Synthesis and interfacial behavior of three homologous glycero neoglycolipids with various chain lengths

Three neoglycolipids 1a–c derived from glycerol were synthezised and their molecular arrangements were studied at the air/water interface through Langmuir–Blodgett technique. The common structural features of these neoglycolipids are: a triethyleneglycol spacer at C-2 of glycerol, a GlcNAc hydrophilic head group at the end of the spacer, two saturated aliphatic chains at C-1 and C-3 of glycerol, linked by ether bonds. Compounds 1a–c differ only by the length of their lipid moieties. By increasing the hydrocarbon chain length from C₁₁ to C₁₆, a densely packed state was reached in the monolayer. The compression isotherms displayed an expanded state during the whole compression for compounds 1a and 1c bearing two C₁₁ or one C₁₁ and one C₁₆ chains. Compound 1b bearing two C₁₆ chains displayed a quite different interfacial behavior. The transfer of these monolayers onto a solid substrate can be obtained only with a trigger molecule, a phosphatidic acid.