Oxidative Destruction of Vesicles of a Functionalized Surfactant

Both giant and small unilamellar vesicles of functionalized surfactant 1 (potassium O,O ‘-didodecylphosphorodithioate) were subjected to oxidation, which converts 1 into disulfide-linked dimer 4 [bis( O,O ‘-didodecylthiophosphoryl) disulfide], with concomitant destruction of the vesicles. Sodium hypochlorite (bleach), ceric ammonium nitrate, hydrogen peroxide, and sodium hydrogenperoxymonocarbonate were used as oxidizing agents. As determined by 31 P NMR, the oxidations of small unilamellar vesicles of 1 to 4 with sodium hypochlorite and ceric ammonium nitrate were complete within 5 min, and they were slower with the other two oxidizing agents. The oxidations of giant vesicles with the same reagents, which were followed in real time by phase-contrast optical microscopy, displayed the same relative rates. With sodium hypochlorite and ceric ammonium nitrate, the giant vesicles were destroyed within ca. 16 and 50 s, respectively. The results suggest that surfactant 1 's vesicles have potential as storage and release devices.