Anion Of Ionic Liquid Research Articles

Strategies to Improve the Quantum Computation Accuracy for Electrochemical Windows of Ionic Liquids.

Rational design of ionic liquids (ILs) with wide electrochemical windows (ECWs) for high-voltage cathodes is essential to elevating the energy density of current rechargeable batteries. It is significant to determine appropriate strategies for accurately predicting the ECWs of ILs. In this study, we compare the calculated ECWs based on three quantum methods, including the highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) method, the ionization potential-electron affinity (IP-EA) method, and the thermodynamic method, under four unique combinations of simulation environments, and assess the discrepancies between the calculated and the experimental results of ECWs. For the three quantum methods, although HOMO-LUMO and IP-EA methods show limited prediction accuracy compared to the experimental values, they can qualitatively rank the anodic limits of anions and the cathodic limits of cations. For the thermodynamic method, we demonstrate that the highest accuracy can be achieved by considering the most rational redox reaction process. By varying the calculation environments, the calculated ECWs tend to be underestimated by considering separate cations and anions of ILs under gas phase, whereas they always exhibit overestimated results when calculating based on the cation-anion pairs. When the computation considers isolated ions with the solvent model plus proper thermodynamic corrections, we observe improved consistency with the experimental results. Though all methods have limitations to achieving perfect predictions of ECWs, we believe rational selection of calculation methods based on application-oriented scenarios can balance the efficiency and accuracy of the results for the development of a high-throughput and accurate database of ECWs for ILs.

Ionic Liquids Microenvironment Modulates the Interface Properties of g-C3N4 for Boosting the Performance of Photodegradation and Infected Wound-Healing Therapy.

The improvement of photocatalytic activity of g-C3N4 is expected for its advanced applications but remains a challenge due to the limitations of current strategies, such as single function, inefficiency, and uneconomical. Herein, a modified g-C3N4 with improved interface properties is constructed through the modulation of the ionic microenvironment affected by ionic liquids (ILs) and exhibits a 2.3-fold enhanced photodegradation efficiency and a 3.5-fold enhanced reaction rate relative to pristine g-C3N4. It has demonstrated excellent performance in photo-therapy bacterial-infected wounds. Theoretical calculation indicated that the precursor can be regulated by designing the specific ILs microenvironment to form "ILs-Mel" clusters due to the diversity of interaction energy and electrostatic potential. The cluster results in uneven stress on the 2D plane, further inducing the reconstruction of the microstructure. The synergistic effect of cations and anions of ILs on regulating the interface properties of g-C3N4 due to the change of skeleton structure during thermolysis of ILs. The microstructure, surface, and optical-electrical properties can be adjusted by selecting different cations of ILs, and the custom-made band structure and wettability can be obtained by selecting different anions. This work provides a facile strategy to modulate the interface properties of g-C3N4 by building specific a microenvironment of precursor.

Understanding the Positive Role of Ionic Liquids in CO2 Capture by Poly(ethylenimine).

CO2 capture technology is one of the most important technical methods for significantly mitigating CO2 emissions in a low-carbon context. The recent invention of mixed absorbents comprising poly(ethylenimine) (PEI) and ionic liquids (ILs) provides a novel strategy for efficiently capturing CO2, and this has garnered widespread attention. However, the intermolecular interactions between the IL and other constituents during the CO2 absorption process remain unclear. In this present work, a series of density functional theory (DFT) calculations and molecular dynamics simulations were conducted to investigate the positive role of IL in CO2 capture by PEI. The results showed that the formation of hydrogen bonds between the IL anion and the amino groups of PEI primarily drives the addition of IL to PEI. During the CO2 absorption process, the IL anion not only can absorb CO2 but also exerts a dehydrogenation effect on the amino group of PEI, facilitating enhanced interaction between PEI and CO2. Additionally, the IL substantially reduces the viscosity of PEI, promoting the diffusion of CO2 within the system and enhancing the absorption rate. Based on the information on interaction energy and viscosity, we can easily make theoretical predictions for the optimal proportion of IL to be added. The above results provide fundamental insights to promote the industrial application of the PEI/IL system for CO2 capture.

