A study of the supramolecular assembly formed by cucurbit[7]uril and 4-cyanophenol

The binding interaction between 4-cyanophenol (4-CY) and cucurbit[7]uril has been studied using 1H NMR spectroscopy, UV–vis absorption spectroscopy, fluorescence spectroscopy and X-ray crystallography. The corresponding absorption and emission spectra obtained in aqueous solution revealed that Q[7] and 4-CY formed a 1:1 host-guest type complex. A single crystal structure was obtained by introducing [ZnCl4]2− and Ca2+ as structural inducers, which revealed that 4-CY was connected to Q[7] or [ZnCl4]2− anion via weak interactions such as hydrogen bonding, C-H···π, ion-dipole, to afford a Q[7]-based supramolecular framework. Interestingly, the framework exhibited a Chinese knot-like structure