The relative stereochemistry (cis or trans) of a 1,3-disubstituted cyclopentane unit placed in the middle of tetraether archaeal bipolar lipid analogues was found to have a dramatic influence on their supramolecular self-assembling properties. The synthesis of two diastereomers varying only by the stereochemistry of the cyclopentyl unit was achieved following a multistep diastereoselective route. The corresponding lipid films were hydrated and were observed by cryoTEM. The micrographs showed several types of unilamellar nano-objects such as lamellas or irregular vesicles for the cis-isomer, whereas the trans-isomer exhibited exclusively multilamellar vesicles with a regular spherical shape. Even if the cyclopentyl ring takes part of a long alkyl chain (32 carbon atoms), the pseudorotation of the carbocycle would influence the global conformation of the bipolar lipid and consequently would modify the orientation of the lactosyl polar headgroups.
© 2011 American Chemical Society