(592a) Z-Bond: New Insight into Ionic Liquid from Structure to Application

Kun Dong, Suojiang Zhang[1]

Beijing Key Laboratory of Ionic Liquids Clean Process, State Key Laboratory of Multiphase Complex System, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China.

Keywords: Ionic Liquids, Z-bond, Properties, Applications

Ionic liquids have attracted intensive attentions in academia and industries due to their unique properties and potential applications. Nowadays, much interest has focused on the quantitative relationship between structures and properties. A most critical question is â??what is the force to determine the properties of ionic liquids.â? Unlike the NaCl in which the Coulomb force is solely dominant, in ionic liquids the H-bonds as the structural directing contributor, are responsible for ionic pairing, stacking and self-assembling, and then influence their properties. ^1-2

By DFT calculations combining with the experimental spectroscopy, we found that coupling with the strong electrostatic force, H-bonds in ILs are very different from the common solvents, such as water. We defined the interaction as Z-bond. ³ More interestingly, the Z-bonds can be extended into a 3D network that is the essential interactive fashion and structural units and determine the many properties of ILs. ⁴

Moreover, involving in some important applications of ILs, the Z-bonds also play the critical roles. ⁵ The typical example is the dissolution of cellulose in ILs that involves in the two steps H-bonded interactions essentially. The first is to break the H-bonded network inside IL, then the active anion can interact with the hydroxyl protons of cellulose by forming Z-bonds. Another, such as CO₂/SO₂ gases absorption, the natural bioactive homologous separation, as electrolyte in lithium batteries, even as catalytic in reactions, involve in the roles of H-bonds. Therefore, the deep insights into structures, in particular the Z-bonds, can provide us with a rational design for the new ILs to fulfill the demands in some complicated chemical processes.

References:

(1) Dong, K.; Zhang, S.; Wang, J. Chem. Commun. 2015.

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(5) Zhang, S.; Sun, J.; Zhang, X.; Xin, J.; Miao, Q.; Wang, J. Chem. Soc. Rev. 2014, 43, 7838.