Solvent Properties and Structure of Imidazolium ILs

The model of non-homogeneous Hquids for ILs may be more helpful not only for the rationahzation of many of their properties but also in allowing the design of new IL materials with tailor-made properties. In order to develop this model a close look at the structure of pure ILs in the solid, liquid and gas phases is necessary, followed by analysis of the interaction of other substances with the ILs through changes in the physico-chemical properties. 

The strongest hydrogen bond always involves the most acidic H2 of the imidazoHum cation followed by the other two hydrogens (H4 and H5) of the imidazoHum nucleus and/or the hydrogens of the N-alkyl radicals. These bonds possess the 

In some cases there are typical jr-jt stacking interactions among the imidazolium rings and in the case of l-alkyl-3-methyHmidazolium salts relatively weak C-H  

It is important to note that effects other than jr-jr stacking, such as the entropy effect and electrostatic interactions, may not favor the formation of structures of the type shown in Fig. 3.5-6. It can be proposed that the best representation for the imidazolium salts in the solid phase is [(DAI) (X) )] +[(DAI), j(X) J] , where DAI is the 1,3-dialkylimidazoHum cation and X is the anion. 

This structural pattern is even maintained in the gas phase and evidence for the clustering - supramolecules formed through association of the 1,3-dialkylimidazolium cations with the anions - has been obtained by mass spectrometry expert- 

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