Anion Of Ionic Liquid Research Articles

Stretchable conducting polymer PEDOT:PSS treated with hard‐cation‐soft‐anion ionic liquid designed from molecular modeling

AbstractPEDOT:PSS, an ionic polymer mixture of positively‐charged poly‐3,4‐ethylenedioxythiophene (PEDOT+) and negatively‐charged poly‐styrenesulfonate (PSS−), is a water‐processable and environmentally‐benign organic semiconductor and electrochemical transistor, which plays a key role in organic (bio)electronic devices. However, pristine PEDOT:PSS films form 10‐to‐30‐nm granular domains, where conducting‐but‐hydrophobic PEDOT‐rich cores are surrounded by hydrophilic‐but‐insulating PSS‐rich shells. Such morphology makes PEDOT:PSS water‐soluble and thermally stable but very poor in conductivity. A tremendous amount of effort has been made to enhance the conductivity of PEDOT:PSS by restoring the extended conduction network of PEDOT. Recently, remarkable ~5000‐fold improvements of conductivity have been achieved by mixing PEDOT:PSS with proper ionic liquids (ILs). In a series of free energy estimations using density functional theory calculation and molecular dynamics simulation, we have demonstrated that the classic hard‐soft acid–base (or cation‐anion) principle of chemistry plays an important role in such improvements. Ion exchange between PEDOT+:PSS− and A+:X− ILs helps PEDOT+ to decouple from PSS− and to grow into large‐scale conducting domains of π‐stacked PEDOT+ decorated by IL anions X−. Thus, the most spontaneous decoupling between soft (hydrophobic) PEDOT+ and hard (hydrophilic) PSS− would be induced by strong interaction with soft anions X− and hard cations A+, respectively. Such hard‐cation‐soft‐anion principles have led us to design ILs containing extremely hydrophilic (i.e., protic) cations and hydrophobic anions. Not only they indeed improve the conductivity of PEDOT:PSS but also enhance its stretchability as well. In summary, our modeling offered molecular‐level insights on the morphological, electrical, and mechanical properties of PEDOT:PSS and a molecular‐interaction‐based enhancement strategy for intrinsically stretchable conductive polymers.

Exploring the Influence of Ionic Liquid Anion Structure on Gas-Ionic Liquid Partition Coefficients of Organic Solutes Using Machine Learning.

This article presents an in-depth investigation into the influence of anionic structures of ionic liquids (ILs) on gas-ionic liquid partition coefficients (log K) of organic solutes in three ILs. While the primary objective was to examine whether there is a relationship between the molecular structure of the IL anion component and log K, additionally it was looked at whether the molecular descriptors of the anion in the relationships encode possible molecular interactions during the miscibility and partitioning in the IL. The research involves the compilation of data series of experimental log K values, where the cation component is constant. Such representative data series were obtained for three solutes─benzene, cyclohexane, and methanol─in three ILs with a uniform cationic component of methylimidazoliums. Using multiple linear regression models enhanced with machine learning techniques, the relationship between anionic structures and log K values was successfully quantified and modeled. Systematically selected molecular descriptors describing the anion structure show that in the case of methanol log K is strongly dependent on hydrogen bonds and Coulomb-dipolar interactions with the anion component, while in the case of benzene and cyclohexane the dispersion forces of the anion component are dominant. The outlier analysis and data interpretation highlight the need for extensive experimental data. The results confirm the initial hypothesis and provide valuable information on the role of the structure of the anionic component in determining the partitioning behavior of organic solutes. This knowledge is important for the design and optimization of ILs for specific applications, particularly as solvents in various industrial processes. The research also provides useful information about molecular interactions taking place in the interfaces of IL and organic additives in complex liquid media such as multicomponent electrolyte solutions, for example in energy storage applications.

Gold(III) Catalysis in Ionic Liquids: The Case Study of Coumarin Synthesis

AbstractWell‐defined (P,C)‐cyclometalated Au(III) complexes proved to be able to catalyze the synthesis of coumarins by intramolecular hydroarylation of a broad range of aryl propiolates under mild and practical conditions (0.1–2 mol% catalyst, 25–40 °C, 1–24 hours). The use of an ionic liquid as reaction solvent allowed to drastically decrease the amount of Brönsted acid used to unlock the catalyst regeneration step. The effect of the nature of the acid additive and of the ionic liquid anion have been assessed. Preliminary results on the extension of this methodology to the cyclization of aryl propargyl ethers are also presented.

