Chiral cones and vesicles from Gemini-type fatty acid–heteroditopic amine mixtures

Abstract

A twin-chiral and twin-tailed Gemini-type fatty acid with a rigid spacer, 2,3-bis(decyloxy) succinic acid, formed chiral self-assembled structures in aqueous solution with heteroditopic amines, such as 6-aminohexanoic acid and 4-aminobutyric acid. The morphology of such structures was governed by the stoichiometry between the fatty acid and the amine. Mixtures with 1 : 2 molar ratio formed exclusively spherical vesicles, while the 1 : 1 mixtures resulted in entropically driven chiral cones in addition to spherical vesicles. Surface tension measurements, light scattering, and TEM studies proved the existence of vesicles in aqueous solution. Cones were formed through disclinations introduced in the hexatic chiral membrane with specific angles, in accordance with θ = arcsin (1 − (n/6)), [0 < θ < π/2, 1 < n < 5]. Mixtures prepared with 4-aminobutyric acid formed only spherical vesicles and no conical self-assemblies, emphasizing the geometry of the Gemini–heteroditopic amine pair, which directs the morphology of the final self-assembled structures.