Inclusion complexation of fractionated alpha-cyclodextrin molecular tube with sodium dodecyl sulfate

Molecular tube (MT) consisting of alpha -cyclodextrins (alpha -CDs) was pre pared fractionated and characterized in terms of MALDI-TOF mass spectroscop y, isothermal titration calorimetry (ITC), and H-NMR titration. MT with var ious molecular weight (2400-23,000) was separated into seven fractions by g el permeation chromatography and the molecular weight of each MT tons deter mined by MALDI-TOF mass spectroscopy. Furthermore, association constant, st oichiometry and thermodynamic parameters for inclusion complexation of MT w ith sodium dodecyl sulfate (SDS) were determined by ITC. From the ITC analy sis, if was found that inclusion complexation between MT and SDS was enthal py driven. Further, the association constant was calculated to be ale order of 10(5) M-I. ITC and H-1-NMR titration measurement revealed that one MT m olecule (M-n = 7,600, M-w/M-n = 1.42) formed an inclusion complex with two SDS molecules. These results suggest that MT acts as a host molecule with t wo binding sites at both ends. Therefore MT is considered to be feasible fo r constructing various kinds of molecular assemblies. Copyright (C) 2000 Jo hn Wiley & Sons, Ltd.