title: Cesium cholate: determination of X-ray crystal structure indicates participation of the ring hydroxyl groups in metal binding.
abstract: The crystal structure of cesium cholate, C(24)H(36)(OH)(3) COOCs has been determined with three-dimensional X-ray diffractometer data. It crystallized in the monoclinic space group P2(1) with unit-cell dimensions a = 11.543(5) A, b = 8.614(3) A, and c = 12.662(5) A, beta(deg) = 107.95(2), V = 1197.7 A(3) and Z = 2. The atomic parameters were refined to a final r = 0.0269 and R(omega) = 0.0280 for 2342 observed reflections. Each Cs(+) is coordinated to 7 oxygen atoms from 5 different cholate anions with Cs-O distances ranging from 2.957(4) A to 3.678(5) A. In this crystal, 5 cholates are coordinated with 1 Cs(+), and 5 Cs(+) are coordinated with 1 cholate anion. Carboxyl and all the 3 ring hydroxyl groups of cholate anion participate in binding to Cs(+) simultaneously, and there is no water molecule coordinated with the Cs(+). The pattern of successive rows arranged with polar (p) and non-polar (n) faces in apposition leads to the formation of a sandwich sheet structure with polar and non-polar channels. The Cs ions lie within the polar interior of the sandwich. The H-bond network is reorganized in forming cesium cholate from cholic acid. All the oxygen atoms in cholate anion are involved in H-bonding reciprocally or with water molecules to form an extensive 3-dimensional network of H-bonds. Compared with cholic acid and other similar type of steroids, the coordination structure and H-bonding of Cs cholate crystal are distinct.
authors.affiliation: Department of Chemistry, Peking University, Beijing, People's Republic of China.
authors.forename: Y
authors.initials: Y
authors.lastname: Sun
authors.forename: R D
authors.initials: RD
authors.lastname: Soloway
authors.forename: Y-Z
authors.initials: YZ
authors.lastname: Han
authors.forename: G-D
authors.initials: GD
authors.lastname: Yang
authors.forename: X-Z
authors.initials: XZ
authors.lastname: Wang
authors.forename: Z-J
authors.initials: ZJ
authors.lastname: Liu
authors.forename: Z-L
authors.initials: ZL
authors.lastname: Yang
authors.forename: Y-Z
authors.initials: YZ
authors.lastname: Xu
authors.forename: J-G
authors.initials: JG
authors.lastname: Wu
mesh_terms: D001665:Binding Sites; D002586:Cesium / Q000737:chemistry*; D020355:Cholates / Q000737:chemistry*; D003460:Crystallization; D006860:Hydrogen Bonding; D006878:Hydroxides / Q000737:chemistry*; D008823:Micelles; D008968:Molecular Conformation; D015394:Molecular Structure; D009934:Organization and Administration; D014961:X-Ray Diffraction
chemical_list: D020355:Cholates; D006878:Hydroxides; D008823:Micelles; D002586:Cesium; C031356:hydroxide ion