Translational Dynamics of Cations and Anions in Ionic Liquids from NMR Field Cycling Relaxometry: Highlighting the Importance of Heteronuclear Contributions.

NMR field cycling relaxometry is a powerful method for determining the rotational and translational dynamics of ions, molecules, and dissolved particles. This is in particular true for ionic liquids (ILs) in which both ions carry NMR sensitive nuclei. In the IL triethylammonium bis(trifluoromethanesulfonyl)imide ([TEA][NTf2]), there are 1H nuclei at the [TEA]+ cations and 19F nuclei at the [NTf2]- anions. Moreover, the high viscosity of this IL leads to frequency-dependent relaxation rates, leaving the so-called extreme narrowing regime. Both the rotational and the translational dynamics of the constituents of ILs can be obtained by separating the contributions of intra- and intermolecular relaxation rates. In particular, the translational dynamics can be obtained separately by applying the so-called "low-frequency approach" (LFA), utilizing the fact that the change in the total relaxation rates at low frequencies results solely from translational motions. However, for systems containing multiple NMR active nuclei, heteronuclear interactions can also affect their relaxation rates. For [TEA][NTf2], the intermolecular relaxation rate is either the sum of 1H-1H cation-cation and 1H-19F cation-anion interactions or the sum of 19F-19F anion-anion and 19F-1H anion-cation interactions. Due to the lack of available experimental information, the 1H-19F heteronuclear intermolecular contribution has often been neglected in the past, assuming it to be negligible. Employing a suitable set of ILs and by making use of isotopic H/D substitution, we show that the 1H-19F heteronuclear intermolecular contribution in fact cannot be neglected and that the LFA cannot be applied to the total 1H and total 19F relaxation rates.

Molecular dynamics simulations of uranyl and plutonyl cations in a task-specific ionic liquid.

Ionic liquids (ILs) are a unique class of solvents with potential applications in advanced separation technologies relevant to the nuclear industry. ILs are salts with low melting points and a wide range of tunable physical properties, such as viscosity, hydrophobiciy, conductivity, and liquidus range. ILs have negligible vapor pressure, are often non-flammable, and can have high thermal stability and a wide electrochemical window, making them attractive for use in separations processes relevant to the nuclear industry. Metal salts generally have a low solubility in ILs; however, by incorporating new functional groups into the IL cation or anion that promote complexation with the metal, the solubility can be greatly increased. One such task-specific ionic liquid (TSIL) is 1-carboxy-N, N, N-trimethylglycine bis(trifluoromethylsulfonyl)imide ([Hbet][Tf2N]) [Nockemann et al., J. Phys. Chem. B 110, 20978-20992 (2006)]. Water, which is detrimental for electrochemical separations, is a common impurity in ILs and can coordinate with actinyl cations, particularly in ILs containing only weakly coordinating components. Understanding the behavior of actinides in TSIL/water mixtures on a molecular level is vital for designing improved separations processes. Classical molecular dynamics simulations of uranyl(VI) and plutonyl(VI) in 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][Tf2N]) with deprotonated Hbet (betaine) and water have been performed to understand the coordination and dynamics of the actinyl cations. We find that betaine is a much stronger ligand than water and prefers to coordinate the metal in a bidentate manner. Potential of mean force simulations yield a relative free energy for betaine coordination of approximately -120 to -90 kJ/mol in mixtures with water. As the amount of betaine coordinated to the actinide increases, the diffusion coefficient of the actinyl cation decreases. Moreover, the betaine ligand is able to bridge between two metal centers, resulting in dimeric complexes with actinide-actinide distances of ∼5Å. Potential of mean force simulations show that these structures are stable, with relative free energies of up to -40 kJ/mol. The crystal structure for [(UO2)2(bet)6(H2O)2][Tf2N]4 shows that the betaine bridges between two uranium atoms to form dimeric complexes similar to those found in our simulations [Nockemann et al. Inorg. Chem. 49, 3351-33601 (2010)].

