A theoretical investigation of water-solute interactions: from facial parallel to guest-host structures

作者：Kalai Cairedine; Zins Emilie Laure; Alikhani Mohammad Esmail^*

来源：Theoretical Chemistry Accounts, 2017, 136(4): 48.

DOI：10.1007/s00214-017-2074-2

• Non-covalent interactions
• Exohedral complex
• Endohedral complex
• Molecular electrostatic potential (MESP)
• Quantum Theory of Atoms in Molecules (QTAIM)

Encapsulation of small (bio-) organic molecules within water cages is governed by a subtle equilibrium between water-water and water-solute interactions. The competition between the formation of exohedral and endohedral complexes is investigated. The first step prior to a theoretical characterization of interactions involved in such complexes lies in the judicious choice of a level of theory. The beta-propiolactone (BPL), a solute for which the micro-hydration was recently characterized by means of high resolution microwave spectroscopy (Angew. Chem. 2015, 127, 993), was selected for the present study, and a calibration step is carried out. It is shown that the dispersion-corrected density functional theory (DFT-D) suitably reproduce the geometric, energetic and spectroscopic features of the BPL:(H2O)(1-5) complexes. The experimentally deduced structures of the BPL:(H2O)(4,5) species are fully understood in terms of the maximization of interactions between complementary sites in the MESPs. DFT-D calculations followed by the topological analysis within the Quantum Theory of Atoms in Molecules framework have shown that the solute could efficiently interact with (H2O)(6,10) clusters in a similar manner that the (H2O)(4,5) clusters do. The interaction of the solute with two larger water clusters is further investigated. The exohedral and endohedral BPL:(H2O)(20) isomers are close in energy with each other, whereas the formation of an inclusion complex is energetically more favored than the facial interaction in the case of the BPL:(H2O)(24) cluster. The topological analysis suggests that the substantial energetic stability is due to interactions between the solute and almost all oxygen atoms of the water cage.

• 出版日期2017-3-14