Physicochemical characterization of paramagnetic ionic liquids 1-vinyl-3-alkylimidazolium tetrahalogenidoferrate(III) [VRIM][FeClmBr4 − m]

Evaluation of Solubility, Physicochemical Properties, and Cytotoxicity of Naproxen-Based Ionic Liquids

To solve the problems associated with poorly water-soluble nonsteroidal anti-inflammatory drugs (NSAIDs), naproxen-based ionic liquids (ILs) containing naproxen as an active pharmaceutical ingredient (API) anion were prepared with benzalkonium (tetradecyldimethylbenzyl ammonium), choline, and 1-octyl-3-methylimidazole as the cation. The structures and thermal properties were analyzed. Through the conductivity method, the solubility at 25 and 37 °C and the critical micelle concentration (CMC) at 25 °C were determined in water and ethanol. The octanol-water partition coefficients (K _ow) at 25 °C were measured with the shake-flask method. The cytotoxicity was evaluated with the MTT method. The results showed that the conversion of naproxen into the API-ILs increased the API's solubility in water by more than 850 times compared with the original API, and the thermostability was satisfactory with a lower glass transition temperature (t _g). Moreover, the variation trends of solubility, hydrophilicity, and K _ow were consistent with the different structures of naproxen-based ILs, except for benzalkonium naproxen. The CMC (10^-5-10^-6 M) in water and ethanol demonstrated that the naproxen-based ILs were surface activite ILs. The IC₅₀ values exhibited the low cytotoxicity of the naproxen-based ILs, which was better than 100 μM. The results provide essential information and a research basis for future topical and transdermal administration and oral administration of naproxen-based ILs.

Magnetic-field-controlled counterion migration within polyionic liquid micropores enables nano-energy harvest

Efficient separation of positive and negative charges is essential for developing high-performance nanogenerators. In this article, we describe a method that was not previously demonstrated to separate charges which enables us to fabricate a magnetic energy harvesting device. The magnetic field induces the migration of the mobile magnetic counterions (Dy(NO₃)₄^-) which establishes anion gradients within a layer of polyionic liquid micropores (PLM). The PLM is covalently cross-linked on which the positive charges are fixed on the matrix, that is, immobile. In a device with a structure of Au/dielectric//mag-PLM//dielectric/Au, the charge gradient is subsequently transformed into the output voltage through electrostatic induction. Removing the magnetic field leads to the backflow of magnetic anions which produces a voltage with a similar magnitude but reversed polarity. The parameters in fabricating the magnetic PLM such as photoinitiator concentration, UV irradiation time, water treatment time, and temperature are found to dramatically influence the size of micropores and the effective concentration of magnetic anions. Under optimized conditions, an output voltage with an amplitude of approximately 4 V is finally achieved. We expect this new method could find practical applications in further improving the output performance.

Confinement Effects on the Magnetic Ionic Liquid 1-Ethyl-3-methylimidazolium Tetrachloroferrate(III)

Confinement effects for the magnetoresponsive ionic liquid 1-ethyl-3-methylimidazolium tetrachloroferrate(III), [C2mim]FeCl4, are explored from thermal, spectroscopic, and magnetic points of view. Placing the ionic liquid inside SBA-15 mesoporous silica produces a significant impact on the material’s response to temperature, pressure, and magnetic fields. Isobaric thermal experiments show melting point reductions that depend on the pore diameter of the mesopores. The confinement-induced reductions in phase transition temperature follow the Gibbs–Thomson equation if a 1.60 nm non-freezable interfacial layer is postulated to exist along the pore wall. Isothermal pressure-dependent infrared spectroscopy reveals a similar modification to phase transition pressures, with the confined ionic liquid requiring higher pressures to trigger phase transformation than the unconfined system. Confinement also impedes ion transport as activation energies are elevated when the ionic liquid is placed inside the mesopores. Finally, the antiferromagnetic ordering that characterizes unconfined [C2mim]FeCl4 is suppressed when the ionic liquid is confined in 5.39-nm pores. Thus, confinement provides another avenue for manipulating the magnetic properties of this compound.

