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

Overview

Journal J Am Chem Soc

Publisher American Chemical Society

Specialty Chemistry

Date 2023 Jan 12

PMID 36633459

Authors

Hongxia Hao

Ellen M Adams

Sarah Funke

Gerhard Schwaab

Martina Havenith

Teresa Head-Gordon

Affiliations

Soon will be listed here.

Abstract

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.

Citing Articles

The role of charge in microdroplet redox chemistry.

Heindel J, LaCour R, Head-Gordon T Nat Commun. 2024; 15(1):3670.

PMID: 38693110 PMC: 11519639. DOI: 10.1038/s41467-024-47879-0.

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