Faculty Work by year
Title
Role of Hydration in Magnesium Versus Calcium Ion Pairing with Carboxylate: Solution and the Aqueous Interface
Document Type
Article
Publication Date
10-2-2021
Publication Title
The Journal of Physical Chemistry B
Volume Number
125
Issue Number
40
DOI
https://doi.org/10.1021/acs.jpcb.1c06108
Abstract
The binding of group II metal cations such as Ca(2+) and Mg(2+) has been largely categorized as electrostatic or ionic using carboxylate symmetric and asymmetric stretching frequency assignments that have been historically used with little regard for the solvation environment of aqueous solutions. However, given the importance of these cations and their binding mechanisms related to biological function and in revealing surface enrichment factors for ocean to marine aerosol transfer, it is imperative that a deeper understanding be sought to include hydration effects. Here, infrared reflection–absorption and Raman spectra for surface and solution phase carboxylate binding information, respectively, are compared against bare (unbound) carboxylate and bidentate Zn(2+) : carboxylate spectral signatures. Spectral non-coincidence effect analysis, temperature studies, and spectral and potential of mean force calculations result in a concise interpretation of binding motifs that include the role of mediating water molecules, that is, contact and solvent-shared ion pairs. Calcium directly binds to the carboxylate group in contact ion pairs where magnesium rarely does. Moreover, we reveal the dominance of the solvent-shared ion pair of magnesium with carboxylate at the air–water interface and in solution.
First Page
11308
Last Page
11319
Recommended Citation
Rudd, Bethany A. Wellen; Vazquez de Vasquez, Maria G.; Baer, Marcel D.; and et al, "Role of Hydration in Magnesium Versus Calcium Ion Pairing with Carboxylate: Solution and the Aqueous Interface" (2021). Faculty Work by year. 55.
https://digitalcommons.owu.edu/faculty_pubs/55
Link Out URL
https://doi.org/10.1021/acs.jpcb.1c06108