A novel synergistic intensification method for CO2 absorption by metal salt and task-specific ionic liquids hybrid solvent in microchannel reactor

A novel metal salt-promoting mass transfer intensification method for CO2 absorption into task-specific ionic liquids aqueous solution was proposed. The mass transfer intensification and intrinsic mechanisms of different concentrations of metal salts (NaBF4, KBF4, KCl, and CuCl2) with task-specific ionic liquids (1-aminopropyl-3-methylimidazolium tetrafluoroborate [Apmim] [BF4]) aqueous solutions for CO2 capture process were visually investigated using a microchannel reactor. The results showed that adding metal salts could remarkably enhance the interaction between metal cations and ionic liquid anions, thereby decreasing the interaction between anions and cations within the ionic liquid molecules and promoting the chemical reaction between ionic liquid cations and CO2. Under the condition of the same salt concentration, the addition of KBF4 has more obvious enhancement for mass transfer in CO2 absorption process. The mass transfer coefficient increases as the gas-liquid phase flow rate rise under slug flow condition. In addition, based on the effects of metal salt concentration, absorbent density, and gas-liquid phase flow rate on the CO2 volumetric mass transfer coefficient kLa, a new correlation for predicting the volumetric mass transfer coefficient of CO2 absorption into the hybrid solvent in microchannel reactor was proposed and validated.

Enhancing Zn‐Metal Anode Stability: Key Effects of Electrolyte Additives on Ion‐Shield‐Like Electrical Double Layer and Stable Solid Electrolyte Interphase

AbstractOwing to zinc dendrites and parasitic reactions, aqueous Zn‐metal batteries often suffer from poor reversibility and cyclability. Electrolyte additives present a promising strategy to improve Zn anode stability. However, the ever‐evolving perspectives and mechanisms, paradoxically, complicate battery design, causing a scenario where any electrolyte additive seems to be effective. Herein, it is taken ionic liquid (IL) additives as an example and detailed explored the impact of three typical IL anions, namely OTF−, TFA−, and BF4−. It is identified that the primary determinant of electrolyte additives as their electrical double layer (EDL) structures and their subsequent solid‐electrolyte interface (SEI) composition. An advantageous EDL structure, akin to an ion‐shield, can reduce the absorption of H2O molecules, which further enrich the SEI with zincophilic and hydrophobic components, thereby mitigating parasitic reactions and Zn dendrite formation. As a result, the Zn||Zn cell with optimal [EMIM]OTF additives demonstrates an exceptional cycling life under challenging conditions, its cumulative plated capacity surpasses most previously reported results by utilizing different IL additives. This work extends beyond performance enhancements, representing a valuable exploration of key criteria for electrolyte additives is believed. These insights are expected to offer fundamental guidance for future research and electrolyte design.

Charge transfer across the ionic liquid/oil interface: Facilitated ion transfer and electron transfer

Facilitated ion transfer (FIT) and electron transfer (ET) across the ionic liquid (IL)/oil (O) interface between ethylamine nitrate (EAN) and 1,4-dichlorobutane (DCB) have been electrochemically studied. Cyclic voltammograms (CVs) for the FIT of Li+ cation in IL by dicyclohexano-18-crown-6 (DCH18C6) across the IL/O interface formed at a micropipette tip show that the onset of the FIT current is significantly shifted due to the facilitation beyond the potential window limit and that the current is proportional to the concentration of DCH18C6 in O limited by the diffusion of DCH18C6 inside the micropipette. CVs for the ET from supporting electrolyte anions in O to NO3−, the IL anion of EAN, across the IL/O interface studied using a closed-bipolar cell show that NO3− in EAN has an ability to oxidize tetraphenylborate ions in O but not tetrakis[3,5-bis(trifluoromethyl)phenyl]borate ions, the latter of which have more oxidation resistance.

On the Key Influence of Amino Acid Ionic Liquid Anions on CO2 Capture.

