Solvation free energies of ion dissociations in dichloromethane: En route to accurate computations
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Author (Corporation)
Publication date
13.06.2025
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Type
01A - Journal article
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Parent work
Journal of Physical Chemistry B
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Volume
129
Issue / Number
25
Pages / Duration
6276-6288
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Publisher / Publishing institution
American Chemical Society
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Abstract
Calculating accurate free energies for solution-phase reactions is notoriously difficult. In our previous joint experimental and computational studies, we observed a striking failure of quantum mechanical calculations with popular implicit solvent models to even qualitatively reproduce the experimental trends of dissociation free energies of numerous proton-bound pyridine dimers in organic solvents [Pollice, R. . J. Am. Chem. Soc. 2017, 139(37), 13126–13140]; [Pollice, R. . Angew. Chem., Int. Ed. 2019, 58(40), 14281–14288]. In this article, we expand the computational study of the dissociation of proton-bound pyridine dimers in the gas phase and in dichloromethane (DCM). In an effort to determine the prerequisites for reproducing the experimental trends and magnitudes of the dissociation free energies (ΔGdiss) in solvent, we investigated the impact of accounting for the ensemble free energy, umbrella sampling, thermodynamic integration, and explicit solvation using semiempirical quantum mechanics and molecular mechanics. We estimated the effect of conformational free energy contributions with semiempirical quantum mechanics (SE). Molecular dynamics (MD) with explicit solvation and classical molecular mechanics (MM) was used as a method to treat not only the solute but also the solvent configurational entropy. We found that explicit solvation with MM is indeed capable of reproducing ΔGdiss in DCM for our test system within an acceptable error margin. We analyze and discuss the results and limitations of our approach for calculating the solvation free energy.
Keywords
Chemical calculations, Free energy, Oligomers, Solvation, Solvents
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ISBN
ISSN
1520-6106
1520-5207
1520-5207
Language
English
Created during FHNW affiliation
Yes
Strategic action fields FHNW
Publication status
Published
Review
Peer review of the complete publication
Open access category
Closed
License
Citation
Savoy, A., Paenurk, E., Pollice, R., Hünenberger, P. H., & Chen, P. (2025). Solvation free energies of ion dissociations in dichloromethane: En route to accurate computations. Journal of Physical Chemistry B, 129(25), 6276–6288. https://doi.org/10.1021/acs.jpcb.5c01446