Abstract
α-Cyclodextrin, a torus shaped molecule with a 5 Å wide central cavity, forms a number of deep green, blue and black crystals when complexed with iodine/metal iodide. In contrast, β-cyclodextrin, having a 6 Å cavity produces only one type of reddish-brown crystal, no matter what metal iodide is used. The complex (β-cyclodextrin)2 ·KI7·9H2O displays space groupP21 (pseudo-C2) with cell constantsa=19.609(5),b=24.513(7),c=15.795(6)Å, β=109.50(2)°,Z=4. The crystal structure was solved inC2 on the basis of 3022 absorption corrected CuKα (Ni-filter) X-ray intensities and refined by full matrix least squares toR=17%. This relatively highR-factor is due to many weak reflections (pseudo-C2) and considerable disorder exhibited by water and iodine. In the complex, β-cyclodextrin adopts a ‘round’ shape with O(2)...O(3) interglucose hydrogen bonds formed and all O(6) hydroxyls pointing away from the cavity. Two molecules are arranged head-to-head to produce a dimer, and dimers are stacked such that a slightly zigzagged cylinder with a 6 Å-wide cavity is formed. In the cavity described by each dimer, an I −7 ion composed of I2·I −3 ·I2 units is located, with I2 and I −3 perpendicular to each other. K+ ions and 9 H2O molecules are found in interstices between the β-cyclodextrin cylinders. This zigzag polyiodide contrasts with the linear form observed in the 5 Å wide α-cyclodextrin channels. It explains differences in color of the crystals and suggests that β-cyclodextrin polyiodide is not a good model for blue starch-iodine.
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References
C. de Claubry:Ann. Chim. (Paris) 90, 87–95 (1814).
W. Banks and C. T. Greenwood, Eds.:Starch and its Components. Edinburgh, University Press (1975).
F. Cramer:Einschlußverbindungen, Springer-Verlag, Heidelberg (1954).
M. Noltemeyer and W. Saenger:J. Amer. Chem. Soc. 102, 2710–2722 (1980).
H. v. Dietrich and F. Cramer:Chem. Ber. 87, 806–817 (1953).
A. D. French and V. G. Murphy:Polymer 18, 489–494 (1977).
R. E. Rundle and D. French:J. Amer. Chem. Soc. 65, 558–561; 1707–1710 (1943).
W. T. Winter and A. Sarko:Biopolymers 13, 1447–1460; 1461–1482 (1974).
F. Cramer, U. Bergmann, P. C. Manor, M. Noltemeyer and W. Saenger:Justus Liebigs Ann. Chem. 1169–1179 (1976).
A. C. T. North, D. C. Phillips, F. S. Mathews:Acta Cryst. A24, 351–359 (1968).
J. A. Hamilton, M. M. Sabesan and L. K. Steinrauf:Carbohydr. Res. 89, 33–53 (1981).
K. Lindner and W. Saenger:Carbohydr. Res. 99, 103–115 (1982).
W. Saenger, Ch. Betzel, B. Hingerty and G. M. Brown,Angew. Chem., in press (1983).
E. H. Wiebenga and E. E. Havinga:Rev. Trav. Chim. Pays-Bas. 78, 724–738 (1959).
W. Saenger:Angew. Chem. Int. Ed. Engl. 19, 344–362 (1980).
E. H. Wiebenga, E. E. Havinga and K. H. Boswijk:Adv. Inorg. Chem. Radiochem. 3, 133–169 (1961).
F. H. Herbstein and M. Kapon:Nature 239, 153–154 (1972).
F. H. Herbstein and M. Kapon:Phil. Trans. Roy. Soc. (London) A291, 199 (1979).
W. Saenger:Naturwiss., in press (1983).
K. Lindner and W. Saenger:Biochem. Biophys. Res. Commun. 92, 933–938 (1980).
Part XIX of the series ‘Topography of Cyclodextrin Inclusion Complexes’. For part XVIII, see K. Lindner and W. Saenger,Carbohydr. Res. 107, 7–16 (1982).
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Dedicated to Prof. Friedrich Cramer on the occasion of his 60th Birthday
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Betzel, C., Hingerty, B., Noltemeyer, M. et al. (β-Cyclodextrin)2·KI7·9 H2O. Spatial fitting of a polyiodide chain to a given matrix. Journal of Inclusion Phenomena 1, 181–191 (1983). https://doi.org/10.1007/BF00656821
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DOI: https://doi.org/10.1007/BF00656821