Fluorophotometric Study on the Formation of Inclusion Complex Between Oleanic Acid and β-Cyclodextrin

It was found that in a buffer solution of H3PO4-H3BO3-HOAc, an inclusion complex was formed between oleanic acid (OLA) and β-cyclodextrin (β-CD) with mole ratio of 1 to 1. Excitation and emission maxima of the complex were found at wavelengths of 355 nm and 404 nm respectively. Value of association constant found at 25 ℃ was 71 L·mol-1, thermodynamic parameters of the complex were also determined. Values of ΔH0 and ΔS0 were both shown to be greater than 0, which proved that the inclusion reaction was endothermic. Value of ΔG0 was found to be smaller than 0, and becoming smaller as the reaction temperature increases, which proved that the inclusion reaction proceeds spontaneously and that the spontaneity of the reaction increases with the raise of reaction temperature.