Supramolecular Self-assembly Formed from Cucurbit[8]uril and p-Hydroxybenzoic Acid

T he binding behavior of cucurbit[8]uril(Q[8]) and p -hydroxybenzoic acid(p-HBA) has been investigated using 1 H NMR titration experiments, UV-Vis absorption, isothermal titration calorimetry(ITC), and X-ray crystallography. Results revealed that the Q[8] can accommodate two p -HBA molecules to form a 1:2 host-guest inclusion complex in solution, namely ( p -HBA) 2 @Q[8]. From a poorly scattering crystal, we were able to identify two symmetry unique Q[8] rings, but with different p -HBA fillings. The structure can be represented as Q[8]+1.5 p -HBA, which gives Q[8]@(p-HBA) 2 ·Q[8]@ p -HBA as the structural formula. This supramolecular structure was screened for its ability to capture iodine. The experimental results showed that the adsorption efficiency of the supramolecular organic framework material for iodine capture was 43.8%, with an equilibrium adsorption capacity of 223.3 mg/g.