Coulomb interactions ionic liquids

The interacting forces between ions in the ionic liquids are the strong electrostatic Coulombic forces. Ionic liquids have no measurable vapor pressure, and hence they may be used in high-vacuum systems to overcome many contaminant problems. Advantage of their non-volatile nature can be taken to conduct product separation by distillation with prevention of uncontrolled evaporation. 

The n values were high for all of the ionic liquids investigated (0.97-1.28) when compared to molecular solvents. The n values result from measuring the ability of the solvent to induce a dipole in a variety of solute species, and they will incorporate the Coulombic interactions from the ions as well as dipole-dipole and polarizability effects. This explains the consistently high values for all of the salts in the studies. The values for quaternary ammonium salts are lower than those for the monoalkylammonium salts. This probably arises from the ability of the charge center on the cation to approach the solute more closely for the monoalkylammonium salts. The values for the imidazolium salts are lower still, probably reflecting the delocalization of the charge in the cation. 

An early theory of ionic recombination in liquids was developed by Jaffe (1913) for application at a relatively high LET. However, in Jaffe s theory, coulombic interactions are ignored and the positive and negative ions are assigned the same mobilities and distribution functions. Therefore, its use in a... 

Temkin was the first to derive the ideal solution model for an ionic solution consisting of more than one sub-lattice [13]. An ionic solution, molten or solid, is considered as completely ionized and to consist of charged atoms anions and cations. These anions and cations are distributed on separate sub-lattices. There are strong Coulombic interactions between the ions, and in the solid state the positively charged cations are surrounded by negatively charged anions and vice versa. In the Temkin model, the local chemical order present in the solid state is assumed to be present also in the molten state, and an ionic liquid is considered using a quasi-lattice approach. If the different anions and the different cations have similar physical properties, it is assumed that the cations mix randomly at the cation sub-lattice and the anions randomly at the anion sub-lattice. 

The selection of the solvent is based on the retention mechanism. The retention of analytes on stationary phase material is based on the physicochemical interactions. The molecular interactions in thin-layer chromatography have been extensively discussed, and are related to the solubility of solutes in the solvent. The solubility is explained as the sum of the London dispersion (van der Waals force for non-polar molecules), repulsion, Coulombic forces (compounds form a complex by ion-ion interaction, e.g. ionic crystals dissolve in solvents with a strong conductivity), dipole-dipole interactions, inductive effects, charge-transfer interactions, covalent bonding, hydrogen bonding, and ion-dipole interactions. The steric effect should be included in the above interactions in liquid chromatographic separation. 

The structure of ionic liquids in the liquid state is determined by the interplay of two interactions. Firstly, a general Coulombic interaction that, in the absence of any others, would result in a concentric shell structure of ions similar to those observed for simple molten salts. Secondly, directional interactions between ions arising from charge distribution over the... 

Generally room-temperature ionic liquids (ILs) consist mostly of ions [1]. In these liquids the Coulomb interaction plays a major role, in contrast to the situation in ordinary molecular liquids where only dipolar and... 

An issue that has been explored is how the relative distribution of charge and mass affect the viscosity of an ionic liquid. Kobrak and Sandalow [183] pointed out that ionic dynamics are sensitive to the distance between the centers of charge and mass. Where these centers are separated, ionic rotation is coupled to Coulomb interactions with neighboring ions where the centers of charge and mass are the same, rotational motion is, in the lowest order description, decoupled from an applied electric field. This is significant, because the Kerr effect experiments and simulation studies noted in Section III. A imply a separation of time scales for ionic libration (fast) and translation (slow) in ILs. Ions in which charge and mass centers are displaced can respond rapidly to an applied electric field via libration. Time-dependent electric fields are generated by the motion of ions in the liquid... 

Motion in ionic liquids is predominantly collective. The strength of interion Coulomb interactions makes independent motion of ions impossible, and transport modes are collective. Further, solvation dynamics involve... 

The first ionic liquid that was discovered as early as 1914 by Walden [34], is ethyl ammonium nitrate (EAN), [NH3C2H5]+[N03]-. It is an explosive liquid, which is soluble in water and alcohols. The liquid structure is determined by the Coulomb interactions but to a large extend also by a network of hydrogen bonds [9],... 

In this context, interactions between ionic liquids and solutes are understood as intermolecular (and in extension interionic) solvation forces, which can be categorised according to Reichardt [4] (Fig. 2) as non-specific induction and dispersion (Coulomb) forces, and specific directional stoichiometric forces (hydrogen bond acceptor and donor, electron pair acceptor and donor) [4],... 

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