Recognition of 1,4-Xylylene Binding Sites in Polyimidazolium Cations by Cucurbit[7]uril: Toward Pseudorotaxane Assembly

The binding interactions between cucurbit[7]uril (CB[7]) and different polyimidazolium cations containing aromatic binding sites (1,4-xylylene units) were studied experimentally by 1D and 2D NMR, high-resolution mass spectrometry (HRMS), and fluorimetry, and, theoretically, by computed geometries and enthalpy changes. CB[7] was found to form [2]- and [3]-pseudorotaxanes with these cations by the inclusion of the internal 1,4-xylylene units.