Thickness recognition of bolaamphiphiles by alpha-cyclodextrin.

The minimum internal diameters of alpha-, beta-, and gamma-cyclodextrin were calculated by a space filling algorithm, MolShape, from the electron density maps created by semiempirical AM1 and PM3 calculations using Gaussian03. In addition, the minimum diameters of a series of dicationic bolaamphiphiles were calculated by MolShape as well. The calculated diameters of these hosts and guests allowed prognosis about the stabilities of the corresponding inclusion compounds. The experimental binding data, obtained by isothermal titration calorimetry (ITC), revealed indeed a very pronounced thickness recognition and correlate well with the calculated diameters.