Structural Aspects of Crystalline Derivatized Cyclodextrins and Their Inclusion Complexes

Derivatization of cyclodextrins (CDs) demands creative chemistry and sound analytical characterization. Structural characterization of solid cyclodextrins and their inclusion compounds places strong reliance on X-ray diffraction (XRD) analysis. In this review, following introductory remarks on the role of single crystal XRD and the under-utilized power of powder XRD, a survey of crystal structures of pure CD hosts and CD inclusion compounds carried out during the last six years is presented. The entries range from simple alkylated derivatives to elegant multi-substituted target CD molecules, with and without included guests. For the majority of the entries described, the main structural features gleaned by XRD methods are outlined and their relevance to applications is highlighted. Keywords: Crystal packing, derivatized cyclodextrins, host conformation, host design, isostructurality, powder X-ray diffraction, single crystal X-ray diffraction, supramolecular structures