The Inclusion Research Of β-Cyclodextrin And Three Aromatic Guest Molecules

Due to the unique structure with hydrophobic central cavity,β- cyclodextrins can selectively bind different guest molecules to form inclusion complexes in order to improve solubility, stability and other properties of guest molecules. Thus,β-cyclodextrins have been widely used in many different fields, such as pharmaceutics, analytics, food and environment, etc.In this paper, by using ofβ-cyclodextrin as host, p-aminobenzoic acid, m-aminobenzoic acid and o-aminobenzoic acid as guest, the inclusion of host and guest was studied by molecule simulation and experiment.In the the molecule simulation, p-aminobenzoic acid, m-aminobenzoic acid and o-aminobenzoic acid were all found to have inclusion withβ-cyclodextrin. In the process of inclusion, the carboxyl of p-aminobenzoic acid and m-aminobenzoic acid was found to take the first place to insert the cavity ofβ-cyclodextrin from the larger side, while in the condition of o-aminobenzoic as guest, the phenyl inserted the cavity ofβ-cyclodextrin from the larger side first. Once the guest molecule inserted into the host molecule as complex, the guest molecule vibrated vertically with the random circumvolution. With the increase of simulation time, there was no found of the separation of duest and host. In molecule simulation, the comparison of vacuum and water as entironment suggested that in the process of inclusion, water played an important role to promote inclusion and stabilize the structure. From the result of pair correlation function in the simulation with the entironment of water, the hydrophobic cavity ofβ-cyclodextrin and the hydrogenolysis betweenβ-cyclodextrin's hydroxide radical and water were observed, which proved the structure of hydrophobic inside and hydrophilic outside. From the comparison of complexes'structures of o-aminobenzoic acid, m-aminobenzoic acid and p-aminobenzoic acid, the conclusion was drew that the space structure and the substitute position of the guest molecule had a considerable influence on the structure of complexes.The result of circular dichroism and 1HNMR accorded with the conclusion of molecule simulation, in addition, crystal structure ofβ-cyclodextrin- p-aminobenzoic acid inclusion compound was consistent with the result of molecule simulation , which proved the correctness of simulation and confirmed the structure of inclusion compound.