Cyclodextrins as Building Blocks for Supramolecular Structures and Functional Units

TLDR

Cyclodextrins are versatile building blocks that can be regioselectively substituted and serve as host molecules with internal cavities capable of accommodating guests, enabling the formation of supramolecular assemblies and applications such as chromatography and drug release. Supramolecular structures are formed in solution and characterized by high‑resolution spectroscopic methods. Chemical conversion of these assemblies produces complex architectures—including catenanes, rotaxanes, polyrotaxanes, and tubes—and cyclodextrins act as active catalysts.

Abstract

Abstract Cyclodextrins are frequently used as building blocks, because they can be linked both covalently and noncovalently with specificity. Thus one, two, three, seven, fourteen, eighteen, or twenty substituents have been linked to one β‐cyclodextrin molecule in a regioselective manner. Furthermore, Cyclodextrins may serve as organic host molecules. Their internal cavity is able to accommodate one or two guest molecules. Conversely, suitable guest molecules can be used to thread one, two, or many (one hundred or more) cyclodextrin rings. The resulting supramolecular structures are often formed in solution, which allows characterization by high‐resolution spectroscopic methods. Chemical conversion of these structures provides molecular architectures such as catenanes, rotaxanes, polyrotaxanes, and tubes, which are not readily prepared by other methods. The particular properties of Cyclodextrins can also be employed, for example, for the chromatographic separation of complex mixtures of substances, even racemates, by molecular recognition. Cyclodextrins and their derivatives have been found to be remarkably active catalysts as well. Finally, since Cyclodextrins can favorably influence the release of drugs, many new applications will certainly be developed in the near future.