Boosting cesium retention efficiency with polyoxometalate-ionic liquid composites: Insights into {WO6} octahedral affinity

Commonly used polyoxometalate (POM) adsorbents exhibit high cesium (Cs) adsorption capacity. However, its impotent ability to sequester adsorbates poses a risk of Cs migration in radioactive waste decontamination and disposal. By leveraging the cesium affinity of POMs and the regulatory properties of ionic liquids (ILs), POM-IL composites hold promise for mitigating the risk of cesium migration through efficient adsorption and retention. Herein, we designed two POM-ILs composed of the phosphotungstate anion (PW) and tetrabutylammonium cation (TBA), i.e., the {WO6}-saturated TBA-PW12 and mono-lacunary TBA-PW11, for the capture and retention of aqueous Cs. The composites were then characterized, and the performance and mechanism of Cs uptake were investigated. TBA-PW12 exhibited ∼300 nm aggregate of particles around 20–60 nm. TBA-PW12 retained the Keggin structural features of PW12O403−, which was proven essential for the binding of Cs+. With a retention efficiency of 97.3% in an NH4Cl eluent and a maximum adsorption capacity of 400.9 mg/g at 338 K, TBA-PW12 exhibited superior Cs capture and retention compared to the POM-IL derived from common Cs adsorbent phosphomolybdate. The Cs adsorption onto TBA-PWs achieved equilibrium within 180 min. Cs uptake by TBA-PWs was monolayer chemisorption of Cs+ accompanied by H+ release, and the removal efficiencies stabilized around initial pH 5–10. Due to intense affinity between {WO6} and Cs+, TBA-PW12 efficiently sequestered Cs + through {WO6} octahedra so that the {WO6}-saturated TBA-PW12 presented better Cs uptake performance than the mono-lacunary TBA-PW11. The IL anion [N(C4H9)4]+ provided a composite-water biphasic interface for aqueous Cs adsorption, while retaining the ability of POM cation PW12O403− to form a stable structure with Cs via its affinity to {WO6} octahedra. These findings support the design of POM-IL composites as efficient adsorbents for capturing and retaining Cs, aiding in the decontamination and safe disposal of radioactive waste, thereby minimizing the risk of nuclide leakage into the environment.

Synergistic Dual Activation Catalysis by Saccharin‐Based Ionic Liquids for Diastereoselective Synthesis of Ferrocene‐Appended Furopyranones, Furochromenones, and Benzofuranones

ABSTRACTA practical and straightforward strategy for the synthesis of ferrocene appended furopyranone, furochromenone, and benzofuranone via a metal‐free annulation reaction of imidazolium ylide with enone mediated by saccharin‐based ionic liquid has been reported. The mechanistic studies show an approach through synergistic dual activation of enone and imidazolium ylide via cation and anion of ionic liquid, respectively. This operationally simple protocol offers an easy and rapid access to a library of ferrocene appended furopyranone, furochromenone, and benzofuranone in moderate to good yields through the involvement of a six‐membered transition state.

Atomistic simulations of polysaccharide materials for insights into their crystal structure, nanostructure, and dissolution mechanism

AbstractCrystalline polysaccharides are abundant in nature and can be transformed into highly functional materials. However, the molecular basis for the formation of higher-order structures remains unclear. Computer simulation is an advanced tool for modeling macromolecular structures, and the atomistic simulations provide valuable information on the crystalline polysaccharides. Fiber deformation, crystalline transition, and novel nanostructures of cellulose were characterized through molecular dynamics simulations and density functional theory calculations of models of molecular chain sheets extracted from the crystal structure of the cellulose polymorphs. Extended ensemble molecular dynamics simulations were applied to analyze the artificial crystal structure of non-natural amylose analog polysaccharides, revealing the hexagonal packing of double helices through the self-assembly of molecular chains dispersed in aqueous solution. Dissolution simulations of the cellulose and chitin crystalline fibers revealed that the anions of ionic liquids, with their solvation power, played a key role in the cleavage of intermolecular hydrogen bonds in the crystal structure, whereas the cations contributed to irreversible molecular chain dispersion. The good correlation between the actual solubility of polysaccharides and the predicted number of intermolecular hydrogen bonds prompted the development of a platform that combined simulations and machine learning for high-throughput screening of solvents for cellulose and chitin.

