Solution and thermal behaviour of novel dicationic imidazolium ionic liquids

Abstract

A new class of functionalised dicationic ionic liquids, containing a central cationic unit capped by a basic functionality (imidazole), has been synthesised. These salts have been characterised in isotropic solution using proton and 2D-NMR spectroscopy, and their thermal stability has been studied by DSC and TGA. All these novel salts contain the 1-(1-imidazolylmethyl)-3,5-di{1-(3'-octylimidazolylmethyl)}-benzene cation as a defining structural motif. Salts of both singly and doubly charged anions were prepared and, in particular, the selected monoanions (Br − , [BF 4 ] − , or [NTf 2 ] − ) differ in size, shape and hydrogenbonding ability, whereas the dianions differ in the nature of the spacer, such as 1,4-benzenedicarboxylate, 2,6-naphthalenedicarboxylate, 1,5-and 2,6-naphthalenedisulfonate, 1,4-butanedicarboxylate, and 1,6-hexanedicarboxylate. These ionic liquids exhibit the presence of different conformers in solution, whose distribution is affected by the nature of the anion. The nature of the anion also affects their thermal stability.

Efficient Conversion of Carbon Dioxide by Imidazolium‐Based Cross‐Linked Nanostructures Containing Polyhedral Oligomeric Silsesquioxane (POSS) Building Blocks

“…This behaviour can be accounted for by some local modifications of the imidazolium cross‐linked network depending on the reaction conditions. This result could support the hypothesis that some reversible dealkylations of the organic salt took place, generating novel arrangements of the cross‐linked network.…”

Functionalised diimidazolium salts: the anion effect on the catalytic ability

“…17 The presence of a neutral imidazole unit on the cation structure made these TSDILs very efficient reaction media for the base catalysed mononuclear rearrangement of heterocycles (MHR) reaction. 17 The presence of a neutral imidazole unit on the cation structure made these TSDILs very efficient reaction media for the base catalysed mononuclear rearrangement of heterocycles (MHR) reaction.…”

Palladium supported on Halloysite-triazolium salts as catalyst for ligand free Suzuki cross-coupling in water under microwave irradiation

“…Dicationic ionic liquids, indeed, have high thermal stability, higher than that normally characterizing the corresponding monocationic; therefore, in terms of designing ionic liquids for specific applications, the dicationic ionic liquids open up the possibility to develop a new system with resistance to high temperature [24]. Furthermore, for an application as support catalyst in the Suzuki reaction, the new support was designed with an aromatic linker to allow -interactions between catalyst and substrates and, therefore, facilitate the cross-coupling reaction.…”