The driving forces in the inclusion complexation of cyclodextrins

The driving forces leading to the inclusion complexation of cyclodextrins were reviewed, which included the electrostatic interaction, van der Waals interaction, hydrophobic interaction, hydrogen bonding, release of conformational strain, exclusion of cavity-bound high-energy water, and charge-transfer interaction. It was shown that except for the release of conformation strain and exclusion of cavity-bound water, the other interactions were indeed contributive to the complex formation. However, it was concluded that the enthalpy and entropy changes of the complexation were not good criteria to be used in judging whether a particular driving force was present or important, mainly because of the occurrence of enthalpy-entropy compensation. On the other hand, the multivariate quantitative structure-activity relationship analyses usually could illustrate which driving forces were important in certain inclusion complexation systems.