title: The first successful crystallographic characterization of a cyclodextrin dimer: efficient synthesis and molecular geometry of a doubly sulfur-bridged beta-cyclodextrin.
abstract: Beta-cyclodextrin is transannularly disulfonylated at the 6(A)- and 6(B)-positions, and then converted to the corresponding 6(A),6(B)-diiodide and 6(A),6(B)-dithiol. Cross-coupling of the latter two species yields a single head-to-head-coupled beta-cyclodextrin dimer 5 with two sulfur linkers at adjacent 6-methylene carbons. NMR and X-ray analysis revealed the trans-type ("aversive") linkage of both beta-cyclodextrin units. In the solid-state structure of 5.5 MeOH.23 H(2)O, the undistorted cyclodextrin macrocycles feature almost parallel ring planes pointing away from each other, leaving 5 with a "handcuff-like" appearance of approximate C(2) symmetry. This work represents the first successful crystallographic study on a cyclodextrin dimer.
authors.affiliation: Faculty of Pharmaceutical Sciences, Nagasaki University Bunkyo-machi, Nagasaki 852-8521, Japan.
authors.forename: De-Qi
authors.initials: DQ
authors.lastname: Yuan
authors.forename: Stefan
authors.initials: S
authors.lastname: Immel
authors.forename: Katzutaka
authors.initials: K
authors.lastname: Koga
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Yamaguchi
authors.forename: Kahee
authors.initials: K
authors.lastname: Fujita
mesh_terms: D002236:Carbohydrate Conformation; D018360:Crystallography, X-Ray; D003505:Cyclodextrins / Q000737:chemistry*; D019281:Dimerization; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015394:Molecular Structure; D013455:Sulfur / Q000737:chemistry*; D047392:beta-Cyclodextrins
chemical_list: D003505:Cyclodextrins; D047392:beta-Cyclodextrins; D013455:Sulfur; C031215:betadex