Magnetic Ionic Liquids in Analytical Microextraction: A Tutorial Review

Ultra-Low Viscosity and High Magnetic Susceptibility Magnetic Ionic Liquids Featuring Functionalized Diglycolic Acid Ester Rare-Earth and Transition Metal Chelates

“…MILs can be categorized as either radical-based or paramagnetic metal-containing solvents . Solvents composed of metal centers can be further classified as metal anion-based MILs (type A) and those formed by a metal cation (type B). , Although roughly 88% of applications requiring enhanced precision and method reproducibility popularly employ type A MILs, those solvents composed of [hfacac – ] metal chelates have been increasingly favored over other anions as they result in enhanced chemical/thermal stabilities and reasonably low viscosities (below 276.6 cP at 23.7 °C). , In an effort to produce ultra-low viscosity MILs with high magnetic susceptibility, it was vital that [hfacac – ]-based anions be paired with suitable cations that permit the incorporation of multiple paramagnetic metals in the MIL chemical structure. While employing dicationic and tricationic cations have previously resulted in the formation of MILs possessing 2–3 [FeCl 3 Br – ] anions, their synthesis is complex, and some combinations often produce highly viscous MILs .…”

“…Owing to advancements made in the design of their chemical structures, different classes of MILs have evolved over the years, , with key features that can influence specific MIL properties having been identified. , For example, bulky alkyl functional groups in the cation/anion can enhance the thermal stability and hydrophobicity of MILs, while employing anionic ligands containing trifluoromethyl moieties (CF 3 ) can expand their hydrophobic nature and result in reduced MIL viscosity. , Aromatic substituents in ligands have also been found to enhance the thermal stability of MILs but generally yield highly viscous solvents . While their magnetic properties are primarily controlled by the type and number of paramagnetic centers, their viscosity and solvation properties (e.g., dipolar and dispersive-type interactions) can also be influenced by the metal employed. − Clearly, both the type of ligands and paramagnetic centers forming the cation/anion can significantly influence the physical and chemical properties of MILs, which truly highlight their designer solvent nature.…”

“…13,14 MILs often possess similar physico-chemical properties to ILs and can additionally respond to an external magnetic field, making them easy to manipulate in many solvents using a hand-held magnet. 13,15 Owing to advancements made in the design of their chemical structures, different classes of MILs have evolved over the years, 16,17 with key features that can influence specific MIL properties having been identified. 18,19 For example, bulky alkyl functional groups in the cation/anion can enhance the thermal stability and hydrophobicity of MILs, while employing anionic ligands containing trifluoromethyl moieties (CF 3 ) can expand their hydrophobic nature and result in reduced MIL viscosity.…”

Green chemistry: Developments and perspectives for sample treatment in forensic methodologies

“…Additionally, there is the possibility of functionalizing diverse groups in order to modulate ILs selectivity (Clark et al, 2018). Among different ILs already described in the literature, magnetic ILs represent a hot topic in microextraction techniques due to their easy recovery, which facilitates automation (Gonz alez- Martín et al, 2022). Besides all these great features, ILs are poorly biodegradable and several studies are being made to determine their potential toxicity to microorganisms, plants, and animals (Gonçalves et al, 2021).…”

Neat and rapid preparation of hydrophobic magnetic ionic liquids composed of transition metal chelates featuring in situ formation capabilities in aqueous matrices

“…2,3 ILs exhibit desirable characteristics such as high chemical and thermal stability, 4,5 negligible vapor pressure, 1,4 tunable viscosities, 6 and catalytic properties. 7 Consequently, they are often used in applications such as organic reactions, 1,8 CO 2 capture, 1,9 nucleic acid analysis, 10 and electrochemistry. 11 Incorporating a paramagnetic metal center in either the cation or anion and/or both produces magnetic ionic liquids (MILs) that can respond to an external magnetic field.…”