Amino acid ionic liquids (AAILs) are promising green materials for CO2 capture and conversion due to their large chemical structural tunability. However, the structural understanding of the AAILs underlying the CO2 reaction dynamics remains uncertain. Herein, we examine the steric effects of AAIL anions with various chemical structures on CO2 capture behavior. Based on ab initio free-energy sampling, we assess reaction mechanisms for carbamate formation via a two-step reaction pathway with a zwitterion intermediate undergoing dynamic proton transfer. Our results show that free-energy barriers for carbamate formation can be significantly reduced as the degree of steric hindrance of the anions decreases. Further analyses reveal that reduced steric hindrance of anions causes markedly stronger intermolecular interactions between zwitterion and anions, leading to an increased kinetically favorable intermolecular proton transfer for carbamate production. We also describe the correlation strength between intramolecular interactions within the zwitterion and intermolecular interactions between the zwitterion and anions. We conclude that the favored structural flexibility due to the less steric hindrance of the zwitterion leads to enhanced intermolecular interactions, facilitating proton transfer to nearby AAIL anions for carbamate formation. Our study provides invaluable insight into the influence of various degrees of steric hindrance of the AAIL anions governing CO2 chemisorption. These findings may aid in the design of optimal AAIL solvents for the CO2 capture process.

Attraction between Like Charged Ions in Ionic Liquids: Unveiling the Enigma of Tetracyanoborate Anions.

Intermolecular interactions in ionic liquids are mainly governed by Coulombic forces. Attraction between cations has been previously observed and was attributed to dispersion interactions between nonpolar moieties, hydrogen bonding, or π stacking. In this study, we present the intriguing behavior of tetracyanoborate anions in ionic liquids that, unlike their dicyanamide and tricyanomethanide counterparts, form dimers in both solid and liquid phases. A joint simulation and experimental study uncovers the origin of such anion-anion attraction: stabilization by induction and dispersion forces between several cyano groups, which is strong enough to overcome electrostatic repulsion. These findings open up new opportunities in the rational design of ionic liquids, where interactions between ions of the same charge can be controlled and fine-tuned by the presence of cyano groups.

A general strategy for recycling polyester wastes into carboxylic acids and hydrocarbons

Chemical recycling of plastic wastes is of great significance for sustainable development, which also represents a largely untapped opportunity for the synthesis of value-added chemicals. Herein, we report a novel and general strategy to degrade polyesters via directly breaking the Calkoxy-O bond by nucleophilic substitution of halide anion of ionic liquids under mild conditions. Combined with hydrogenation over Pd/C, 1-butyl-2,3-dimethylimidazolium bromide can realize the deconstruction of various polyesters including aromatic and aliphatic ones, copolyesters and polyester mixtures into corresponding carboxylic acids and alkanes; meanwhile, tetrabutylphosphonium bromide can also achieve direct decomposition of the polyesters with β-H into carboxylic acids and alkenes under hydrogen- and metal-free conditions. It is found that the hydrogen-bonding interaction between ionic liquid and ester group in polyester enhances the nucleophilicity of halide anion and activates the Calkoxy-O bond. The findings demonstrate how polyester wastes can be a viable feedstock for the production of carboxylic acids and hydrocarbons.

Unravelling the complex speciation of halozincate ionic liquids using X-ray spectroscopies and calculations.

Using a combination of liquid-phase X-ray spectroscopy experiments and small-scale calculations we have gained new insights into the speciation of halozincate anions in ionic liquids (ILs). Both core and valence X-ray photoelectron spectroscopy (XPS) experiments were performed directly on the liquid-phase ILs, supplemented by Zn 1s X-ray absorption near edge structure (XANES) spectroscopy. Density functional theory (DFT) calculations were carried out on both 1- and 2- halozincate anions, in both a generalised solvation model SMD (Solvation Model based on Density) and the gas phase, to give XP spectra and total energy differences; time-dependent DFT was used to calculate XANES spectra. Speciation judgements were made using a combination of the shape and width of the experimental spectra, and visual matches to the calculated spectra. For 2- halozincate anions, excellent matches were found between the experimental and calculated XP spectra, clearly showing that only 2- halozincate anions were present at all zinc halide mole fractions, x, studied. At specific values of x (0.33, 0.50, 0.60) only one halozincate anion was present; equilibria of different halozincate anions at those values of x were not observed. All findings show that chlorozincate anion and bromozincate anion speciation matched at the same x. Based on the results, predictions are made of the halozincate anion speciation for all values of x up to 0.67. Caution is advised when using differences in calculated total energies obtained from DFT to judge halozincate anion speciation, even when the SMD was employed, as predictions based on total energy differences did not always match the findings from the experimental and calculated spectra. Our findings clearly establish that the combination of high-quality experimental data from multiple spectroscopies and a wide range of calculated structures are essential to have high confidence in halozincate anion speciation identification.

