| Abstract
| - The assembled structure of the heptane bolaamphiphile, bis(N-α-amido-glycylglycine)-1,7-heptane dicarboxylate, displays a sensitivity to the acidity of a solution. At pH 4, the heptane bolaamphiphile grows to acrystalline tubule in two weeks. At pH 8, a helical ribbon structure is formed in one week. The degree ofcarboxylic acid protonation was used to control the final assembled structures since the structures are determinedby the strengths of the amide−amide and carboxylic acid dimer hydrogen bonds. Direct structural transformationbetween tubules and helical ribbons was also confirmed as a function of pH using optical microscopy andRaman microscopy. Conversion from the helical ribbons to the tubules occurs within one day, while thereverse conversion, from the tubules to the helical ribbons, is ten times slower.
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