Acta Crystallographica Section B

Structural Science

Volume 58, Part 4 (August 2002)

research papers

Acta Cryst. (2002). B58, 710-720 [ doi:10.1107/S0108768102005608 ]

Crystal structures of ecdysteroids: the role of solvent molecules in hydrogen bonding and isostructurality

L. Fábián, G. Argay, A. Kálmán and M. Báthori

Abstract: Three crystal forms of the steroid 20-hydroxyecdysone were identified by single-crystal X-ray diffraction analysis: a solvent-free modification, a methanol solvate hydrate and a trihydrate. The structure of a closely related steroid, polypodine B (the 5,20-dihydroxy derivative of ecdysone), was determined in its monohydrate form. Since the unit-cell volume of unsolvated 20-hydroxyecdysone was found to be considerably smaller than that of ecdysone [Huber & Hoppe (1965). Chem. Ber. 98, 2403-2424], a new structure determination of ecdysone was performed, which confirmed the unexpected difference between the unit-cell volumes. The crystals of ecdysone and 20-hydroxyecdysone are isostructural, while the mixed solvate of 20-hydroxyecdysone is homostructural with the hydrate of polypodine B. A detailed analysis of the hydrogen-bond networks in these closely related crystal pairs highlights their packing similarities, demonstrates the role of solvent molecules, and explains the unexpectedly small cell volume of 20-hydroxyecdysone.

Keywords: hydrogen-bond networks; molecular structure modifications; single-crystal X-ray diffraction analysis; crystal packing; solvent incorporation; polypodine B; 20-hydroxyecdysone.


	Structure factor file (CIF format) (265.0 kbytes) Contains datablock I

	Structure factor file (CIF format) (222.6 kbytes) Contains datablock II

	Structure factor file (CIF format) (282.7 kbytes) Contains datablock III

	Structure factor file (CIF format) (569.9 kbytes) Contains datablock IV

	Structure factor file (CIF format) (271.9 kbytes) Contains datablock V

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