The role of hydrogen bonding in solubilizing camptothecin in hydrophilic and hydrophobic ionic liquids

Utilizing ionic liquid (IL)-water mixtures as selective extraction solvents for raw materials from natural sources represents an efficacious approach; however, elucidating the underlying mechanisms inherent in various types of IL-aqueous solutions continues to pose a significant challenge. In this study, molecular dynamics simulations and density functional theory calculations are employed to illuminate the influence of the functional anion within ILs and the water content on the solvation mechanism and phase separation phenomena observed during the extraction of camptothecin (CPT) using aqueous IL solutions. The simulation results show that the anions in ILs preferentially dissolve CPT through hydrogen bonding at low water concentrations. As the water concentration increases, the hydrophobic IL binds more tightly to CPT, enabling the water to self-aggregate. The anions in hydrophilic IL form hydrogen bonds with water instead, further enhancing the dissolution of CPT. This work reveals the mechanism of phase separation and solvation of different types of IL aqueous solutions, which is helpful in developing new drug extraction and purification technologies.

Synthesis, Characterization, and Physicochemical Properties of New [Emim][BF3X] Complex Anion Ionic Liquids.

A new series of complex anion ionic liquids (ILs) [Emim][BF3X] (X = CH3SO3, EtSO4, HSO4, Tosylate) were synthesized and characterized by nuclear magnetic resonance, elemental analysis, differential scanning calorimetry analysis, and thermogravimetry. The physicochemical properties of these ILs, such as density, viscosity, conductivity, and surface tension, were measured and correlated with thermodynamic and empirical equations in the temperature range of 293.15-358.15 K under ambient conditions, and the thermal expansion coefficient, standard molar entropy, lattice potential energy, viscosity activation energy, surface enthalpy, and surface entropy were further calculated from experimental values. According to the temperature-dependent viscosity and conductivity, [Emim][BF3X] ILs follow the Walden rule, and they are classified as "good (or super) ionic liquids".

Regulating the structural polymorphism and protein corona composition of phytantriol-based lipid nanoparticles using choline ionic liquids

Lipid-based lyotropic liquid crystalline nanoparticles (LCNPs) face stability challenges in biological fluids during clinical translation. Ionic Liquids (ILs) have emerged as effective solvent additives for tuning the structure of LCNP’s and enhancing their stability. We investigated the effect of a library of 21 choline-based biocompatible ILs with 9 amino acid anions as well as 10 other organic/inorganic anions during the preparation of phytantriol (PHY)-based LCNPs, followed by incubation in human serum and serum proteins. Small angle X-ray scattering (SAXS) results show that the phase behaviour of the LCNPs depends on the IL concentration and anion structure. Incubation with human serum led to a phase transition from the inverse bicontinuous cubic (Q2) to the inverse hexagonal (H2) mesophase, influenced by the specific IL present. Liquid chromatography-mass spectrometry (LC-MS) and proteomics analysis of selected samples, including PHY control and those with choline glutamate, choline hexanoate, and choline geranate, identified abundant proteins in the protein corona, including albumin, apolipoproteins, and serotransferrin. The composition of the protein corona varied among samples, shedding light on the intricate interplay between ILs, internal structure and surface chemistry of LCNPs, and biological fluids.

Impact of functional group positioning in the anion of ionic liquids on aqueous solubility: a study through DFT calculations

Impact of functional group positioning in the anion of ionic liquids on aqueous solubility: a study through DFT calculations

Extraction and Selective Separation of ZrIV from LnIII/AnIII Using an Undiluted Phosphonium Ionic Liquid.

Solvent extraction of Zr(IV) in an undiluted phosphonium based ionic liquid (IL) and its selective separation from Ln(III) and An(III) has been investigated in the present study. Eu(III)/Am(III) were chosen as the representative Ln(III)/An(III). Tri(hexyl)tetradecylphosphonium nitrate ([P66614][NO3]) was chosen as IL phase and the feed phase was nitric acid containing the target metal ions. The extraction process was accomplished at different experimental parameters such as the concentration of initial nitric acid, initial feed metal concentration and equilibration time to explore the extractability of the proposed IL towards Zr(IV). The efficient extraction of Zr(IV) without any external ligand in IL phase and negligible extraction of Eu(III)/Am(III) were distinctly discerned leading to noteworthy separation factors for Zr(IV). The loading experiment revealed a noticeable growth of equilibrium concentrations of Zr(IV) in IL phase while that of Eu(III) was very less irrespective of the initial feed concentration. The association of two IL moieties in the complex formation process has been inferred. Nitrate ion was found to be superior as IL anion in terms of metal loading in comparison to other anions. Thermodynamics of extraction and the stripping of the loaded Zr(IV) from IL phase using a suitable stripping solution have also been investigated.

