title: Stereochemical effect revealed in self-assemblies based on archaeal lipid analogues bearing a central five-membered carbocycle: a SAXS study.
abstract: The relative stereochemistry (cis or trans) of a 1,3-disubstituted cyclopentane unit in the middle of tetraether archaeal bipolar lipid analogues was found to have a dramatic influence on their supramolecular self-assembly properties. SAXS studies of two synthetic diastereomeric archaeal lipids bearing two lactosyl polar head groups at opposite ends revealed different lyotropic behaviors. The cis isomer led to L(c)-L(α)-Q(II) transitions whereas the trans isomer retained an L(α) phase from 20 to 100 °C. These main differences originate from the conformational equilibrium (pseudorotation) of 1,3-disubstituted cyclopentanes. Indeed, this pseudorotation exhibits quite similar orientations of the two substituents in a trans isomer whereas several orientations of the two alkyl chains are expected in a cis-1,3-dialkyl cyclopentane, thus authorizing more conformational flexibility in the lipid packing.
authors.affiliation: Ecole Nationale Supérieure de Chimie de Rennes, CNRS, UMR 6226, Avenue du Général Leclerc, CS 50837, 35708 Rennes Cedex 7, France.
authors.forename: Alicia
authors.initials: A
authors.lastname: Jacquemet
authors.forename: Cristelle
authors.initials: C
authors.lastname: Mériadec
authors.forename: Loïc
authors.initials: L
authors.lastname: Lemiègre
authors.forename: Franck
authors.initials: F
authors.lastname: Artzner
authors.forename: Thierry
authors.initials: T
authors.lastname: Benvegnu
mesh_terms: D003517:Cyclopentanes / Q000737:chemistry*; D008055:Lipids / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D053838:Scattering, Small Angle; D013237:Stereoisomerism; D013696:Temperature; D014961:X-Ray Diffraction
chemical_list: D003517:Cyclopentanes; D008055:Lipids