抄録
This review mainly describes the progress of recent studies on the inclusion properties of large-ring cyclodextrins with guest molecules in aqueous solution. Complex formations of large-ring cyclodextrins (CDs) having degree of polymerization 11-40 with iodine and sodium dodecyl sulfate (SDS) were examined mainly by isothermal titration calorimetry. The term CDn is used to represent a generalized form for a CD, where represents the degree of polymerization. The curves obtained for the titration of the CD21 to CD33 with iodinecannot be analyzed by a model based on a single set of identical sites, but, rather, by a model assuming 1 : 2complex formations with identical interacting sites. These two binding constants, defined relative to the progressof saturation, and the corresponding enthalpies of binding were determined. These thermodynamic data indicate that the binding process is enthalpically driven. The titration curve for CD26 with SDS can be analyzedusing a model that assumes 1 : 2 complex formation with identical interacting sites as well, and the binding of a second SDS molecule to CD26 is rather strong. For other CDs, the titration curves are consistentwith a 1 : 1 complex formation with weak interaction in contrast to the case of CD26-SDS. The strong binding of the second SDS molecule to CD26 was simulated using molecular dynamics calculations based on the recently reported crystal structure of CD26.
