PD Dr. Stefan Immel - Cyclofructins

TUD Organische Chemie

Immel

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Poster

Abstract 06

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Cyclofructins: Geometries, Electrostatic and Lipophilicity Patterns, and Inclusion Complexes

Stefan Immel, Guido Schmitt, and Frieder W. Lichtenthaler

XVIII^th International Carbohydrate Symposium, Milano, Italy, July 21-26, 1996, Abstract AO027.

Cyclofructins composed of six (α-CF, 1) to ten (5) β(1→2)-linked fructofuranose units (i.e. cyclo[D-Frufβ(1→2)]_n with n = 6 - 10) were subjected to conformational analysis using "Monte-Carlo" simulations based on the PIMM91^[1] force field^[2,3]. Far-reaching similarities and identical over-all conformations of the solid-state geometry^[4] of -cyclofructin (1) and its computer-generated form provide information about the reliability of the computational analysis.

1 cyclo[D-Frufβ(1→2)]₆
2 cyclo[D-Frufβ(1→2)]₇
3 cyclo[D-Frufβ(1→2)]₈
4 cyclo[D-Frufβ(1→2)]₉
5 cyclo[D-Frufβ(1→2)]₁₀

Calculation of the molecular surfaces for the energy-minimum structures establishes a disk-type shape of the cyclofructins with six to eight residues, ring enlargement to nine and ten residues leads to torus-shaped molecules with central cavities that conceivably allow for the formation of inclusion complexes. The color-coded projection of molecular lipophilicity patterns (MLPs)^[5] and electrostatic potential profiles (MEPs) onto these surfaces displays the crown ether-like properties of the disk-shaped cyclofructins. The central cavities of 4 and 5 should be amenable to the formation of inclusion complexes similar to those formed by cyclodextrins.



cyclo[D-Frufβ(1→2)]₆	cyclo[D-Frufβ(1→2)]₇	cyclo[D-Frufβ(1→2)]₈	cyclo[D-Frufβ(1→2)]₉	cyclo[D-Frufβ(1→2)]₁₀

Fig. 1. Geometries with the dotted contact surfaces and cross section plots of the global energy-minimum structures (PIMM91) of the cyclofructins 1 - 5 composed of six to ten (1→2)-linked fructose units.

[1] A. E. Smith, H. J. Lindner,J. Comput.-Aided Mol. Des. 1991, 5, 235-262.

[2] S. Immel, F. W. Lichtenthaler, Liebigs Ann. Chem. 1996, 39-44.

[3] S. Immel, F. W. Lichtenthaler, to be submitted.

[4] M. Sawada, T. Tanaka, Y. Takai, T. Hanafusa, T. Taniguchi, M. Kawamura, T. Uchiyama, Carbohydr. Res. 1991, 217, 7-17.

[5] M. Waldherr-Teschner, T. Goetze, W. Heiden, M. Knoblauch, H. Vollhardt, J. Brickmann, in: Advances in Scientific Visualization (Eds.: F. H. Post, A. J. S. Hin), Springer Verlag, Heidelberg, 1992, pp. 58-67.

Additional Graphics: Cyclofructins

[1]	A. E. Smith, H. J. Lindner,J. Comput.-Aided Mol. Des. 1991, 5, 235-262.
[2]	S. Immel, F. W. Lichtenthaler, Liebigs Ann. Chem. 1996, 39-44.
[3]	S. Immel, F. W. Lichtenthaler, to be submitted.
[4]	M. Sawada, T. Tanaka, Y. Takai, T. Hanafusa, T. Taniguchi, M. Kawamura, T. Uchiyama, Carbohydr. Res. 1991, 217, 7-17.
[5]	M. Waldherr-Teschner, T. Goetze, W. Heiden, M. Knoblauch, H. Vollhardt, J. Brickmann, in: Advances in Scientific Visualization (Eds.: F. H. Post, A. J. S. Hin), Springer Verlag, Heidelberg, 1992, pp. 58-67.