Self-assembly behavior of tail-to-tail superstructure formed by mono-6-O-(4-carbamoylmethoxy-benzoyl)-β-cyclodextrin in solution and the solid state

• A novel mono-6-O-(4-carbamoylmethoxy-benzoyl)-β-cyclodextrin was newly synthesized.
• The self-assembly structure was constructed by mono-modified β-cyclodextrin.
• A novel supramolecular structure displayed a ‘Yin-Yang’-like packing mode.

A novel mono-modified β-cyclodextrin (β-CD) consisting of 4-carbamoylmethoxy-benzoyl unit at the primary side was synthesized and its self-assembly behavior was determined by X-ray crystallography and NMR spectroscopy. The crystal structure shows a ‘Yin-Yang’-like packing mode, in which the modified β-CD exhibits a channel superstructure formed by a tail-to-tail dimer as the repeating motif with the substituted group embedded within the hydrophobic cavity of the facing β-CD. The geometry of the substituted group is determined by the inclusion of the cavity and is further stabilized by two intermolecular hydrogen bonds between the carbonyl O atom and phenyl group. Furthermore, NMR ROESY investigation indicates that the self-assembly behavior of the substituted group within the β-CD cavity is retained in aqueous solution, and the effective binding constant Ka was calculated to be 1330 M−1 by means of 1H NMR titration according to iterative determination.

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