Insights into the Formation and Structures of Molecular Gels by Diimidazolium Salt Gelators in Ionic Liquids or “Normal” Solvents

Abstract

Insights are provided into the properties of molecular gels formed by diimidazolium salts both in "normal" solvents and ionic liquids. These materials can be interesting for applications in green and sustainable chemistry in which ionic liquids play a significant role, like catalysis and energy. In particular, two positional isomers of a diimidazolium cation have been examined with a wide range of anions for their ability to form gel phases. In particular, di-, tri-, and tetravalent anions bearing aliphatic or aromatic spacers were paired with the divalent cations. The properties of the organo- and ionogels formed have been analyzed by means of several different techniques, including calorimetry, rheology, resonance light scattering, UV/Vis absorption, polarizing optical microscopy, and powder X-ray diffraction measurements. The investigations performed enabled us to obtain a wide range of conductive materials characterized by a high thermal stability and a low corrosiveness of the gelator (organogels) or of both gelator and solvent (ionogels). The information gained should be useful in the broader quest to identify and promote their applications.

Carbohydrate-supramolecular gels: Adsorbents for chromium(VI) removal from wastewater

“…As expected, ionogels display a higher thermal stability than the analogous hydrogels, when an IL with a high crosslinking ability, such as [bmim][PF 6 ], is used as gelation solvent. [29,38]…”

“…The imidazolium cation bearing a long alkyl chain represents a hydrophobic counter cation to the hydrophilic, carbohydrate-derived anions. Furthermore, given that a different stoichiometry between the cation and anion of the gelator can influence the gel properties, [38] we have also synthesised a gelator formed from monocationic imidazolium and dianionic units:…”

Cationic Supramolecular Hydrogels for Overcoming the Skin Barrier in Drug Delivery

“…Interesting examples include supramolecular gels for which host–guest interactions induce self‐assembly only above a certain temperature and melt below it, as opposed to the majority of thermoreversible gels . Also, the use of bis‐imidazolium derivatives as LMWGs has been reported, but gel formation can also need the presence of additional solvents such as glycerol and octanol or ionic liquids …”

Metallosurfactant Ionogels in Imidazolium and Protic Ionic Liquids as Precursors To Synthesize Nanoceria as Catalase Mimetics for the Catalytic Decomposition of H2O2

“…They can self-assemble into various microstructures [9,12,13,15] through noncovalent interactions, such as hydrogen bonding, electrostatic interactions, coordination, and van der Waals forces. [22,23] The dicationic organic salts displayed good gelation ability for variousI Ls and provided useful information about the preparation of ionogels. [22,23] The dicationic organic salts displayed good gelation ability for variousI Ls and provided useful information about the preparation of ionogels.…”

“…[6,21] For example, D'Annaa nd co-workers constructed interesting ionogels by using diimidazoliuma nd dipyrrolidinium salts. [22,23] The dicationic organic salts displayed good gelation ability for variousI Ls and provided useful information about the preparation of ionogels. The advantage of LMWGs is the easy design of structures, although applications of ionogels formed by LMWGs need to be further expanded.…”