Evaluation of the 1-octanol/water partition coefficient of quinolones and quinolones compounds via free energy estimated in quantum chemical calculations

A rapid screening assay for the measurement of octanolwater partition coefficients (logP) of pharmaceuticals such as quinolines, quinolones and fluoroquinolones compounds were developed by using quantum chemical calculations. In this paper, we report the logP of the pharmaceutical derivatives compounds that determined by the calculation of the difference in the solvation free energies in wateroctanol using the thermodynamic integration method. The logP values calculated in this method are closer to the experimental values compared to other ab initio methods. Solvation free energy in water and octanol, free energy of cavity formation in water and Henry’s constants, and some other parameters are determined at the density functional theory (DFT) and HartreeFock (HF) level with 631++G** basis set. Moreover, surface area, mass, refractivity, volume, polarizability have been calculated for some of the compounds with the same levels.