title: Synthesis, Conformational Studies, X-ray Structures, and Complexation Properties of Semirigid Macrocyclic Phosphonamides.
abstract: The semirigid phosphonamide ligands 1-5 have been synthesized from the macrocyclic precursors 6-9 by reaction with 1,3-propanediol ditosylate or 1,2-dichloroethane. For the thiophosphoryl compounds 1 and 2, and the phosphoryl derivative 5, the reactions were carried out in biphasic aqueous NaOH solutions. The phosphoryl derivatives 3 and 4 were better obtained from NaH in anhydrous tetrahydrofuran. The conformations of the hosts in solution were deduced from low-temperature NMR and NOE difference experiments. Conformational equilibria between exo and endo forms are observed for the 18-membered macrocycles 1 and 3. The exo conformer predominates in solution for the 21-membered macrocycle 2, whereas 4 exists as rapidly exchanging conformers. The X-ray crystal structures of macrocycles 1, 2, and 5 have been determined as well as the complexes 1.Hg(SCN)(2) and 5.LiNO(3). In the Hg(2+) complex the metal ion is located out of the macrocyclic cavity and is coordinated to the thiophosphoryl unit. In 5.LiNO(3)()()the Li(+) cation is located inside the macrocyclic cavity and is coordinated to a tetrahedral array of oxygen donors. Free energies of complexation (DeltaG degrees ) of the phosphorylated ligands 3-5 with alkali metal and ammonium cations were determined in CHCl(3) saturated with H(2)O by picrate extraction experiments. The -DeltaG degrees values are greatest for 4 complexing K(+) and NH(4)(+) (7.3 and 8.0 kcal/mol, respectively). The relationships between structure and binding are discussed.
authors.affiliation: Stéréochimie et Interactions Moléculaires, UMR CNRS 117, Ecole Normale Supérieure de Lyon, 46 allée d'Italie, F-69364 Lyon Cedex 07, France, and Laboratoire de Chimie Physique et de Cristallographie, Université Catholique de Louvain, 1 place Louis Pasteur, B-1348 Louvain La Neuve, Belgium.
authors.forename: Pascale
authors.initials: P
authors.lastname: Delangle
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Dutasta
authors.forename: Luc
authors.initials: L
authors.lastname: Van Oostenryck
authors.forename: Bernard
authors.initials: B
authors.lastname: Tinant
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Declercq