OAc-treated samples. Their formation likely proceeds via nucleophilic addition of the N-heterocyclic carbene (NHC), derived from the bmim cation by deprotonation with the highly basic acetate anion, to aldehyde groups. The action of [bmim]Cl primarily induces acid-catalyzed transformations of lignin with minimal covalent modification. These findings redefine imidazolium ILs as reactive media in biorefining, where their covalent interactions can influence the properties of lignin but complicate its native structure and the recyclability of the IL. Full article

In this work, the adsorption of imidazolium-based ionic liquids containing the bis(trifluoromethanesulfonyl) imide anion (NTf₂⁻) from aqueous phase was evaluated using different activated carbons (ACs). Three commercial Acs and two Acs prepared from grape seeds (one produced by pyrolysis and the other by hydrothermal carbonization (HTC), both activated with potassium hydroxide) were tested, assessing the adsorption of both the cation and the anion. For commercial ACs, similar adsorption performances were observed, with maximum adsorption capacities ranging from 0.85 to 1.08 mmol g⁻¹. These values increased under acidic conditions (pH 4), reaching 1.74 mmol g⁻¹ for the 1-butyl-3-methylimidazolium cation (Bmim⁺) and 1.87 mmol g⁻¹ for NTf₂⁻. Among the prepared ACs, the HTC-derived AC showed slightly higher capacities than the commercial samples, while the pyrolysis-derived AC exhibited the highest adsorption capacity for BmimNTf₂ (3.36 mmol g⁻¹ at pH 4). In terms of reusability, the pyrolysis-derived AC maintained 84% of its initial adsorption capacity between the third and fifth regeneration cycles. These results highlight the high adsorption performance and recyclability of grape-seed-derived activated carbons, demonstrating their potential for the removal of ionic liquids from aqueous environments. Full article

Due to high thermodynamic stability, the direct generation of formic acid by CO₂ hydrogenation is not easy to achieve experimentally. However, when Nakahara and coworkers studied the equilibrium of formic acid reversibly decomposing into CO₂ and H₂, they found that using imidazolium formate ionic liquid as an additive could shift the reaction equilibrium to the formic acid side. Subsequently, imidazolium acetate ionic liquid and imidazolium bicarbonate ionic liquid have also been experimentally proven to be able to be used for CO₂ hydrogenation to directly produce formic acid. In order to investigate the mechanism of action of ionic liquids in the process of CO₂ catalyzed hydrogenation to formic acid, we performed DFT calculations. The results showed that, after the hydrogenation of CO₂ to formic acid, the ionic liquids and formic acid molecules form adducts through hydrogen bonding, and then stabilize the product formic acid. The further use of methyl to replace H at the position of the cation R3 of the ionic liquids can improve the ability of the ionic liquids to stabilize formic acid, which also supports the experimental work of Nakahara and coworkers. In addition, among the three ionic liquids, the imidazolium acetate ionic liquid had the best stabilizing effect on formic acid, and the second best is the imidazolium formate ionic liquid, while the imidazolium bicarbonate ionic liquid has a relatively weak stabilizing ability. Full article

This study investigates the interfacial behavior of four phosphate ester ionic liquids (ILs) with contrasting cation hydrophobicity under humid environments. Through tribological tests, surface analysis, and molecular dynamics simulations, we reveal how moisture absorption governs lubricant film organization at metal interfaces. Aromatic ILs (imidazolium/pyridinium cations) exhibit significant degradation in lubrication after moisture exposure, with friction coefficients increasing by 0.03–0.05 and wear volumes scaling with humidity. This deterioration arises from competitive water–cation adsorption, where hydrogen bonding disrupts Fe-cation coordination bonds and destabilizes the protective film. In contrast, aliphatic ILs (tetraalkylammonium/phosphonium cations) maintain robust tribological performance. Their alkyl chains spatially confine water to outer adsorption layers (>17 Å from the surface), preserving a stable core lubricating film (~14 Å thick). Molecular dynamics simulations confirm that water co-adsorbs with aromatic cations (RDF peak: 2.5 Å), weakening interfacial interactions, while aliphatic ILs minimize cation–water affinity (RDF peak: 4 Å). These findings establish cation hydrophobicity as a critical design parameter for humidity-resistant lubricants, providing fundamental insights into water-mediated interfacial phenomena in complex fluid systems. Full article

