Supramolecular Self‐Assembly of Cucurbit[6]uil and Ionic Liquid in Non‐aqueous System

A novel [2]pseudorotaxane of cucurbit[6]uril(CB[6]) and 1‐butyl‐3‐methyl‐imidazolium bromide ([C 4 mim]Br) was synthesized by directly mixing the host and the guest molecules in non‐aqueous system. Structural characterizations of the [2]pseudorotaxane were carried out by 1D, 2D NMR and X‐ray crystallography techniques both in solution and in crystal structure. The crystal structure demonstrated that CB[6] and [C 4 mim]Br formed a complex with the ratio 1:1, in which one guest [C 4 mim]Br was included inside the CB[6], while two other [C 4 mim]Br molecules were free and surrounded the [2]pseudorotaxane as solvent molecules, which could stabilize the crystal structure through hydrogen bonds. Moreover, parallel solvent channels consisting by free [C 4 mim]Br molecules occupied the pores among the frame of the pseudorotaxanes and formed zigzag lines in the crystal structure. [C 4 mim]Br can serve as not only the guest reactant but also the solvent in the formation of [2]pseudorotaxane formation.