2.2. COSMO-RS simulations

Simulations of the partition coefficient for the selected small molecules were based on COSMO-RS (COnductor like Screening MOdel for Real Solvents) [14,15]. Here, every component is regarded in a liquid state at an infinite dilution. The chemical potential of the solute molecule is calculated throughout the surface interaction with the surrounding solvent based on quantum chemical equations. 3D structures of (S)-(+)-carvone and terpinen-4-ol were exported from a database (www.chemspider.com, CSID: 15855 and 10756) as initial geometries for further optimization and simulation. Ab initio electron structure calculation and primary geometrical optimization were done with the TURBOMOLE v. 7.1 package, where the density functional theory (DFT) has been selected as the underlying method. Further conformation generation was conducted through COSMOconf v. 4.1 [41], in which the optimized structure from TURBOMOLE was taken as an initial conformation. Throughout a multiple and arbitrary conformation generation and selection of the energetically most favourable ones, a bundle of conformations with a triple ζ valence electron plus polarization with diffusion function (TZVPD-FINE) parametrization is generated. For each molecule, the resulting σ-profiles of a conformation set were implemented into the COSMOtherm v. 17.0 database [42,43]. Water and all organic solvents were taken from the existing COSMO-RS database with the same parametrization. Liquid phase equilibria for the aqueous and organic phases were determined separately and taken for the simulation of the partition coefficient of the solutes in an infinite dilution. Additionally, salt and glycerine concentrations in the liquid were also taken into consideration.