Chromic Ionic Liquids

Abstract

One of the most prominent features of ionic liquids (ILs) is the possible introduction of a desired functionality that is originally inherited from the functional group tethered to its component ions as well as the rational control of liquid properties by selecting the component ions. In this Review, we present the development of ILs with chromism, which is attributed to the colorimetric response to certain external stimuli such as temperature, light, electric field, pH, and chemicals, mainly focusing on the molecular design of the component ions.

Acidic Ionic Liquids as Metal-Free and Recyclable Catalysts for Direct Reduction of Aromatic Allylic Alcohol in Dimethyl Carbonate via Hydrogen Transfer

“…Although the system was efficient and up to 94% yield was obtained, the system needed neutralization after the reaction and the catalyst could not be reused. Ionic liquids (ILs) have many distinguished advantages, such as negligible vapor pressure, good chemical and thermal stability, etc. − More importantly, ILs are designable and used as metal-free catalysts by introducing the corresponding functionalized groups. − Herein, acid-functionalized ionic liquids as metal-free and non-halogen catalysts can provide the proton to activate the hydroxyl group under mild conditions, thus benefiting the deoxygenation. Then, the recovery and recycling experiments of ionic liquids as catalysts have been extensively explored, showing broad application prospects. − Meanwhile, simple alcohols are used as reducing agents to effectively participate in the reduction of various functional groups, − which avoids the formation of stoichiometric metallic salts. , The use of green solvents is a crucial factor in reducing environmental impact during the chemical transformation.…”

High Ionic Conductivities of Ionic Materials as Potential Electrolytes

“…We have prepared and assessed three series of dicationic salts as novel ionic liquid electrolytes: dicationic stilbazolium salts, dicationic asymmetric viologens, and dicationic ionic liquids. Our general strategy for their synthesis is based on quaternization by S N 2 aka Menshutkin reactions, followed by metathesis of anions [12][13][14][15][16][17][18][19][20][21]23].…”

“…The introduction of multiple charges in low-molar ionic liquids and poly(ionic liquid)s widens the range of physical properties, leading to improvements in density, surface tension and viscosity, facilitated by their higher molecular weights [12,13]. The large charge densities and electrostatic interactions normally increase the ILs thermal stabilities [14,15] and electrical capacities [16,17], and results in better performance as antimicrobial agents [18] and stationary phases for gas chromatography [19], among others [20,21].…”

Recent advances in 3-aminoindazoles as versatile synthons for the synthesis of nitrogen heterocycles

“…Over the past decades, ionic liquids have emerged as an appealing alternative to organic solvents due to low cost, stability, easy separation and reusability. 14 In 2019, the Jeong group disclosed straightforward access to diverse chromeno pyrimido[1,2- b ]indazolone derivatives through one-pot three-component assembly of 3-aminoindazoles, aldehydes and 4-hydroxycoumarin. 15 This three-component coupling reaction proceeded with effective and almost complete conversion under solvent-free conditions.…”