Minimum Hydration Shells of Small Polar Organic Hydrogen-Bond Acceptors in Explicit Water Clusters
- 1Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Coyoacán, Mexico City C.P. 04510, Mexico
- 2School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, Scotland, UK
- 3Department of Analytical and Physical Chemistry, University of Oviedo, E-33006 Oviedo, Spain
Abstract
Water plays an active role in organic chemistry, yet the number of explicit water molecules required to describe the local solvation environment of small organic substrates remains poorly established. Herein, we examine the solvation of five small polar hydrogen-bond (HB) acceptors using explicit molecular clusters containing two to twelve water molecules. Conformational searches, electronic structure calculations, and Interacting Quantum Atoms (IQA) energy decomposition were combined to assess energetic convergence and the nature of solute–water interactions. Binding and water deformation energies converge at approximately ten water molecules, defining a practical minimum hydration shell for these substrates. Solute–water interactions are largely confined to the first solvation shell, within ca. 3.5 Å of the heteroatom of the organic substrate, while more distant water molecules recover a bulk-like local environment. Except for trimethylamine, the strongest solute–water contact is weaker than the average HB among water molecules. IQA further shows that differences among interaction energies are governed mainly by the exchange-correlation component, revealing an important covalent contribution to hydrogen bonding. Multiacceptor hydrogen-bonded sites preferentially form water networks around only one HB acceptor rather than bridged independent hydration spheres around each HB acceptor. These results provide practical criteria for constructing compact, chemically meaningful explicit solvation models in aqueous organic chemistry.
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BibTeX
@article{romeromontalvo2026minimum,
title = {{Minimum Hydration Shells of Small Polar Organic Hydrogen-Bond Acceptors in Explicit Water Clusters}},
author = {Eduardo Romero-Montalvo and Jesús Iván Salazar-Barrientos and José Manuel Guevara-Vela and Samuel García-García and Evelio Francisco and Tomás Rocha-Rinza and Ángel Martín Pendás},
journal = {Molecules},
year = {2026},
month = oct,
doi = {10.3390/molecules31203583},
url = {https://www.mdpi.com/1420-3049/31/20/3583},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Minimum Hydration Shells of Small Polar Organic Hydrogen-Bond Acceptors in Explicit Water Clusters
AU - Eduardo Romero-Montalvo
AU - Jesús Iván Salazar-Barrientos
AU - José Manuel Guevara-Vela
AU - Samuel García-García
AU - Evelio Francisco
AU - Tomás Rocha-Rinza
AU - Ángel Martín Pendás
PY - 2026
DA - 2026/10/01
JO - Molecules
DO - 10.3390/molecules31203583
UR - https://www.mdpi.com/1420-3049/31/20/3583
AB - Water plays an active role in organic chemistry, yet the number of explicit water molecules required to describe the local solvation environment of small organic substrates remains poorly established. Herein, we examine the solvation of five small polar hydrogen-bond (HB) acceptors using explicit molecular clusters containing two to twelve water molecules. Conformational searches, electronic structure calculations, and Interacting Quantum Atoms (IQA) energy decomposition were combined to assess energetic convergence and the nature of solute–water interactions. Binding and water deformation energies converge at approximately ten water molecules, defining a practical minimum hydration shell for these substrates. Solute–water interactions are largely confined to the first solvation shell, within ca. 3.5 Å of the heteroatom of the organic substrate, while more distant water molecules recover a bulk-like local environment. Except for trimethylamine, the strongest solute–water contact is weaker than the average HB among water molecules. IQA further shows that differences among interaction energies are governed mainly by the exchange-correlation component, revealing an important covalent contribution to hydrogen bonding. Multiacceptor hydrogen-bonded sites preferentially form water networks around only one HB acceptor rather than bridged independent hydration spheres around each HB acceptor. These results provide practical criteria for constructing compact, chemically meaningful explicit solvation models in aqueous organic chemistry.
SN - 1420-3049
ER -