Electrochemical control of vesicle formation with a double-tailed cationic surfactant bearing ferrocenyl moieties

We already reported spontaneous vesicle formation in aqueous solutions of bis(11-ferrocenyl(undecyl))dimethylammonium bromide (11-BFDMA), a newly synthesized ferrocene-modified double-chain-type cationic surfactant (Kakizawa, Y.; Sakai, H.; Nishiyama, K.; Abe, hl. Langmuir 1996, 12, 921.). We have examined in this study electrochemical control of vesicle formation of 11-BFDMA using the redox reaction of ferrocenyl groups in their molecules. Static light scattering, conductivity, and cyclic voltammogram measurements on the solution revealed that vesicles made of the reduced form of 11-BFDMA disintegrate and change into smaller molecular aggregates including micelles through oxidation of ferrocenyl groups. Oxidation of ferrocenyl groups also caused a remarkable decrease in the solubilization equilibrium constant for benzene in 11-BFDMA solution and release into the bulk phase of benzene solubilized in bimolecular layers of 11-BFDMA vesicles. In addition, glucose entrapped in the inner aqueous phase of the vesicles was found to be released into the bulk phase after about 50% oxidation of 11-BFDMA.