Abstract:
Structural and dynamical properties of the 18-crown-6 molecule at the water–
CCl4 interface and the porphyrazine (PzH2) molecule at the water–air interface were
studied using molecular dynamics simulations. The solvation structures of uncomplex
18-crown-6 in CCl4 solution and that of 18-crown-6/K+ complex in aqueous solution were
also investigated using the Monte Carlo (MC) method. The MC simulation study of 18-
crown-6/K+ in aqueous solution revealed that although a number of water molecules in
the first hydration shell is the same as that of the non-complex case, hydration structures
for the two cases were significantly different. However, solvation structure of the 18-
crown-6 in CCl4 is less dominant than that in an aqueous solution due to weak interaction
between 18-crown-6 and CCl4.
The molecular dynamics (MD) simulations of the 18-crown-6 and 18-crown-6/K+
complex at the water–CCl4 interface indicated that most solute molecules are preferential
to adsorb at the interface region. The presence of K+ ions for the 18-crown-6 complex affects
not only the migration of solute molecules to the bulk phase, but also the orientation
of 18-crown-6 molecules at the interface. The MD simulation study of PzH2 monolayer
at the water–air interface reveled that increment of the number of PzH2 molecules results
to the significantly decreased water density and the layered structures of water. Moreover,
the orientations of water molecules at the interface became more regular while the
number of PzH2 molecules increased.