Complexes of carbohydrates with metal cations. XVI•Di-D-fructose and di-L-sorbose dianhydrides

Di-D-fructose 2′, 1:2,1′-dianhydrides form complexes with metal cations if the two anomeric carbon atoms have the same configuration. Such anomers have the central 1,4-dioxane ring in a flexible form; complex formation involves O-1, O-1′, O-3, and O-3′, as confirmed by the X-ray crystal structure of the strontium complex of the β,β-dipyranose anomer. The α,β-anomers, and dianhydrides containing only furanose rings, do not form such complexes. Keywords: difructose dianhydrides, complex formation with cations, crystal structure of complex, chromatographic separation on ion-exchange resins.