Ar Solvation Shells in K⁺–HFBz: From Cluster Rearrangement to Solvation Dynamics

Abstract

The effect of some leading intermolecular interaction components on specific features of weakly bound clusters involving an aromatic molecule, a closed shell ion, and Ar atoms is analyzed by performing molecular dynamics simulations on potential energy surfaces properly formulated in a consistent way. In particular, our investigation focuses on the three-dimensional Ar distributions around the K(+)-hexafluorobenzene (K(+)-HFBz) dimer, in K(+)-HFBz-Ar(n) aggregates (n ≤ 15), and on the gradual evolution from cluster rearrangement to solvation dynamics when ensembles of 50, 100, 200, and 500 Ar atoms are taken into account. Results indicate that the Ar atoms compete to be placed in such a way to favor an attractive interaction with both K(+) and HFBz, occupying positions above and below the aromatic plane but close to the cation. When these positions are already occupied, the Ar atoms tend to be placed behind the cation, at larger distances from the center of mass of HFBz. Accordingly, three different groups of Ar atoms are observed when increasing n, with two of them surrounding K(+), thus, disrupting the K(+)-HFBz equilibrium geometry and favoring the dissociation of the solvated cation when the temperature increases. The selective role of the leading intermolecular interaction components directly depending on the ion size repulsion is discussed in detail by analyzing similarities and differences on the behavior of the Ar-solvated K(+)-HFBz and Cl(-)-Bz aggregates.

Microsolvation of the Potassium Ion with Aromatic Rings: Comparison between Hexafluorobenzene and Benzene

“…As it was made previously to investigate large systems, , the HFBz–HFBz interaction has been constructed by further decomposing the CC and CF bond polarizability in effective atomic components (whose values are different, often minor, from those of the corresponding isolated gas phase atoms), in order to account for the many-body effects arising from the formation of chemical bonds. However, their sum must be consistent with the value of the molecular polarizability.…”

Ion Size Influence on the Ar Solvation Shells of M+–C6F6 Clusters (M = Na, K, Rb, Cs)

“…These results are in agreement with the three-dimensional probability density of the Ar atoms shown in Figure . The represented isosurfaces can be interpreted as Ar orbitals (see for instance refs , , and ). As can be seen, for Na + –C 6 F 6 –Ar 5 four Ar atoms interact with both C 6 F 6 and Na + but the fifth atom is placed behind the cation.…”

“…V nel results from the balancing of both dispersion and induction attraction, dominant at long-range, with exchange (size) repulsion, dominant at short-range, and it is described by considering that the polarizability of the interaction partners is the key property to scale attraction and repulsion in systems involving noncovalent interactions . In the present study, the molecular polarizability of C 6 F 6 has been decomposed in two different ways: (1) bond polarizabilities (see, for instance, ref ) and (2) atom effective polarizabilities (see, for instance, ref ). In the first decomposition, each bond is identified with an ellipsoid of electric charge with an assigned value of the polarizability, whereas in the second, only used to represent the Ar–C 6 F 6 interaction energy in the more complex systems, i.e., in those systems containing more than 30 Ar atoms, each bond polarizability is further decomposed in effective polarizabilities associated to the atoms forming the molecule.…”

“…For instance, both K + −C 6 F 6 and Cl − −C 6 H 6 form equilibrium on plane bifurcated structures; however, due to the different strength of the ion−Ar interactions, K + −C 6 F 6 −Ar is more stable than Cl − −C 6 H 6 −Ar. The lower Cl − −Ar interaction energy, in comparison with the K + −Ar one, originates differences on the K + −C 6 F 6 −Ar n and the Cl − −C 6 H 6 −Ar n aggregates, 48 which are also evident when the number of Ar atoms increases. Accordingly, noticeable differences on the Ar solvation shells of K + −C 6 F 6 and Cl − − C 6 H 6 are observed.…”

Carbon Capture and Separation from CO2/N2/H2O Gaseous Mixtures in Bilayer Graphtriyne: A Molecular Dynamics Study

“…The ILJ function so formulated versatile improves the energy profile at equilibrium distance and at short and long range compared to the traditional Lennard-Jones (LJ) function. For a full account of the advantages of the ILJ function see Refs [36][37][38][39][40][41][42] and references therein. All of the ILJ parameters used in this report were improved and tested in comparison with high level ab initio calculations as reported in the Ref [34].…”