Anion Specific Effects at Negatively Charged Interfaces: Influence of Cl^-, Br^-, I^-, and SCN^- on the Interactions of Na⁺ with the Carboxylic Acid Moiety.

ABSTRACT: Unlike counterion interactions with charged interfaces, the influence of co-ions is only scarcely reported in the literature. In this work, the effect of SCN^- and the halide co-ions in the interactions of Na⁺ with carboxylic acid Langmuir monolayers is investigated by using vibrational sum frequency spectroscopy. At 1 M concentrations in the subphase, the identity of the anion is shown to have a remarkable influence on the charging behavior and degree of deprotonation of the monolayer, with ions ordering in the sequence I^- > SCN^- > Cl^- ≈ Br^-. The same trend is observed at both pH 6 and pH 9 when the monolayer is intrinsically more charged. Spectroscopic evidence is found for both the presence of I^- and SCN^-</

SUBMITTER: Sthoer APA 

PROVIDER: S-EPMC8591606 | biostudies-literature | 2021 Nov

REPOSITORIES: biostudies-literature