Molecular dynamics simulation of the interaction between ionic liquid [OPy][BF4] and SO2

Ionic liquids possess novel properties and can efficiently absorb harmful gases, potentially serving as a new type of absorbent. In this study, the binary system of ionic liquid N-octylpyridinium tetrafluoroborate [OPy][BF4] and sulfur dioxide (SO2) has been selected as the research object, and the structure and properties of the system have been studied by molecular dynamics simulation. The interaction between SO2 and ionic liquids is explored by using the radial distribution functions (RDFs), coordination numbers (CNs) and spatial distribution functions (SDFs). The results of microstructures show that due to the strong interaction with anions, SO2 is mostly orderly distributed around the anions of ionic liquids. However, the coordination ability of the polar region of the ionic liquid and SO2 is nearly equivalent to that of the non-polar region. At the same time, it is found that the addition of SO2 enhanced the order degree of the polar and the non-polar regions of ionic liquids, especially on non-polar regions. Through the discussion of the interaction between [OPy][BF4] and SO2, it can be concluded that the mechanism of SO2 absorption by [OPy][BF4] is the combined effect of anions and cations. This study aims to provide new insights for the potential applications of ionic liquids in industrial fields such as petroleum and flue gas desulfurization.

Influence of some parameters on synthesis processes of triethyl ammonium oleate and triethyl ammonium stearate

Two ionic liquids named triethyl ammonium oleate ([TEA][Oleate] and triethyl ammonium stearate ([TEA][Stearate]) were synthesized from triethyl amine and oleic/stearic acids in water and in ethanol solvents. The synthesized ionic liquids were characterized by FT-IR and NMR spectra to confirm their structure. The influence of some parameters such as structure of ionic liquid anion, solvent, reaction time, reaction temperature, and acid/amine molar ratio on the synthesis processes of triethyl ammonium oleate and triethyl ammonium stearate was investigated. Ethanol was found suitable as a solvent for these processes because it dissolves formed ionic liquids but does not dissolve co-product KCl. In order to shift the equilibrium to increase the ionic liquid yields, an access amount of acids was used. Stearate-based ionic liquid should be synthesized at higher a temperature and longer time than oleic-based ionic liquids.

The Role of Asymmetry of Perfluoro anion in Ionic Liquids: From Basic Physical Properties to the Application in Lithium Batteries

Room-temperature ionic liquids (RTILs) have attracted significant attention as non-volatile, non-flammable electrolytes over the past three decades. While the synthesis of cationic species is relatively well-established through the quaternization reaction of tertiary amines, the synthesis of perfluoro anions is much more difficult, resulting in a more limited variety compared to cations. In this study, we explore the influence of anionic species on both fundamental properties, such as thermal properties and transport properties, and on the performance of lithium-ion batteries, particularly their rate capabilities. Furthermore, we highlight how novel anionic species not only improve the properties of RTILs but also lead to the development of unique electrolyte systems, such as organic ionic plastic crystals and medium-low temperature lithium molten salts. Through our research results, we would like to demonstrate the importance of developing new anionic species from fundamental studies to practical applications in RTILs.

Ionic Liquids-Induced Recovery of the G-Quadruplex DNA Destabilized by Dodine Fungicide.

Dodine is an important surfactant-based chemical fungicide used widely to kill fungi associated with black spot and foliar diseases on several fruit plants, such as apples, pears, peaches, and strawberries. However, the extensive use of dodine depicts the genotoxic effect, which may cause gene-associated diseases. Dodine can destabilize G-quadruplex (G4) DNA, which is one of the key targets for cancer therapy. Hence, finding an eco-friendly medium that can reduce or reverse the destabilization effect of dodine on G4 is important. This study investigates the efficacy of ionic liquids (ILs) containing a 1,1,3,3-tetramethyl guanidinium (TMG) cation with various anions (chloride, acetate, trifluoroacetate, octanoate, and perfluorooctanoate) in restoring the structure and stability of G4 induced by dodine. Our findings demonstrate that all ILs effectively reverse dodine-induced destabilization of G4, with the required concentration varying based on the lipophilicity of IL's anions. Specifically, higher concentrations of TMG-chloride and TMG-acetate are needed compared to TMG-perfluorooctanoate for the same effect. The IL anions remove dodine from G4 binding sites, while the TMG cation's interaction with G4 mitigates the destabilizing effect of dodine. This study indicates that ILs can be an eco-friendly medium for the storage of dodine to reverse the effect of dodine on G4.

