Solvation structure and dynamics of favipiravir in supercritical CO2. A molecular dynamics investigation

Abstract

The solvation structure and related dynamics of favipiravir diluted in supercritical CO2 in a wide density range (0.2–––2.0 ρc) along a near-critical isotherm (1.03 Tc) have been extensively studied by performing classical molecular dynamics simulations. The potential model of favipiravir developed in our previous studies was used in combination with the well-established EPM2 model of CO2 in the simulations. The results obtained have revealed that the local density augmentation of CO2 inside the first solvation shell of favipiravir is maximized at 0.67 ρc and is about 5.6 times larger than the corresponding value for pure supercritical CO2 at the same conditions. The local solvation structure around the favipiravir solute has also been investigated in terms of the atom–atom radial distribution functions. The intermittent residence dynamics of CO2 molecules in the first solvation shell of favipiravir, as well as the single translational and reorientational dynamics of favipiravir have also been investigated, revealing the important role of the local density augmentation of CO2 around the favipiravir solute upon these specific dynamic properties.* Corresponding authors.