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The crystal structures of two ester compounds (a monomer in its methyl ester form,with anamino isophthalic group, and a dimer in which the two steroid units are linked by a urea bridgerecrystallized from ethyl acetate/methanol) derived from cholic acid are described. Average bondlengths and bond angles from the crystal structures of 26 monomers and four dimers (some of themin several solvents) of bile acids and esters (and derivatives) are used for proposing a standardsteroid nucleus. The hydrogen bond network and conformation of the lateral chain are also discussed.This standardstructure was used to compare with the structures of both progesterone and cholesterol The authors thank the Ministerio de Ciencia y Tecnología (Project MAT2013-45657-P) forfinancial support SI

The 18th International Electronic Conference on Synthetic Organic Chemistry session General Organic Synthesis A head-to-head dimer of cholic acid linked at C3 carbon atoms by a urea bridge was synthesized and the crystal structure was studied. The crystal belongs to the monoclinic crystal system, space group I2. The packing shows a bilayer structure with alternating hydrophobic and hydrophilic layers. The horizontal and vertical planes of the two cholic residues are almost parallel to each other, the vertical ones being perpendicular to the bilayers. The hydrogen bond network is two-dimensional as it does not propagate in the direction perpendicular to the bilayers. It is noteworthy that the nitrogen atoms of the urea bridge do not participate in that network. The carbonyl urea group and only one of the ester of the two side chains form hydrogen bonds with two other dimers through the steroid hydroxy O7-H and O12-H groups. This means that each dimer forms eight hydrogen bonds but only four are different

The G-1 dendrimer 4,4',4'',4'''-methanetetrayltetrakis(N-(3,5-dicarboxyphenyl)benzamide) has been obtained from 4,4',4'',4'''-methanetetrayltetrabenzoic acid and isophtalic acid. The compound was recrystallized from methanol and its structure resolved. The crystal belongs to the tetragonal crystal system space group I-4 2d, the cell lengths being a=b=18.9585(16) A, and c=23.703(2) A. The crystal structure evidences the formation of cavities. Only one type of hydrogen bond is observed implying the nitrogen atom (acting as donor) and the oxygen atom of one carboxy group of the aminoisophtalic residue (as acceptor), while the other carboxy group does not participate in the network. The donor-acceptor distance is 3.024(2) A.

The 13th International Electronic Conference on Synthetic Organic Chemistry session Polymer and Supramolecular Chemistry

The 13th International Electronic Conference on Synthetic Organic Chemistry session Polymer and Supramolecular Chemistry The binding constants, standard molar enthalpy, Gibbs free energy, and entropy changes were determined for the formation of complexes between adamantyl derivatives and a β-cyclodextrin dimer. It is concluded that, within experimental error, the two cyclodextrin residues in the dimer behave independent to each other when complexing the adamantyl derivatives The authors from USC thank the Ministerio de Ciencia y Tecnología (Project MAT2004-04606) and Xunta de Galicia (PGIDIT05PXIC26201PN) for financial support

The 13th International Electronic Conference on Synthetic Organic Chemistry session Polymer and Supramolecular Chemistry The binding constants, standard molar enthalpy, Gibbs free energy, and entropy changes were determined for the formation of inclusion complexes between 3α,7α,12α- trihydroxy-5β-cholan-24-amine, C24NH2, and β-cyclodextrin and γ-cyclodextrin. The stoichiometry of both complexes is 1:1 in agreement with previously reported results for other trihydroxy bile salts. The equilibrium constant values for the formation of the inclusion complex are similar as well. The structure of the C24NH2/γ-cyclodextrin complex was studied by ROESY experiments. These results suggest that B, C and Drings of the steroid skeleton, as well as the side chain, interact with the cyclodextrin cavity, while the A ring of the steroid nucleus remains outside the cavity The authors from USC thank the Ministerio de Ciencia y Tecnología (Project MAT2004-04606) and Xunta de Galicia (PGIDIT05PXIC26201PN) for financial support

The 12th International Electronic Conference on Synthetic Organic Chemistry session Supramolecular Chemistry A new gemini steroid surfactant derived from 3a,7a,12a-trihydroxy-5ß-cholan-24-amine (steroid residue) and ethylenediamintetraacetic acid (spacer) was synthesized and characterized in aqueous solution by surface tension measurements and fluorescence intensity of pyrene. These techniques evidence the existence of a threshold concentration, cac, below which a three layers film is formed at the air-water interface. At high concentrations, the intensity ratio of the vibronic peaks of pyrene, I1/I3, (= 0.81) is very close to published values for sodium cholate micelles, indicating that the probe is located in a region with a very low polarity and far from water The authors from USC thank the Ministerio de Ciencia y Tecnología (Project MAT2004-04606) and Xunta de Galicia (PGIDIT05PXIC26201PN) for financial support

The 10th International Electronic Conference on Synthetic Organic Chemistry session Supramolecular Chemistry The self-aggregation in aqueous solution of a new neo-pentyl amide of the 3-β-amino derivative of cholic acid (Na-n-penC) has been investigated in aqueous solution by surface tension and steady state-fluorescence spectroscopy of pyrene (used as a probe). The nature of the agregates was determined by transmission electron microscopy (TEM) revealing that vesicles are formed. The structure of the compound in the solid state was resolved by X-ray spectroscopy. The synthesis of the compound is also given