Highly Altered State of Proton Transport in Acid Pools in Charged Reverse Micelles

Research output: Contribution to journalResearch articleContributedpeer-review


  • Hongxia Hao - , University of California at Berkeley (Joint first author)
  • Ellen Marie Adams - , Physical Chemistry of Biomolecular Condensates (Junior Research Group) (Joint first author)
  • Sarah Funke - , Ruhr University Bochum (Author)
  • Gerhard Schwaab - , Ruhr University Bochum (Author)
  • Martina Havenith - , Ruhr University Bochum (Author)
  • Teresa Head-Gordon - , University of California at Berkeley, Chemical Science Division, Lawrence Berekely National Laboratory (Author)


Transport mechanisms of solvated protons of 1 M HCl acid pools, confined within reverse micelles (RMs) containing the negatively charged surfactant sodium bis(2-ethylhexyl) sulfosuccinate (NaAOT) or the positively charged cetyltrimethylammonium bromide (CTABr), are analyzed with reactive force field simulations to interpret dynamical signatures from TeraHertz absorption and dielectric relaxation spectroscopy. We find that the forward proton hopping events for NaAOT are further suppressed compared to a nonionic RM, while the Grotthuss mechanism ceases altogether for CTABr. We attribute the sluggish proton dynamics for both charged RMs as due to headgroup and counterion charges that expel hydronium and chloride ions from the interface and into the bulk interior, thereby increasing the pH of the acid pools relative to the nonionic RM. For charged NaAOT and CTABr RMs, the localization of hydronium near a counterion or conjugate base reduces the Eigen and Zundel configurations that enable forward hopping. Thus, localized oscillatory hopping dominates, an effect that is most extreme for CTABr in which the proton residence time increases dramatically such that even oscillatory hopping is slow.


Original languageEnglish
Pages (from-to)1826-1834
Number of pages9
JournalJournal of the American Chemical Society
Issue number3
Publication statusPublished - 12 Jan 2023

External IDs

Scopus 85146330582
WOS 000918806100001
ORCID /0000-0002-8120-8553/work/142251735



  • Hydrated excess protons, Hydroxide ions, Water, Dynamics, Spectroscopy, Solvation, Model, Confinement, Grotthuss, Membranes