Hydrophilicity Dependent Distribution of Water at Ionic Liquids/Metal Interface Monitored by Electrochemical SERS.

The understanding of the interfacial processes is critically important for extending the practical application of ionic liquids, particularly for the role of interfacial water. In the electrochemical system based on ionic liquid electrolytes, small amounts of water at the interface generate a significant change in the electrochemical behaviors of ionic liquids. Therefore, the investigation on the interfacial behavior of water is highly desired in ionic liquids with different anions, water content, and hydrophilicity. Herein, based on the probe strategy, in situ surface enhanced Raman spectroscopy (SERS) combined with electrochemical control (EC-SERS) was developed to investigate the influence of hydrophilicity/hydrophobicity of ionic liquids on the interfacial water. The water-sensitive transformation reaction of 4,4'-dimercaptoazobenzene (DMAB) to para-aminothiophenol (PATP) was employed as a probe reaction for investigating the behavior of interfacial water. The changes of relative SERS intensities of DMAB to PATP served as an indication of the quantity variation of interfacial water. The results show that the transformation reaction efficiencies were critically dependent on the additional water contents, potential, and hydrophilicity of ionic liquids. With a very low molar fraction of additional water (Xw = 0.01), transformation efficiency of DMAB (the amount of interfacial water) followed the sequence of [BMIm]BF4 < [BMIm]PF6 < [BMIm]Tf2N. It was in agreement with the hydrophobicity order of the ionic liquids. With the increase in additional water content, the potential for the full transformation was positively moved, and the efficiency increased significantly. The stronger hydrophobicity allowed more water molecules to migrate to the interface, which was attributed to the difference in interactions between water and the anions of ionic liquids. It demonstrated that the small amount of water tended to gather at the interface in hydrophobic ionic liquids. Compared to traditional cyclic voltammetry, the EC-SERS technique combined with probe reactions is more sensitive to interfacial water. It is anticipated to develop as a promising tool for the investigating water-related issues at interfaces and to provide guidance to screen ionic liquids for practical application.

Superparamagnetic composites of lignin regenerated from ionic liquid solutions for the efficient and selective removal of cationic dyes

Magnetic lignin nanoparticles (MLNs) were prepared by inducing their self-assembly through lignin regeneration in the [N-methyl-2-pyrrolidone][C1–C4 carboxylic acid] ionic liquids ([NMP]ILs), which are low-cost protic ionic liquid. [NMP]ILs are self-assembling solvent that can enhance the adsorption capacity of MLNs to a greater degree than tetrahydrofuran or H2O. Additionally, the anion types of [NMP]IL greatly influence the physiochemical properties of MLNs. The MLNs prepared through self-assembly with [NMP][formate] (MLN/[NMP][For]) exhibited a higher maximum adsorption capacity (134.53 mg/g) than the [NMP]ILs of C2–C4 carboxylate anions. MLN/[NMP][For] demonstrated stable adsorption within a pH range of 6–10 or at high salt concentrations (0.01–0.5 mol/L), retaining over 80 % of its regeneration efficiency after 5 cycles. In addition, MLN/[NMP][For] selectively removed cationic dyes in mixed binary anionic–cationic dye solutions. This work demonstrated the feasibility of preparing magnetic biosorbents with good selectivity and stability though regeneration and by adjusting the anions of ionic liquids.

Monte Carlo QM/MM simulation studies of the Cannizzaro reaction in ionic liquids for improved biofuel production.