A series of sulfur dissolving tetrathionate ionic liquids (ILs), featuring imidazolium and pyridinium cationic heads, have been prepared and characterized along with their chloride IL precursors. A novel synthetic approach for the preparation of the proposed tetrathionate ILs has been introduced and successfully tested in the current work, yielding the desired compounds in quantitative yield and high purity, offering a significant advancement over the traditional Volynskii–Smolyaninov reaction. The presented method addresses key challenges of the traditional approach, solving the issues deriving from the influence of the IL cation on the reaction outcome and the unpredictability of the formed polythionate species. The solubility of elemental sulfur in the considered tetrathionate ILs has been investigated at various temperatures, providing good preliminary evidence of the suitability of these ILs as convenient and effective sulfur solubilizing media readily available on the field in “sour” gas extraction plants. Furthermore, the use of ILs instead of traditional organic solvents in operative conditions represents a noteworthy safety improvement due to their lower flammability and volatility. Finally, interesting results were obtained studying binary mixtures of organic solvents and ILs, with cooperative effects or salting-out effects being observed in relation to the type of solvent used. Full article

A series of functionalized calix[4]arenes were prepared that contain mono- and bis-(alkoxy)imidazolium groups that are linked to the lower rim of a t-butylcalix[4]arene framework. These molecules have potential as anion-complexation reagents and as precursors to N-heterocyclic carbene complexes that are attached to a calixarene framework. They were prepared by the preliminary reaction α,ω-dibromoalkanes with the parent t-butylcalix[4]arene to give bis-ω-bromoalkoxy groups that are connected to the calix[4]arene framework in the 25- and 27-positions. The reaction of the bis-substituted calixarenes with TiCl₄ led to the removal of one bromoalkoxy group to give mono-substituted derivatives. Both the mono- and bis-functionalized calixarenes were reacted with N-substituted imidazoles to give a series of mono- or bis-imidazolium salts with the imidazolium group tethered to the calix[4]arene via O–(CH₂)_n– linkages (n = 2, 4, or 6). Unexpected bis-calix[4]arene products, in which the calixarenes are linked together via bridging organic groups, were obtained in some of these reactions. One bridge consists of two calixarenes linked together via two –C₂H₄– groups while the other had a –O–C₄H₈–imidazolium-C₄H₈–O– linker tethering the two calix[4]arenes together. Both these species were characterized by single crystal X-ray diffraction studies. The structures both had significant disorder but, nevertheless, the data do establish their structures. That the imidazolium-substituted calix[4]arene cations are precursors to N-heterocyclic carbene complexes of nickel was demonstrated by the reaction of a mono-imidazolium-substituted calix[4]arene with nickelocene to give the fully characterized N-heterocyclic carbene nickel complex linked to the calix[4]arene group. Full article

Structure–property relationships in imidazolium-based hybrid Sb(III) chlorides provide critical guidance for designing high-performance materials. Three zero-dimensional metal halides, namely, [C₃mmim]₂SbCl₅ (1, [C₃mmim]⁺ = 1-propyl-2,3-dimethylimidazolium), [C₅mmim]₂SbCl₅ (2, [C₅mmim]⁺ = 1-pentyl-2,3-dimethylimidazolium), and [C₅mim]₂SbCl₅ (3, [C₅mim]⁺ = 1-pentyl-3-methylimidazolium), are synthesized by ionothermal methods. These compounds exhibit markedly distinctly photophysical properties at their optimal excitation wavelengths. Structural analyses reveal that elongated alkyl chains in compounds 2 and 3 increase Sb–Sb distances compared to that in 1, effectively isolating [SbCl₅]²⁻ units, suppressing inter-center energy transfer, and reducing non-radiative transitions, thereby enhancing the photoluminescence quantum yield (PLQY). Furthermore, methyl substitution at the C2-position of the imidazolium ring in compounds 1 and 2 induces asymmetric coordination environments around the [SbCl₅]²⁻ emission centers, leading to pronounced structural distortion. This distortion promotes non-radiative decay pathways and diminishes luminescent efficiency. Furthermore, temperature-dependent spectroscopy analysis and fitting of the Huang–Rhys factor (S) reveal significant electron–phonon coupling in compounds 1–3, which effectively promotes the formation of self-trapped excitons (STEs). However, compound 1 exhibits extremely high S, which significantly enhances phonon-mediated non-radiative decay and ultimately reduces its PLQY. Overall, compound 3 has the highest PLQYs. Full article

