Local molecular environment drives speciation and reactivity of ion complexes in concentrated salt solution

0545501 - ÚOCHB 2022 RIV NL eng J - Journal Article
Rampal, N. - Wang, H.-W. - Biriukov, Denys - Brady, A. B. - Neuefeind, J. C. - Předota, M. - Stack, A. G.
Local molecular environment drives speciation and reactivity of ion complexes in concentrated salt solution.
Journal of Molecular Liquids. Roč. 340, Oct 15 (2021), č. článku 116898. ISSN 0167-7322. E-ISSN 1873-3166
Institutional support: RVO:61388963
Keywords : concentrated aqueous solutions * ion complexes * neutron diffraction * rare event methods * reaction mechanisms
OECD category: Physical chemistry
Impact factor: 6.633, year: 2021
Method of publishing: Open access
https://doi.org/10.1016/j.molliq.2021.116898

The speciation and reactivity of aqueous salt solutions are important for a wide variety of applications. However, application of this information is inhibited by broad disagreement about composition, mechanisms, and structure in concentrated solutions especially. Here, neutron diffraction with isotopic substitution measurements on aqueous zinc chloride solutions are used to calibrate molecular dynamics simulations that include effective electronic polarization. This allows us to probe the origin of speciation and reactivity of zinc chloride-water ion complexes, ZnClx(H2O)y2-x (x ≤ 4 and y ≤ 6), by comparing the reactivity of species in concentrated (4.5 m) and dilute (0.01 m) conditions. Within the concentrated solution, it is found that the extended solvation environment is dominated by solvent-separated ion complexes whose presence increases the free energy of activation for interconversion of species while simultaneously enhancing their thermodynamic stability. This concentration-dependent reactivity and stability suggests that other reactions, such as the nucleation of solid phases, will also be affected.
Permanent Link: http://hdl.handle.net/11104/0322180