Host-guest interaction based on Morokuma-Ziegler analysis
The analysis of host-guest interactions based on the Morokuma-Ziegler
decomposition scheme has proven successful procedure for interpretation
of the nature of the interaction between the two structures. In the case
of MOFs, analysis of the interaction has recently been reported,
considering the MOF and the guest as the two molecular fragments that
constitute the whole system.33-35
From this perspective, the energy decomposition analyses (EDA) was
carried out, where each system studied was divided into two fragments:
Zn-MOF and the analyte (i.e . nitrobenzene and toluene). Due to
our interest in the dispersive forces (van der Waals force) acting
between the fragments [Zn-MOF] and [analyte], were incorporating
Grimme’s (D3) dispersion correction this analysis. According to the
results, interaction energies for all systems does not exceed -6
kcal/mol, which indicates the predominant the long-range interactions.
The Zn-MOF-analyte interactions are more intense in the case of analytes
more electron-deficient (i.e. nitrobenzene), for which electrostatic
interaction represents 51% of interaction energy. While the toluene,
containing the electron-donating group, shows that weaker interaction
energy with Zn-MOF, in which the dispersive contribution represents 67
%, see Table 3. These results evidence that in the case of the
Zn-MOF-nitrobenzene is possible a charge transfer between the Zn-MOF and
nitrobenzene.
Table 3. Morokuma–Ziegler’s scheme energy decomposition
analysis (EDA kcal/mol) of denoting the Zn-MOF-analyte interaction.