A novel pH-sensitive chiral amphiphile, N-(4-decyloxy-2-hydroxybenzylidene)-L-leucine, was synthesized. Two kinds of vesicles were found at different pH ranges, 6.5-8.0 and 11.5-12.5, and a helical structure was observed at pH = 11.0. This unique behavior can be attributed to the formation of a dimeric structure. The interaction between this amphiphile and beta-cyclodextrin was investigated by fluorescence emission spectra, H-1 NMR, and molecular modeling.