Wedge-shaped molecules with a sulfonate group at the tip--a new class of self-assembling amphiphiles

The synthesis of 4-N-3',4',5'-tris(dodecyloxy)benzamido]benzene-4-sulfonic acid (1) and 4'-3",4",5"-tris(dodecyloxy)benzoyloxy]azobenzene-4-sulfonic acid (2) is described. Pure acid 1 is stable, while 2 can be stored only in solution. Both acids were obtained from their sodium salts and were quantitatively transformed into the pyridinium salts. The phase behavior of these acids, as well as the sulfonates was investigated by differential scanning calorimetry and polarizing optical microscopy. The investigated compounds exhibit columnar mesophases. The formation of columnar superstructures was demonstrated for the sodium sulfonates by scanning force microscopy, gelation experiments, and proton magnetic resonance spectroscopy.