Reversibly Redox‐Switchable Anionic Surfactant Contains Two Selenium Atoms

To better control the interfacial activities of selenium‐containing surfactants, a redox‐switchable anionic surfactant containing 2 selenium atoms, namely sodium 3‐((3‐(benzylselanyl)propyl)selanyl)propyl sulfate (SBSe 2 S), has been designed and synthesized. Upon oxidation by H 2 O 2 , the 2 divalent selenide groups in the hydrophobic tail of SBSe 2 S are converted into the corresponding selenoxides. The initial hydrophobic tail of SBSe 2 S gets separated into 3 segments by 2 hydrophilic selenoxide groups, destroying the bola‐type structure. The interfacial activities of SBSe 2 S in aqueous solution could thereby be switched off to a greater degree than in the case of its counterparts containing only a single selenium atom. After reduction with Na 2 SO 3 , the 2 selenoxide groups in SBSe 2 S‐Ox are restored to the initial selenide. Consequently, the interfacial activities of SBSe 2 S could be reversibly switched by alternate addition of H 2 O 2 and Na 2 SO 3 , without obvious deterioration over 5 cycles.