Minimum Hydration Shells of Small Polar Organic Hydrogen-Bond Acceptors in Explicit Water Clusters

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 wea

Evelio Francisco Miguélez

Associate Professor

Associate Professor of Physical Chemistry at the University of Oviedo. Expert in the development and application of quantum chemical topology methods, IQA analysis, and electron correlation descriptors.