A theoretical study was performed using Density Functional Theory (DFT) to investigate the impact of π-conjugated aliphatic chain growth on the chemical and electronic properties of hybrid antimony pentachloride salts with pyridine- and imidazolium-based cations. Ten molecular systems were optimized to determine their ground-state geometry. Using conceptual DFT, parameters such as chemical hardness, electrophilicity index, electroaccepting power, and electrodonating power were studied. The energy gap was obtained for all ten molecular systems, ranging from −4.038 to −3.706 eV as the chain length increased, favoring intramolecular charge transfer in long-chain systems. Natural bond orbital (NBO) analysis showed charge redistribution between anion and cation as the π-conjugated aliphatic chain grows. At the same time, non-covalent interaction (NCI) studies revealed key attractions and repulsive interactions, such as H···Cl and Cl···π, which are modulated by chain length. These results demonstrate that the structural modification of the cation allows for the fine-tuning of the electronic properties of ionic liquids (ILs). Increasing the conjugated aliphatic chain length was observed to reduce the chemical hardness and electrophilicity index, as well as affecting the Egap of the molecular systems. This work demonstrates that there is an optimal size for the inorganic ion, allowing it to form an optimal IL compound. Full article

Ionic liquids (ILs) have attained considerable attention as cellulose solvents. Nevertheless, the detailed mechanism of cellulose dissolution in ILs is not clearly defined. It is crucial to recognize the role of the individual components of the ILs to fully understand this mechanism. During this study, the effect of alkyl chain length in imidazolium cation was examined using synthesized ILs which are composed of common acetate anion and imidazolium cations with different alkyl substituents. This study also aimed to investigate the odd–even effect of alkyl chain carbons. Furthermore, whereas most published investigations on cellulose dissolution in ILs used microcrystalline cellulose (MCC), which has a far lower degree of polymerization, in this study, cotton cellulose was used. During the dissolution experiments, cotton cellulose (5% w/w) was added to each IL, and the progress of the dissolution was monitored using polarized light microscopy (PLM). The regeneration of cellulose was performed by using water as the anti-solvent, and the regenerated cellulose was characterized by Fourier-transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). During these experiments, it was noted that ILs with odd C3 and C5 carbon chains were less effective at dissolving cellulose than those with even C2 and C4 alkyl chains. Additionally, after regeneration, biomaterials for a variety of applications could be produced. Full article

Ionic liquids (ILs) can ideally reduce defects and improve the film stability of emissive metal halide perovskite films. In this work, we measure how the structure and emission of methylammonium lead tribromide (MAPbBr₃) perovskite films is modulated by long alkyl chain-containing pyridinium, imidazolium, or pyrrolidinium ILs. Two different film deposition methods are compared, with the resultant films characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence (PL) spectroscopy. For the latter, the differences in PL intensity of the perovskite are quantified using photoluminescence quantum efficiency (PLQE) measurements. It is found that a spin coating method in conjunction with the use of an imidazolium-containing IL (for a given precursor concentration) produces the strongest emissive perovskite. This optimal enhancement is attributed to a function of accessible surface charges associated with the heterocyclic cation of a given IL and perovskite defect passivation by bromide, the latter elucidated with the help of density functional theory. Proof-of-concept device fabrication is demonstrated for the case of a light emitting diode (LED) with the IL present in the emissive perovskite layer. Full article

Aiming to obtain insight into the dynamic properties of ionogels, ¹H NMR relaxation experiments were performed for an ionogel composed of 1-butyl-3-methyl-imidazolium chloride [BMIM][Cl] and propylene carbonate. The experiments were conducted in the frequency range of 10 kHz to 20 MHz, spanning the temperature range of 273 K to 338 K. The data were analyzed in term s of a relaxation model including two relaxation contributions—one of them associated with anisotropic (two-dimensional) translation diffusion, the second one representing a power law dependence of spin-lattice relaxation rates on the resonance frequency. The power law relaxation term (characterized by a very low power law factor of about 0.1) was attributed to the collective dynamics of the partially immobilized propylene carbonate matrix, while the relaxation contribution associated with anisotropic translation diffusion was attributed to the movement of BMIM cations in the matrix; the translation diffusion coefficient was estimated as varying in the range of 10⁻¹³ m²/s–10⁻¹² m²/s. Moreover, other parameters were determined as a result of the analysis, such as the residence lifetime on the matrix surfaces. Subsequently, the temperature dependencies of the determined parameters were assessed. Full article

