Acta Crystallographica Section B

Structural Science

Volume 52, Part 3 (June 1996)

research papers

Acta Cryst. (1996). B52, 550-554 [ doi:10.1107/S0108768195017071 ]

Crystal and molecular structure of 1,25-dihydroxycholecalciferol

K. Suwinska and A. Kutner

Abstract: The structure of 1,25-dihydroxycholecalciferol, 1,25-dihydroxy-9,10-secocholesta-5,7,10(19)-trien-3-ol, has been solved by direct methods and refined against F² to R₁ = 0.08 for 2637 reflections with F > 4(F) and 0.222 for all 3412 data. Crystal data: C₂₇H₄₄O₃.3H₂O, M_r = 470.67, orthorhombic, P2₁2₁2₁, a = 6.234 (2), b = 15.628 (3), c = 30.749 (10) Å, V = 2995.7 (15) Å³, Z= 4, D_x = 1.044 Mg m^-3, (Cu K [alpha] ) = 1.54178 Å, = 0.572 mm^-1, F(000) = 1040, room temperature. Of the three water molecules present in the crystals of this compound, one is involved in a network of hydrogen bonds formed with the hydroxyl groups of the compound, the remaining two are disorderly arranged in channels formed along the crystallographic x axis with no hydrogen-bonding interactions with the compound molecules. The conformation of the cyclohexane-like ring A was found to be exclusively in the form. Stabilization of the conformer in the solid state may be due to the formation of hydrogen bonds to water molecules, as well as to the symmetry-related 1,25-(OH)₂-vitamin D₃ molecules.