The conversion of biomass to 5-hydroxymethylfurfural (HMF) holds substantial promise as a renewable energy source. Notably, HMF can be transformed into 2,5-bis(hydroxymethyl)furan (BHMF), a crucial reactant in biofuel production, but requires harsh operating conditions, H2, and precious metal catalysts. A recently reported Cannizzaro reaction of HMF to BHMF, characterized by its efficiency, mild conditions, and eco-friendliness, instead employed ionic liquids (ILs) to achieve high yields. In this study, combined quantum mechanical and molecular mechanical (QM/MM) simulations in conjunction with Metropolis Monte Carlo statistical mechanics and free-energy perturbation theory utilized M06-2X/6-31+G(d), PDDG/PM3, and the OPLS-VSIL force field to uncover important solute-solvent interactions present in the HMF to BHMF reaction pathway. The Cannizzaro reaction was examined in water and in five ILs composed of the 1-butyl-3-methylimidazolium [BMIM] cation coupled to hexafluorophosphate, tetrafluoroborate, thiocyanate, chloride, and bromide. Energetic and structural analysis of the rate-determining hydride transfer between HMF and the hydride-donor anion HMFOH- attributed the enhanced reactivity to highly organized solvent interactions featuring (1) hydrogen bonding between the ring protons of [BMIM] and the negatively charged carbonyl oxygen atoms on the transition structure, (2) favorable electrostatic interactions between the IL anions and solute hydroxyl groups, and (3) beneficial π-π stacking interactions between [BMIM] and the two aromatic rings present in HMF and HMFOH-.

Effects of Heterogeneous Mixing of Imidazolium-Based Ionic Liquids with Alcohols on Complex Formation of Ni(II) Ion.

Understanding the complex formation of metal ions in room-temperature ionic liquids (ILs) is essential for the application of ILs in solvent extraction. Nevertheless, the research on metal complex formation in ILs lags behind other applications. The complex formation equilibria may be influenced by specific interactions among the metal ion, ligand molecule, and IL cation and anion. In the present investigation, the complex formation of Ni2+ with ethanol (EtOH) and methanol (MeOH) molecules in ILs, 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([CNmim][TFSA], where N represents the alkyl chain lengths of 2 and 8) was discussed in terms of the microscopic interactions among alcohol molecules, [CNmim]+ and [TFSA]-, and the mesoscopic mixing states of alcohols in [CNmim][TFSA], with N = 2-12. The microscopic interaction of alcohol molecules with the imidazolium ring H atoms in the ILs was evaluated by using ATR-IR and 1H and 13C NMR spectroscopies. The self-hydrogen bonding of alcohol molecules was clarified from the O-H stretching vibration of alcohol molecules. MeOH molecules can be more strongly hydrogen-bonded with themselves than EtOH molecules due to the less steric hindrance and the weaker dispersion force of MeOH with the IL cation's alkyl chain. In fact, small-angle neutron scattering (SANS) experiments revealed the more heterogeneous mixing of MeOH with the ILs by the self-hydrogen bonding among MeOH molecules than EtOH. The longer the IL cation's alkyl chain, the more the MeOH clusters significantly form. In contrast, the formation of EtOH clusters becomes weaker with elongating the alkyl chain. Ultraviolet (UV)-visible spectroscopic measurements on Ni2+-[CNmim][TFSA]-alcohol solutions with N = 2 and 8 revealed that di-, tetra-, and hexa-alcohol-Ni2+ complexes are formed in both the ILs. With N = 2, the stabilities of Ni2+-EtOH and Ni2+-MeOH complexes are comparable in the IL. However, with N = 8, the complexes are more stable in the EtOH solutions than in the MeOH solutions. This is because the less heterogeneous mixing of EtOH molecules with the IL results in the larger enthalpic contribution in the complex formation, as shown by the thermodynamic parameters estimated by the van't Hoff plots on the stability constants at several temperatures.

