Investigations of structure property relationships of highly hygroscopic Imidazolium and Choline based ILs for the prediction of thermodynamic trends

1,3-alkyl-imidazolium-based ionic liquids show a wide range of applications from use as a "designer solvent", in catalysis^1-3 up to material science^4-6. The interaction between cation and anion can be investigated by analyzing the crystal structure.⁷ In our work, we synthesized various 1,3-functionalized imidazolium and choline based Ils for the use as drying agent in sorption systems. Here especially substances with organic anion such as acetate, lactate and formate were quiet interesting because they expected, among other beneficial properties, a low melting point and a strongly pronounced hygroscopic behavior. However, the purification of the synthesized compounds showed a number of previously unknown crystal structures which offers interesting thermodynamic aspects, as well as the interaction of cations and anions could be examined. In addition, the crystal structure data provided the molecular volume of the ions, which is used to predict thermodynamic aspects.

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