Deciphering the Role of Anions of Ionic Liquids in Modulating the Structure and Stability of ct-DNA in Aqueous Solutions.

Stabilizing biomolecules under ambient conditions can be extremely beneficial for various biological applications. In this context, the utilization of ionic liquids (ILs) in enhancing the stability and preservation of nucleic acids in aqueous solutions is found to be promising. While the role of the cationic moiety of ILs in the said event has been thoroughly explored, the importance of the anionic moiety in ILs, if any, is rather poorly understood. Herein, we examine the function of anions of ILs in nucleic acid stabilization by examining the stability and structure of calf thymus-DNA (ct-DNA) in the presence of various ILs composed of a common 1-ethyl-3-methylimidazolium cations (Emim+) and different anions, which includes Cl-, Br-, , and by employing various spectroscopic techniques as well as Molecular Dynamics (MD) simulation studies. Analysis of our data suggests that the chemical nature of anions including polarity, basicity, and hydrophilicity become an important factor in the overall DNA-IL interaction event. At lower concentrations, the interplay of intermolecular interaction between the IL anions with their respective cations and the solvent molecules becomes a very crucial factor in inducing their stabilizing effect on ct-DNA. However, at higher concentrations of ILs, the ct-DNA stabilization is additionally governed by specific-ion effect. MD simulation studies have also provided valuable insights into molecular-level understanding of the DNA-IL interaction event. Overall, the present study clearly demonstrated that along with the cationic moiety of ILs, the anions of ILs can play a significant role in deciding the stability of duplex DNA in aqueous solution. The findings of this study are expected to enhance our knowledge on understanding of IL-DNA interactions in a better manner and will be helpful in designing optimized IL systems for nucleic acid based applications.

X-ray Diffraction, Spectroscopy, Optical Properties, NPA, NBO, FMO, and Hirshfeld Surface Analyses of Two Newly Synthesized Piperidinium Ionic Liquids

The present study elaborates on the synthesis, crystal structure, and computational studies of two new ionic liquids. In the crystal structure, [C5H12N][C21H14ClN2O2S] (4a), the anions form chains along the a-axis direction through C—H···π(ring) interactions. These are connected into layers that run approximately parallel to the ac plane by a variety of hydrogen bonds. In the compound structure, [C5H12N][C18H15N2O2S] (4b), the two ions are primarily associated by an N—H···N hydrogen bond. In the crystal structure, layers parallel to the bc plane are formed by pairs of C—H···O and N—H···S hydrogen bonds and by C—H···π(ring) interactions. A theoretical study reveals that 4a has lower energy than 4b and is more stable. The NBO and DOS studies further confine the liquids’ structural reactivity and electronic properties. The quantum theory of atoms in a molecule (QTAIM) analysis reveals the important non-covalent interactions among the fragments and charge transfer. The global reactivity descriptors indicate their molecular reactivity relationship with the presence of functional groups. The remarkable polarizability (αo) and hyperpolarizability (βo) values indicate their optical and nonlinear optical (NLO) properties. Furthermore, the analysis performed by CrystalExplorer shows the intermolecular interactions and reactive sites between cations and anions in ionic liquids. The 2D fingerprint plots and Hirshfeld surfaces indicate the major interactions of crystals with neighboring elements in crystal packing. For both compounds, the H···H interactions are significantly higher than the other element interactions.