(Invited) Tunable Infrared Optoelectronics Achieved by the Reversible Intercalation of Ionic Liquid Anions in Multilayer Graphene in the Mid-Infrared Wavelength Range

We report the use of multilayer graphene (MLG) grown by chemical vapor deposition (CVD) approximately 75 layers (26 nm) thick configured in a simple electrochemical device. Applying a voltage of 3–4 V drives the intercalation of anion [TFSI-] (ion liquid diethylmethyl(2-methoxyethyl)ammonium bis(trifluoromethylsulfonyl)imide [DEME][TFSI]]) resulting in the reversible modulation of the properties of this optically dense material. Upon intercalation, we observe an abrupt shift of 35 cm−1 in the G band Raman mode, an abrupt increase in FTIR reflectance over the wavelength range from 1.67 to 5 μm (2000–6000 cm−1 ), and an abrupt increase in luminescent background observed in the Raman spectra of graphene. All of these abrupt changes in the optical properties of this material arise from the intercalation of the TFSI− ion and the associated change in the free carrier density (Δn = 1021 cm−3). Suppression of the 2D band Raman mode observed around 3 V corresponds to Pauli blocking of the double resonance Raman process and indicates a modulation of the Fermi energy of ΔEF= 1.1 eV. The thermal emissivity of the MLG device is also substantially modulated over the range from 7 – 14 µm. Using this device, have demonstrated free-space optical communication that utilizes ambient Planck radiation from a warm body and modulates the emitted intensity. We present an experimental demonstration achieving error-free communications at 100 bits per second over laboratory scales. We have also developed an AC Raman technique for measuring the Raman spectra during the intercalation−deintercalation half cycles in a multilayer graphene (MLG) device operating at 0.2−10 Hz. Raman spectra taken just 200 ms apart show the emergence and disappearance of the intercalated G band mode at around 1610 cm−1 . By integration of over hundreds of cycles, a significant Raman signal can be obtained. The intercalation/ deintercalation is also monitored with thermal imaging via voltage-induced changes in the carrier density, complex dielectric function ε(ω), and thermal emissivity of the device. “Dynamic Study of Intercalation/Deintercalation of Ionic Liquids in Multilayer Graphene Using an Alternating Current Raman Spectroscopy Technique” Zhi Cai, Haley Weinstein, Indu Aravind, Ruoxi Li, Sizhe Weng, Boxin Zhang, Jonathan L. Habif, and Stephen B. Cronin. Journal of Physical Chemistry Letters, 14, 7223 (2023).“Gate-tunable modulation of the optical properties of multilayer graphene by the reversible intercalation of ionic liquid anions” Zhi Cai, Indu Aravind, Haley Weinstein, Ruoxi Li, Jiangbin Wu, Han Wang, Jonathan Habif, and Stephen Cronin. Journal of Applied Physics. 132, 095102 (2022).“Harvesting Planck radiation for free-space optical communications in the long-wave infrared band“ Haley A. Weinstein, Zhi Cai, Stephen B. Cronin, and Jonathan L. Habif, Optics Letters. 47, 6225-6228 (2022). Figure 1

Ionic Liquid Induced Aggregation and Precipitation Behavior of Pinacyanol

AbstractIn this paper, we demonstrate the unique role of ionic liquids (ILs) as dye aggregation and precipitation promoter. Specifically, we have observed that the presence of small amount of IL such as 1‐butyl‐3‐methylimidazolium hexaflurophosphate ([bmim][PF6]), 1‐butyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide ([bmim][Tf2N]), 1‐butyl‐3‐methylimidazolium trifluoromethanesulfonate ([bmim][OTf]), 1‐butyl‐3‐methylimidazolium tetrafluoroborate ([bmim][BF4]) and 1‐butyl‐1‐methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([bmpyrr][Tf2N]) in aqueous milieu can help in the conversion of a cyanine dye 1,1’‐Diethyl‐2,2’‐carbocyanine iodide (Pinacyanol iodide) into J‐ and H‐aggregates followed by time dependent precipitation of the dye. The anion of the added IL strongly affects the aggregation process in aqueous solution. Addition of small amount of BF4− anion based IL [bmim][BF4] to aqueous solution of the dye initially induces J‐ and H‐aggregation followed by quick precipitation of the dye in time dependent manner. Presence of small amount of other anion containing ILs such as ([bmim][PF6]), ([bmim][OTf]), ([bmim][Tf2N]) and ([bmpyrr][Tf2N]) strongly supports H‐aggregation of the dye in aqueous solution whereas higher wt % of added ILs also caused precipitation of the dye in a time dependent manner. The nature of the IL anion, wt % of added IL and temperature conditions decides efficiencies of aggregation and precipitation processes. The dual yet unique behavior of ILs as an additive influence the aggregation of cyanine dyes and precipitation has been demonstrated. The observed results can contribute towards various application for dye aggregates and in the removal of dyes from water. The developed process can find potential applications in the field of material science, wastewater treatment, future light harvesting systems, and opto‐electronics related fields.

