Low-Molecular-Weight Supramolecular Ionogel Based on Host-Guest Interaction.

Supramolecular ionogels were prepared by self-assembly of small molecules through host-guest interaction between β-cyclodextrin (β-CD) and a room-temperature ionic liquid (IL) 3-(1-methyl-3-imidazolio)propanesulfonate-lithium bis(trifluoromethanesulfonyl)imide (MIPS-LiTFSI) which contains zwitterion MIPS. 19F NMR and 2D ROESY 1H NMR have been used to prove that only TFSI- is involved in the complexation. 1H NMR, FT-IR, and comparative tests indicated that the electrostatic interaction between imidazole cation and TFSI- anion and intermolecular hydrogen bonding between three compounds also contribute to the formation of supramolecular ionogel. Ionogels with different gel-sol phase transition temperatures can be obtained by adjusting the molar ratio between β-CD and MIPS-LiTFSI. In addition, the supramolecular ionogels composed of "channel type" structural β-CD have been constructed. The ionogel with high conductivity and low activation energy open a door to new fields for special applications.