Formation of Stable Monolayer Membranes and Related Structures in Dilute Aqueous Solution from Two-Headed Ammonium Amphiphiles

Two-headed, single-chain ammonium amphiphiles in which the hydrophobic chain was made of the flexible decamethylene unit and the rigid diphenylazomethine or biphenyl unit were synthesized. These amphiphiles produced huge (10⁶10⁷daltons) aggregates in dilute aqueous solution. The basic structure of the aggregates was shown by electron microscopy to be the monolayer membrane. A rod-like structure resulted, when the flexible moiety increased. Addition of second components drastically changed the aggregate structure. For instance, rigid lamellae were converted to large single-walled vesicles by incorporation of cholesterol. The present finding is the first example of the formation of stable monolayer membranes.