Acta Crystallographica Section B

Structural Science

Volume 58, Part 2 (April 2002)

research papers

Acta Cryst. (2002). B58, 260-264 [ doi:10.1107/S0108768101018729 ]

Structure and pseudosymmetry of cholesterol at 310 K

L.-Y. Hsu, J. W. Kampf and C. E. Nordman

Abstract: The structure of cholesterol above the (304.8 K) phase transition, previously published in preliminary form [Hsu & Nordman (1983). Science, 220, 604-606], has been fully refined using augmented X-ray data. The crystals are triclinic, space group P1, with (reassigned) cell parameters a = 27.565 (10), b = 38.624 (16), c = 10.748 (4) Å, [alpha] = 93.49 (3), [beta] = 90.90 (3), [gamma] = 117.15 (3)°, and V = 10151 (7) Å³. The unit cell contains Z = 16 molecules, of which eight are related to the other eight by unusual twofold rotational pseudosymmetry. The structure is related to the room-temperature phase, with Z = 8, by a rearrangement of some of the molecules, and by a doubling of the a axis.

Keywords: pseudosymmetry; cholesterol; phase transition.

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