Identification of 1,3-Dialkylimidazolium Salt Supramolecular Aggregates in Solution

Abstract

The nature of the interactions between 1,3-dialkylimidazolium cations and noncoordinating anions such as tetrafluoroborate, hexafluorophosphate, and tetraphenylborate has been studied in the solid state by X-ray diffraction analysis and in solution by (1)H NMR spectroscopy, conductivity, and microcalorimetry. In the solid state, these compounds show an extended network of hydrogen-bonded cations and anions in which one cation is surrounded by at least three anions and one anion is surrounded by at least three imidazolium cations. In the pure form, imidazolium salts are better described as polymeric supramolecules of the type {[(DAI)(3)(X)](2+)[(DAI)(X)(3)](2-)}(n) (where DAI is the dialkylimidazolium cation and X is the anion) formed through hydrogen bonds of the imidazolium cation with the anion. In solution, this supramolecular structural organization is maintained to a great extent, at least in solvents of low dielectric constant, indicating that mixtures of imidazolium ionic liquids with other molecules can be considered as nanostructured materials. This model is very useful for the rationalization of the majority of the unusual behavior of the ionic liquids.

Solution and thermal behaviour of novel dicationic imidazolium ionic liquids

“…Indeed, both the nature of the dicationic head groups and the core structure may significantly affect the three-dimensional supramolecular structure. [18][19][20][21] In terms of designing ionic liquids for specific applications, these dicationic ionic liquids open up the possibility of combining a resistance to high temperature with catalytic activity. In order to pursue this goal, the catalytic functionality could be situated on the anion, on the cationic head group, or alternatively on the spacer (for example, in the present case a benzene core), yielding multi-functionalised ionic liquids.…”

Spectroscopic Evidence of Nanodomains in THF/RTIL Mixtures: Spectroelectrochemical and Voltammetric Study of Nickel Porphyrins

“…6 The formation of these nanodomains can lead to additional stabilization of the electrogenerated species. Li et al 7 studied the micropolarity and aggregation behavior of RTILs with organic solvents.…”

Entanglement network of agarose in various solvents

“…It has been proposed that ionic liquids form three-dimensional structures even in the liquid state because of cation-anion hydrogen bonding and cation-cation ring stacking. [11][12][13] The threedimensional structure may contribute to the modulus of the solutions; if the elasticity due to the network of solvent molecules contributes to the plateau modulus (G N 0 ), then M e,melt is reduced. The aim of this study is to clarify whether or not the network formed by the ionic liquid molecules contributes to G N 0 .…”