title: Crystal structure of head-to-head dimers of cholic and deoxycholic acid derivatives with different symmetric bridges.
abstract: The crystal structure of three head-to-head dimers (having two cholic acid or deoxycholic acid units) linked at carbon atoms C3 by aromatic or alkyl bridges is studied. An internal coordinates system is necessary for describing the relative orientation in the space of the two bile acid residues. Five angles (three torsion and two common ones) are necessary for defining the relative position of both steroid residues in space. Carbon atoms C3 (which always carries a α-hydroxy group in natural bile acids), and C10 and C13 (which always carry β-methyl groups) of each steroid residue are suitable for this purpose. Furthermore, the distance between each C3 carbon atoms of both steroid residues will allow one to locate the steroids in space. The three dimers selected provide a large range of values for these angles. The packing, hydrogen bond network, and location of guest in the three crystals are discussed.
authors.affiliation: Departamento de Química Física, Facultad de Ciencias, Universidad de Santiago de Compostela, Avda. Alfonso X El Sabio s/n, 27002 Lugo, Spain.
authors.forename: Francisco
authors.initials: F
authors.lastname: Meijide
authors.forename: Juan V
authors.initials: JV
authors.lastname: Trillo
authors.forename: Santiago
authors.initials: S
authors.lastname: de Frutos
authors.forename: Luciano
authors.initials: L
authors.lastname: Galantini
authors.forename: Nicolae Viorel
authors.initials: NV
authors.lastname: Pavel
authors.forename: Victor H
authors.initials: VH
authors.lastname: Soto
authors.forename: Aida
authors.initials: A
authors.lastname: Jover
authors.forename: José Vázquez
authors.initials: JV
authors.lastname: Tato
mesh_terms: D018360:Crystallography, X-Ray; D003840:Deoxycholic Acid / Q000737:chemistry*; D019281:Dimerization; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008968:Molecular Conformation; D013256:Steroids / Q000737:chemistry; D054159:Torsion, Mechanical
chemical_list: D013256:Steroids; D003840:Deoxycholic Acid