Symmetrical dialkyl-benzotriazolium as gel polymer electrolyte for energy storage and their alkyl chain trend on their electrochemical property

This work is on reporting development of symmetrically dialkylated series of benzotriazolium ionic liquids with tetrafluoroborate and hexafluorophosphate anion and their electrochemical properties. Also fabrication, and testing of ionic liquid as solid state gel polymer electrolyte using poly (vinylidenefluoride co hexa-fluoropropylene) as host polymer and testing their efficiency in electrical double layer capacitor. Structural characterizations done with 1H NMR, and 13C NMR and their property characterizations like electrochemical properties and the thermal properties of salts were done. All ionic liquids shows a potential window of ∼4.0 V. Cytotoxicity studies for understanding environmental friendliness of benzotriazolium ILs also studied using MTT assay which proved their alkyl chain effect on toxicity. The series of 1,3-dialkyl-1,2,3-benzotriazolium cationic and BF4ˉand PF6ˉ anionic ionic liquids shows are promising efficiency for energy storage application. Solid state gel polymer electrolyte using 1,3-dipropBTBF4 tested with symmetrical electrical double layer capacitor which shows 0–7.0 V excellent operating window. And at 0–3.5 V shows a good specific capacitance of 56.96 Fg−1 at scan rate of 2 mVs−1, and at a current density of 0.45 Ag−1 from galvanostatic charge discharge cycle a specific capacitance of 1.78 Fg−1 with energy density of 3.09 mWh and 509.45 mWg−1 power density. The prototype retains capacitance of 91.89 % even after 2000 cycles. Even after 2000 cycles the film stability is not much affected and resistance is not varied drastically. Single Swagelok cell charged at 2 V for 20 min was able to light red (1.7 V, 20 mA) LED brightly for 8 min, using two Swagelok cell charged individually up to 2 V for 20 min was enough to lit a blue LED of 2.7 V connected in series for 7 min brightly, which demonstrated its practical applicability. The unused IL remaining in the gel polymer electrolyte is easily and completely recovered out of the polymer host after studies which found to be advantages towards environmental friendliness in line with their disposal.

Prediction of nitrogen solubility in ionic liquids by machine learning methods based on COSMO-derived descriptors

The inertness of nitrogen (N2) results in extremely low N2 solubility in most solvents. However, in some important reactions, such as the nitrogen reduction reaction (NRR) driven by light or electrical energy, sufficient N2 feedstock in electrolyte allows the reaction to proceed more smoothly. In this context, the study concerning N2 solubility is of great significance. Previous research has demonstrated that ionic liquids (ILs) have many special characteristics and can be taken as green solvents to enhance N2 solubility. Herein, two quantitative structure–property relationship (QSPR) models are established to predict the N2 solubility in ILs by combining machine learning methods of random forest (RF) and gradient boosting regressor (GBR) with ionic fragments contribution (IFC) method. Firstly, a database with 385 N2 solubilities in 38 ILs at various temperatures and pressures is collected, in which the ILs are separated into 27 ionic fragments. Then COSMO-derived descriptors for the cations and anions of ILs are calculated and used as input variables. In specific, the determination of coefficient (R2) for the training sets by RF-IFC and GBR-IFC is 0.9983 and 0.9999, respectively. The application examples of N2 solubility in 1-hexyl-3-methyl-imidazolium tris(pentafluoroethyl)trifluorophosphate ([HMIM][eFAP]) confirm the availability and usefulness of RF-IFC and GBR-IFC models, indicating that both two models are feasible and reliable for predicting N2 solubility in ILs, and hopefully can be used to design and screen ILs in the future.

Correlation between absorbed acetylene spectral characteristic and nature of ionic liquids studied by in situ ATR-FTIR spectroscopy

Ionic liquids (ILs) are believed to be a prospective replacement for molecular solvents and are suggested to be used for storing and/or purifying acetylene. Systematic studies of the nature of the interaction between acetylene and different ILs may be necessary to predict new types of ionic liquids. Therefore, in order to investigate the absorption of acetylene by ionic liquids, in situ ATR-FTIR spectroscopy has been applied for the first time. Two series of ILs, such as [C2‍–‍10MIM][BF4] and ILs based on imidazolium with various anions, have been considered. A detailed analysis of the spectra of absorbed acetylene is given, with special attention being paid to the basicity of IL anions as well as the influence of the cation alkyl chain length. It has been found that the magnitude of the band shift associated with the CH stretching vibration and the antisymmetric CH bending vibration of absorbed acetylene correlates well with the change in the Kamlet-Taft β parameter of the ILs. Moreover, neither the free volume nor the IL polarity plays a key role in acetylene solubility. In addition, the enthalpy and entropy of absorption have been calculated for several ILs.