Air/water interface study of cyclopentane-containing archaeal bipolar lipid analogues.

The synthesis of novel archaeal lipid analogues is described. The hydrophobic core of these tetraether bipolar lipids were based on a disubstituted 1,3-cyclopentane unit which was further equipped with mannosyl polar head groups. This hemimacrocylcic tetraether structure that can be compared to rare archaeal lipids permit to establish the behavior of such bipolar lipid at the air/water interface. The two oxygen atoms and the cyclopentane ring were found to be of importance on this behavior. Indeed, the air/water interface comparative study of tetraether- and diether-type lipids led to conclusions on a bent conformation of the tetraether at the air/water interface in the presence of a cyclopentane unit even if the presence of the two oxygen atoms favored an opened bent shape at the beginning of the compression.