Fast Responsive and High-Strain Electro-Ionic Soft Actuator Based on the 3D-Structure MXene-EGaIn/MXene Bilayer Composite Electrode.

Electro-ionic soft actuators have garnered significant attention owing to their promising applications in flexible electronics, wearable devices, and soft robotics. However, achieving high actuation performance (large bending strain and fast response time) of these soft actuators under low voltage has been challenging due to issues related to ion diffusion and accumulation. In this study, an electro-ionic soft actuator is fabricated using Ti3C2Tx MXene and eutectic gallium-indium (EGaIn) composite material as the bilayer electrode and methylammonium formate/1-ethyl-3-methylimidazolium tetrafluoroborate/poly(vinylidene fluoride) (MAF-EMIMBF4/PVDF) as the ionic liquid-type electrolyte. The research results indicate that the prepared soft actuator exhibits excellent actuation performance with a peak-to-peak displacement of 35 mm and a bending strain of 0.69% (a peak-to-peak strain of 1.38%) under a low voltage (3 V). The electro-ionic soft actuator shows a wide frequency range (0.1-10 Hz), fast response time (0.35 s), and a rise time of 7.5 s. Furthermore, it demonstrates good cyclic durability, with a retention rate of 92.5% of its performance for 10 000 cycles. These excellent performances are attributed to the 3D structure of the Ti3C2Tx-EGaIn/Ti3C2Tx bilayer composite electrode, as well as the characteristics of the low viscosity, high conductivity, small ion volume, and larger volume difference between cations and anions in MAF ionic liquid. The high-performance electro-ionic soft actuator can be used in various fields such as artificial muscles, tactile devices, and soft robots.

The role of the cation and anion in aqueous liquid chromatography with sodium dodecyl sulphate and imidazolium-based ionic liquids as mobile phase reagents

BackgroundIn reversed-phase liquid chromatography, solute retention is primarily influenced by interactions between a nonpolar stationary phase and a moderately polar hydro-organic mobile phase, based on the solute lipophilicity. However, challenges regarding retention and peak tailing can arise due to ionic interactions between positively charged analytes and free silanols present on silica-based stationary phases. To address these challenges, incorporating surfactants and ionic liquids (ILs) into the mobile phase offers an effective solution. These additives synergistically enhance chromatographic performance through electrostatic and lipophilic interactions, which enable fine-tuning of selectivity and improved separation efficiency. ResultsThis study explores the chromatographic behaviour of several basic compounds in aqueous mixtures containing the anionic surfactant sodium dodecyl sulphate (SDS), above its critical micellar concentration, combined with various 1-alkyl-3-methylimidazolium-based ionic liquids (ILs) featuring chloride, tetrafluoroborate, and hexafluorophosphate anions, all without the addition of organic solvents. Specifically, this research investigates the influence of different anion types within the ILs and considers the impact of the IL cations. Analysis of solute peak profiles reveals narrow and symmetrical peaks. By introducing tetrafluoroborate and hexafluorophosphate IL anions into a mobile phase that contains an anionic surfactant, the study sheds light on the interactions occurring within the chromatographic column. This enhanced understanding of the combined effects of surfactants and ILs contributes to refining chromatographic methodologies. SignificanceThis research highlights the importance of carefully selecting the appropriate IL when incorporating it into a micellar mobile phase alongside SDS. This combination results in practical retention times that surpass the performance achieved with either the surfactant or IL alone in the mobile phase. The study particularly emphasises the impact of the IL anion, especially in the absence of SDS and organic solvents. This unveils interactions that are otherwise obscured in micellar and hydro-organic media, providing new insights into chromatographic dynamics.