An overview of magnetic ionic liquids: From synthetic strategies to applications in microextraction techniques

Remarkable progress has been achieved in the application of magnetic ionic liquids in microextraction-based procedures. These materials exhibit unique physicochemical properties of ionic liquids featuring additional responses to magnetic fields by incorporating a paramagnetic component within the chemical structure. This intriguing property can open new horizons in analytical extractions because the solvent manipulation is facilitated. Moreover, the tunable chemical structures of magnetic ionic liquids also allow for task-specific extractions that can significantly increase the method selectivity. This review aimed at providing an up-to-date overview of articles involving synthesis, physicochemical properties, and applications of magnetic ionic liquids highlighting recent developments and configurations. Moreover, a section containing critical evaluation and future trends in magnetic ionic liquid-based extractions is included.

The Nature of Cation-Anion Interactions in Magnetic Ionic Liquids as Revealed Using High-Pressure Fourier Transform Infrared (FT-IR) Spectroscopy

Magnetic ionic liquids are a group of magneto-responsive compounds that typically possess high ionic conductivities and low vapor pressures. In spite of the general interest in these materials, a number of questions concerning the fundamental interactions among the ions remain unanswered. We used vibrational spectroscopy to gain insight into the nature of these interactions. Intramolecular vibrational modes of the ions are quite sensitive to their local potential energy environments, which are ultimately defined by cation-anion coordination schemes present among the ions. Ambient pressure Fourier transform infrared (FT-IR) spectroscopy indicates comparable interaction motifs for 1-ethyl-3-methylimidazolium tetrachloroferrate(III), [emim]FeCl₄, and 1-ethyl-3-methylimidazolium tetrabromoferrate(III), [emim]FeBr₄, magnetic ionic liquids. However, the vibrational modes of [emim]FeCl₄ generally occur at slightly higher frequencies than those of [emim]FeBr₄. These differences reflect different interaction strengths between the [emim]⁺ cations and FeCl4- or FeBr4- anions. This conclusion is supported by gas-phase ab initio calculations of single [emim]FeCl₄ and [emim]FeBr₄ ion pairs that show longer C-H···Br-Fe interaction lengths compared to C-H···Cl-Fe. Although the IR spectra of [emim]FeCl₄ and [emim]FeBr₄ are comparable at ambient pressure, a different series of spectroscopic changes transpire when pressure is applied to these compounds. This suggests [emim]⁺ cations experience different types of interaction with the anions under high-pressure conditions. The pressure-dependent FT-IR spectra highlights the critical role ligands attached to the tetrahalogenoferrate(III) anions play in modulating cation-anion interactions in magnetic ionic liquids.

Investigating the effect of ligand and cation on the properties of metal fluorinated acetylacetonate based magnetic ionic liquids

The effect of chemical structure on various physiochemical properties including thermal stability, solvent miscibility, magnetic susceptibility and viscosity is studied for acetylacetone based magnetic ionic liquids.

Inorganic/organic hybrid magnetic polymers based on POSS and pyridinium FeCl4: the effect of self-assembly

The inorganic/organic hybrid POSS-P4VP[FeCl₄] self-assembled into spheres with POSS aggregates as the core and P4VP[FeCl₄] as the shell. Its magnetic susceptibility was affected by self-assembly and molecular weight.

Triple-stimuli responsive polymers with fine tuneable magnetic responses

The formation of multi-stimuli responsive polymers exhibiting magnetic, pH and light sensitivity is reported.

Thermoresponsive magnetic ionic liquids: synthesis and temperature switchable magnetic separation

Thermoresponsive magnetic ionic liquids (MILs) with lower critical solution temperature (LCST) below 60 °C are synthesized.

Magnetic ionic liquids: synthesis, properties and applications

Magnetic ionic liquids are room temperature ionic liquids, which have paramagnetic properties by themselves without the need of adding magnetic particles.