Host-guest interactions between oleic acid and β-cyclodextrin: A combined experimental and theoretical study

The physicochemical properties and interactions of the complex of oleic acid (OA) and β-cyclodextrin (β-CD) were studied by experimental and computational methods. Differential scanning calorimetry and X-ray diffraction confirmed the successful preparation of OA/β-CD inclusion complex. The stability of the complex was improved, exhibiting a 61.2 °C higher degradation temperature and a lower peroxide value than OA. Raman and Fourier transform infrared spectroscopy studies revealed that the carboxyl group of OA entered into the β-CD cavity to form hydrogen bonds, which was confirmed by conformational search and weak interactions analysis. Dispersion energy from van der Waals (–290.79 kJ/mol) contributed 87.3% to total interaction energy (–253.88 kJ/mol). Topological analysis showed that four moderate hydrogen bonds were formed between OA and β-CD with the bond energy ranging from –76.05 to –30.25 kJ/mol. This work provided theoretical basis for the development of nutritional supplements containing unsaturated fatty acids encapsulated by β-CD.