The core challenge of integrated carbon capture and utilization (ICCU) technology lies in developing electrolytes that combine efficient carbon dioxide (CO₂) capture with electrocatalytic conversion capabilities. This review analyzes the structure–performance relationship between electrolyte properties and CO₂ electrochemical reduction (eCO₂RR), revealing the key regulatory mechanisms. Research shows that the performance of bicarbonate electrolytes heavily depends on the cation type, where Cs⁺ can achieve over 90% CO selectivity by suppressing the hydrogen evolution reaction (HER) and stabilizing reaction intermediates, though its strong corrosiveness limits practical applications. Although amine absorbents excel in carbon capture (efficiency > 90%), they tend to undergo competitive adsorption during electrocatalysis, making formic acid the primary product (FE = 15%); modifying electrodes with ionomers can enhance their activity by 1.15 times. Ionic liquids (ILs) demonstrate unique advantages due to their tunability: imidazolium-based ILs improve formate selectivity to 85% via carboxylate intermediate formation, while amino-functionalized task-specific ILs (TSILs) achieve a 1:1 stoichiometric CO₂ absorption ratio. Recent breakthroughs reveal that ternary IL hybrid electrolytes can achieve nearly 100% CO Faradaic efficiency (FE) through microenvironment modulation, while L-histidine additives boost CH₄ selectivity by 23% via interface modification. Notably, constructing a “bulk acidic–interfacial neutral” pH gradient system addresses carbonate deposition issues in traditional alkaline conditions, increasing C₂₊ product efficiency to 50%. Studies also highlight that cation–anion synergy (e.g., K⁺/I⁻) significantly enhances C-C coupling through electrostatic interactions, achieving 97% C₂₊ selectivity on Ag electrodes. These findings provide new insights for ICCU electrolyte design, with future research focusing on machine learning-assisted material optimization and reactor engineering to advance industrial applications. Full article

Colonization of surfaces by bacteria followed by biofilm formation is a cause of wound infections associated with the use of medical devices as stents, catheters, implants, etc. For prevention of such infections, the preparation of surfaces with antifouling, anti-adhesive and antibacterial properties is of great interest. In this context, four zwitterionic (styrenic or methacrylic) monomers bearing a pyridinium, imidazolium or ammonium cationic group linked to a sulfonate anionic group were chosen and polymerized on ceramic for implant technology. Zwitterionic polymers were successfully grafted onto zirconia pellets through surface-initiated radical polymerization with blue-light photoactivation (“grafting from”). Wettability measurements showed the formation of hydrophilic surfaces with water contact angles in the range of 35–40°. Detailed X-ray photoelectron spectroscopy analysis revealed a surface where the zirconia pellets exhibited zwitterionic polymer brushes with high coverage. The core-level spectra of C1s, N1s and S2p were separated into many components, allowing their attribution to the different atoms in the monomer unit and confirming that zwitterionic polymers were successfully grafted from zirconia surfaces. Full article

Strategic utilization of carbon dioxide as both a carbon mitigation tool and a sustainable C1 feedstock represents a pivotal pathway toward green chemistry. Although poly(ionic liquid)s (PILs) exhibit promise in CO₂ conversion, conventional divinylbenzene (DVB) cross-linked architectures are limited by reduced ionic density and limited accessibility of active sites. Herein, we reported a binuclear imidazolium-functionalized PIL catalyst (P-BVIMCl), synthesized through a simple self-polymerization process, derived from rationally designed ionic liquid monomers formed by quaternization of 1,4-bis(chloromethyl)benzene with N-vinylimidazole. The dual active sites in P-BVIMCl-quaternary ammonium cation (N⁺) and nucleophilic chloride anion (Cl⁻) synergistically enhanced CO₂ adsorption/activation and epoxide ring-opening. Under optimal catalyst preparation conditions (100 °C, 24 h, water/ethanol = 1:3 (v/v), 10 wt% AIBN initiator) and reaction conditions (100 °C, 2.0 MPa CO₂, 10 mmol epichlorohydrin, 6.7 wt% catalyst loading, 3.0 h), P-BVIMCl catalyzed the synthesis of glycerol carbonate (GLC) with a yield of up to 93.4% and selectivity of 99.6%, maintaining activity close to 90% after five cycles. Systematic characterization and density functional theory (DFT) calculations confirmed the synergistic activation mechanism. This work established a paradigm for constructing high-ionic-density catalysts through molecular engineering, advancing the development of high-performance PILs for industrial CO₂ valorization. Full article