The effect of urea moiety in amino acid binding by ß-cyclodextrin derivatives: A 1000-fold increase in efficacy comparing to native ß-cyclodextrin.

Water soluble amphiphilic anion receptors based on urea-substituted ß-cyclodextrin were synthesized via a copper(I) mediated azide-alkyne coupling reaction. The synthetic route was designed to minimize the number of operations of cyclodextrins. Stable products were obtained in 90% yield. They were successfully tested as amino acid receptors, showing excellent affinity constants (103-104M-1) in a highly competitive environment (pH 8 phosphate-buffered water solution). Isothermal titration calorimetry indicated that complex formation strongly depends on the hydrophobic nature of the guest and that the urea moiety of the receptor is necessary to efficiently bind amino acids.

Long-chain-linked ß-cyclodextrin dimers: Synthesis and relationship between reactivity and inclusion complex formation.

We synthesized ditopic compounds bearing two ß-cyclodextrin moieties linked by long aryl-alkyl linkers. The process of linker inclusion into ß-cyclodextrin cavity was observed during Sharpless click-chemistry conjugation. The target cyclodextrin dimers exhibit self-complexation via a glucose unit inversion phenomenon that is significantly weaker as compared with earlier reported analogs. It was confirmed that both cavities of such cyclodextrin dimers are available for interaction with larger guest molecules.