Association of Some Polynuclear Aromatic Hydrocarbons with Cyclodextrins in Aqueous Medium

Complex formation using cyclodextrins (CyDs) as hosts and anthracene, phenanthrene, and naphthacene as guests has been studied in aqueous medium at 25 °C by measuring the guest volatilization rate. The results obtained are compared with those previously determined for benzene and naphthalene. Factors governing the host–guest association are discussed based on the dehydration energy of the guest derived from the Henry’s law constant. It was suggested that van der Waals force is the main factor to stabilize the polynuclear aromatic hydrocarbons in the CyD cavity and that the contribution of hydrophobic interaction is less important. The additional van der Waals stabilization does not work fully for naphthacene of the longest molecular axis among the guests studied.