Ionic Liquids of Chelated Orthoborates as Model Ionic Glassformers

Abstract

Ionic liquids based on various chelated orthoborate anions of different N-containing onium cations have been synthesized using an economic synthesis strategy. Most orthoborates do not crystallize. They are found to have much higher glass transition temperatures and room-temperature viscosities than those with perfluorinated anions such as TFSI-, BF4 -, and CF3SO3 - (Tf-), as predicted from anion polarizability arguments. The ambient conductivities of the new ionic liquids are low relative to those with perfluorinated anions. The transport properties all show that cohesion in these liquids increases, and ionic mobilities decrease, as anion size increases, implying that van der Waals interactions, not Coulomb interactions, have become the controlling influence. In view of their resistance to crystallization, the large range of temperature over which these liquids can be studied, their hydrophobic properties, and their high fragilities, these liquids may provide good model systems for fundamental liquid state investigations and interesting solvents for large-molecule dissolution.

Novel 2-alkyl-1-ethylpyridinium ionic liquids: synthesis, dissociation energies and volatility

“…62,63 Despite the decrease of the electrostatic interactions, the pyridinium based ionic liquids have been found to be associated with a higher cohesion than the imidazolium ionic liquids, which is associated to the importance of cation-cation dispersive interactions. 64,65 The molecular interactions between the ions and their structural arrangement results in a complex structural/ nanostructural organization and hence interesting properties. Therefore, the knowledge of the dependence of ionic liquids properties on their molecular structures is of great importance.…”

Imidazolium-Based Ionic Liquid Binary Solvent System as an Extraction Medium in Enhancing the Rotenone Yield Extracted from Derris elliptica Roots

“…The density (ρ) of ionic liquids (ILs) decreases with the increase in organic cation bulkiness and anion selection affects ILs' density. Normally, the density of ILs varies in the range of 1.05-1.36 g/cm 3 at ambient temperature [43,44]. In terms of ILs' thermal stability, a research conducted had observed that thermal stability was dependent on both the cation and the anion of ILs.…”

Glass Transition Behavior of the Quaternary Ammonium-Type Ionic Liquid: N,N-Diethyl-N-methyl-N-(2-methoxyethyl)ammonium Bromide-H2O Mixtures

“…Thus, the liquid structures of RTILs are determined by a balance between long-range electrostatic forces and local geometric factors. As a result, many RTILs can be easily supercooled and form the glassy state [5][6][7]. Changes in the cation and anion combinations allow the physical and chemical properties of ionic liquids to be effectively tuned, for example, for manipulating the solvent properties of RTILs in order to achieve different purposes [7][8][9].…”