Cyclodextrins conformational flexibility

Unlike isotropic media, where molecules have equal mobility and conformational flexibility in all dimensions, in an organized medium their mobility and flexibility are restricted or constrained in at least one dimension. For example, the reaction cavities of a micelle and cyclodextrins are made up of a hydrophobic core and a hydrophilic exterior (Fig. 11). A highly polar boundary separates the hydrophobic core from the aqueous exterior. Such a boundary provides unique features to these media that are absent in isotropic solution. Translational motion of a guest present within the reaction cavity is hindered by the well-defined boundary. 

Bell AF, Hecht L and Barron LD (1997) New evidence for conformational flexibility in cyclodextrins from vibrational Raman optical activity. Chemistry - A European Journal 3 1292-1298. 

Cyclodextrins are macrocycles with limited flexibility. In all the crystal structure analyses of cyclodextrins, the glucose units have the D-pyranose configuration with the normal 4Ct chair conformation [556, 558, 559]. This chair form is nearly rigid, as illustrated by only small variations (<7°) of the intrapyranose ring tor-... 

Fujita. K. Chen, W.-H. Yuan, D.-Q. Nogami, Y. Koga, T. Fujioka, T. Minashi. K. Immel. S. Lichtenthaler. F.W. Guest-induced conformational change in a flexible host Mono-a/rra-P-cyclodextrin. Tetrahedron Asymmetry 1999. 10 (9). 1689-1696. 

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