Assembly of Acidic Amphiphiles into Inverted Hexagonal Phases Using an l-Alanine-Based Surfactant as a Structure-Directing Agent

Several taper-shaped, Brønsted acidic amphiphiles containing an amide linkage near the headgroup were synthesized with the goal of generating acidic, inverted hexagonal (HII) lyotropic liquid crystal (LLC) phases that can be stabilized by polymerization. These polymerizable acidic amphiphiles were synthesized by reacting the acyl chloride of 3,4,5-tris(11‘-acryloxyundecyloxy)benzoic acid with several amino acids (l-alanine, β-alanine, l-phenylalanine) and 2-aminoethanesulfonic acid. Of these derivatives, only the l-alanine derivative (1) was found to form the HII phase, using N,N-dimethylformamide as the hydrophilic solvent. To our knowledge, this is one of the rare examples (if not the only example) of a Brønsted acidic amphiphile capable of forming a high-curvature LLC phase. Monomer 1 was also found to be able to direct the formation of the other amide-containing acidic derivatives into the HII phase when blended together. IR analysis revealed that intermolecular amide H-bonding near the headgroup plays a major role in the LLC assembly and structure-directing behavior of these systems.