Facile preparation of deep eutectic solvents having high electrical conductivities

In the present study, we demonstrate the facile preparation of deep eutectic solvents (DESs) composed of various imidazolium iodides and iodine. The electrical conductivity of the DESs was high and was control-lable by changing the composition of the mixtures and the imidazolium cation species. In particular, the DES composed of 1-ethyl-3-methylimidazolium iodide and iodine in a 1:4 molar ratio showed an electri-cal conductivity as high as 70 mS cm-1, which was higher than that of ionic liquid (1-butyl-3-methylimidazolium iodide and 1-hexyl-3-methylimidazolium iodide) mixtures with iodine. The electri-cal conductivity of DESs based on 1-alkyl-3-methylimidazolium iodides increased with increasing iodine content. The high electrical conductivity of DESs was attributed to the Grotthuss mechanism in polyio-dide based on the viscosity results, Raman spectrum measurements, and quantum chemistry calculations.(c) 2022 Elsevier B.V. All rights reserved.

Automated summary

In this study, we demonstrated the easy preparation of deep eutectic solvents (DESs) using various imidazolium iodides and iodine. The electrical conductivity of the DESs could be controlled by changing the mixture composition and imidazolium cation species. Especially, the DES composed of 1-ethyl-3-methylimidazolium iodide and iodine in a 1:4 molar ratio exhibited a high electrical conductivity of 70 mS cm-1, which was higher than that of the ionic liquid mixtures with iodine. The high electrical conductivity of DESs can be attributed to the Grotthuss mechanism in polyiodide based on viscosity results, Raman spectrum measurements, and quantum chemistry calculations.