The mono-modified -cyclodextrin derivative, 6-O-(4-aminobenzoyl)--cyclodextrin (1), was synthesized and characterized. We compared its self-assembling behavior with structurally related -cyclodextrin derivative, 6-O-(4-hydroxybenzoyl)--cyclodextrin (2), in aqueous solution and in the solid state using NMR spectroscopy and single crystal X-ray structure analysis. The two complexes displayed different self-assembling behaviors. Complex 1 formed a head-to-tail helical columnar superstructure in which the substituent group penetrated deeply into the hydrophobic cavity of the adjacent -cyclodextrin from the second side and aligned along the screw axis, whereas 2 exhibited a channel superstructure with a tail-to-tail dimer as the repeating motif. Further NMR studies in aqueous solution supported the result of the solid state. The influence of substituent groups on the self-assembly behavior was examined in mono-modified -cyclodextrins by means of substituting an amino group for a hydroxyl group, which indicates that the weak intermolecular interaction is a critical factor in determining the self-assembling behavior.cyclodextrin, self-assembling behavior, crystal structure, supramolecular chemistry