Cyclodextrins

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α-Cyclodextrin structure

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β-Cyclodextrin structure

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γ-Cyclodextrin structure

In the above structures, the flexible 6-OH hydroxyl groups are shown in the trans (O5-C5-C6-O6 torsion) conformation forming linking hydrogen bonds around the bottom rim of the conical cavity. Such regular linkages are destabilized by dipolar effects, easily dissociated in aqueous solution and not found in cyclodextrin crystals. Usually these O5-C5-C6-O6 torsions are found in the (+)-gauche or (-)-gauche conformations where they may hydrogen bond to the ring oxygen atom of the same glucose residue via a linked water molecule.

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