Competitive recognition between 1:2 ternary complex of zwitterion and H3PO4 towards 3D cucurbit[8]uril frameworks

Two competitive recognition modes between [C(3)SO(3)mim] and H3PO4 for cucurbit[8]uril (CB[8]) have been demonstrated. At a [C(3)SO(3)mim]/H3PO4 ratio of 1: 1, a three-dimensional CB[8] framework with 1D channel has been constructed wherein unusual octameric cluster of phosphoric acid facilitates the linkage of CB[8] units. When increasing [C(3)SO(3)mim]/H3PO4 ratio to 2: 1, 1: 2 ternary complex acts as building block to form a three-dimensional honeycomb CB[8] framework, presenting both cavity binding of imidazolium cations and side binding of sulfonate anions.