Large-ring Cyclodextrins

Cyclodextrin (CD) is the common name for cyclic alpha-1,4-glucans; alpha-, beta- and gamma-CD, which are composed of 6, 7, 8 D-glucopyranose units, are well-known. However, most scientists have not recognized large-ring cyclodextrins (LR-CDs) composed of more than 9 D-glucopyranose units until recently, although the existence of LR-CDs containing 9-13 D-glucopyranose units in macrocycle was reported about a half century ago. The characteristics of LR-CDs have been studied for the last quarter century, and they are still relatively new materials. In this minireview, the unique characteristics of LR-CDs, including molecular structure, physicochemical properties and inclusion complex formation ability, are discussed. Preparation and purification methods are also reviewed.