Inclusion complexes of bisphenol A with cyclomaltoheptaose (β-cyclodextrin): solubilization and structure Original Research Article

The inclusion complexation behavior and the solubilization effects of Bisphenol A (BPA, an endocrine-disrupting chemical) by cyclomaltohexaose, -heptaose, and -octaose (α-, β-, and γ-cyclodextrins) were investigated by 1H NMR spectroscopy and by elemental analysis. The results showed that β- and γ-cyclodextrins gave the satisfactory solubilization ability to BPA up to 7.2 × 103 mg L−1 and 9.0 × 103 mg L−1, respectively. X-ray crystallographic diffraction and ROESY spectroscopy were also employed to investigate the structure of the β-CD/BPA inclusion complex in both aqueous solution and the solid state. The result showed that this complex adopted a 2:2 stoichiometry in the solid state, that is, a head-to-head β-CD dimer accommodated two BPA molecules. The inclusion of BPA led to the desolvation of the β-CD cavity and the destruction of the circularly closed hydrogen-bond network in the secondary side of β-CD, which made the complex more soluble.